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Thalamic T-Type Calcium Channels as Targets for Hypnotics and General Anesthetics. Int J Mol Sci 2022; 23:ijms23042349. [PMID: 35216466 PMCID: PMC8876360 DOI: 10.3390/ijms23042349] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 12/19/2022] Open
Abstract
General anesthetics mainly act by modulating synaptic inhibition on the one hand (the potentiation of GABA transmission) or synaptic excitation on the other (the inhibition of NMDA receptors), but they can also have effects on numerous other proteins, receptors, and channels. The effects of general anesthetics on ion channels have been the subject of research since the publication of reports of direct actions of these drugs on ion channel proteins. In particular, there is considerable interest in T-type voltage-gated calcium channels that are abundantly expressed in the thalamus, where they control patterns of cellular excitability and thalamocortical oscillations during awake and sleep states. Here, we summarized and discussed our recent studies focused on the CaV3.1 isoform of T-channels in the nonspecific thalamus (intralaminar and midline nuclei), which acts as a key hub through which natural sleep and general anesthesia are initiated. We used mouse genetics and in vivo and ex vivo electrophysiology to study the role of thalamic T-channels in hypnosis induced by a standard general anesthetic, isoflurane, as well as novel neuroactive steroids. From the results of this study, we conclude that CaV3.1 channels contribute to thalamocortical oscillations during anesthetic-induced hypnosis, particularly the slow-frequency range of δ oscillations (0.5–4 Hz), by generating “window current” that contributes to the resting membrane potential. We posit that the role of the thalamic CaV3.1 isoform of T-channels in the effects of various classes of general anesthetics warrants consideration.
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Coulter I, Timic Stamenic T, Eggan P, Fine BR, Corrigan T, Covey DF, Yang L, Pan JQ, Todorovic SM. Different roles of T-type calcium channel isoforms in hypnosis induced by an endogenous neurosteroid epipregnanolone. Neuropharmacology 2021; 197:108739. [PMID: 34339750 PMCID: PMC8478885 DOI: 10.1016/j.neuropharm.2021.108739] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 07/09/2021] [Accepted: 07/29/2021] [Indexed: 12/31/2022]
Abstract
BACKGROUND Many neuroactive steroids induce sedation/hypnosis by potentiating γ-aminobutyric acid (GABAA) currents. However, we previously demonstrated that an endogenous neuroactive steroid epipregnanolone [(3β,5β)-3-hydroxypregnan-20-one] (EpiP) exerts potent peripheral analgesia and blocks T-type calcium currents while sparing GABAA currents in rat sensory neurons. This study seeks to investigate the behavioral effects elicited by systemic administration of EpiP and to characterize its use as an adjuvant agent to commonly used general anesthetics (GAs). METHODS Here, we utilized electroencephalographic (EEG) recordings to characterize thalamocortical oscillations, as well as behavioral assessment and mouse genetics with wild-type (WT) and different knockout (KO) models of T-channel isoforms to investigate potential sedative/hypnotic and immobilizing properties of EpiP. RESULTS Consistent with increased oscillations in slower EEG frequencies, EpiP induced an hypnotic state in WT mice when injected alone intra-peritoneally (i.p.) and effectively facilitated anesthetic effects of isoflurane (ISO) and sevoflurane (SEVO). The CaV3.1 (Cacna1g) KO mice demonstrated decreased sensitivity to EpiP-induced hypnosis when compared to WT mice, whereas no significant difference was noted between CaV3.2 (Cacna1h), CaV3.3 (Cacna1i) and WT mice. Finally, when compared to WT mice, onset of EpiP-induced hypnosis was delayed in CaV3.2 KO mice but not in CaV3.1 and CaV3.3 KO mice. CONCLUSION We posit that EpiP may have an important role as novel hypnotic and/or adjuvant to volatile anesthetic agents. We speculate that distinct hypnotic effects of EpiP across all three T-channel isoforms is due to their differential expression in thalamocortical circuitry.
