Publications by authors named "Yannick Goumon"

51 Publications

Somatostatin analogue pasireotide (SOM230) inhibits catecholamine secretion in human pheochromocytoma cells.

Cancer Lett 2021 Oct 9. Epub 2021 Oct 9.

Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000, Strasbourg, France. Electronic address:

Increasingly common, neuroendocrine tumors (NETs) are regarded nowadays as neoplasms potentially causing debilitating symptoms and life-threatening medical conditions. Pheochromocytoma is a NET that develops from chromaffin cells of the adrenal medulla, and is responsible for an excessive secretion of catecholamines. Consequently, patients have an increased risk for clinical symptoms such as hypertension, elevated stroke risk and various cardiovascular complications. Somatostatin analogues are among the main anti-secretory medical drugs used in current clinical practice in patient with NETs. However, their impact on pheochromocytoma-associated catecholamine hypersecretion remains incompletely explored. This study investigated the potential efficacy of octreotide and pasireotide (SOM230) on human tumor cells directly cultured from freshly resected pheochromocytomas using an implemented catecholamine secretion measurement by carbon fiber amperometry. SOM230 treatment efficiently inhibited nicotine-induced catecholamine secretion both in bovine chromaffin cells and in human tumor cells whereas octreotide had no effect. Moreover, SOM230 specifically decreased the number of exocytic events by impairing the stimulation-evoked calcium influx as well as the nicotinic receptor-activated inward current in human pheochromocytoma cells. Altogether, our findings indicate that SOM230 acts as an inhibitor of catecholamine secretion through a mechanism involving the nicotinic receptor and might be considered as a potential anti-secretory treatment for patients with pheochromocytoma.
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http://dx.doi.org/10.1016/j.canlet.2021.10.009DOI Listing
October 2021

The endocannabinoid system is modulated in reward and homeostatic brain regions following diet-induced obesity in rats: a cluster analysis approach.

Eur J Nutr 2021 Jun 24. Epub 2021 Jun 24.

Laboratoire de Neurosciences Cognitives Et Adaptatives (LNCA), UMR7364, Université́ de Strasbourg, CNRS, 12 rue Goethe, 67000, Strasbourg, France.

Objectives: Increased availability of high-calorie palatable food in most countries has resulted in overconsumption of these foods, suggesting that excessive eating is driven by pleasure, rather than metabolic need. The behavior contributes to the rise in eating disorders, obesity, and associated pathologies like diabetes, cardiac disease, and cancers. The mesocorticolimbic dopamine and homeostatic circuits are interconnected and play a central role in palatable food intake. The endocannabinoid system is expressed in these circuits and represents a potent regulator of feeding, but the impact of an obesogenic diet on its expression is not fully known.

Methods: Food intake and body weight were recorded in male Wistar rats over a 6-week free-choice regimen of high fat and sugar; transcriptional regulations of the endocannabinoid system were examined post-mortem in brain reward regions (prefrontal cortex, nucleus accumbens, ventral tegmental area, and arcuate nucleus). K-means cluster analysis was used to classify animals based on individual sensitivity to obesity and palatable food intake. Endocannabinoid levels were quantified in the prefrontal cortex and nucleus accumbens. Gene expression in dopamine and homeostatic systems, including ghrelin and leptin receptors, and classical homeostatic peptides, were also investigated.

Results: The free-choice high-fat -and sugar diet induced hyperphagia and obesity in rats. Cluster analysis revealed that the propensity to develop obesity and excessive palatable food intake was differently associated with dopamine and endocannabinoid system gene expression in reward and homeostatic brain regions. CB2 receptor mRNA was increased in the nucleus accumbens of high sugar consumers, whereas CB1 receptor mRNA was decreased in obesity prone rats.

Conclusions: Transcriptional data are consistent with observations of altered dopamine function in rodents that have access to an obesogenic diet and point to cannabinoid receptors as GPCR targets involved in neuroplasticity mechanisms associated with maladaptive intake of palatable food.
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http://dx.doi.org/10.1007/s00394-021-02613-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8222960PMC
June 2021

Binge sucrose-induced neuroadaptations: A focus on the endocannabinoid system.

Appetite 2021 09 14;164:105258. Epub 2021 Apr 14.

Université de Strasbourg, Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), Centre de la Recherche Nationale Scientifique, 12 rue Goethe, F-67000, Strasbourg France. Electronic address:

Binge eating, the defining feature of binge eating disorder (BED), is associated with a number of adverse health outcomes as well as a reduced quality of life. Animals, like humans, selectively binge on highly palatable food suggesting that the behaviour is driven by hedonic, rather than metabolic, signals. Given the links to both reward processing and food intake, this study examined the contribution of the endocannabinoid system (ECS) to binge-like eating in rats. Separate groups were given intermittent (12 h) or continuous (24 h) access to 10% sucrose and food over 28 days, with only the 12 h access group displaying excessive sucrose intake within a discrete period of time (i.e., binge eating). Importantly, this group also exhibited alterations in ECS transcripts and endocannabinoid levels in brain reward regions, including an increase in cannabinoid receptor 1 (CB1R) mRNA in the nucleus accumbens as well as changes in endocannabinoid levels in the prefrontal cortex and hippocampus. We then tested whether different doses (1 and 3 mg/kg) of a CB1R antagonist, Rimonabant, modify binge-like intake or the development of a conditioned place preference (CPP) to sucrose. CB1R blockade reduced binge-like intake of sucrose and blocked a sucrose CPP, but only in rats that had undergone 28 days of sucrose consumption. These findings indicate that sucrose bingeing alters the ECS in reward-related areas, modifications that exacerbate the effect of CB1R blockade on sucrose reward. Overall, our results broaden the understanding of neural alterations associated with bingeing eating and demonstrate an important role for CB1R mechanisms in reward processing. In addition, these findings have implications for understanding substance abuse, which is also characterized by excessive and maladaptive intake, pointing towards addictive-like properties of palatable food.
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http://dx.doi.org/10.1016/j.appet.2021.105258DOI Listing
September 2021

Action of mefloquine/amitriptyline THN101 combination on neuropathic mechanical hypersensitivity in mice.

Pain 2021 Mar 24. Epub 2021 Mar 24.

Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France Theranexus, Lyon, France.

