Publications by authors named "Jason J Paris"

58 Publications

Allopregnanolone and neuroHIV: Potential benefits of neuroendocrine modulation in the era of antiretroviral therapy.

J Neuroendocrinol 2021 Oct 3:e13047. Epub 2021 Oct 3.

Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS, USA.

Forty years into the HIV pandemic, approximately 50% of infected individuals still suffer from a constellation of neurological disorders collectively known as 'neuroHIV.' Although combination antiretroviral therapy (cART) has been a tremendous success, in its present form, it cannot eradicate HIV. Reservoirs of virus reside within the central nervous system, serving as sources of HIV virotoxins that damage mitochondria and promote neurotoxicity. Although understudied, there is evidence that HIV or the HIV regulatory protein, trans-activator of transcription (Tat), can dysregulate neurosteroid formation potentially contributing to endocrine dysfunction. People living with HIV commonly suffer from endocrine disorders, including hypercortisolemia accompanied by paradoxical adrenal insufficiency upon stress. Age-related comorbidities often onset sooner and with greater magnitude among people living with HIV and are commonly accompanied by hypogonadism. In the post-cART era, these derangements of the hypothalamic-pituitary-adrenal and -gonadal axes are secondary (i.e., relegated to the brain) and indicative of neuroendocrine dysfunction. We review the clinical and preclinical evidence for neuroendocrine dysfunction in HIV, the capacity for hormone therapeutics to play an ameliorative role and the future steroid-based therapeutics that may have efficacy as novel adjunctives to cART.
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http://dx.doi.org/10.1111/jne.13047DOI Listing
October 2021

Red Algal Sulfated Galactan Binds and Protects Neural Cells from HIV-1 gp120 and Tat.

Pharmaceuticals (Basel) 2021 Jul 23;14(8). Epub 2021 Jul 23.

Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS 38677-1848, USA.

The potential neuroprotective capacity of four different sulfated glycans: -derived sulfated galactan (BoSG) (MW > 100 kDa), -derived sulfated fucan (LvSF) (MW~90 kDa), high-molecular weight dextran sulfate (DxS) (MW 100 kDa), and unfractionated heparin (UFH) (MW~15 kDa), was assessed in response to the HIV-1 proteins, R5-tropic glycoprotein 120 (gp120) and/or trans-activator of transcription (Tat), using primary murine neurons co-cultured with mixed glia. Compared to control-treated cells in which HIV-1 proteins alone or combined were neurotoxic, BoSG was, among the four tested sulfated glycans, the only one capable of showing significant concentration-dependent neuroprotection against Tat and/or gp120, alone or combined. Surface plasmon resonance-based data indicate that BoSG can bind both HIV-1 proteins at nM concentrations with preference for Tat (7.5 × 10 M) over gp120 (3.2 × 10 M) as compared to UFH, which bound gp120 (8.7 × 10 M) over Tat (5.7 × 10 M). Overall, these data support the notion that sulfated glycan extracted from the red alga , BoSG, can exert neuroprotection against HIV-1 Tat and gp120, potentially via direct molecular interactions.
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http://dx.doi.org/10.3390/ph14080714DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8398392PMC
July 2021

HIV-1 Tat Protein Promotes Neuroendocrine Dysfunction Concurrent with the Potentiation of Oxycodone's Psychomotor Effects in Female Mice.

Viruses 2021 04 30;13(5). Epub 2021 Apr 30.

Department of BioMolecular Sciences, University of Mississippi School of Pharmacy, Oxford, MS 38677-1848, USA.

Human immunodeficiency virus (HIV) is associated with neuroendocrine dysfunction which may contribute to co-morbid stress-sensitive disorders. The hypothalamic-pituitary-adrenal (HPA) or -gonadal (HPG) axes are perturbed in up to 50% of HIV patients. The mechanisms are not known, but we have found the HIV-1 trans-activator of transcription (Tat) protein to recapitulate the clinical phenotype in male mice. We hypothesized that HPA and/or HPG dysregulation contributes to Tat-mediated interactions with oxycodone, an opioid often prescribed to HIV patients, in females. Female mice that conditionally-expressed the Tat protein [Tat(+) mice] or their counterparts that did not [Tat(-) control mice] were exposed to forced swim stress (or not) and behaviorally-assessed for motor and anxiety-like behavior. Some mice had glucocorticoid receptors (GR) or corticotropin-releasing factor receptors (CRF-R) pharmacologically inhibited. Some mice were ovariectomized (OVX). As seen previously in males, Tat elevated basal corticosterone levels and potentiated oxycodone's psychomotor activity in females. Unlike males, females did not demonstrate adrenal insufficiency and oxycodone potentiation was not regulated by GRs or CRF-Rs. Rather OVX attenuated Tat/oxycodone interactions. Either Tat or oxycodone increased anxiety-like behavior and their combination increased hypothalamic allopregnanolone. OVX increased basal hypothalamic allopregnanolone and obviated Tat or oxycodone-mediated fluctuations. Together, these data provide further evidence for Tat-mediated dysregulation of the HPA axis and reveal the importance of HPG axis regulation in females. HPA/HPG disruption may contribute vulnerability to affective and substance use disorders.
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http://dx.doi.org/10.3390/v13050813DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8147167PMC
April 2021

In vivo proton magnetic resonance spectroscopy detection of metabolite abnormalities in aged Tat-transgenic mouse brain.

Geroscience 2021 08 5;43(4):1851-1862. Epub 2021 Apr 5.

McLean Imaging Center, McLean Hospital/Harvard Medical School, Belmont, MA, 02478, USA.

Most individuals living with HIV in the USA are over 45 years old and are vulnerable to the combined effects of HIV and aging. Antiretroviral therapies reduce HIV morbidity and mortality but do not prevent HIV trans-activator of transcription (Tat) protein expression or development of HIV-associated neurocognitive disorder (HAND), which may be caused by Tat. Tat-transgenic (Tat-tg) mice are used to study Tat's effects, typically after transgene induction with doxycycline. However, uninduced Tat-tg mice experience transgene leak and model aspects of HAND when aged, including neuroinflammation. We used in vivo 9.4-tesla proton magnetic resonance spectroscopy to compare neurochemistry in aged versus young female and male uninduced Tat-tg mice. Aged Tat-tg mice demonstrated measurable tat mRNA brain expression and had lower medial prefrontal cortex (MPFC) GABA, glutamate, and taurine levels and lower striatal GABA and taurine levels. Females had lower MPFC glutathione and taurine and lower striatal taurine levels. Brain testosterone levels were negatively correlated with age in aged males but not females. Aged mice had cortical abnormalities not previously reported in aged wild-type mice including lower MPFC GABA and taurine levels. As glutathione and taurine levels reflect inflammation and oxidative stress, our data suggest that Tat may exacerbate these processes in aged Tat-tg mice. However, additional studies in controls not expressing Tat are needed to confirm this point and to deconvolve individual effects of age and Tat expression. Sex steroid hormone supplements, which counter climacteric effects, increase taurine levels, and reduce inflammation and oxidative stress, could attenuate some of the brain abnormalities we identified in aged Tat-tg mice.
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http://dx.doi.org/10.1007/s11357-021-00354-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8492857PMC
August 2021

HIV-1 Tat and Morphine Differentially Disrupt Pyramidal Cell Structure and Function and Spatial Learning in Hippocampal Area CA1: Continuous versus Interrupted Morphine Exposure.

eNeuro 2021 May-Jun;8(3). Epub 2021 May 24.