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Affiliation(s)
- Ian Coulter
- Department of Anesthesiology, University of Colorado,
Anschutz Medical Campus, Aurora 80045
| | - Tamara Timic Stamenic
- Department of Anesthesiology, University of Colorado,
Anschutz Medical Campus, Aurora 80045
| | - Pierce Eggan
- Department of Anesthesiology, University of Colorado,
Anschutz Medical Campus, Aurora 80045
| | - Brier R. Fine
- Department of Anesthesiology, University of Colorado,
Anschutz Medical Campus, Aurora 80045
| | - Timothy Corrigan
- Department of Pediatrics, Division of Neurology,
Translational Epilepsy Research Program, University of Colorado, Anschutz Medical
Campus, Aurora, CO 80045, USA
| | - Douglas F. Covey
- Department of Developmental Biology, Washington University
School of Medicine, St. Louis, MO 63110, USA;,Taylor Family Institute for Innovative Psychiatric
Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Lingling Yang
- Stanley Center for Psychiatric Research, Broad Institute of
Harvard and MIT
| | - Jen Q. Pan
- Stanley Center for Psychiatric Research, Broad Institute of
Harvard and MIT
| | - Slobodan M. Todorovic
- Department of Anesthesiology, University of Colorado,
Anschutz Medical Campus, Aurora 80045;,Neuroscience, University of Colorado, Anschutz Medical
Campus, Aurora 80045;,Pharmacology Graduate Programs, University of Colorado,
Anschutz Medical Campus, Aurora 80045
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Epipregnanolone as a Positive Modulator of GABA A Receptor in Rat Cerebellar and Hippocampus Neurons. Biomolecules 2021; 11:biom11060791. [PMID: 34074021 PMCID: PMC8225200 DOI: 10.3390/biom11060791] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/17/2021] [Accepted: 05/20/2021] [Indexed: 11/24/2022] Open
Abstract
Epipregnanolone (3β-hydroxy-5β-pregnan-20-one, Epi) is an endogenous steroid with important physiological effects and high affinity for GABAA receptors. The effect of Epi on GABA-induced chloride current (IGABA) in native neurons has hardly been studied. In this work, we studied the influence of Epi on the IGABA in the Purkinje cells of rat cerebellum and pyramidal neurons of rat hippocampus with the patch clamp technique. We showed that Epi is a positive modulator of the IGABA with EC50 of 5.7 µM in Purkinje cells and 9.3 µM in hippocampal neurons. Epi-induced potentiation of the IGABA was more potent at low vs. high GABA concentrations. Isopregnanolone (3β-hydroxy-5α-pregnan-20-one, Iso) counteracted Epi, reducing its potentiating effect by 2–2.3 times. Flumazenil, a nonsteroidal GABAA receptor antagonist, does not affect the Epi-induced potentiation. Comparison of the potentiating effects of Epi and allopregnanolone (3α-hydroxy-5α-pregnan-20-one, ALLO) showed that ALLO is, at least, a four times more potent positive modulator than Epi. The combined application of ALLO and Epi showed that the effects of these two steroids are not additive. We conclude that Epi has a dual effect on the IGABA increasing the current in the control solution and decreasing the stimulatory effect of ALLO.
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Abstract
OBJECTIVES Anxiety and adjustment disorders are among the most prevalent mental health conditions. This review focuses on γ-aminobutyric acid receptor type A (GABAAR)-mediated anxiolysis, describing the action of both endogenous and exogenous modulators of GABAAR. Future directions and innovative strategies to alleviate anxiety symptoms are discussed, with a particular emphasis on etifoxine. METHODS We used available data from the recent literature to update the mode of action of anxiolytics. We focussed our search on anxiolytics acting at GABAARs, as well as on the pharmacological properties of formerly and currently prescribed anxiolytics. RESULTS Considering the adverse effects of current treatments aimed at increasing inhibitory controls, optimisation of existing pharmacotherapies is of crucial importance. Among the alternative compounds targeting the GABAergic system, translocator protein (TSPO) ligands, such as etifoxine (EFX), which promote endogenous neurosteroidogenesis, are emerging as promising candidates for anxiety relief. In several papers comparing the efficacy of benzodiazepines and EFX, EFX showed interesting properties with limited side effects. Indeed, neurosteroids are potent GABAAR modulators with highly underrated anxiolytic properties. CONCLUSIONS Novel therapeutic strategies have been emerging following the recognition of neurosteroids as potent anxiolytics. Featured at the top of the list for well-tolerated anxiety relief, TSPO ligands such as etifoxine appear promising.
