Publications by authors named "Guilherme Lucas"

15 Publications

  • Page 1 of 1

Exercise-Induced MicroRNA Regulation in the Mice Nervous System is Maintained after Activity Cessation.

Microrna 2021 Apr 25. Epub 2021 Apr 25.

Neuroscience and Behavior Training Program, Department of Experimental Psychology, Institute of Psychology, University of São Paulo, São Paulo. Brazil.

Background: Physical exercise can improve synaptic function and protect the nervous system against many diseases by altering gene regulation. MicroRNAs (miRs) have emerged as vital regulators of gene expression and protein synthesis not only in the muscular system, but also in the brain.

Objective: Here we investigated whether exercise-induced miRs expression in the nervous and muscular systems is activity-dependent or it remain regulated even after exercise cessation.

Methods: The expression profile of miR-1, -16, and -206 was monitored by RT-PCR in the dorsal root ganglion, in the spinal cord dorsal and ventral horn, and in the soleus muscle of mice after 5 weeks of swimming training and after swimming exercise followed by 4 weeks of sedentary conditions. Control animals consisted of mice that swan daily for 30s during the 5-weeks training period, returning to the non-swimming activity for additional 4 weeks.

Results: After exercise, miR-1 was upregulated in all tissues investigated. However, the upregulation of miR-1 continued significantly high in both aspects of the spinal cord, and in the soleus muscle. The expression profiles of miR-16, and -206 were increased only in the nervous system. However, miR-16 upregulation persisted in the DRG and in the spinal cord after exercise interruption, whereas miR-206 continued upregulated only in the spinal cord ventral horn.

Conclusion: Exercise training can cause long-lasting changes in the expression of miRs independently of exercise maintenance. Spatial and temporal expression of miRs is to some extent dependent on this activity. The data raised a new conceptual hypothesis on the biogenesis of miRs indicating that long-lasting and systematic exercise can potentially cause irreversible miR regulation after activity cessation.
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http://dx.doi.org/10.2174/2211536610666210426101437DOI Listing
April 2021

S100A9 plays a pivotal role in a mouse model of herpetic neuralgia via TLR4/TNF pathway.

Brain Behav Immun 2020 08 31;88:353-362. Epub 2020 Mar 31.

Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil. Electronic address:

Herpetic neuralgia is a painful condition following herpes zoster disease, which results from Varicella-zoster virus reactivation in the dorsal or trigeminal sensory ganglia. Nevertheless, the pathophysiological mechanisms involved in herpetic neuralgia are not well understood. Recently, we identified, that neuroimmune-glia interactions in the sensory ganglion is a critical mechanism for the development of herpetic neuralgia. Here, we investigate the contribution of S100A9, a well-known pro-inflammatory molecule produced by myeloid cells, for the development of herpetic neuralgia using a murine model of HSV-1 infection. We found that cutaneous HSV-1 infection results in an increase of S100A9 expression in the Dorsal Root Ganglia (DRGs). Infiltrating neutrophils into the DRGs were the main source of S100A9 post HSV-1 infection. Functionally, genetic or pharmacological inhibition of S100A9 impairs the development of HSV-1 infection-induced mechanical pain hypersensitivity. Finally, we found that the pronociceptive role of S100A9 in herpetic neuralgia depends on the TLR4/TNF pathway. These results unraveled previously unknown mechanisms involved in the pathophysiology of herpetic neuralgia and indicate that S100A9 might be an important target for novel therapies aiming acute herpetic neuralgia.
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http://dx.doi.org/10.1016/j.bbi.2020.03.033DOI Listing
August 2020

Dynamic expression of glial fibrillary acidic protein and ionized calcium binding adaptor molecule 1 in the mouse spinal cord dorsal horn under pathological pain states.

Neurol Res 2019 Jul 19;41(7):633-643. Epub 2019 Apr 19.

a Department of Physiology, Laboratory of Pain Neurobiology, Ribeirão Preto School of Medicine , University of São Paulo , Ribeirão Preto , Brazil.