Abstract: Tricyclic antidepressants that inhibit serotonin and noradrenaline reuptake, such as amitriptyline, are among the first-line treatments for neuropathic pain, which is caused by a lesion or disease affecting the somatosensory nervous system. These treatments are, however, partially efficient to alleviate neuropathic pain symptoms, and better treatments are still highly required. Interactions between neurons and glial cells participate in neuropathic pain processes, and importantly, connexins-transmembrane proteins involved in cell-cell communication-contribute to these interactions. In a neuropathic pain model in rats, mefloquine, a connexin inhibitor, has been shown to potentiate the antihyperalgesic effect of amitriptyline, a widely used antidepressant. In this study, we further investigated this improvement of amitriptyline action by mefloquine, using the cuff model of neuropathic pain in mice. We first observed that oral mefloquine co-treatment prolonged the effect of amitriptyline on mechanical hypersensitivity by 12 hours after administration. In addition, we showed that this potentiation was not due to pharmacokinetic interactions between the 2 drugs. Besides, lesional and pharmacological approaches showed that the prolonged effect was induced through noradrenergic descending pathways and the recruitment of α2 adrenoceptors. Another connexin blocker, carbenoxolone, also improved amitriptyline action. Additional in vitro studies suggested that mefloquine may also directly act on serotonin transporters and on adenosine A1 and A2A receptors, but drugs acting on these other targets failed to amplify amitriptyline action. Together, our data indicate that pharmacological blockade of connexins potentiates the therapeutic effect of amitriptyline in neuropathic pain.
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http://dx.doi.org/10.1097/j.pain.0000000000002276DOI Listing
March 2021

Astrocytes mediate the effect of oxytocin in the central amygdala on neuronal activity and affective states in rodents.

Nat Neurosci 2021 04 15;24(4):529-541. Epub 2021 Feb 15.

Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique UMR 7241, Institut National de la Santé et de la Recherche Médicale U1050, Labex Memolife, PSL Research University, Paris, France.

Oxytocin (OT) orchestrates social and emotional behaviors through modulation of neural circuits. In the central amygdala, the release of OT modulates inhibitory circuits and, thereby, suppresses fear responses and decreases anxiety levels. Using astrocyte-specific gain and loss of function and pharmacological approaches, we demonstrate that a morphologically distinct subpopulation of astrocytes expresses OT receptors and mediates anxiolytic and positive reinforcement effects of OT in the central amygdala of mice and rats. The involvement of astrocytes in OT signaling challenges the long-held dogma that OT acts exclusively on neurons and highlights astrocytes as essential components for modulation of emotional states under normal and chronic pain conditions.
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http://dx.doi.org/10.1038/s41593-021-00800-0DOI Listing
April 2021

Long-lasting analgesic and neuroprotective action of the non-benzodiazepine anxiolytic etifoxine in a mouse model of neuropathic pain.

Neuropharmacology 2021 01 16;182:108407. Epub 2020 Nov 16.

Centre National de la Recherche Scientifique and University of Strasbourg, Institute for Cellular and Integrative Neuroscience (INCI), 67000, Strasbourg, France. Electronic address:

Neuropathic pain is frequently associated with anxiety and major depressive disorders, which considerably impact the overall patient experience. Favoring GABAergic inhibition through the pain matrix has emerged as a promising strategy to restore proper processing of nociceptive and affective information in neuropathic pain states. In this context, the non-benzodiazepine anxiolytic etifoxine (EFX), known to amplify GABAergic inhibition through positive modulation of GABA receptors and neurosteroidogenesis, presents several advantages. Therefore, we sought to investigate the preclinical therapeutic potential of EFX on the somatosensory and affective components of neuropathic pain. Here, we used a murine model in which neuropathic pain was induced by the implantation of a compressive cuff around the sciatic nerve (mononeuropathy). We showed that the intraperitoneal EFX treatment for five consecutive days (50 mg/kg) relieved mechanical allodynia in a sustained manner. Besides its effect on evoked mechanical hypersensitivity, EFX also alleviated aversiveness of ongoing pain as well as anxiodepressive-like consequences of neuropathic pain following cuff-induced mononeuropathy. This effect was also seen 12 weeks after induction of the neuropathy when allodynia was no longer present. Analgesic and neuroprotective actions of EFX were also seen by the absence of neuropathic pain symptoms if a second sciatic nerve constriction injury was applied to the contralateral hindpaw. Mass spectrometry analysis revealed a normalization of brainstem serotonin levels in EFX-treated animals and an increase in norepinephrine. This study suggests that EFX presents promising therapeutic potential for the relief of both somatosensory and affective consequences of neuropathic pain, a beneficial effect that is likely to involve monoamine descending controls.
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http://dx.doi.org/10.1016/j.neuropharm.2020.108407DOI Listing
January 2021

Chromogranin A preferential interaction with Golgi phosphatidic acid induces membrane deformation and contributes to secretory granule biogenesis.

FASEB J 2020 05 29;34(5):6769-6790. Epub 2020 Mar 29.

Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France.

Chromogranin A (CgA) is a key luminal actor of secretory granule biogenesis at the trans-Golgi network (TGN) level but the molecular mechanisms involved remain obscure. Here, we investigated the possibility that CgA acts synergistically with specific membrane lipids to trigger secretory granule formation. We show that CgA preferentially interacts with the anionic glycerophospholipid phosphatidic acid (PA). In accordance, bioinformatic analysis predicted a PA-binding domain (PABD) in CgA sequence that effectively bound PA (36:1) or PA (40:6) in membrane models. We identified PA (36:1) and PA (40:6) as predominant species in Golgi and granule membranes of secretory cells, and we found that CgA interaction with these PA species promotes artificial membrane deformation and remodeling. Furthermore, we demonstrated that disruption of either CgA PABD or phospholipase D (PLD) activity significantly alters secretory granule formation in secretory cells. Our findings show for the first time the ability of CgA to interact with PLD-generated PA, which allows membrane remodeling and curvature, key processes necessary to initiate secretory granule budding.
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http://dx.doi.org/10.1096/fj.202000074RDOI Listing
May 2020

Unveiling the Impact of Morphine on Tamoxifen Metabolism in Mice .

Front Oncol 2020 21;10:25. Epub 2020 Feb 21.