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Affiliation(s)
- Pierrick Poisbeau
- a Centre National de la Recherche Scientifique and University of Strasbourg, Institute for Cellular and Integrative Neuroscience (INCI) , Strasbourg , France
| | - Geraldine Gazzo
- a Centre National de la Recherche Scientifique and University of Strasbourg, Institute for Cellular and Integrative Neuroscience (INCI) , Strasbourg , France
| | - Laurent Calvel
- a Centre National de la Recherche Scientifique and University of Strasbourg, Institute for Cellular and Integrative Neuroscience (INCI) , Strasbourg , France
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Moran-Santa Maria MM, Sherman BJ, Brady KT, Baker NL, Hyer JM, Ferland C, McRae-Clark AL. Impact of endogenous progesterone on reactivity to yohimbine and cocaine cues in cocaine-dependent women. Pharmacol Biochem Behav 2017; 165:63-69. [PMID: 29126857 DOI: 10.1016/j.pbb.2017.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/30/2017] [Accepted: 11/02/2017] [Indexed: 10/18/2022]
Abstract
BACKGROUND AND OBJECTIVE Data from clinical and preclinical models of relapse suggest that progesterone attenuates cocaine-seeking behavior. In a recent study, we found that cocaine-dependent women reported greater subjective responses to cues that were preceded by a stressor than cocaine-dependent men. The objective of this study was to examine the impact of endogenous progesterone on the subjective and endocrine responses to a drug-paired cue that was preceded by a stressor in cocaine-dependent women. METHODS Cocaine-dependent women with low (<4ng/ml; n=16) and high (≥4ng/ml; n=9) plasma progesterone levels received either the alpha-2 adrenergic receptor antagonist yohimbine (21.6mg) or placebo before each of two cocaine-cue exposure sessions. Participants were tested under both conditions in a counterbalanced, double-blind fashion. Data were collected after study drug administration, immediately and at 5, 30, and 60min after the cue. RESULTS The anxiety response to the cue was differentially modified by progesterone levels under the two administration conditions (condition×progesterone level interaction, F1,23=9.8, p=0.005). Progesterone levels also modified the craving response to the cue differently under the placebo condition as compared to the yohimbine condition (condition×progesterone level interaction, F1,23=13.9, p=0.001). In both cases, high progesterone levels attenuated craving and anxiety response to the cue following yohimbine administration. There was no effect of progesterone levels on salivary cortisol or dehydroepiandrosterone under the placebo condition or under the yohimbine condition. CONCLUSIONS These preliminary data suggest that high levels of endogenous progesterone attenuate subjective responses to drug-cues that are preceded by a stressor. Importantly, these data support a growing literature demonstrating the protective effects of progesterone on the vulnerability to cocaine relapse in women.
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Affiliation(s)
- Megan M Moran-Santa Maria
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, 67 President Street, Charleston, SC 29425, USA
| | - Brian J Sherman
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, 67 President Street, Charleston, SC 29425, USA.
| | - Kathleen T Brady
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, 67 President Street, Charleston, SC 29425, USA; Ralph H Johnson VAMC, 109 Bee Street, Charleston, SC 29401, USA
| | - Nathaniel L Baker
- Department of Public Health Sciences, Medical University of South Carolina, 135 Cannon Street, Charleston, SC 29425, USA
| | - J Madison Hyer
- Department of Public Health Sciences, Medical University of South Carolina, 135 Cannon Street, Charleston, SC 29425, USA
| | - Chantelle Ferland
- Department of Neurosciences, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425, USA
| | - Aimee L McRae-Clark
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, 67 President Street, Charleston, SC 29425, USA
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Zeitler A, Kamoun N, Goyon S, Wahis J, Charlet A, Poisbeau P, Darbon P. Favouring inhibitory synaptic drive mediated by GABA(A) receptors in the basolateral nucleus of the amygdala efficiently reduces pain symptoms in neuropathic mice. Eur J Neurosci 2016; 43:1082-8. [PMID: 26913957 DOI: 10.1111/ejn.13217] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 02/16/2016] [Accepted: 02/18/2016] [Indexed: 01/06/2023]
Abstract
Pain is an emotion and neuropathic pain symptoms are modulated by supraspinal structures such as the amygdala. The central nucleus of the amygdala is often called the 'nociceptive amygdala', but little is known about the role of the basolateral amygdala. Here, we monitored the mechanical nociceptive thresholds in a mouse model of neuropathic pain and infused modulators of the glutamate/GABAergic transmission in the basolateral nucleus of the amygdala (BLA) via chronically-implanted cannulas. We found that an N-methyl-D-aspartate-type glutamate receptor antagonist (MK-801) exerted a potent antiallodynic effect, whereas a transient allodynia was induced after perfusion of bicuculline, a GABA(A) receptor antagonist. Potentiating GABA(A) receptor function using diazepam or etifoxine (a non-benzodiazepine anxiolytic) fully but transiently alleviated mechanical allodynia. Interestingly, the antiallodynic effect of etifoxine disappeared in animals that were incapable of producing 3α-steroids. Diazepam had a similar effect but of shorter duration. As indicated by patch-clamp recordings of BLA neurons, these effects were mediated by a potentiation of GABA(A) receptor-mediated synaptic transmission. Together with a presynaptic elevation of miniature inhibitory postsynaptic current frequency, the duration and amplitude of GABA(A) miniature inhibitory postsynaptic currents were also increased (postsynaptic effect). The analgesic contribution of endogenous neurosteroid seemed to be exclusively postsynaptic. This study highlights the importance of the BLA and the local inhibitory/excitatory neuronal network activity while setting the mechanical nociceptive threshold. Furthermore, it appears that promoting inhibition in this specific nucleus could fully alleviate pain symptoms. Therefore, the BLA could be a novel interesting target for the development of pharmacological or non-pharmacological therapies.