Department of Pharmacology and Toxicology, Virginia Commonwealth University, School of Medicine, Richmond, VA 23298-0613

About half the people infected with human immunodeficiency virus (HIV) have neurocognitive deficits that often include memory impairment and hippocampal deficits, which can be exacerbated by opioid abuse. To explore the effects of opioids and HIV on hippocampal CA1 pyramidal neuron structure and function, we induced HIV-1 transactivator of transcription (Tat) expression in transgenic mice for 14 d and co-administered time-release morphine or vehicle subcutaneous implants during the final 5 d (days 9-14) to establish steady-state morphine levels. Morphine was withheld from some slices during recordings to begin to assess the initial pharmacokinetic consequences of opioid withdrawal. Tat expression reduced hippocampal CA1 pyramidal neuronal excitability at lower stimulating currents. Pyramidal cell firing rates were unaffected by continuous morphine exposure. Behaviorally, exposure to Tat or high dosages of morphine impaired spatial memory Exposure to Tat and steady-state levels of morphine appeared to have largely independent effects on pyramidal neuron structure and function, a response that is distinct from other vulnerable brain regions such as the striatum. By contrast, acutely withholding morphine (from morphine-tolerant slices) revealed unique and selective neuroadaptive shifts in CA1 pyramidal neuronal excitability and dendritic plasticity, including some interactions with Tat. Collectively, the results show that opioid-HIV interactions in hippocampal area CA1 are more nuanced than previously assumed, and appear to vary depending on the outcome assessed and on the pharmacokinetics of morphine exposure.
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http://dx.doi.org/10.1523/ENEURO.0547-20.2021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8146490PMC
July 2021

An efficient synthetic route to l-γ-methyleneglutamine and its amide derivatives, and their selective anticancer activity.

RSC Adv 2021 Feb 10;11(13):7115-7128. Epub 2021 Feb 10.

Department of BioMolecular Sciences, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, Mississippi 38677, USA. Email:

In cancer cells, glutaminolysis is the primary source of biosynthetic precursors, fueling the TCA cycle with glutamine-derived α-ketoglutarate. The enhanced production of α-ketoglutarate is critical to cancer cells as it provides carbons for the TCA cycle to produce glutathione, fatty acids, and nucleotides, and contributes nitrogens to produce hexosamines, nucleotides, and many nonessential amino acids. Efforts to inhibit glutamine metabolism in cancer using amino acid analogs have been extensive. l-γ-Methyleneglutamine was shown to be of considerable biochemical importance, playing a major role in nitrogen transport in and plants. Herein we report for the first time an efficient synthetic route to l-γ-methyleneglutamine and its amide derivatives. Many of these l-γ-methyleneglutamic acid amides were shown to be as efficacious as tamoxifen or olaparib at arresting cell growth among MCF-7 (ER/PR/HER2), and SK-BR-3 (ER/PR/HER2) breast cancer cells at 24 or 72 h of treatment. Several of these compounds exerted similar efficacy to olaparib at arresting cell growth among triple-negative MDA-MB-231 breast cancer cells by 72 h of treatment. None of the compounds inhibited cell growth in benign MCF-10A breast cells. Overall, -phenyl amides and -benzyl amides, such as , , , and , arrested the growth of all three (MCF-7, SK-BR-3, and MDA-MB-231) cell lines for 72 h and were devoid of cytotoxicity on MCF-10A control cells; -benzyl amides with an electron withdrawing group at the position, such as and , inhibited the growth of triple-negative MDA-MB-231 cells commensurate to olaparib. These compounds hold promise as novel therapeutics for the treatment of multiple breast cancer subtypes.
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http://dx.doi.org/10.1039/d0ra08249jDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7968037PMC
February 2021

HIV-1 Tat Dysregulates the Hypothalamic-Pituitary-Adrenal Stress Axis and Potentiates Oxycodone-Mediated Psychomotor and Anxiety-Like Behavior of Male Mice.

Int J Mol Sci 2020 Nov 3;21(21). Epub 2020 Nov 3.

Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS 38677-1848, USA.

Human immunodeficiency virus (HIV) is associated with co-morbid affective and stress-sensitive neuropsychiatric disorders that may be related to dysfunction of the hypothalamic-pituitary-adrenal (HPA) stress axis. The HPA axis is perturbed in up to 46% of HIV patients, but the mechanisms are not known. The neurotoxic HIV-1 regulatory protein, trans-activator of transcription (Tat), may contribute. We hypothesized that HPA dysregulation may contribute to Tat-mediated interactions with oxycodone, a clinically-used opioid often prescribed to HIV patients. In transgenic male mice, Tat expression produced significantly higher basal corticosterone levels with adrenal insufficiency in response to a natural stressor or pharmacological blockade of HPA feedback, recapitulating the clinical phenotype. On acute exposure, HIV-1 Tat interacted with oxycodone to potentiate psychomotor and anxiety like-behavior in an open field and light-dark transition tasks, whereas repeated exposure sensitized stress-related psychomotor behavior and the HPA stress response. Pharmacological blockade of glucocorticoid receptors (GR) partially-restored the stress response and decreased oxycodone-mediated psychomotor behavior in Tat-expressing mice, implicating GR in these effects. Blocking corticotrophin-releasing factor (CRF) receptors reduced anxiety-like behavior in mice that were exposed to oxycodone. Together, these effects support the notion that Tat exposure can dysregulate the HPA axis, potentially raising vulnerability to stress-related substance use and affective disorders.
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http://dx.doi.org/10.3390/ijms21218212DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7662349PMC
November 2020

HIV-1 Tat promotes age-related cognitive, anxiety-like, and antinociceptive impairments in female mice that are moderated by aging and endocrine status.

Geroscience 2021 02 17;43(1):309-327. Epub 2020 Sep 17.

Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, 315 Faser Hall, P.O. Box 1848, University, MS, 38677-1848, USA.

Hypogonadism is a common comorbidity associated with HIV-1 that is more prevalent among infected individuals over the age of 45. The underlying mechanisms are unknown, but both combined antiretroviral therapeutics and HIV-1 proteins, such as trans-activator of transcription protein (Tat), dysregulate steroid-synthetic mechanisms including lipid storage/synthesis and mitochondrial function. Thus, Tat expression may accelerate age-related comorbidities partly by impairing endocrine function. Few studies exist of Tat-mediated behavioral deficits in aged animals and effects of endocrine status have not been investigated. Accordingly, we tested whether conditional Tat expression in aged (~ 1.5 years old), female, Tat-transgenic [Tat(+)] mice increases anxiety-like behavior, impairs cognition, and augments mechanical allodynia, when compared to age-matched controls that do not express Tat protein [Tat(-)]. We further tested whether aged mice that maintained their endocrine status (pre-estropausal) were more resilient to Tat/age-related comorbidities than peri- or post-estropausal mice. Tat and endocrine aging status exerted separate and interacting effects that influenced anxiety-like and cognitive behaviors. Peri- and post-estropausal mice exhibited greater anxiety-like behavior in the elevated plus-maze and impaired learning in the radial arm water maze compared to pre-estropausal mice. Irrespective of estropause status, Tat(+) mice demonstrated impaired learning, reduced grip strength, and mechanical allodynia compared to Tat(-) mice. Tat exposure reduced circulating estradiol in post-estropausal mice and increased the estradiol-to-testosterone ratio in pre-estropausal mice. Changes in circulating estradiol, testosterone, and progesterone correlated with grip strength. Thus, endocrine status is an important factor in age-related anxiety, cognition, neuromuscular function, and allodynia that can be accelerated by HIV-1 Tat protein.
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http://dx.doi.org/10.1007/s11357-020-00268-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8050151PMC
February 2021

Conditional expression of HIV-1 tat in the mouse alters the onset and progression of tonic, inflammatory and neuropathic hypersensitivity in a sex-dependent manner.