CNRS UPR3212, Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, University of Strasbourg, Strasbourg, France.

Tamoxifen is used to treat breast cancer and cancer recurrences. After administration, tamoxifen is converted into two more potent antitumor compounds, 4OH-tamoxifen and endoxifen by the CYP3A4/5 and 2D6 enzymes in human. These active compounds are inactivated by the same UDP-glucuronosyltransferase isoforms as those involved in the metabolism of morphine. Importantly, cancer-associated pain can be treated with morphine, and the common metabolic pathway of morphine and tamoxifen suggests potential clinically relevant interactions. Mouse liver microsomes were used to determine the impact of morphine on 4OH-tamoxifen metabolism . For experiments, female mice were first injected with tamoxifen alone and then with tamoxifen and morphine. Blood was collected, and LC-MS/MS was used to quantify tamoxifen, 4OH-tamoxifen, N-desmethyltamoxifen, endoxifen, 4OH-tamoxifen-glucuronide, and endoxifen-glucuronide. , we found increased values for the production of 4OH-tamoxifen-glucuronide in the presence of morphine, suggesting an inhibitory effect on 4OH-tamoxifen glucuronidation. Conversely, morphine treatment decreased 4OH-tamoxifen levels in the blood while dramatically increasing the formation of inactive metabolites 4OH-tamoxifen-glucuronide and endoxifen-glucuronide. Our findings emphasize the need for caution when extrapolating results from metabolic assays to drug metabolism interactions. Importantly, morphine strongly impacts tamoxifen metabolism in mice. It suggests that tamoxifen efficiency could be reduced when both drugs are co-administered in a clinical setting, e.g., to relieve pain in breast cancer patients. Further studies are needed to assess the potential for tamoxifen-morphine metabolic interactions in humans.
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http://dx.doi.org/10.3389/fonc.2020.00025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7046683PMC
February 2020

A Nonpeptide Oxytocin Receptor Agonist for a Durable Relief of Inflammatory Pain.

Sci Rep 2020 02 20;10(1):3017. Epub 2020 Feb 20.

Centre National de la Recherche Scientifique and University of Strasbourg, UPR3212 Institute of Cellular and Integrative Neurosciences, Strasbourg, France.

Oxytocin possesses several physiological and social functions, among which an important analgesic effect. For this purpose, oxytocin binds mainly to its unique receptor, both in the central nervous system and in the peripheral nociceptive terminal axon in the skin. However, despite its interesting analgesic properties and its current use in clinics to facilitate labor, oxytocin is not used in pain treatment. Indeed, it is rapidly metabolized, with a half-life in the blood circulation estimated at five minutes and in cerebrospinal fluid around twenty minutes in humans and rats. Moreover, oxytocin itself suffers from several additional drawbacks: a lack of specificity, an extremely poor oral absorption and distribution, and finally, a lack of patentability. Recently, a first non-peptide full agonist of oxytocin receptor (LIT-001) of low molecular weight has been synthesized with reported beneficial effect for social interactions after peripheral administration. In the present study, we report that a single intraperitoneal administration of LIT-001 in a rat model induces a long-lasting reduction in inflammatory pain-induced hyperalgesia symptoms, paving the way to an original drug development strategy for pain treatment.
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http://dx.doi.org/10.1038/s41598-020-59929-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7033278PMC
February 2020

Corrigendum: Morphine Binds Creatine Kinase B and Inhibits Its Activity.

Front Cell Neurosci 2019;13:292. Epub 2019 Jul 2.

Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR3212 and Université de Strasbourg, Strasbourg, France.

[This corrects the article DOI: 10.3389/fncel.2018.00464.].
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http://dx.doi.org/10.3389/fncel.2019.00292DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6614683PMC
July 2019

A Fear Memory Engram and Its Plasticity in the Hypothalamic Oxytocin System.

Neuron 2019 07 16;103(1):133-146.e8. Epub 2019 May 16.

Schaller Research Group on Neuropeptides, German Cancer Research Center, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany; Department of Neuropeptide Research for Psychiatry, Central Institute of Mental Health, Heidelberg University, J5, 68159 Mannheim, Germany. Electronic address:

Oxytocin (OT) release by axonal terminals onto the central nucleus of the amygdala exerts anxiolysis. To investigate which subpopulation of OT neurons contributes to this effect, we developed a novel method: virus-delivered genetic activity-induced tagging of cell ensembles (vGATE). With the vGATE method, we identified and permanently tagged a small subpopulation of OT cells, which, by optogenetic stimulation, strongly attenuated contextual fear-induced freezing, and pharmacogenetic silencing of tagged OT neurons impaired context-specific fear extinction, demonstrating that the tagged OT neurons are sufficient and necessary, respectively, to control contextual fear. Intriguingly, OT cell terminals of fear-experienced rats displayed enhanced glutamate release in the amygdala. Furthermore, rats exposed to another round of fear conditioning displayed 5-fold more activated magnocellular OT neurons in a novel environment than a familiar one, possibly for a generalized fear response. Thus, our results provide first evidence that hypothalamic OT neurons represent a fear memory engram.
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http://dx.doi.org/10.1016/j.neuron.2019.04.029DOI Listing
July 2019

Morphine Binds Creatine Kinase B and Inhibits Its Activity.

Front Cell Neurosci 2018 3;12:464. Epub 2018 Dec 3.

Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR3212 and Université de Strasbourg, Strasbourg, France.

Morphine is an analgesic alkaloid used to relieve severe pain, and irreversible binding of morphine to specific unknown proteins has been previously observed. In the brain, changes in the expression of energy metabolism enzymes contribute to behavioral abnormalities during chronic morphine treatment. Creatine kinase B (CK-B) is a key enzyme involved in brain energy metabolism. CK-B also corresponds to the imidazoline-binding protein I which binds dopamine (a precursor of morphine biosynthesis) irreversibly. Using biochemical approaches, we show that recombinant mouse CK-B possesses a μM affinity for morphine and binds to morphine . The complex formed by CK-B and morphine is resistant to detergents, reducing agents, heat treatment and SDS-polyacrylamide gel electrophoresis (SDS-PAGE). CK-B-derived peptides CK-B and CK-B were identified as two specific morphine binding-peptides. , morphine (1-100 μM) significantly reduces recombinant CK-B enzymatic activity. Accordingly, morphine administration (7.5 mg/kg, i.p.) to mice significantly decreased brain extract CK-B activity compared to saline-treated animals. Together, these results show that morphine strongly binds CK-B and inhibits its activity and .
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http://dx.doi.org/10.3389/fncel.2018.00464DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6286964PMC
December 2018

A Dual Noradrenergic Mechanism for the Relief of Neuropathic Allodynia by the Antidepressant Drugs Duloxetine and Amitriptyline.