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Affiliation(s)
- Alexandre Zeitler
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR 3212 CNRS, Centre National de la Recherche Scientifique and University of Strasbourg, 5 rue Blaise Pascal, F-67084, Strasbourg Cedex, France
| | - Nisrine Kamoun
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR 3212 CNRS, Centre National de la Recherche Scientifique and University of Strasbourg, 5 rue Blaise Pascal, F-67084, Strasbourg Cedex, France
| | - Stéphanie Goyon
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR 3212 CNRS, Centre National de la Recherche Scientifique and University of Strasbourg, 5 rue Blaise Pascal, F-67084, Strasbourg Cedex, France
| | - Jérôme Wahis
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR 3212 CNRS, Centre National de la Recherche Scientifique and University of Strasbourg, 5 rue Blaise Pascal, F-67084, Strasbourg Cedex, France
| | - Alexandre Charlet
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR 3212 CNRS, Centre National de la Recherche Scientifique and University of Strasbourg, 5 rue Blaise Pascal, F-67084, Strasbourg Cedex, France.,University of Strasbourg Institute for Advanced Study (USIAS), Strasbourg, France
| | - Pierrick Poisbeau
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR 3212 CNRS, Centre National de la Recherche Scientifique and University of Strasbourg, 5 rue Blaise Pascal, F-67084, Strasbourg Cedex, France
| | - Pascal Darbon
- Institut des Neurosciences Cellulaires et Intégratives (INCI), UPR 3212 CNRS, Centre National de la Recherche Scientifique and University of Strasbourg, 5 rue Blaise Pascal, F-67084, Strasbourg Cedex, France
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Chakrabarti S, Qian M, Krishnan K, Covey DF, Mennerick S, Akk G. Comparison of Steroid Modulation of Spontaneous Inhibitory Postsynaptic Currents in Cultured Hippocampal Neurons and Steady-State Single-Channel Currents from Heterologously Expressed α1β2γ2L GABA(A) Receptors. Mol Pharmacol 2016; 89:399-406. [PMID: 26769414 DOI: 10.1124/mol.115.102202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 01/13/2016] [Indexed: 12/18/2022] Open
Abstract
Neuroactive steroids are efficacious modulators of γ-aminobutyric acid type A receptor (GABA(A)) receptor function. The effects of steroids on the GABA(A) receptor are typically determined by comparing steady-state single-channel open probability or macroscopic peak responses elicited by GABA in the absence and presence of a steroid. Due to differences in activation conditions (exposure duration, concentration of agonist), it is not obvious whether modulation measured using typical experimental protocols can be used to accurately predict the effect of a modulator on native receptors under physiologic conditions. In the present study, we examined the effects of 14 neuroactive steroids and analogs on the properties of spontaneous inhibitory postsynaptic currents (sIPSCs) in cultured rat hippocampal neurons. The goal was to determine whether the magnitude of modulation of the decay time course of sIPSCs correlates with the extent of modulation and kinetic properties of potentiation as determined in previous single-channel studies. The steroids were selected to cover a wide range of efficacy on heterologously expressed rat α1β2γ2L GABA(A) receptors, ranging from essentially inert to highly efficacious (strong potentiators of single-channel and macroscopic peak responses). The data indicate a strong correlation between prolongation of the decay time course of sIPSCs and potentiation of single-channel open probability. Furthermore, changes in intracluster closed time distributions were the single best predictor of prolongation of sIPSCs. We infer that the information obtained in steady-state single-channel recordings can be used to forecast modulation of synaptic currents.