Eur J Pain 2020 09 16;24(8):1609-1623. Epub 2020 Jul 16.

Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA.

Background: At least one-third of HIV-1-afflicted individuals experience peripheral neuropathy. Although the underlying mechanisms are not known, they may involve neurotoxic HIV-1 proteins.

Methods: We assessed the influence of the neurotoxic HIV-1 regulatory protein, Tat, on inflammatory and neuropathic nociceptive behaviours using transgenic male and female mice that conditionally expressed (or did not express) HIV-1 Tat in fibrillary acidic protein-expressing glia in the central and peripheral nervous systems.

Results: Tat induction significantly attenuated the time spent paw-licking following formalin injection (2.5%, i.pl.) in both male and female mice. However, significant sex differences were observed in the onset and magnitude of inflammation and sensory sensitivity following complete Freund's adjuvant (CFA) injection (10%, i.pl.) after Tat activation. Unlike female mice, male mice showed a significant attenuation of paw swelling and an absence of mechanical/thermal hypersensitivity in response to CFA after Tat induction. Male Tat(+) mice also showed accelerated recovery from chronic constrictive nerve injury (CCI)-induced neuropathic mechanical and thermal hypersensitivity compared to female Tat(+) mice. Morphine (3.2 mg/kg) fully reversed CCI-induced mechanical hypersensitivity in female Tat(-) mice, but not in Tat(+) females.

Conclusions: The ability of Tat to decrease oedema, paw swelling, and limit allodynia suggests a sequel of events in which Tat-induced functional deficits precede the onset of mechanical hypersensitivity. Moreover, HIV-1 Tat attenuated responses to inflammatory and neuropathic insults in a sex-dependent manner. HIV-1 Tat appears to directly contribute to HIV sensory neuropathy and reveals sex differences in HIV responsiveness and/or the underlying peripheral neuroinflammatory and nociceptive mechanisms.
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http://dx.doi.org/10.1002/ejp.1618DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7856573PMC
September 2020

Pregnane steroidogenesis is altered by HIV-1 Tat and morphine: Physiological allopregnanolone is protective against neurotoxic and psychomotor effects.

Neurobiol Stress 2020 May 29;12:100211. Epub 2020 Jan 29.

Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, VA, 23298, USA.

Pregnane steroids, particularly allopregnanolone (AlloP), are neuroprotective in response to central insult. While unexplored , AlloP may confer protection against the neurological dysfunction associated with human immunodeficiency virus type 1 (HIV-1). The HIV-1 regulatory protein, trans-activator of transcription (Tat), is neurotoxic and its expression in mice increases anxiety-like behavior; an effect that can be ameliorated by progesterone, but not when 5α-reduction is blocked. Given that Tat's neurotoxic effects involve mitochondrial dysfunction and can be worsened with opioid exposure, we hypothesized that Tat and/or combined morphine would perturb steroidogenesis in mice, promoting neuronal death, and that exogenous AlloP would rescue these effects. Like other models of neural injury, conditionally inducing HIV-1 Tat in transgenic mice significantly increased the central synthesis of pregnenolone and progesterone's 5α-reduced metabolites, including AlloP, while decreasing central deoxycorticosterone (independent of changes in plasma). Morphine significantly increased brain and plasma concentrations of several steroids (including progesterone, deoxycorticosterone, corticosterone, and their metabolites) likely via activation of the hypothalamic-pituitary-adrenal stress axis. Tat, but not morphine, caused glucocorticoid resistance in primary splenocytes. In neurons, Tat depolarized mitochondrial membrane potential and increased cell death. Physiological concentrations of AlloP (0.1, 1, or 10 nM) reversed these effects. High-concentration AlloP (100 nM) was neurotoxic in combination with morphine. Tat induction in transgenic mice potentiated the psychomotor effects of acute morphine, while exogenous AlloP (1.0 mg/kg, but not 0.5 mg/kg) was ameliorative. Data demonstrate that steroidogenesis is altered by HIV-1 Tat or morphine and that physiological AlloP attenuates resulting neurotoxic and psychomotor effects.
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http://dx.doi.org/10.1016/j.ynstr.2020.100211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7109513PMC
May 2020

Central Actions of 3α,5α-THP Involving NMDA and GABA Receptors Regulate Affective and Sexual Behavior of Female Rats.

Front Behav Neurosci 2020 11;14:11. Epub 2020 Feb 11.

Department of Psychology, The University at Albany-The State University of New York (SUNY), Albany, NY, United States.

The neurosteroid, 5α-pregnan-3α-ol-20-one (known as "allopregnanolone" or 3α,5α-THP), is produced in the midbrain ventral tegmental area (VTA), independent of peripheral sources of progestogens, where it has potential actions at N-methyl-D-aspartate (NMDA) and GABA receptors to facilitate rodent sexual behavior. Progestogens can also have anti-anxiety effects, but whether these involve actions of centrally-derived 3α,5α-THP or these receptors to support reproductively-relevant behavior is not well understood. We investigated the extent to which 3α,5α-THP's actions NMDA and/or GABA receptors in the midbrain VTA influence reproductive behaviors. Estradiol-primed, ovariectomized/adrenalectomized (OVX/ADX) rats received midbrain VTA infusions of vehicle, an NMDA receptor blocker (MK-801; 200 ng), or a GABA receptor blocker (bicuculline; 100 ng) followed by a second infusion of vehicle or 3α,5α-THP (100 ng). Reproductively-relevant behaviors were assessed: sexual (paced mating), anxiety-like (elevated plus maze), and social (partner preference, social interaction) behavior. Compared to vehicle, intra-VTA infusions of MK-801 exerted anxiolytic-like effects on elevated plus maze behavior and enhanced lordosis. Unlike prior observations in gonadally-intact rats, intra-VTA bicuculline had no effect on the behavior of OVX/ADX rats (likely due to a floor effect). Subsequent infusions of 3α,5α-THP reversed effects on lordosis and infusions of bicuculline inhibited 3α,5α-THP-facilitated lordosis. Thus, NMDA and GABA receptors may act as mediators for reproductive behavioral effects of 3α,5α-THP in the midbrain VTA.
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http://dx.doi.org/10.3389/fnbeh.2020.00011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7026732PMC
February 2020

Combined HIV-1 Tat and oxycodone activate the hypothalamic-pituitary-adrenal and -gonadal axes and promote psychomotor, affective, and cognitive dysfunction in female mice.

Horm Behav 2020 03 13;119:104649. Epub 2019 Dec 13.