J Neurosci 2018 11 24;38(46):9934-9954. Epub 2018 Sep 24.

Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, 67000 Strasbourg, France,

In addition to treating depression, antidepressant drugs are also a first-line treatment for neuropathic pain, which is pain secondary to lesion or pathology of the nervous system. Despite the widespread use of these drugs, the mechanism underlying their therapeutic action in this pain context remains partly elusive. The present study combined data collected in male and female mice from a model of neuropathic pain and data from the clinical setting to understand how antidepressant drugs act. We show two distinct mechanisms by which the selective inhibitor of serotonin and noradrenaline reuptake duloxetine and the tricyclic antidepressant amitriptyline relieve neuropathic allodynia. One of these mechanisms is acute, central, and requires descending noradrenergic inhibitory controls and α adrenoceptors, as well as the mu and delta opioid receptors. The second mechanism is delayed, peripheral, and requires noradrenaline from peripheral sympathetic endings and β adrenoceptors, as well as the delta opioid receptors. We then conducted a transcriptomic analysis in dorsal root ganglia, which suggested that the peripheral component of duloxetine action involves the inhibition of neuroimmune mechanisms accompanying nerve injury, including the downregulation of the TNF-α-NF-κB signaling pathway. Accordingly, immunotherapies against either TNF-α or Toll-like receptor 2 (TLR2) provided allodynia relief. We also compared duloxetine plasma levels in the animal model and in patients and we observed that patients' drug concentrations were compatible with those measured in animals under chronic treatment involving the peripheral mechanism. Our study highlights a peripheral neuroimmune component of antidepressant drugs that is relevant to their delayed therapeutic action against neuropathic pain. In addition to treating depression, antidepressant drugs are also a first-line treatment for neuropathic pain, which is pain secondary to lesion or pathology of the nervous system. However, the mechanism by which antidepressant drugs can relieve neuropathic pain remained in part elusive. Indeed, preclinical studies led to contradictions concerning the anatomical and molecular substrates of this action. In the present work, we overcame these apparent contradictions by highlighting the existence of two independent mechanisms. One is rapid and centrally mediated by descending controls from the brain to the spinal cord and the other is delayed, peripheral, and relies on the anti-neuroimmune action of chronic antidepressant treatment.
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http://dx.doi.org/10.1523/JNEUROSCI.1004-18.2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6596240PMC
November 2018

Pharmacological rescue of nociceptive hypersensitivity and oxytocin analgesia impairment in a rat model of neonatal maternal separation.

Pain 2018 Dec;159(12):2630-2640

Centre National de la Recherche Scientifique, University of Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France.

Oxytocin (OT), known for its neurohormonal effects around birth, has recently been suggested for being a critical determinant in neurodevelopmental disorders. This hypothalamic neuropeptide exerts a potent analgesic effect through an action on the nociceptive system. This endogenous control of pain has an important adaptive value but might be altered by early life stress, possibly contributing to its long-term consequences on pain responses and associated comorbidities. We tested this hypothesis using a rat model of neonatal maternal separation (NMS) known to induce long-term consequences on several brain functions including chronic stress, anxiety, altered social behavior, and visceral hypersensitivity. We found that adult rats with a history of NMS were hypersensitive to noxious mechanical/thermal hot stimuli and to inflammatory pain. We failed to observe OT receptor-mediated stress-induced analgesia and OT antihyperalgesia after carrageenan inflammation. These alterations were partially rescued if NMS pups were treated by intraperitoneal daily injection during NMS with OT or its downstream second messenger allopregnanolone. The involvement of epigenetic changes in these alterations was confirmed since neonatal treatment with the histone deacetylase inhibitor SAHA, not only normalized nociceptive sensitivities but also restored OT receptor-mediated stress-induced analgesia and the endogenous antihyperalgesia in inflamed NMS rats. There is growing evidence in the literature that early life stress might impair the nociceptive system ontogeny and function. This study suggests that these alterations might be restored while stimulating OT receptor signaling or histone deacetylase inhibitors, using molecules that are currently available or part of clinical trials for other pathologies.
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http://dx.doi.org/10.1097/j.pain.0000000000001375DOI Listing
December 2018

Stable isotope-labelled morphine to study in vivo central and peripheral morphine glucuronidation and brain transport in tolerant mice.

Br J Pharmacol 2018 10 31;175(19):3844-3856. Epub 2018 Aug 31.

CNRS UPR3212, Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique and University of Strasbourg, Strasbourg, France.

Background And Purpose: Chronic administration of medication can significantly affect metabolic enzymes leading to physiological adaptations. Morphine metabolism in the liver has been extensively studied following acute morphine treatment, but such metabolic processes in the CNS are poorly characterized. Long-term morphine treatment is limited by the development of tolerance, resulting in a decrease of its analgesic effect. Whether or not morphine analgesic tolerance affects in vivo brain morphine metabolism and blood-brain barrier (BBB) permeability remains a major question. Here, we have attempted to characterize the in vivo metabolism and BBB permeability of morphine after long-term treatment, at both central and peripheral levels.

Experimental Approach: Male C57BL/6 mice were injected with morphine or saline solution for eight consecutive days in order to induce morphine analgesic tolerance. On the ninth day, both groups received a final injection of morphine (85%) and d3-morphine (morphine bearing three H; 15%, w/w). Mice were then killed and blood, urine, brain and liver samples were collected. LC-MS/MS was used to quantify morphine, its metabolite morphine-3-glucuronide (M3G) and their respective d3-labelled forms.

Key Results: We found no significant differences in morphine CNS uptake and metabolism between control and tolerant mice. Interestingly, d3-morphine metabolism was decreased compared to morphine without any interference with our study.