Animal models of chronic pain have demonstrated that glial cells are promising target for development of analgesic drugs. However, preclinical studies on glial response under chronic pain conditions vary depending on the cellular markers, the species used, the experimental design and model. Therefore, we investigate the expression profile of GFAP and Iba-1 during the behavioral manifestation of sensory disorder in inflammatory and neuropathic pain models. the expression profile of fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule-1 (Iba-1) were quantitated in the spinal dorsal horn of Balb/C mice submitted to six models of chronic pain. Protein analysis was performed by western blot and the results colligated with pain-related behavior. Using the same method to quantitate proteins we observed that while GFAP is upregulated after axotomy, partial nerve injury and cutaneous inflammation, its expression is not changed during muscle inflammation, non-inflammatory muscle pain, and in a viral-associated pain. Differently, Iba-1 is downregulated after axotomy but upregulated after partial lesion of peripheral nerve as well as after virus inoculation and during non-inflammatory muscle pain. Cutaneous and muscle inflammation induced no change in Iba-1 expression in the dorsal horn.In spite of a marked time-dependent variation in protein expression, mechanical allodynia was present at any time of all the models investigated. Under distinct pain conditions, GFAP and Iba-1 expression is dependent on the origin of the stimulus, disease progression and tissue affected. Moreover, their expression and is not necessarily associated to the behavior manifestation of pain.
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http://dx.doi.org/10.1080/01616412.2019.1603804DOI Listing
July 2019

Effect of swimming training on nerve morphological recovery after compressive injury.

Neurol Res 2018 Nov 9;40(11):955-962. Epub 2018 Aug 9.

e Department of Biology, Center of Biological and Health Sciences , Paraíba State University , Campina Grande , Brazil.

Objective: This study aims to investigate morphological alterations caused by partial sciatic nerve ligation (PNL) and the efficacy of a moderate-intensity swimming training as therapeutic strategy for nerve regeneration.

Methods: A number of 30 male adult mice were equally divided in control, 14 days after PNL (PNL 14 days), 42 days after PNL (PNL 42 days), 70 days after PNL (PNL 70 days) and 5-week exercise training after 7 days post-lesion (PNL trained 35 days) groups. PNL trained 35 days group began with a 10-min session for 3 days and this time was gradually increased by 10 min every three sessions until the animals had swum for 50 min per session. Morphoquantitative analysis was carried out to assess nerve regeneration in each group.

Results: PNL 14 days group exhibited less degenerating signs than PNL 42 days group, where most post-lesion alterations were visualized. Nerve area and minimum diameter were significantly lower (p < 0.05) than control group. PNL 70 days group showed a greater degree of regenerating fibers and similar morphometric parameters to control group. PNL trained 35 days demonstrated signs of regeneration, reaching control group values in the morphometric analysis.

Discussion: PNL promotes great histopathological changes, which became more visible at 42 post-injury days. A natural nerve-regeneration tendency was observed throughout time, as observed in PNL 70 days group; nevertheless, moderate swimming training was found to be a therapeutic resource for nerve regeneration, accelerating such process from a morphoquantitative perspective.

Abbreviations: ANOVA: One-way analysis of variance; BDNF: Brain-derived neurotrophic factor; FGF-2: Fibroblast growth factor 2; GDNF: Glial cell line derived neurotrophic factor; IGF: Insulin-link growth factor; IL-1β: Interleukin-1β; NGF: Neural growth factor; PBS: Phosphate-buffered saline; PNL: Partial sciatic nerve ligation.
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http://dx.doi.org/10.1080/01616412.2018.1504180DOI Listing
November 2018

Neuroimmune-Glia Interactions in the Sensory Ganglia Account for the Development of Acute Herpetic Neuralgia.

J Neurosci 2017 07 2;37(27):6408-6422. Epub 2017 Jun 2.