Department of BioMolecular Sciences, University of Mississippi, School of Pharmacy, University, MS 38677-1848, USA; Research Institute of Pharmaceutical Sciences, University of Mississippi, University, MS 38677, USA. Electronic address:

The majority of HIV patients present with neuroendocrine dysfunction and ~50% experience co-morbid neurological symptoms including motor, affective, and cognitive dysfunction, collectively termed neuroHIV. In preclinical models, the neurotoxic HIV-1 regulatory protein, trans-activator of transcription (Tat), promotes neuroHIV pathology that can be exacerbated by opioids. We and others find gonadal steroids, estradiol (E) or progesterone (P), to rescue Tat-mediated pathology. However, the combined effects of Tat and opioids on neuroendocrine function and the subsequent ameliorative capacity of gonadal steroids are unknown. We found that conditional HIV-1 Tat expression in naturally-cycling transgenic mice dose-dependently potentiated oxycodone-mediated psychomotor behavior. Tat increased depression-like behavior in a tail-suspension test among proestrous mice, but decreased it among diestrous mice (who already demonstrated greater depression-like behavior); oxycodone reversed these effects. Combined Tat and oxycodone produced apparent behavioral disinhibition of anxiety-like responding which was greater on diestrus than on proestrus. These mice made more central entries in an open field, but spent less time there and demonstrated greater circulating corticosterone. Tat increased the E:P ratio of circulating steroids on diestrus and acute oxycodone attenuated this effect, but repeated oxycodone exacerbated it. Corticotropin-releasing factor was increased by Tat expression, acute oxycodone exposure, and was greater on diestrus compared to proestrus. In human neuroblastoma cells, Tat exerted neurotoxicity that was ameliorated by E (1 or 10 nM) or P (100, but not 10 nM) independent of oxycodone. Oxycodone decreased gene expression of estrogen and κ-opioid receptors. Thus, neuroendocrine function may be an important target for HIV-1 Tat/opioid interactions.
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http://dx.doi.org/10.1016/j.yhbeh.2019.104649DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7071558PMC
March 2020

Dynorphins in Development and Disease: Implications for Cardiovascular Disease.

Curr Mol Med 2020 ;20(4):259-274

Department of Biomolecular Sciences, Division of Pharmacology, University of Mississippi, United States.

It is well-established that cardiovascular disease continues to represent a growing health problem and significant effort has been made to elucidate the underlying mechanisms. In this review, we report on past and recent high impact publications in the field of intracrine network signaling, focusing specifically on opioids and their interrelation with key modulators of the cardiovascular system and the onset of related disease. We present an overview of studies outlining the scope of cardiovascular and cerebrovascular processes that are affected by opioids, including heart function, ischemia, reperfusion, and blood flow. Specific emphasis is placed on the importance of dynorphin molecules in cerebrovascular and cardiovascular regulation. Evidence suggests that excessive or insufficient dynorphin could make an important contribution to cardiovascular physiology, yet numerous paradoxical observations frequently impede a clear understanding of the role of dynorphin. Thus, we argue that dynorphin-mediated signaling events for which an immediate regulatory effect is disputed should not be dismissed as unimportant, as they may play a role in cross-talk with other signaling networks. Finally, we consider the most recent evidence on the role of dynorphin during cardiovascular-related inflammation and on the potential value of endogenous and exogenous inhibitors of kappa-opioid receptor, a major dynorphin A receptor, to limit or prevent cardiovascular disease and its related sequelae.
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http://dx.doi.org/10.2174/1566524019666191028122559DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7457512PMC
June 2021

Cell-type specific differences in antiretroviral penetration and the effects of HIV-1 Tat and morphine among primary human brain endothelial cells, astrocytes, pericytes, and microglia.

Neurosci Lett 2019 11 3;712:134475. Epub 2019 Sep 3.

Department of Pharmacotherapy and Outcomes Science, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA. Electronic address:

The inability to achieve adequate intracellular antiretroviral concentrations may contribute to HIV persistence within the brain and to neurocognitive deficits in opioid abusers. To investigate, intracellular antiretroviral concentrations were measured in primary human astrocytes, microglia, pericytes, and brain microvascular endothelial cells (BMECs), and in an immortalized brain endothelial cell line (hCMEC/D3). HIV-1 Tat and morphine effects on intracellular antiretroviral concentrations also were evaluated. After pretreatment for 24 h with vehicle, HIV-1 Tat, morphine, or combined Tat and morphine, cells were incubated for 1 h with equal concentrations of a mixture of tenofovir, emtricitabine, and dolutegravir at one of two concentrations (5 μM or 10 μM). Intracellular drug accumulation was measured using LC-MS/MS. Drug penetration differed depending on the drug, the extracellular concentration used for dosing, and cell type. Significant findings included: 1) Dolutegravir (at 5 μM or 10 μM) accumulated more in HBMECs than other cell types. 2) At 5 μM, intracellular emtricitabine levels were higher in microglia than other cell types; while at 10 μM, emtricitabine accumulation was greatest in HBMECs. 3) Tenofovir (5 or 10 μM extracellular dosing) displayed greater accumulation inside HBMECs than in other cell types. 4) After Tat and/or morphine pretreatment, the relative accumulation of antiretroviral drugs was greater in morphine-exposed HBMECs compared to other treatments. The opposite effect was observed in astrocytes in which morphine exposure decreased drug accumulation. In summary, the intracellular accumulation of antiretroviral drugs differed depending on the particular drug involved, the concentration of the applied antiretroviral drug, and the cell type targeted. Moreover, morphine, and to a lesser extent Tat, exposure also had differential effects on antiretroviral accumulation. These data highlight the complexity of optimizing brain-targeted HIV therapeutics, especially in the setting of chronic opioid use or misuse.
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http://dx.doi.org/10.1016/j.neulet.2019.134475DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6941658PMC
November 2019

HIV-1 Tat and opioids act independently to limit antiretroviral brain concentrations and reduce blood-brain barrier integrity.

J Neurovirol 2019 08 17;25(4):560-577. Epub 2019 May 17.

Department of Pharmacotherapy and Outcomes Science, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA.

Poor antiretroviral penetration may contribute to human immunodeficiency virus (HIV) persistence within the brain and to neurocognitive deficits in opiate abusers. To investigate this problem, HIV-1 Tat protein and morphine effects on blood-brain barrier (BBB) permeability and drug brain penetration were explored using a conditional HIV-1 Tat transgenic mouse model. Tat and morphine effects on the leakage of fluorescently labeled dextrans (10-, 40-, and 70-kDa) into the brain were assessed. To evaluate effects on antiretroviral brain penetration, Tat+ and Tat- mice received three antiretroviral drugs (dolutegravir, abacavir, and lamivudine) with or without concurrent morphine exposure. Antiretroviral and morphine brain and plasma concentrations were determined by LC-MS/MS. Morphine exposure, and, to a lesser extent, Tat, significantly increased tracer leakage from the vasculature into the brain. Despite enhanced BBB breakdown evidenced by increased tracer leakiness, morphine exposure led to significantly lower abacavir concentrations within the striatum and significantly less dolutegravir within the hippocampus and striatum (normalized to plasma). P-glycoprotein, an efflux transporter for which these drugs are substrates, expression and function were significantly increased in the brains of morphine-exposed mice compared to mice not exposed to morphine. These findings were consistent with lower antiretroviral concentrations in brain tissues examined. Lamivudine concentrations were unaffected by Tat or morphine exposure. Collectively, our investigations indicate that Tat and morphine differentially alter BBB integrity. Morphine decreased brain concentrations of specific antiretroviral drugs, perhaps via increased expression of the drug efflux transporter, P-glycoprotein.
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http://dx.doi.org/10.1007/s13365-019-00757-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6750988PMC
August 2019

Effects of HIV-1 Tat on oligodendrocyte viability are mediated by CaMKIIβ-GSK3β interactions.