Conclusions And Implications: Our data suggests that tolerance to the analgesic effects of morphine is not linked to increased glucuronidation to M3G or to altered global BBB permeability of morphine.
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http://dx.doi.org/10.1111/bph.14454DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6135784PMC
October 2018

Light rescues circadian behavior and brain dopamine abnormalities in diurnal rodents exposed to a winter-like photoperiod.

Brain Struct Funct 2018 Jul 20;223(6):2641-2652. Epub 2018 Mar 20.

Institute of Cellular and Integrative Neurosciences, CNRS-UPR3212, 5 rue Blaise Pascal, 67084, Strasbourg Cedex, France.

Seasonal affective disorder (SAD), beyond mood changes, is characterized by alterations in daily rhythms of behavior and physiology. The pathophysiological conditions of SAD involve changes in day length and its first-line treatment is bright light therapy. Animal models using nocturnal rodents have been studied to elucidate the neurobiological mechanisms of depression, but might be ill suited to study the therapeutic effects of light in SAD since they exhibit light-aversive responses. Here Arvicanthis ansorgei, a diurnal rodent, was used to determine behavioral, molecular and brain dopamine changes in response to exposure to a winter-like photoperiod consisting of a light-dark cycle with 8 h of light, under diminished light intensity, and 16 h of darkness. Furthermore, we evaluated whether timed-daily bright light exposure has an effect on behavior and brain physiology of winter-like exposed animals. Arvicanthis under a winter-like condition showed alterations in the synchronization of the locomotor activity rhythm to the light-dark cycle. Moreover, alterations in day-night activity of dopaminergic neurotransmission were revealed in the nucleus accumbens and the dorsal striatum, and in the day-night clock gene expression in the suprachiasmatic nucleus. Interestingly, whereas dopamine disturbances were reversed in animals exposed to daily light at early or late day, altered phase of the daily rhythm of locomotion was reverted only in animals exposed to light at the late day. Moreover, Per2 gene expression in the SCN was also affected by light exposure at late day in winter-like exposed animals. These findings suggest that light induces effects on behavior by mechanisms that rely on both circadian and rhythm-independent pathways influencing the dopaminergic circuitry. This last point might be crucial for understanding the mechanisms of non-pharmacological treatment in SAD.
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http://dx.doi.org/10.1007/s00429-018-1655-8DOI Listing
July 2018

Lithium reverses mechanical allodynia through a mu opioid-dependent mechanism.

Mol Pain 2018 Jan-Dec;14:1744806917754142. Epub 2018 Jan 21.

1 CNRS UPR3212, Institut des Neurosciences Cellulaires et Intégratives, 27051 Centre National de la Recherche Scientifique , Strasbourg, France.

Background Lithium is widely used to treat bipolar disorders and displays mood stabilizing properties. In addition, lithium relieves painful cluster headaches and has a strong analgesic effect in neuropathic pain rat models. Objectives To investigate the analgesic effect of lithium on the cuff model of neuropathic pain. Methods We used behavioral and pharmacological approaches to study the analgesic effect of a single injection of lithium in wild-type and mu opioid receptor (MOR) null cuffed neuropathic mice. Mass spectrometry and enzyme-linked immunosorbent assay allowed to measure the levels of endogenous MOR agonist beta-endorphin as well as monoamines in brain and plasma samples 4 h after lithium administration. Results A single injection of lithium chloride (100 mg/kg, ip) alleviated mechanical allodynia for 24 h, and this effect was absent in MOR null neuropathic mice. Biochemical analyses highlight a significant increase in beta-endorphin levels by 30% in the brain of lithium-treated mice compared to controls. No variation of beta-endorphin was detected in the blood. Conclusions Together, our results provide evidence that lithium induces a long-lasting analgesia in neuropathic mice presumably through elevated brain levels of beta-endorphin and the activation of MORs.
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http://dx.doi.org/10.1177/1744806917754142DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5788089PMC
October 2018

Morphine-induced hyperalgesia involves mu opioid receptors and the metabolite morphine-3-glucuronide.

Sci Rep 2017 09 4;7(1):10406. Epub 2017 Sep 4.

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.

Opiates are potent analgesics but their clinical use is limited by side effects including analgesic tolerance and opioid-induced hyperalgesia (OIH). The Opiates produce analgesia and other adverse effects through activation of the mu opioid receptor (MOR) encoded by the Oprm1 gene. However, MOR and morphine metabolism involvement in OIH have been little explored. Hence, we examined MOR contribution to OIH by comparing morphine-induced hyperalgesia in wild type (WT) and MOR knockout (KO) mice. We found that repeated morphine administration led to analgesic tolerance and hyperalgesia in WT mice but not in MOR KO mice. The absence of OIH in MOR KO mice was found in both sexes, in two KO global mutant lines, and for mechanical, heat and cold pain modalities. In addition, the morphine metabolite morphine-3beta-D-glucuronide (M3G) elicited hyperalgesia in WT but not in MOR KO animals, as well as in both MOR flox and MOR-Nav1.8 sensory neuron conditional KO mice. M3G displayed significant binding to MOR and G-protein activation when using membranes from MOR-transfected cells or WT mice but not from MOR KO mice. Collectively our results show that MOR is involved in hyperalgesia induced by chronic morphine and its metabolite M3G.
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http://dx.doi.org/10.1038/s41598-017-11120-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5583172PMC
September 2017

Sleep Deprivation and Caffeine Treatment Potentiate Photic Resetting of the Master Circadian Clock in a Diurnal Rodent.

J Neurosci 2017 04 20;37(16):4343-4358. Epub 2017 Mar 20.

Regulation of Circadian Clocks Team, Institute of Cellular and Integrative Neurosciences.