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Affiliation(s)
- Sampurna Chakrabarti
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Mingxing Qian
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Kathiresan Krishnan
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Douglas F Covey
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Steven Mennerick
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Gustav Akk
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
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Rahmani B, Ghasemi R, Dargahi L, Ahmadiani A, Haeri A. Neurosteroids; potential underpinning roles in maintaining homeostasis. Gen Comp Endocrinol 2016; 225:242-250. [PMID: 26432100 DOI: 10.1016/j.ygcen.2015.09.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 09/14/2015] [Accepted: 09/28/2015] [Indexed: 12/31/2022]
Abstract
The neuroactive steroids which are synthesized in the brain and nervous system are known as "Neurosteroids". These steroids have crucial functions such as contributing to the myelination and organization of the brain connectivity. Under the stressful circumstances, the concentrations of neurosteroid products such as allopregnanolone (ALLO) and allotetrahydrodeoxycorticosterone (THDOC) alter. It has been suggested that these stress-derived neurosteroids modulate the physiological response to stress. Moreover, it has been demonstrated that the hypothalamic-pituitary-adrenal (HPA) axis mediates the physiological adaptation following stress in order to maintain homeostasis. Although several regulatory pathways have been introduced, the exact role of neurosteroids in controlling HPA axis is not clear to date. In this review, we intend to discern specific pathways associated with regulation of HPA axis in which neuroactive steroids have the main role. In this respect, we propose pathways that may be initiated after neurosteroidogenesis in different brain subregions following acute stress which are potentially capable of activating or inhibiting the HPA axis.
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Affiliation(s)
- Behrouz Rahmani
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Rasoul Ghasemi
- Department of Physiology and Neurophysiology Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Leila Dargahi
- NeuroBiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Abolhassan Ahmadiani
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Ali Haeri
- Department of Pharmacology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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Zell V, Juif PÉ, Hanesch U, Poisbeau P, Anton F, Darbon P. Corticosterone analgesia is mediated by the spinal production of neuroactive metabolites that enhance GABAergic inhibitory transmission on dorsal horn rat neurons. Eur J Neurosci 2014; 41:390-7. [DOI: 10.1111/ejn.12796] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 10/01/2014] [Accepted: 10/29/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Vivien Zell
- Centre National de la Recherche Scientifique and University of Strasbourg; Institut des Neurosciences Cellulaires et Intégratives; 5 rue Blaise Pascal F-67084 Strasbourg France
- Laboratory of Neurophysiology and Psychobiology; University of Luxembourg; Luxembourg City Luxembourg
| | - Pierre-Éric Juif
- Centre National de la Recherche Scientifique and University of Strasbourg; Institut des Neurosciences Cellulaires et Intégratives; 5 rue Blaise Pascal F-67084 Strasbourg France
| | - Ulrike Hanesch
- Laboratory of Neurophysiology and Psychobiology; University of Luxembourg; Luxembourg City Luxembourg
| | - Pierrick Poisbeau
- Centre National de la Recherche Scientifique and University of Strasbourg; Institut des Neurosciences Cellulaires et Intégratives; 5 rue Blaise Pascal F-67084 Strasbourg France
| | - Fernand Anton
- Laboratory of Neurophysiology and Psychobiology; University of Luxembourg; Luxembourg City Luxembourg
| | - Pascal Darbon
- Centre National de la Recherche Scientifique and University of Strasbourg; Institut des Neurosciences Cellulaires et Intégratives; 5 rue Blaise Pascal F-67084 Strasbourg France
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Ayoola C, Hwang SM, Hong SJ, Rose KE, Boyd C, Bozic N, Park JY, Osuru HP, DiGruccio MR, Covey DF, Jevtovic-Todorovic V, Todorovic SM. Inhibition of CaV3.2 T-type calcium channels in peripheral sensory neurons contributes to analgesic properties of epipregnanolone. Psychopharmacology (Berl) 2014; 231:3503-3515. [PMID: 24800894 PMCID: PMC4135044 DOI: 10.1007/s00213-014-3588-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 04/10/2014] [Indexed: 11/28/2022]
Abstract