J Neurochem 2019 04 15;149(1):98-110. Epub 2019 Mar 15.

Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.

Myelin disruptions are frequently reported in human immunodeficiency virus (HIV)-infected individuals and can occur in the CNS very early in the disease process. Immature oligodendrocytes (OLs) are quite sensitive to toxic increases in [Ca ] caused by exposure to HIV-1 Tat (transactivator of transcription, a protein essential for HIV replication and gene expression), but sensitivity to Tat-induced [Ca ] is reduced in mature OLs. Tat exposure also increased the activity of Ca /calmodulin-dependent kinase IIβ (CaMKIIβ), the major isoform of CaMKII expressed by OLs, in both immature and mature OLs. Since CaMKIIβ is reported to interact with glycogen synthase kinase 3β (GSK3β), and GSK3β activity is implicated in OL apoptosis as well as HIV neuropathology, we hypothesized that disparate effects of Tat on OL viability with maturity might be because of an altered balance of CaMKIIβ-GSK3β activities. Tat expression in vivo led to increased CaMKIIβ and GSK3β activity in multiple brain regions in transgenic mice. In vitro, immature murine OLs expressed higher levels of GSK3β, but much lower levels of CaMKIIβ, than did mature OLs. Exogenous Tat up-regulated GSK3β activity in immature, but not mature, OLs. Tat-induced death of immature OLs was rescued by the GSK3β inhibitors valproic acid or SB415286, supporting involvement of GSK3β signaling. Pharmacologically inhibiting CaMKIIβ increased GSK3β activity in Tat-treated OLs, and genetically knocking down CaMKIIβ promoted death in mature OL cultures treated with Tat. Together, these results suggest that the effects of Tat on OL viability are dependent on CaMKIIβ-GSK3β interactions, and that increasing CaMKIIβ activity is a potential approach for limiting OL/myelin injury with HIV infection.
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http://dx.doi.org/10.1111/jnc.14668DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6438763PMC
April 2019

Reduced intraepidermal nerve fibre density, glial activation, and sensory changes in HIV type-1 Tat-expressing female mice: involvement of Tat during early stages of HIV-associated painful sensory neuropathy.

Pain Rep 2018 May 14;3(3):e654. Epub 2018 May 14.

Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA.

Introduction: HIV infection is associated with chronic pain states, including sensory neuropathy, which affects greater than 40% of patients.

Objectives And Methods: To determine the impact of HIV-Tat induction on nociceptive behaviour in female mice conditionally expressing HIV Tat protein through a doxycycline (DOX)-driven glial fibrillary acidic protein promoter, intraepidermal nerve fibre density and immune cell activation in the dorsal root ganglion (DRG) and spinal cord were assessed by immunohistochemistry. Mice were assessed for mechanical and thermal sensitivity for 9 weeks using von-Frey and Hargreaves tests.

Results: Intraepidermal nerve fibre density was significantly reduced after 6 weeks of Tat induction, similar to sensory neuropathy seen in clinical HIV infection. Tat induction through DOX caused a significant reduction in paw withdrawal thresholds in a time-dependent manner starting the 4th week after Tat induction. No changes in paw withdrawal latencies were seen in Tat(-) control mice lacking the transgene. Although reductions in paw withdrawal thresholds increased throughout the study, no significant change in spontaneous motor activity was observed. Spinal cord (cervical and lumbar), DRG, and hind paw skin were collected at 8 days and 6 weeks after Tat induction. HIV-Tat mRNA expression was significantly increased in lumbar DRG and skin samples 8 days after DOX treatment. Tat induced a significant increase in the number of Iba-1 positive cells at 6 weeks, but not after 8 days, of exposure. No differences in glial fibrillary acidic protein immunoreactivity were observed.

Conclusion: These results suggest that Tat protein contributes to painful HIV-related sensory neuropathy during the initial stages of the pathogenesis.
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http://dx.doi.org/10.1097/PR9.0000000000000654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5999412PMC
May 2018

Characterization of cell-cell junction changes associated with the formation of a strong endothelial barrier.

Tissue Barriers 2018 01 1;6(1):e1405774. Epub 2018 Feb 1.

b Department of Biomedical Engineering , Virginia Commonwealth University , Richmond , VA , USA.

A principal function of endothelial cells is the formation of a barrier between the blood and tissues.  This barrier arises from the physical connections at cell-cell junctions, which includes cytoskeletal tight junction and adherens junction proteins. Methods that alter barrier function must therefore affect these cell-cell connections. The blood brain barrier (BBB) represents perhaps the most selective endothelial barrier, which arises from endothelial cell interactions with astrocytes and pericytes. Even in non-central nervous system (CNS) endothelial cells, barrier properties can be enhanced, mimicking the BBB, through induction of intercellular junctions, by either direct co-culture with astrocytes, supplementation with astrocyte conditioned medium (ACM) and/or pharmacologic enhancement of cAMP. To understand how cell-cell junctions change during endothelial barrier enhancement, we examined the effects of ACM and/or cAMP donors added to standard media on human umbilical vein endothelial cells (HUVEC). HUVEC cultured with cAMP-elevating agents had the most enhanced barrier function as measured by Electric Cell-substrate Impedance Sensing (ECIS®), a real-time, label-free, impedance based method of studying cell barrier properties. However, subtle differences in actin and cell-cell junction proteins were seen across all four culture conditions. cAMP-elevating agents also triggered the redistribution of ZO-1 and VE-cadherin to cell-cell junctions, and intensified the actin microfilament network at the cell cortex.  Using a VE-cadherin FRET-force sensor, we observed a decrease in VE-cadherin force in HUVEC cultured with ACM with cAMP donors. Our data indicate cAMP elevation induces both junctional strengthening and reduced VE-cadherin forces. Additionally, treatment with an inhibitor of formin, which reduced actin stress fibers, enhanced barrier function. These data suggest that barrier function is modulated both through the trafficking of proteins to cell-cell junctions, and through the modulation and a relaxation of mechanical force through adherens junctions as intercellular junctional complexes become established.
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http://dx.doi.org/10.1080/21688370.2017.1405774DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5823545PMC
January 2018

CCR5 mediates HIV-1 Tat-induced neuroinflammation and influences morphine tolerance, dependence, and reward.

Brain Behav Immun 2018 03 13;69:124-138. Epub 2017 Nov 13.