Circadian rhythms in nocturnal and diurnal mammals are primarily synchronized to local time by the light/dark cycle. However, nonphotic factors, such as behavioral arousal and metabolic cues, can also phase shift the master clock in the suprachiasmatic nuclei (SCNs) and/or reduce the synchronizing effects of light in nocturnal rodents. In diurnal rodents, the role of arousal or insufficient sleep in these functions is still poorly understood. In the present study, diurnal Sudanian grass rats, , were aroused at night by sleep deprivation (gentle handling) or caffeine treatment that both prevented sleep. Phase shifts of locomotor activity were analyzed in grass rats transferred from a light/dark cycle to constant darkness and aroused in early night or late night. Early night, but not late night, sleep deprivation induced a significant phase shift. Caffeine on its own induced no phase shifts. Both sleep deprivation and caffeine treatment potentiated light-induced phase delays and phase advances in response to a 30 min light pulse, respectively. Sleep deprivation in early night, but not late night, potentiated light-induced c-Fos expression in the ventral SCN. Caffeine treatment in midnight triggered c-Fos expression in dorsal SCN. Both sleep deprivation and caffeine treatment potentiated light-induced c-Fos expression in calbindin-containing cells of the ventral SCN in early and late night. These findings indicate that, in contrast to nocturnal rodents, behavioral arousal induced either by sleep deprivation or caffeine during the sleeping period potentiates light resetting of the master circadian clock in diurnal rodents, and activation of calbindin-containing suprachiasmatic cells may be involved in this effect. Arousing stimuli have the ability to regulate circadian rhythms in mammals. Behavioral arousal in the sleeping period phase shifts the master clock in the suprachiasmatic nuclei and/or slows down the photic entrainment in nocturnal animals. How these stimuli act in diurnal species remains to be established. Our study in a diurnal rodent, the Grass rat, indicates that sleep deprivation in the early rest period induces phase delays of circadian locomotor activity rhythm. Contrary to nocturnal rodents, both sleep deprivation and caffeine-induced arousal potentiate the photic entrainment in a diurnal rodent. Such enhanced light-induced circadian responses could be relevant for developing chronotherapeutic strategies.
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http://dx.doi.org/10.1523/JNEUROSCI.3241-16.2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6596565PMC
April 2017

The TLR4-Active Morphine Metabolite Morphine-3-Glucuronide Does Not Elicit Macrophage Classical Activation .

Front Pharmacol 2016 17;7:441. Epub 2016 Nov 17.

Pharmacy Australia Centre of Excellence, School of Pharmacy, University of Queensland, Woolloongabba QLD, Australia.

Macrophages are abundant in the tumor microenvironment where they adopt a pro-tumor phenotype following alternative polarization induced by paracrine factors from cancer and stromal cells. In contrast, classically activated macrophages have tumoricidal activities, such that the polarization of tumor-associated macrophages has become a novel therapeutic target. Toll-like receptor 4 engagement promotes classical activation of macrophages, and recent literature suggests TLR4 agonism to prevent metastasis and promote survival in experimental metastasis models. A growing number of studies indicate that TLR4 can respond to opioids, including the opioid receptor-inactive morphine metabolite morphine-3-glucuronide (M3G). We measured the activation of TLR4 in a reporter cell line exogenously expressing TLR4 and TLR4 co-receptors, and confirmed that M3G weakly but significantly activates TLR4. We hypothesized that M3G would promote the expression of classical activation signature genes in macrophages . We exposed mouse and human macrophage cell lines to M3G or the TLR4 activator lipopolysaccharide (LPS), alone or in combination with interferon gamma (IFN-γ). The classical macrophage activation markers tested were iNOS, CD86, IL-6, or TNF-α in RAW 264.7 cells and IL-6, IL-12, IL-23, TNF-α, CXCL10, and CXCL11 in THP1 cells. Our results show that despite exhibiting TLR4-activation ability, M3G does not elicit the expression of classical activation markers in LPS-responsive macrophages.
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http://dx.doi.org/10.3389/fphar.2016.00441DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5112272PMC
November 2016

Morphine decreases the pro-angiogenic interaction between breast cancer cells and macrophages in vitro.

Sci Rep 2016 08 12;6:31572. Epub 2016 Aug 12.

University of Queensland School of Pharmacy, PACE, 20 Cornwall Street. Woollloongabba QLD 4102, Australia.

Interactions between the various cell types that constitute a solid tumour are essential to the biology of the tumour. We evaluated the effect of morphine on the proangiogenic interaction taking place between macrophages and breast cancer cells in vitro. The conditioned medium (CM) from breast cancer cells co-cultured with macrophages elicited endothelial cell proliferation and tube formation. This effect was inhibited if the co-culture occurred in the presence of morphine. The CM from breast cancer cells or macrophages grown individually, whether or not prepared in the presence of morphine, was ineffective in stimulating EC proliferation or tube formation. Using a mouse antibody array, we identified several angiogenesis-regulating factors differentially expressed in the CM of co-cultured cells prepared in the presence or absence of morphine, amongst which interleukin (IL)-6, tumour necrosis factor (TNF)-α and vascular endothelial growth factor (VEGF)-A. VEGF was induced in both cell types by the co-culture and this was prevented by morphine in a non-naloxone reversible fashion. The effect of CM from co-cultured cells on endothelial tube formation, but not proliferation, was prevented by anti-VEGF neutralizing antibody. Our results indicate that morphine prevents, in part via modulating VEGF-A expression, the pro-angiogenic interaction between macrophages and breast cancer cells.
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http://dx.doi.org/10.1038/srep31572DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4981855PMC
August 2016

A New Population of Parvocellular Oxytocin Neurons Controlling Magnocellular Neuron Activity and Inflammatory Pain Processing.

Neuron 2016 Mar 3;89(6):1291-1304. Epub 2016 Mar 3.

Schaller Research Group on Neuropeptides at German Cancer Research Center (DKFZ) and Cell Network Cluster of Excellence at the University of Heidelberg, Heidelberg 69120, Germany; Max Planck Institute for Medical Research, Heidelberg 69120, Germany; Central Institute of Mental Health (ZI), Mannheim 68159, Germany. Electronic address:

Oxytocin (OT) is a neuropeptide elaborated by the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei. Magnocellular OT neurons of these nuclei innervate numerous forebrain regions and release OT into the blood from the posterior pituitary. The PVN also harbors parvocellular OT cells that project to the brainstem and spinal cord, but their function has not been directly assessed. Here, we identified a subset of approximately 30 parvocellular OT neurons, with collateral projections onto magnocellular OT neurons and neurons of deep layers of the spinal cord. Evoked OT release from these OT neurons suppresses nociception and promotes analgesia in an animal model of inflammatory pain. Our findings identify a new population of OT neurons that modulates nociception in a two tier process: (1) directly by release of OT from axons onto sensory spinal cord neurons and inhibiting their activity and (2) indirectly by stimulating OT release from SON neurons into the periphery.
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http://dx.doi.org/10.1016/j.neuron.2016.01.041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5679079PMC
March 2016

Neurophysiological responses to unpleasant stimuli (acute electrical stimulations and emotional pictures) are increased in patients with schizophrenia.