RATIONALE T-type calcium channels (T-channels) play an important role in controlling excitability of nociceptors. We have previously shown that a synthetic series of 5β-reduced steroids induce a voltage-dependent blockade of T-currents in rat dorsal root ganglia (DRG) cells in vitro and induce potent analgesia to thermal stimuli in rats in vivo (Mol Pharmacol 66:1223-1235, 2004). OBJECTIVES Here, we investigated the effects of the endogenous 5β-reduced neuroactive steroid molecule, epipregnanolone [(3β,5β)-3-hydroxypregnan-20-one], on peripheral nociception. METHODS We used acutely dissociated DRG cells in vitro from adult rats as well as in vivo pain studies in mice and rats to investigate the effects of epipregnanolone on DRG T-channels. RESULTS We found that epipregnanolone reversibly blocked DRG T-currents with a half-maximal inhibitory concentration (IC50) of 2 μM and stabilized the channel in the inactive state. However, sodium, potassium, and gamma-aminobutyric acid (GABA)-gated ionic currents were not sensitive to the blocking effects of epipregnanolone even at 10 μM. In ensuing in vivo studies, we found that intraplantar (i.pl.) injections of epipregnanolone directly into peripheral receptive fields reduced responses to nociceptive heat stimuli in rats in a dose-dependent fashion. Furthermore, i.pl. epipregnanolone injections effectively reduced responses to peripheral nociceptive thermal and mechanical stimuli in wild-type mice but had no effect on the responses of CaV3.2 knockout mice. CONCLUSIONS We conclude that the inhibition of peripheral CaV3.2 T-channels contributes to the potent analgesic effect of the endogenous steroid epipregnanolone.
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Affiliation(s)
- Christine Ayoola
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA
| | - Sung Mi Hwang
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA,Department of Anesthesiology and Pain Medicine, Chuncheon Sacred Heart Hospital, College of Medicine, Hallym University, Seoul, Republic of Korea
| | - Sung Jun Hong
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA,Department of Anesthesiology and Pain Medicine, Kangdong Sacred Heart Hospital, College of Medicine, Hallym University Seoul, Republic of Korea
| | - Kirstin E. Rose
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA
| | - Christopher Boyd
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA
| | - Neda Bozic
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA
| | - Ji-Yong Park
- Department of Anesthesiology and Pain Medicine, College of Medicine, Korea University, Seoul, Republic of Korea
| | - Hari Prasad Osuru
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA
| | - Michael R. DiGruccio
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA,Department of Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, VA
| | - Douglas F. Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO
| | - Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA,Department of Neuroscience, University of Virginia Health System, Charlottesville, VA,Department of Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, VA
| | - Slobodan M. Todorovic
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA,Department of Neuroscience, University of Virginia Health System, Charlottesville, VA,Department of Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, VA,Corresponding Author: Slobodan M. Todorovic Department of Anesthesiology University of Virginia Health System PO Box 800710 Charlottesville, VA 22908 Phone 434-924-2283; Fax 434-982-0019
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Zell V, Hanesch U, Poisbeau P, Anton F, Darbon P. Plasma glucocorticoids differentially modulate phasic and tonic GABA inhibition during early postnatal development in rat spinal lamina II. Neurosci Lett 2014; 578:39-43. [DOI: 10.1016/j.neulet.2014.06.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 06/05/2014] [Accepted: 06/10/2014] [Indexed: 10/25/2022]
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Poisbeau P, Keller AF, Aouad M, Kamoun N, Groyer G, Schumacher M. Analgesic strategies aimed at stimulating the endogenous production of allopregnanolone. Front Cell Neurosci 2014; 8:174. [PMID: 24987335 PMCID: PMC4060572 DOI: 10.3389/fncel.2014.00174] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Accepted: 06/05/2014] [Indexed: 01/07/2023] Open
Abstract
A growing number of studies indicate that 3-alpha reduced neurosteroids are remarkable analgesics in various pain states. This is the case for allopregnanolone (AP), one of the most potent endogenous positive allosteric modulators of GABAA receptor function. From the pioneering work of Hans Selye, who described the sedative properties of steroids, synthetic compounds resembling the progesterone metabolite AP have been developed. If some of them have been used as anesthetics, it seems difficult to propose them as a therapeutic option for pain since they display several adverse side effects such as sedation, amnesia and functional tolerance. An alternative strategy, chosen by few laboratories around the world, is aimed at stimulating the local production of 3-alpha reduced neurosteroids in order to limit these well-known side effects. This pharmacological approach has the advantage of targeting specific structures, fully equipped with the necessary biosynthetic enzymatic machinery, where neurosteroids already act as endogenous pain modulators. The various pharmacological trials which attempted to treat pain symptoms by stimulating the production of 3-alpha reduced neurosteroids are reviewed here, as well as novel neurotransmitter systems possibly regulating their endogenous production.