Department of Pharmacology and Toxicology, Virginia Commonwealth University, Medical College of Virginia (MCV) Campus, Richmond, P.O. Box 980613, VA 23298-0613, USA; Department of BioMolecular Sciences, University of Mississippi, School of Pharmacy, P.O. Box 1848, University, MS 38677-1848, USA; Research Institute of Pharmaceutical Sciences, University of Mississippi, School of Pharmacy, P.O. Box 1848, University, MS 38677-1848, USA. Electronic address:

The HIV-1 regulatory protein, trans-activator of transcription (Tat), interacts with opioids to potentiate neuroinflammation and neurodegeneration within the CNS. These effects may involve the C-C chemokine receptor type 5 (CCR5); however, the behavioral contribution of CCR5 on Tat/opioid interactions is not known. Using a transgenic murine model that expresses HIV-1 Tat protein in a GFAP-regulated, doxycycline-inducible manner, we assessed morphine tolerance, dependence, and reward. To assess the influence of CCR5 on these effects, mice were pretreated with oral vehicle or the CCR5 antagonist, maraviroc, prior to morphine administration. We found that HIV-1 Tat expression significantly attenuated the antinociceptive potency of acute morphine (2-64 mg/kg, i.p.) in non-tolerant mice. Consistent with this, Tat attenuated withdrawal symptoms among morphine-tolerant mice. Pretreatment with maraviroc blocked the effects of Tat, reinstating morphine potency in non-tolerant mice and restoring withdrawal symptomology in morphine-tolerant mice. Twenty-four hours following morphine administration, HIV-1 Tat significantly potentiated (∼3.5-fold) morphine-conditioned place preference and maraviroc further potentiated these effects (∼5.7-fold). Maraviroc exerted no measurable behavioral effects on its own. Protein array analyses revealed only minor changes to cytokine profiles when morphine was administered acutely or repeatedly; however, 24 h post morphine administration, the expression of several cytokines was greatly increased, including endogenous CCR5 chemokine ligands (CCL3, CCL4, and CCL5), as well as CCL2. Tat further elevated levels of several cytokines and maraviroc pretreatment attenuated these effects. These data demonstrate that CCR5 mediates key aspects of HIV-1 Tat-induced alterations in the antinociceptive potency and rewarding properties of opioids.
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http://dx.doi.org/10.1016/j.bbi.2017.11.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5857418PMC
March 2018

Conditional Human Immunodeficiency Virus Transactivator of Transcription Protein Expression Induces Depression-like Effects and Oxidative Stress.

Biol Psychiatry Cogn Neurosci Neuroimaging 2017 Oct 20;2(7):599-609. Epub 2017 Apr 20.

McLean Imaging Center, Department of Psychiatry, McLean Hospital/Harvard Medical School, Belmont, MA 02478.

Background: The prevalence of major depression in those with HIV/AIDS is substantially higher than in the general population. Mechanisms underlying this comorbidity are poorly understood. HIV-transactivator of transcription (Tat) protein, produced and excreted by HIV, could be involved. We determined whether conditional Tat protein expression in mice is sufficient to induce depression-like behaviors and oxidative stress. Further, as oxidative stress is associated with depression, we determined whether decreasing or increasing oxidative stress by administering methylsulfonylmethane (MSM) or diethylmaleate (DEM), respectively, altered depression-like behavior.

Methods: GT-tg bigenic mice received intraperitoneal saline or doxycycline (Dox, 25-100 mg/kg/day) to induce Tat expression. G-tg mice, which do not express Tat protein, also received Dox. Depression-like behavior was assessed with the tail suspension test (TST) and the two-bottle saccharin/water consumption task. Reactive oxygen/nitrogen species (ROS/RNS) were assessed ex vivo. Medial frontal cortex (MFC) oxidative stress and temperature were measured in vivo with 9.4-Tesla proton magnetic resonance spectroscopy (MRS).

Results: Tat expression increased TST immobility time in an exposure-dependent manner and reduced saccharin consumption. MSM decreased immobility time while DEM increased it in saline-treated GT-tg mice. Tat and MSM behavioral effects persisted for 28 days. Tat and DEM increased while MSM decreased ROS/RNS levels. Tat expression increased MFC glutathione levels and temperature.

Conclusions: Tat expression induced rapid and enduring depression-like behaviors and oxidative stress. Increasing/decreasing oxidative stress increased/decreased, respectively, depression-like behavior. Thus, Tat produced by HIV may contribute to the high depression prevalence among those with HIV. Further, mitigation of oxidative stress could reduce depression severity.
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http://dx.doi.org/10.1016/j.bpsc.2017.04.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5648358PMC
October 2017

Selective Vulnerability of Striatal D2 versus D1 Dopamine Receptor-Expressing Medium Spiny Neurons in HIV-1 Tat Transgenic Male Mice.

J Neurosci 2017 06 4;37(23):5758-5769. Epub 2017 May 4.

Department of Pharmacology and Toxicology,

Despite marked regional differences in HIV susceptibility within the CNS, there has been surprisingly little exploration into the differential vulnerability among neuron types and the circuits they underlie. The dorsal striatum is especially susceptible, harboring high viral loads and displaying marked neuropathology, with motor impairment a frequent manifestation of chronic infection. However, little is known about the response of individual striatal neuron types to HIV or how this disrupts function. Therefore, we investigated the morphological and electrophysiological effects of HIV-1 -activator of transcription (Tat) in dopamine subtype 1 (D1) and dopamine subtype 2 (D2) receptor-expressing striatal medium spiny neurons (MSNs) by breeding transgenic Tat-expressing mice to -tdTomato- or -eGFP-reporter mice. An additional goal was to examine neuronal vulnerability early during the degenerative process to gain insight into key events underlying the neuropathogenesis. In D2 MSNs, exposure to HIV-1 Tat reduced dendritic spine density significantly, increased dendritic damage (characterized by swellings/varicosities), and dysregulated neuronal excitability (decreased firing at 200-300 pA and increased firing rates at 450 pA), whereas insignificant morphologic and electrophysiological consequences were observed in Tat-exposed D1 MSNs. These changes were concomitant with an increased anxiety-like behavioral profile (lower latencies to enter a dark chamber in a light-dark transition task, a greater frequency of light-dark transitions, and reduced rearing time in an open field), whereas locomotor behavior was unaffected by 2 weeks of Tat induction. Our findings suggest that D2 MSNs and a specific subset of neural circuits within the dorsal striatum are preferentially vulnerable to HIV-1. Despite combination antiretroviral therapy (cART), neurocognitive disorders afflict 30-50% of HIV-infected individuals and synaptodendritic injury remains evident in specific brain regions such as the dorsal striatum. A possible explanation for the sustained neuronal injury is that the neurotoxic HIV-1 regulatory protein -activator of transcription (Tat) continues to be expressed in virally suppressed patients on cART. Using inducible Tat-expressing transgenic mice, we found that dopamine subtype 2 (D2) receptor-expressing medium spiny neurons (MSNs) are selectively vulnerable to Tat exposure compared with D1 receptor-expressing MSNs. This includes Tat-induced reductions in D2 MSN dendritic spine density, increased dendritic damage, and disruptions in neuronal excitability, which coincide with elevated anxiety-like behavior. These data suggest that D2 MSNs and specific circuits within the basal ganglia are preferentially vulnerable to HIV-1.
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http://dx.doi.org/10.1523/JNEUROSCI.0622-17.2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5469310PMC
June 2017

HIV-1 Tat disrupts blood-brain barrier integrity and increases phagocytic perivascular macrophages and microglia in the dorsal striatum of transgenic mice.

Neurosci Lett 2017 02 3;640:136-143. Epub 2017 Jan 3.