Department of Pharmacology,

Herpetic neuralgia is the most important symptom of herpes zoster disease, which is caused by Nevertheless, the pathophysiological mechanisms involved in herpetic neuralgia are not totally elucidated. Here, we examined the neuroimmune interactions at the sensory ganglia that account for the genesis of herpetic neuralgia using a murine model of Herpes Simplex Virus Type-1 (HSV-1) infection. The cutaneous HSV-1 infection of mice results in the development of a zosteriform-like skin lesion followed by a time-dependent increase in pain-like responses (mechanical allodynia). Leukocytes composed mainly of macrophages and neutrophils infiltrate infected DRGs and account for the development of herpetic neuralgia. Infiltrating leukocytes are responsible for driving the production of TNF, which in turn mediates the development of herpetic neuralgia through downregulation of the inwardly rectifying K channel Kir4.1 in satellite glial cells. These results revealed that neuroimmune-glia interactions at the sensory ganglia play a critical role in the genesis of herpetic neuralgia. In conclusion, the present study elucidates novel mechanisms involved in the genesis of acute herpetic pain and open new avenues for its control. Acute herpetic neuralgia is the most important symptom of herpes zoster disease and it is very difficult to treat. Using a model of peripheral infection of mice with HSV-1, we have characterized for the first time the neuroimmune-glia interactions in the sensory ganglia that account for the development of acute herpetic neuralgia. Among these mechanisms, leukocytes composed mainly of macrophages and neutrophils infiltrate infected sensory ganglia and are responsible for driving the production of TNF. TNF, via TNFR1, mediates herpetic neuralgia development through downregulation of the inwardly rectifying K channel Kir4.1 in satellite glial cells. This study elucidates novel mechanisms involved in the genesis of acute herpetic neuralgia and open new avenues for its control.
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http://dx.doi.org/10.1523/JNEUROSCI.2233-16.2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6596605PMC
July 2017

BDNF-TRKB signaling system of the dorsal periaqueductal gray matter is implicated in the panicolytic-like effect of antidepressant drugs.

Eur Neuropsychopharmacol 2015 Jun 17;25(6):913-22. Epub 2015 Mar 17.

Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Brazil. Electronic address:

A wealth of evidence implicates the BDNF-TRKB system in the therapeutic effects of antidepressant drugs (ADs) on mood disorders. However, little is known about the involvement of this system in the panicolytic property also exerted by these compounds. In the present study we evaluated the participation of the BDNF-TRKB system of the dorsal periaqueductal gray matter (DPAG), a core structure involved in the pathophysiology of panic disorder, in AD-induced panicolytic-like effects in rats. The results showed that short- (3 days) or long-term (21 days) systemic treatment with the tricyclic ADs imipramine, clomipramine or desipramine increased BDNF levels in the DPAG. Only longterm treatment with the selective serotonin reuptake inhibitor fluoxetine was able to increase BDNF levels in this structure. After 21-day treatment, fluoxetine and the three tricyclic ADs used also increased BDNF concentration in the hippocampus, a key area implicated in their mood-related actions. Neither in the DPAG nor hippocampus did long-term treatment with the standard anxiolytics diazepam, clonazepam or buspirone affect BDNF levels. Imipramine, both after short and long-term administration, and fluoxetine under the latter regimen, raised the levels of phosphorylated TRKB in the DPAG. Short-term treatment with imipramine or BDNF microinjection inhibited escape expression in rats exposed to the elevated T maze, considered as a panicolytic-like effect. This anti-escape effect was attenuated by the intra-DPAG administration of the TRK receptor antagonist k252a. Altogether, our data suggests that facilitation of the BDNF-TRKB system in the DPAG is implicated in the panicolytic effect of ADs.
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http://dx.doi.org/10.1016/j.euroneuro.2015.03.004DOI Listing
June 2015

Exercise therapy normalizes BDNF upregulation and glial hyperactivity in a mouse model of neuropathic pain.