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Affiliation(s)
- Pierrick Poisbeau
- Molecular Determinants of Pain, Institute for Cellular and Integrative Neurosciences (INCI), UPR Centre National de la Recherche Scientifique (CNRS) 3212 and University of Strasbourg Strasbourg, France
| | - Anne Florence Keller
- Molecular Determinants of Pain, Institute for Cellular and Integrative Neurosciences (INCI), UPR Centre National de la Recherche Scientifique (CNRS) 3212 and University of Strasbourg Strasbourg, France ; Rhenovia Pharma Mulhouse, France
| | - Maya Aouad
- Molecular Determinants of Pain, Institute for Cellular and Integrative Neurosciences (INCI), UPR Centre National de la Recherche Scientifique (CNRS) 3212 and University of Strasbourg Strasbourg, France
| | - Nisrine Kamoun
- Molecular Determinants of Pain, Institute for Cellular and Integrative Neurosciences (INCI), UPR Centre National de la Recherche Scientifique (CNRS) 3212 and University of Strasbourg Strasbourg, France
| | - Ghislaine Groyer
- UMR 788 Neuroprotection and Neuroregeneration: Neuroactive Small Molecules, Institut National de la Santé et de la Recherche Médicale (INSERM) and University Paris-Sud Kremlin-Bicêtre, France
| | - Michael Schumacher
- UMR 788 Neuroprotection and Neuroregeneration: Neuroactive Small Molecules, Institut National de la Santé et de la Recherche Médicale (INSERM) and University Paris-Sud Kremlin-Bicêtre, France
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Dysfunctional astrocytic and synaptic regulation of hypothalamic glutamatergic transmission in a mouse model of early-life adversity: relevance to neurosteroids and programming of the stress response. J Neurosci 2014; 33:19534-54. [PMID: 24336719 DOI: 10.1523/jneurosci.1337-13.2013] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Adverse early-life experiences, such as poor maternal care, program an abnormal stress response that may involve an altered balance between excitatory and inhibitory signals. Here, we explored how early-life stress (ELS) affects excitatory and inhibitory transmission in corticotrophin-releasing factor (CRF)-expressing dorsal-medial (mpd) neurons of the neonatal mouse hypothalamus. We report that ELS associates with enhanced excitatory glutamatergic transmission that is manifested as an increased frequency of synaptic events and increased extrasynaptic conductance, with the latter associated with dysfunctional astrocytic regulation of glutamate levels. The neurosteroid 5α-pregnan-3α-ol-20-one (5α3α-THPROG) is an endogenous, positive modulator of GABAA receptors (GABAARs) that is abundant during brain development and rises rapidly during acute stress, thereby enhancing inhibition to curtail stress-induced activation of the hypothalamic-pituitary-adrenocortical axis. In control mpd neurons, 5α3α-THPROG potently suppressed neuronal discharge, but this action was greatly compromised by prior ELS exposure. This neurosteroid insensitivity did not primarily result from perturbations of GABAergic inhibition, but rather arose functionally from the increased excitatory drive onto mpd neurons. Previous reports indicated that mice (dams) lacking the GABAAR δ subunit (δ(0/0)) exhibit altered maternal behavior. Intriguingly, δ(0/0) offspring showed some hallmarks of abnormal maternal care that were further exacerbated by ELS. Moreover, in common with ELS, mpd neurons of δ(0/0) pups exhibited increased synaptic and extrasynaptic glutamatergic transmission and consequently a blunted neurosteroid suppression of neuronal firing. This study reveals that increased synaptic and tonic glutamatergic transmission may be a common maladaptation to ELS, leading to enhanced excitation of CRF-releasing neurons, and identifies neurosteroids as putative early regulators of the stress neurocircuitry.