Sci Rep 2016 Mar 3;6:22542. Epub 2016 Mar 3.

INSERM U-1114, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Département de Psychiatrie, Hôpitaux Universitaires de Strasbourg; 1, place de l'Hôpital, 67000 Strasbourg, France.

Patients with schizophrenia have often been described as insensitive to nociceptive signals, but objective evidence is sparse. We address this question by combining subjective behavioral and objective neurochemical and neurophysiological measures. The present study involved 21 stabilized and mildly symptomatic patients with schizophrenia and 21 control subjects. We applied electrical stimulations below the pain threshold and assessed sensations of pain and unpleasantness with rating scales, and Somatosensory Evoked Potentials (SEPs/EEG). We also measured attention, two neurochemical stress indices (ACTH/cortisol), and subjective VEPs/EEG responses to visual emotional stimuli. Our results revealed that, subjectively, patients' evaluations do not differ from controls. However, the amplitude of EEG evoked potentials was greater in patients than controls as early as 50 ms after electrical stimulations and beyond one second after visual processing of emotional pictures. Such responses could not be linked to the stress induced by the stimulations, since stress hormone levels were stable. Nor was there a difference between patients and controls in respect of attention performance and tactile sensitivity. Taken together, all indices measured in patients in our study were either heightened or equivalent relative to healthy volunteers.
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http://dx.doi.org/10.1038/srep22542DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4776095PMC
March 2016

Morphine Modulates Interleukin-4- or Breast Cancer Cell-induced Pro-metastatic Activation of Macrophages.

Sci Rep 2015 Jun 16;5:11389. Epub 2015 Jun 16.

University of Queensland School of Pharmacy, PACE, 20 Cornwall Street, Woollloongabba QLD 4102, Australia.

Interactions between cancer cells and stromal cells in the tumour microenvironment play a key role in the control of invasiveness, metastasis and angiogenesis. Macrophages display a range of activation states in specific pathological contexts and alternatively activated (M2) macrophages can promote tumour aggressiveness. Opioids are able to modulate tumour growth and metastasis. We tested whether morphine modulates the activation of macrophages induced by (i) interleukin-4 (IL-4), the prototypical M2 polarization-inducing cytokine, or (ii) coculture with breast cancer cells. We showed that IL-4 causes increased MMP-9 production and expression of the alternative activation markers arginase-1 and MRC-1. Morphine prevented IL-4-induced increase in MMP-9 in a naloxone- and methylnaltrexone-reversible fashion. Morphine also prevented IL-4-elicited alternative activation of RAW264.7 macrophages. Expression of MMP-9 and arginase-1 were increased when RAW264.7 were subjected to paracrine activation by 4T1 cells, and this effect was prevented by morphine via an opioid receptor-mediated mechanism. Morphine further decreased 4T1 breast cancer cell invasion elicited by co-culture with RAW264.7. Reduction of MMP-9 expression and alternative activation of macrophages by morphine was confirmed using mouse bone marrow-derived macrophages. Taken together, our results indicate that morphine may modulate tumour aggressiveness by regulating macrophage protease production and M2 polarization within the tumour microenvironment.
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http://dx.doi.org/10.1038/srep11389DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4468425PMC
June 2015

Defective response inhibition and collicular noradrenaline enrichment in mice with duplicated retinotopic map in the superior colliculus.

Brain Struct Funct 2015 20;220(3):1573-84. Epub 2014 Mar 20.

Laboratory of Adaptative and Cognitive Neurosciences, CNRS, University of Strasbourg UMR 7364, 67000, Strasbourg, France,

The superior colliculus is a hub for multisensory integration necessary for visuo-spatial orientation, control of gaze movements and attention. The multiple functions of the superior colliculus have prompted hypotheses about its involvement in neuropsychiatric conditions, but to date, this topic has not been addressed experimentally. We describe experiments on genetically modified mice, the Isl2-EphA3 knock-in line, that show a well-characterized duplication of the retino-collicular and cortico-collicular axonal projections leading to hyperstimulation of the superior colliculus. To explore the functional impact of collicular hyperstimulation, we compared the performance of homozygous knock-in, heterozygous knock-in and wild-type mice in several behavioral tasks requiring collicular activity. The light/dark box test and Go/No-Go conditioning task revealed that homozygous mutant mice exhibit defective response inhibition, a form of impulsivity. This defect was specific to attention as other tests showed no differences in visually driven behavior, motivation, visuo-spatial learning and sensorimotor abilities among the different groups of mice. Monoamine quantification and gene expression profiling demonstrated a specific enrichment of noradrenaline only in the superficial layers of the superior colliculus of Isl2-EphA3 knock-in mice, where the retinotopy is duplicated, whereas transcript levels of receptors, transporters and metabolic enzymes of the monoaminergic pathway were not affected. We demonstrate that the defect in response inhibition is a consequence of noradrenaline imbalance in the superficial layers of the superior colliculus caused by retinotopic map duplication. Our results suggest that structural abnormalities in the superior colliculus can cause defective response inhibition, a key feature of attention-deficit disorders.
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http://dx.doi.org/10.1007/s00429-014-0745-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4409641PMC
January 2016

Etifoxine analgesia in experimental monoarthritis: a combined action that protects spinal inhibition and limits central inflammatory processes.

Pain 2014 Feb 14;155(2):403-412. Epub 2013 Nov 14.

Centre National de la Recherche Scientifique and University of Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France.