Pain 2015 Mar;156(3):504-513

Laboratory of Pain Neurobiology, Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Brazil Department of Biochemistry and Immunology, Ribeirão Preto School of Medicine, University of São Paulo, Brazil Federal Institute of Education, Science and Technology of Goiás, Brazil School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, Brazil.

Treatment of neuropathic pain is a clinical challenge likely because of the time-dependent changes in many neurotransmitter systems, growth factors, ionic channels, membrane receptors, transcription factors, and recruitment of different cell types. Conversely, an increasing number of reports have shown the ability of extended and regular physical exercise in alleviating neuropathic pain throughout a wide range of mechanisms. In this study, we investigate the effect of swim exercise on molecules associated with initiation and maintenance of nerve injury-induced neuropathic pain. BALB/c mice were submitted to partial ligation of the sciatic nerve followed by a 5-week aerobic exercise program. Physical training reversed mechanical hypersensitivity, which lasted for an additional 4 weeks after exercise interruption. Swim exercise normalized nerve injury-induced nerve growth factor, and brain-derived neurotrophic factor (BDNF) enhanced expression in the dorsal root ganglion, but had no effect on the glial-derived neurotrophic factor. However, only BDNF remained at low levels after exercise interruption. In addition, exercise training significantly reduced the phosphorylation status of PLCγ-1, but not CREB, in the spinal cord dorsal horn in response to nerve injury. Finally, prolonged swim exercise reversed astrocyte and microglia hyperactivity in the dorsal horn after nerve lesion, which remained normalized after training cessation. Together, these results demonstrate that exercise therapy induces long-lasting analgesia through various mechanisms associated with the onset and advanced stages of neuropathy. Moreover, the data support further studies to clarify whether appropriate exercise intensity, volume, and duration can also cause long-lasting pain relief in patients with neuropathic pain.
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http://dx.doi.org/10.1097/01.j.pain.0000460339.23976.12DOI Listing
March 2015

Long-term antidepressant treatment inhibits neuropathic pain-induced CREB and PLCγ-1 phosphorylation in the mouse spinal cord dorsal horn.

J Pain 2013 Oct 29;14(10):1162-72. Epub 2013 Jun 29.

Pain Neurobiology Laboratory, Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, São Paulo, Brazil.

Unlabelled: The effect of long-term administration of imipramine, a tricyclic antidepressant, on the phosphorylation status of cyclic adenosine monophosphate-responsive element-binding protein (CREB), mitogen-activated protein kinase family members, and phospholipase γ-1 (PLCγ-1) was investigated in the dorsal horn of the spinal cord following peripheral nerve lesion. Nerve injury induced an ipsilateral long-lasting increased phosphorylation of CREB and PLCγ-1 but not extracellular signal-regulated kinase (ERK1,2), p38, and c-Jun N-terminal kinase. Daily administration of imipramine (5, 10, or 30 mg/kg) for 21 days progressively reduced both tactile-induced neuropathic pain hypersensitivity and thermal hyperalgesia. After withdrawal of treatment, the antinociceptive effect of imipramine was gradually abolished but still remained for at least 3 weeks. Conversely, no analgesic effect was observed with short-term imipramine treatment. Moreover, imipramine therapy reversed nerve injury-induced CREB and PLCγ-1 phosphorylation but had no effect on ERK1,2, p38, and c-Jun N-terminal kinase activity. These results indicate that long-term administration of imipramine may prevent some of the harmful changes in the spinal cord dorsal horn following nerve injury. However, imipramine analgesic effect takes time to develop and mature, which might explain in part why the clinical analgesic effect of tricyclic antidepressants develops with a delay after the beginning of treatment. Our data also provide evidence that prolonged imipramine treatment may induce antinociception in neuropathic pain conditions because of its action on the PLCγ-1/CREB-signaling pathway.