Department of Pharmacotherapy and Outcomes Science, School of Pharmacy, Virginia Commonwealth University, Richmond, VA 23298, USA. Electronic address:

HIV-1 infection results in blood-brain barrier (BBB) disruption, which acts as a rate-limiting step for HIV-1 entry into the CNS and for subsequent neuroinflammatory/neurotoxic actions. One mechanism by which HIV may destabilize the BBB involves actions of the HIV-1 regulatory protein, trans-activator of transcription (Tat). We utilized a conditional, Tat-expressing transgenic murine model to examine the influence of Tat expression on BBB integrity and to assess the relative numbers of phagocytic perivascular macrophages and microglia within the CNS in vivo. The effects of Tat exposure on sodium-fluorescein (Na-F; 0.376kDa), horseradish peroxidase (HRP; 44kDa), and Texas Red-labeled dextran (70kDa) leakage into the brain were assessed in Tat-exposed (Tat+) and control (Tat-) mice. Exposure to HIV-1 Tat significantly increased both Na-F and HRP, but not the larger sized Texas Red-labeled dextran, confirming BBB breakdown and also suggesting the breach was limited to molecules <70kDa. Additionally, at 5 d after Tat induction, Alexa Fluor 488-labeled dextran was bilaterally infused into the lateral ventricles 5 d before the termination of the experiment. Within the caudate/putamen, Tat induction increased the proportion of dextran-labeled Iba-1+ phagocytic perivascular macrophages (∼5-fold) and microglia (∼3-fold) compared to Tat- mice. These data suggest that HIV-1 Tat exposure is sufficient to destabilize BBB integrity and to increase the presence of activated, phagocytic, perivascular macrophages and microglia in an in vivo model of neuroAIDS.
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http://dx.doi.org/10.1016/j.neulet.2016.12.073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5401762PMC
February 2017

HIV-1 Tat causes cognitive deficits and selective loss of parvalbumin, somatostatin, and neuronal nitric oxide synthase expressing hippocampal CA1 interneuron subpopulations.

J Neurovirol 2016 12 13;22(6):747-762. Epub 2016 May 13.

Department of Pharmacology & Toxicology, Virginia Commonwealth University School of Medicine, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298-0613, USA.

Memory deficits are characteristic of HIV-associated neurocognitive disorders (HAND) and co-occur with hippocampal pathology. The HIV-1 transactivator of transcription (Tat), a regulatory protein, plays a significant role in these events, but the cellular mechanisms involved are poorly understood. Within the hippocampus, diverse populations of interneurons form complex networks; even subtle disruptions can drastically alter synaptic output, resulting in behavioral dysfunction. We hypothesized that HIV-1 Tat would impair cognitive behavior and injure specific hippocampal interneuron subtypes. Male transgenic mice that inducibly expressed HIV-1 Tat (or non-expressing controls) were assessed for cognitive behavior or had hippocampal CA1 subregions evaluated via interneuron subpopulation markers. Tat exposure decreased spatial memory in a Barnes maze and mnemonic performance in a novel object recognition test. Tat reduced the percentage of neurons expressing neuronal nitric oxide synthase (nNOS) without neuropeptide Y immunoreactivity in the stratum pyramidale and the stratum radiatum, parvalbumin in the stratum pyramidale, and somatostatin in the stratum oriens, which are consistent with reductions in interneuron-specific interneuron type 3 (IS3), bistratified, and oriens-lacunosum-moleculare interneurons, respectively. The findings reveal that an interconnected ensemble of CA1 nNOS-expressing interneurons, the IS3 cells, as well as subpopulations of parvalbumin- and somatostatin-expressing interneurons are preferentially vulnerable to HIV-1 Tat. Importantly, the susceptible interneurons form a microcircuit thought to be involved in feedback inhibition of CA1 pyramidal cells and gating of CA1 pyramidal cell inputs. The identification of vulnerable CA1 hippocampal interneurons may provide novel insight into the basic mechanisms underlying key functional and neurobehavioral deficits associated with HAND.
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http://dx.doi.org/10.1007/s13365-016-0447-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5107352PMC
December 2016

Central HIV-1 Tat exposure elevates anxiety and fear conditioned responses of male mice concurrent with altered mu-opioid receptor-mediated G-protein activation and β-arrestin 2 activity in the forebrain.

Neurobiol Dis 2016 08 1;92(Pt B):124-36. Epub 2016 Feb 1.

Department of Anatomy & Neurobiology, Virginia Commonwealth University, Medical College of Virginia (MCV) Campus, Richmond, VA 23298-0709, USA; Department of Pharmacology & Toxicology, Virginia Commonwealth University, Medical College of Virginia (MCV) Campus, Richmond, VA 23298-0613, USA; Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, VA 23298-0059, USA. Electronic address:

Co-exposure to opiates and HIV/HIV proteins results in enhanced CNS morphological and behavioral deficits in HIV(+) individuals and in animal models. Opiates with abuse liability, such as heroin and morphine, bind preferentially to and have pharmacological actions through μ-opioid-receptors (MORs). The mechanisms underlying opiate-HIV interactions are not understood. Exposure to the HIV-1 transactivator of transcription (Tat) protein causes neurodegenerative outcomes that parallel many aspects of the human disease. We have also observed that in vivo exposure to Tat results in apparent changes in morphine efficacy, and thus have hypothesized that HIV proteins might alter MOR activation. To test our hypothesis, MOR-mediated G-protein activation was determined in neuroAIDS-relevant forebrain regions of transgenic mice with inducible CNS expression of HIV-1 Tat. G-protein activation was assessed by MOR agonist-stimulated [(35)S]guanosine-5'-O-(3-thio)triphosphate ([(35)S]GTPγS) autoradiography in brain sections, and in concentration-effect curves of MOR agonist-stimulated [(35)S]GTPγS binding in membranes isolated from specific brain regions. Comparative studies were done using the MOR-selective agonist DAMGO ([D-Ala(2), N-MePhe(4), Gly-ol]-enkephalin) and a more clinically relevant agonist, morphine. Tat exposure reduced MOR-mediated G-protein activation in an agonist, time, and regionally dependent manner. Levels of the GPCR regulatory protein β-arrestin-2, which is involved in MOR desensitization, were found to be elevated in only one affected brain region, the amygdala; amygdalar β-arrestin-2 also showed a significantly increased association with MOR by co-immunoprecipitation, suggesting decreased availability of MOR. Interestingly, this correlated with changes in anxiety and fear-conditioned extinction, behaviors that have substantial amygdalar input. We propose that HIV-1 Tat alters the intrinsic capacity of MOR to signal in response to agonist binding, possibly via a mechanism involving altered expression and/or function of β-arrestin-2.
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http://dx.doi.org/10.1016/j.nbd.2016.01.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4907901PMC
August 2016

5α-reduced progestogens ameliorate mood-related behavioral pathology, neurotoxicity, and microgliosis associated with exposure to HIV-1 Tat.

Brain Behav Immun 2016 07 13;55:202-214. Epub 2016 Jan 13.