Inflammatory and degenerative diseases of the joint are major causes of chronic pain. Long-lasting pain symptoms are thought to result from a central sensitization of nociceptive circuits. These processes include activation of microglia and spinal disinhibition. Using a monoarthritic rat model of pain, we tried to potentiate neural inhibition by using etifoxine (EFX), a nonbenzodiazepine anxiolytic that acts as an allosteric-positive modulator of gamma-aminobutyric acid type A (GABAA) receptor function. Interestingly, EFX also can bind to the mitochondrial translocator protein (TSPO) complex and stimulate the synthesis of 3α-reduced neurosteroids, the most potent positive allosteric modulator of GABAA receptor function. Here we show that a curative and a preventive treatment with 50mg/kg of EFX efficiently reduced neuropathic pain symptoms. In the spinal cord, EFX analgesia was accompanied by a reduction in microglial activation and in the levels of proinflammatory mediators. Using electrophysiological tools, we found that EFX treatment not only amplified spinal GABAergic inhibition, but also prevented prostaglandin E2-induced glycinergic disinhibition and restored a "normal" spinal pain processing. Because EFX is already distributed in several countries under the trade name of Stresam for its anxiolytic actions in humans, new clinical trials are now required to further extend its therapeutic indications as pain killer.
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http://dx.doi.org/10.1016/j.pain.2013.11.003DOI Listing
February 2014

Long-lasting spinal oxytocin analgesia is ensured by the stimulation of allopregnanolone synthesis which potentiates GABA(A) receptor-mediated synaptic inhibition.

J Neurosci 2013 Oct;33(42):16617-26

Centre National de la Recherche Scientifique and University of Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67084 Strasbourg, France.

Hypothalamospinal control of spinal pain processing by oxytocin (OT) has received a lot of attention in recent years because of its potency to reduce pain symptoms in inflammatory and neuropathic conditions. However, cellular and molecular mechanisms underlying OT spinal antinociception are still poorly understood. In this study, we used biochemical, electrophysiological, and behavioral approaches to demonstrate that OT levels are elevated in the spinal cord of rats exhibiting pain symptoms, 24 h after the induction of inflammation with an intraplantar injection of λ-carrageenan. Using a selective OT receptor antagonist, we demonstrate that this elevated OT content is responsible for a tonic analgesia exerted on both mechanical and thermal modalities. This phenomenon appeared to be mediated by an OT receptor-mediated stimulation of neurosteroidogenesis, which leads to an increase in GABA(A) receptor-mediated synaptic inhibition in lamina II spinal cord neurons. We also provide evidence that this novel mechanism of OT-mediated spinal antinociception may be controlled by extracellular signal-related protein kinases, ERK1/2, after OT receptor activation. The oxytocinergic inhibitory control of spinal pain processing is emerging as an interesting target for future therapies since it recruits several molecular mechanisms, which are likely to exert a long-lasting analgesia through nongenomic and possibly genomic effects.
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http://dx.doi.org/10.1523/JNEUROSCI.3084-12.2013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6618538PMC
October 2013

Endogenous morphine-6-glucuronide (M6G) is present in the plasma of patients: validation of a specific anti-M6G antibody for clinical and basic research.

Biofactors 2014 Jan-Feb;40(1):113-20. Epub 2013 Jul 17.

CNRS UPR3212, Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique and University of Strasbourg, Strasbourg, France.

Endogenous morphine and its derivatives (morphine-6-glucuronide [M6G]; morphine-3-glucuronide [M3G]) are formed by mammalian cells from dopamine. Changes in the concentrations of endogenous morphine have been demonstrated in several pathologies (sepsis, Parkinson's disease, etc.), and they might be relevant as pathological markers. While endogenous morphine levels are detectable using enzyme-linked immunosorbant assay (ELISA), mass spectrometry (MS) analysis was, so far, the only approach to detect and quantify M6G. This study describes the preparation of a specific anti-M6G rabbit polyclonal antibody and its validation. The specificity of this antibody was assessed against 30 morphine-related compounds. Then, a M6G-specific ELISA-assay was tested to quantify M6G in the plasma of healthy donors, morphine-treated, and critically ill patients. The antibody raised against M6G displays a strong affinity for M6G, codeine-6-glucuronide, and morphine-3-6-glucuronide, whereas only weak cross-reactivities were observed for the other compounds. Both M6G-ELISA and LC-MS/MS approaches revealed the absence of M6G in the plasma of healthy donors (controls, n = 8). In all positive donors treated with morphine-patch (n = 5), M6G was detected using both M6G-ELISA and LC-MS/MS analysis. Finally, in a study on critically ill patients with circulating endogenous morphine (n = 26), LC-MS/MS analysis revealed that 73% of the positive-patients (19 of 26), corresponding to high M6G-levels in M6G-ELISA, contained M6G. In conclusion, we show that endogenous M6G can be found at higher levels than morphine in the blood of morphine-naive patients. With respect to the interest of measuring endogenous M6G in pathologies, we provide evidences that our ELISA procedure represents a powerful tool as it can easily and specifically detect endogenous M6G levels.
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http://dx.doi.org/10.1002/biof.1107DOI Listing
October 2014

CTIP2 is a negative regulator of P-TEFb.

Proc Natl Acad Sci U S A 2013 Jul 12;110(31):12655-60. Epub 2013 Jul 12.

Institut de Parasitologie et de Pathologie Tropicale, Fédération de Médecine Translationnelle, University of Strasbourg, 67000 Strasbourg, France.

The positive transcription elongation factor b (P-TEFb) is involved in physiological and pathological events including inflammation, cancer, AIDS, and cardiac hypertrophy. The balance between its active and inactive form is tightly controlled to ensure cellular integrity. We report that the transcriptional repressor CTIP2 is a major modulator of P-TEFb activity. CTIP2 copurifies and interacts with an inactive P-TEFb complex containing the 7SK snRNA and HEXIM1. CTIP2 associates directly with HEXIM1 and, via the loop 2 of the 7SK snRNA, with P-TEFb. In this nucleoprotein complex, CTIP2 significantly represses the Cdk9 kinase activity of P-TEFb. Accordingly, we show that CTIP2 inhibits large sets of P-TEFb- and 7SK snRNA-sensitive genes. In hearts of hypertrophic cardiomyopathic mice, CTIP2 controls P-TEFb-sensitive pathways involved in the establishment of this pathology. Overexpression of the β-myosin heavy chain protein contributes to the pathological cardiac wall thickening. The inactive P-TEFb complex associates with CTIP2 at the MYH7 gene promoter to repress its activity. Taken together, our results strongly suggest that CTIP2 controls P-TEFb function in physiological and pathological conditions.
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http://dx.doi.org/10.1073/pnas.1220136110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3732990PMC
July 2013
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