Perspective: This article demonstrates that long-term treatment with imipramine reverses some of the marked effects induced by peripheral nerve injury in the spinal dorsal horn that contribute to long-term maintenance of sensory disorder, providing a new view to the mechanisms of action of these drugs.
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http://dx.doi.org/10.1016/j.jpain.2013.04.015DOI Listing
October 2013

Differential expression of microRNAs in mouse pain models.

Mol Pain 2011 Mar 7;7:17. Epub 2011 Mar 7.

Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, Brazil.

Background: MicroRNAs (miRNAs) are short non-coding RNAs that inhibit translation of target genes by binding to their mRNAs. The expression of numerous brain-specific miRNAs with a high degree of temporal and spatial specificity suggests that miRNAs play an important role in gene regulation in health and disease. Here we investigate the time course gene expression profile of miR-1, -16, and -206 in mouse dorsal root ganglion (DRG), and spinal cord dorsal horn under inflammatory and neuropathic pain conditions as well as following acute noxious stimulation.

Results: Quantitative real-time polymerase chain reaction analyses showed that the mature form of miR-1, -16 and -206, is expressed in DRG and the dorsal horn of the spinal cord. Moreover, CFA-induced inflammation significantly reduced miRs-1 and -16 expression in DRG whereas miR-206 was downregulated in a time dependent manner. Conversely, in the spinal dorsal horn all three miRNAs monitored were upregulated. After sciatic nerve partial ligation, miR-1 and -206 were downregulated in DRG with no change in the spinal dorsal horn. On the other hand, axotomy increases the relative expression of miR-1, -16, and 206 in a time-dependent fashion while in the dorsal horn there was a significant downregulation of miR-1. Acute noxious stimulation with capsaicin also increased the expression of miR-1 and -16 in DRG cells but, on the other hand, in the spinal dorsal horn only a high dose of capsaicin was able to downregulate miR-206 expression.

Conclusions: Our results indicate that miRNAs may participate in the regulatory mechanisms of genes associated with the pathophysiology of chronic pain as well as the nociceptive processing following acute noxious stimulation. We found substantial evidence that miRNAs are differentially regulated in DRG and the dorsal horn of the spinal cord under different pain states. Therefore, miRNA expression in the nociceptive system shows not only temporal and spatial specificity but is also stimulus-dependent.
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http://dx.doi.org/10.1186/1744-8069-7-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3060138PMC
March 2011

Differential regulation of TRP channels in a rat model of neuropathic pain.

Pain 2009 Jul 15;144(1-2):187-99. Epub 2009 May 15.

Department of Bioscience, AstraZeneca R&D Mölndal, 431 83 Mölndal, Sweden.

Neuropathic pain is a chronic disease resulting from dysfunction of the nervous system often due to peripheral nerve injury. Hypersensitivity to sensory stimuli (mechanical, thermal or chemical) is a common source of pain in patients and ion channels involved in detecting these stimuli are possible candidates for inducing and/or maintaining the pain. Transient receptor potential (TRP) channels expressed on nociceptors respond to different sensory stimuli and a few of them have been studied previously in the models of neuropathic pain. Using real-time PCR for quantification of all known TRP channels we identified several TRP channels, which have not been associated with nociception or neuropathic pain before, to be expressed in the DRG and to be differentially regulated after spared nerve injury (SNI). Of all TRP channel members, TRPML3 showed the most dramatic change in animals exhibiting neuropathic pain behaviour compared to control animals. In situ hybridisation showed a widespread increase of expression in neurons of small, medium and large cell sizes, indicating expression in multiple subtypes. Co-localisation of TRPML3 with CGRP, NF200 and IB4 staining confirmed a broad subtype distribution. Expression studies during development showed that TRPML3 is an embryonic channel that is induced upon nerve injury in three different nerve injury models investigated. Thus, the current results link for the first time a re-expression of TRPML3 with the development of neuropathic pain conditions. In addition, decreased mRNA levels after SNI were seen for TRPM6, TRPM8, TRPV1, TRPA1, TRPC3, TRPC4 and TRPC5.
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http://dx.doi.org/10.1016/j.pain.2009.04.013DOI Listing
July 2009

Lack of the central nervous system- and neural crest-expressed forkhead gene Foxs1 affects motor function and body weight.