Department of Pharmacology and Toxicology, Virginia Commonwealth University, Medical College of Virginia (MCV) Campus, Richmond, VA 23298-0613, USA; Department of Anatomy and Neurobiology, Virginia Commonwealth University, MCV Campus, Richmond, VA 23298-0709, USA; Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, VA, USA. Electronic address:

Human immunodeficiency virus (HIV) is associated with motor and mood disorders, likely influenced by reactive microgliosis and subsequent neural damage. We have recapitulated aspects of this pathology in mice that conditionally express the neurotoxic HIV-1 regulatory protein, trans-activator of transcription (Tat). Progestogens may attenuate Tat-related behavioral impairments and reduce neurotoxicity in vitro, perhaps via progesterone's 5α-reductase-dependent metabolism to the neuroprotective steroid, allopregnanolone. To test this, ovariectomized female mice that conditionally expressed (or did not express) central HIV-1 Tat were administered vehicle or progesterone (4mg/kg), with or without pretreatment of a 5α-reductase inhibitor (finasteride, 50mg/kg). Tat induction significantly increased anxiety-like behavior in an open field, elevated plus maze and a marble burying task concomitant with elevated protein oxidation in striatum. Progesterone administration attenuated anxiety-like effects in the open field and elevated plus maze, but not in conjunction with finasteride pretreatment. Progesterone also attenuated Tat-promoted protein oxidation in striatum, independent of finasteride pretreatment. Concurrent experiments in vitro revealed Tat (50nM)-mediated reductions in neuronal cell survival over 60h, as well as increased neuronal and microglial intracellular calcium, as assessed via fura-2 AM fluorescence. Co-treatment with allopregnanolone (100nM) attenuated neuronal death in time-lapse imaging and blocked the Tat-induced exacerbation of intracellular calcium in neurons and microglia. Lastly, neuronal-glial co-cultures were labeled for Iba-1 to reveal that Tat increased microglial numbers in vitro and co-treatment with allopregnanolone attenuated this effect. Together, these data support the notion that 5α-reduced pregnane steroids exert protection over the neurotoxic effects of HIV-1 Tat.
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http://dx.doi.org/10.1016/j.bbi.2016.01.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4899138PMC
July 2016

Exposure to HIV-1 Tat in brain impairs sensorimotor gating and activates microglia in limbic and extralimbic brain regions of male mice.

Behav Brain Res 2015 Sep 22;291:209-218. Epub 2015 May 22.

Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL 34987, USA; Northeastern University, Department of Psychology, Boston, MA 02115, USA. Electronic address:

Human immunodeficiency virus (HIV) infection is associated with mood disorders and behavioral disinhibition. Impairments in sensorimotor gating and associated neurocognitive disorders are reported, but the HIV-proteins and mechanisms involved are not known. The regulatory HIV-1 protein, Tat, is neurotoxic and its expression in animal models increases anxiety-like behavior concurrent with neuroinflammation and structural changes in limbic and extra-limbic brain regions. We hypothesized that conditional expression of HIV-1 Tat1-86 in the GT-tg bigenic mouse model would impair sensorimotor gating and increase microglial reactivity in limbic and extralimbic brain regions. Conditional Tat induction via doxycycline (Dox) treatment (0-125 mg/kg, i.p., for 1-14 days) significantly potentiated the acoustic startle reflex (ASR) of GT-tg mice and impaired prepulse inhibition (PPI) of this response in a dose-dependent manner when Dox (100mg/kg) was administered for brief (1 day) or prolonged (daily for 7 days) intervals. A greater proportion of active/reactive Iba1-labeled microglia was seen in the anterior cingulate cortex (ACC), dentate gyrus, and nucleus accumbens core when Tat protein was induced under either brief or prolonged expression conditions. Other subregions of the medial prefrontal cortex, amygdala, hippocampal formation, ventral tegmental area, and ventral pallidum also displayed Tat-induced microglial activation, but only the activation observed in the ACC recapitulated the pattern of ASR and PPI behaviors. Tat exposure also increased frontal cortex GFAP. Pretreatment with indomethacin attenuated the behavioral effects of brief (but not prolonged) Tat-exposure. Overall, exposure to HIV-1 Tat protein induced sensorimotor deficits associated with acute and persistent neuroinflammation in limbic/extralimbic brain regions.
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http://dx.doi.org/10.1016/j.bbr.2015.05.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4497922PMC
September 2015

Contribution of HIV-Tat protein to HIV-sequelae.

Curr HIV Res 2015 ;13(1)

Torrey Pines Institute for Molecular Studies 11350 SW Village Parkway Port Saint Lucie FL 34987 USA.

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http://dx.doi.org/10.2174/1570162x1301150317101233DOI Listing
December 2015

Contribution of HIV-Tat protein to HIV-sequelae (part 1).

Curr HIV Res 2014 ;12(6):377

Torrey Pines Institute for Molecular Studies 11350 SW Village Parkway Port Saint Lucie FL 34987 USA.

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http://dx.doi.org/10.2174/1570162x1206150311152342DOI Listing
October 2015

HIV-1 Tat protein exposure potentiates ethanol reward and reinstates extinguished ethanol-conditioned place preference.

Curr HIV Res 2014 ;12(6):415-23

Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port Saint Lucie, FL 34987, USA.

Exposure to HIV-1 trans-activator of transcription (Tat) protein potentiates the psychostimulant effects of cocaine, but the functional consequences of the interaction between HIV-1 Tat and other abused drugs is poorly understood. We hypothesized that exposure to HIV-1 Tat would potentiate the rewarding effects of ethanol. GT-tg transgenic mice, where Tat protein is conditionally expressed in brain by a doxycycline-dependent GFAP-linked promoter, were used to test the effects of Tat on ethanol-conditioned place preference (CPP). Compared to uninduced littermates or doxycycline-treated C57BL/6J mice, Tat-induced GT-tg mice demonstrated a 3-fold increase in ethanol-CPP. The potentiation of ethanol-CPP was dependent on the dose and duration of doxycycline treatment used to express Tat protein. Moreover, induction of Tat protein after the extinction of CPP produced reinstatement without additional exposure to ethanol. Together, these data suggest that CNS exposure to HIV-1 Tat protein potentiates the rewarding effects of ethanol in mice.
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http://dx.doi.org/10.2174/1570162x1206150311160133DOI Listing
October 2015

Opiate addiction therapies and HIV-1 Tat: interactive effects on glial [Ca²⁺]i, oxyradical and neuroinflammatory chemokine production and correlative neurotoxicity.

Curr HIV Res 2014 ;12(6):424-34

Few preclinical studies have compared the relative therapeutic efficacy of medications used to treat opiate addiction in relation to neuroAIDS. Here we compare the ability of methadone and buprenorphine, and the prototypic opiate morphine, to potentiate the neurotoxic and proinflammatory ([Ca²⁺]i, ROS, H₂O₂, chemokines) effects of HIV-1 Tat in neuronal and/or mixed-glial co-cultures. Repeated observations of neurons during 48 h exposure to combinations of Tat, equimolar concentrations (500 nM) of morphine, methadone, or buprenorphine exacerbated neurotoxicity significantly above levels seen with Tat alone. Buprenorphine alone displayed marked neurotoxicity at 500 nM, prompting additional studies of its neurotoxic effects at 5 nM and 50 nM concentrations ± Tat. In combination with Tat, buprenorphine displayed paradoxical, concentration-dependent, neurotoxic and neuroprotective actions. Buprenorphine neurotoxicity coincided with marked elevations in [Ca²⁺]i, but not increases in glial ROS or chemokine release. Tat by itself elevated the production of CCL5/RANTES, CCL4/MIP-1β, and CCL2/MCP-1. Methadone and buprenorphine alone had no effect, but methadone interacted with Tat to further increase production of CCL5/RANTES. In combination with Tat, all drugs significantly increased glial [Ca²⁺]i, but ROS was only significantly increased by co-exposure with morphine. Taken together, the increases in glial [Ca²⁺]i, ROS, and neuroinflammatory chemokines were not especially accurate predictors of neurotoxicity. Despite similarities, opiates displayed differences in their neurotoxic and neuroinflammatory interactions with Tat. Buprenorphine, in particular, was partially neuroprotective at a low concentration, which may result from its unique pharmacological profile at multiple opioid receptors. Overall, the results reveal differences among addiction medications that may impact neuroAIDS.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4475822PMC
http://dx.doi.org/10.2174/1570162x1206150311161147DOI Listing
October 2015
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