Mol Cell Biol 2005 Jul;25(13):5616-25

Medical Genetics, Department of Medical Biochemistry, Göteborg University, Medicinareg. 9A, Box 440, SE 405 30 Göteborg, Sweden.

To gain insight into the expression pattern and functional importance of the forkhead transcription factor Foxs1, we constructed a Foxs1-beta-galactosidase reporter gene "knock-in" (Foxs1beta-gal/beta-gal) mouse, in which the wild-type (wt) Foxs1 allele has been inactivated and replaced by a beta-galactosidase reporter gene. Staining for beta-galactosidase activity reveals an expression pattern encompassing neural crest-derived cells, e.g., cranial and dorsal root ganglia as well as several other cell populations in the central nervous system (CNS), most prominently the internal granule layer of cerebellum. Other sites of expression include the lachrymal gland, outer nuclear layer of retina, enteric ganglion neurons, and a subset of thalamic and hypothalamic nuclei. In the CNS, blood vessel-associated smooth muscle cells and pericytes stain positive for Foxs1. Foxs1beta-gal/beta-gal mice perform significantly better (P < 0.01) on a rotating rod than do wt littermates. We have also noted a lower body weight gain (P < 0.05) in Foxs1beta-gal/lbeta-gal males on a high-fat diet, and we speculate that dorsomedial hypothalamic neurons, expressing Foxs1, could play a role in regulating body weight via regulation of sympathetic outflow. In support of this, we observed increased levels of uncoupling protein 1 mRNA in Foxs1beta-gal/beta-gal mice. This points toward a role for Foxs1 in the integration and processing of neuronal signals of importance for energy turnover and motor function.
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http://dx.doi.org/10.1128/MCB.25.13.5616-5625.2005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1157007PMC
July 2005

Brain-derived neurotrophic factor and antidepressant drugs have different but coordinated effects on neuronal turnover, proliferation, and survival in the adult dentate gyrus.

J Neurosci 2005 Feb;25(5):1089-94

Neuroscience Center, University of Helsinki, 00014 Helsinki, Finland.

Antidepressants increase proliferation of neuronal progenitor cells and expression of brain-derived neurotrophic factor (BDNF) in the hippocampus. We investigated the role of BDNF signaling in antidepressant-induced neurogenesis by using transgenic mice with either reduced BDNF levels (BDNF+/-) or impaired trkB activation (trkB.T1-overexpressing mice). In both transgenic strains, chronic (21 d) imipramine treatment increased the number of bromodeoxyuridine (BrdU)-positive cells to degree similar to that seen in wild-type mice 24 h after BrdU administration, although the basal proliferation rate was increased in both transgenic strains. Three weeks after BrdU administration and the last antidepressant injection, the amount of newborn (BrdU- or TUC-4-positive) cells was significantly reduced in both BDNF+/- and trkB.T1-overexpressing mice, which suggests that normal BDNF signaling is required for the long-term survival of newborn hippocampal neurons. Moreover, the antidepressant-induced increase in the surviving BrdU-positive neurons seen in wild-type mice 3 weeks after treatment was essentially lost in mice with reduced BDNF signaling. Furthermore, we observed that chronic treatment with imipramine or fluoxetine produced a temporally similar increase in both BrdU-positive and terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end-labeled neurons in the dentate gyrus, indicating that these drugs simultaneously increase both neurogenesis and neuronal elimination. These data suggest that antidepressants increase turnover of hippocampal neurons rather than neurogenesis per se and that BDNF signaling is required for the long-term survival of newborn neurons in mouse hippocampus.
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http://dx.doi.org/10.1523/JNEUROSCI.3741-04.2005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6725966PMC
February 2005

Attenuation of acute experimental colitis by preventing NPY Y1 receptor signaling.

Am J Physiol Gastrointest Liver Physiol 2005 Mar 21;288(3):G550-6. Epub 2004 Oct 21.

Unit of Molecular Neurobiology, Scheeles vag 1, Medical Biochemistry and Biophysics, Karolinska Institute, S-17177 Stockholm, Sweden.

Neuropeptide Y (NPY), a 36-amino acid peptide, is widely expressed in the central and peripheral nervous system. NPY is involved in the regulation of several physiological processes, including energy balance, food intake, and nociception. Recently, we showed that activation of the NPY Y1 receptor is required for cutaneous neurogenic inflammation. Because neurogenic inflammation could participate in colitis, the aim of this study was to investigate the role of the NPY Y1 receptor in acute colitis using mice genetically deficient of NPY Y1 receptor. In addition, the Y1 receptor antagonist H409/22, was also investigated. Animals received 5% dextran sulfate sodium (DSS) in drinking water for 7 days. One group of animals also received the Y1 receptor antagonist, administered intraperitoneally twice daily. Disease activity was assessed daily for 7 days in all groups. DSS induced colitis in all animals resulting in weight loss, diarrhea, epithelial damage, crypt shortening, and inflammatory infiltration. However, clinical manifestation of the disease was markedly attenuated in Y1 null mutant mice as well as in mice receiving the Y1 antagonist. Histological analysis showed that tissue damage and ulceration were less severe in Y1-deficient animals. Consistent with the clinical and histological data, capsaicin-induced plasma extravasation was significantly reduced in the gut of Y1 null mutant animals compared with treated wild-type animals. These data indicate that NPY and Y1 receptor are involved in intestinal inflammation and suggest that inhibition of NPY Y1 receptor signaling may provide a novel therapeutic approach in the treatment of colonic inflammation.
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http://dx.doi.org/10.1152/ajpgi.00182.2004DOI Listing
March 2005

Neurotrophin-4 mediated TrkB activation reinforces morphine-induced analgesia.

Nat Neurosci 2003 Mar;6(3):221-2

Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-17177 Stockholm, Sweden.

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http://dx.doi.org/10.1038/nn1021DOI Listing
March 2003

Activation of the TrkB neurotrophin receptor is induced by antidepressant drugs and is required for antidepressant-induced behavioral effects.

J Neurosci 2003 Jan;23(1):349-57

Department of Neurobiology, A. I. Virtanen Institute, University of Kuopio, 70211 Kuopio, Finland.

Recent studies have indicated that exogenously administered neurotrophins produce antidepressant-like behavioral effects. We have here investigated the role of endogenous brain-derived neurotrophic factor (BDNF) and its receptor trkB in the mechanism of action of antidepressant drugs. We found that trkB.T1-overexpressing transgenic mice, which show reduced trkB activation in brain, as well as heterozygous BDNF null (BDNF(+/)-) mice, were resistant to the effects of antidepressants in the forced swim test, indicating that normal trkB signaling is required for the behavioral effects typically produced by antidepressants. In contrast, neurotrophin-3(+/)- mice showed a normal behavioral response to antidepressants. Furthermore, acute as well as chronic antidepressant treatment induced autophosphorylation and activation of trkB in cerebral cortex, particularly in the prefrontal and anterior cingulate cortex and hippocampus. Tyrosines in the trkB autophosphorylation site were phosphorylated in response to antidepressants, but phosphorylation of the shc binding site was not observed. Nevertheless, phosphorylation of cAMP response element-binding protein was increased by antidepressants in the prefrontal cortex concomitantly with trkB phosphorylation and this response was reduced in trkB.T1-overexpressing mice. Our data suggest that antidepressants acutely increase trkB signaling in a BDNF-dependent manner in cerebral cortex and that this signaling is required for the behavioral effects typical of antidepressant drugs. Neurotrophin signaling increased by antidepressants may induce formation and stabilization of synaptic connectivity, which gradually leads to the clinical antidepressive effects and mood recovery.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6742146PMC
January 2003