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Enhanced GABAergic transmission in the central nucleus of the amygdala of genetically selected Marchigian Sardinian rats: alcohol and CRF effects. Neuropharmacology 2012; 67:337-48. [PMID: 23220399 DOI: 10.1016/j.neuropharm.2012.11.026] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 11/21/2012] [Accepted: 11/23/2012] [Indexed: 12/31/2022]
Abstract
The GABAergic system in the central amygdala (CeA) plays a major role in ethanol dependence and the anxiogenic-like response to ethanol withdrawal. Alcohol dependence is associated with increased corticotropin releasing factor (CRF) influence on CeA GABA release and CRF type 1 receptor (CRF(1)) antagonists prevent the excessive alcohol consumption associated with dependence. Genetically selected Marchigian Sardinian (msP) rats have an overactive extrahypothalamic CRF(1) system, are highly sensitive to stress, and display an innate preference for alcohol. The present study examined differences in CeA GABAergic transmission and the effects of ethanol, CRF and a CRF(1) antagonist in msP, Sprague Dawley, and Wistar rats using an electrophysiological approach. We found no significant differences in membrane properties or mean amplitude of evoked GABA(A)-inhibitory postsynaptic potentials (IPSPs). However, paired-pulse facilitation (PPF) ratios of evoked IPSPs were significantly lower and spontaneous miniature inhibitory postsynaptic current (mIPSC) frequencies were higher in msP rats, suggesting increased CeA GABA release in msP as compared to Sprague Dawley and Wistar rats. The sensitivity of spontaneous GABAergic transmission to ethanol (44 mM), CRF (200 nM) and CRF(1) antagonist (R121919, 1 μM) was comparable in msP, Sprague Dawley, and Wistar rats. However, a history of ethanol drinking significantly increased the baseline mIPSC frequency and decreased the effects of a CRF(1) antagonist in msP rats, suggesting increased GABA release and decreased CRF(1) sensitivity. These results provide electrophysiological evidence that msP rats display distinct CeA GABAergic activity as compared to Sprague Dawley and Wistar rats. The elevated GABAergic transmission observed in naïve msP rats is consistent with the neuroadaptations reported in Sprague Dawley rats after the development of ethanol dependence.
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Johansson AGM, Nikamo P, Schalling M, Landén M. AKR1C4 gene variant associated with low euthymic serum progesterone and a history of mood irritability in males with bipolar disorder. J Affect Disord 2011; 133:346-51. [PMID: 21570127 DOI: 10.1016/j.jad.2011.04.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 04/08/2011] [Accepted: 04/08/2011] [Indexed: 01/27/2023]
Abstract
BACKGROUND Irritable mood during mood elevation is common in bipolar disorder. The progesterone metabolite allopregnanolone (ALLO) has been implicated in other disorders presenting with irritability. This study aimed to test whether a history of manic/hypomanic irritability is associated with low serum progesterone levels; and whether single nucleotide polymorphisms (SNPs) in gene coding for steroidogenetic enzymes (HSD3B2, SRD5A1 and AKR1C4 were coupled to previous manic irritability and/or with serum progesterone concentrations. METHODS Morning serum progesterone concentrations during euthymic phase of bipolar illness types 1 and 2 were assessed in 71 males and 107 females. Previous manic/hypomanic irritability was assessed using the Affective Disorders Evaluation. Selected SNPs were analyzed: i) aldoketoreductase-type-4 (AKR1C4 - rs17306779, rs3829125, rs10904440, rs12762017, and rs11253048), ii) 3-β-hydroxysteroid-dehydrogenase (HSD3B2 - rs4659174, rs2854964, and rs3765948), iii) steroid-5-α-reductase (SRD5A1 - rs8192139, rs181807, rs3822430, and rs3736316). RESULTS In males, progesterone concentrations were lower in those who had shown manic/hypomanic irritability compared with nonirritable (F=7.05, p=0.0099). SNPs rs17306779, rs3829125, and rs10904440 were associated with manic/hypomanic irritability. A cystine to serine change at position 145 in AKR1C4 (rs3829125) was associated with lower serum progesterone (F=6.34, p=0.014). There were no associations in females. LIMITATIONS Relatively small sample sizes. CONCLUSION Low progesterone levels and a cystine to serine change at position 145 in AKR1C4 gene are associated with manic/hypomanic irritability in males. Given that the enzyme AKR1C4 has both dehydrogenating and reductive activities in the steroidogenetic pathway, a missense variation in the gene may predispose to manic/hypomanic irritability by altering the relationship between progesterone and ALLO concentrations in the brain.
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Affiliation(s)
- Anette G M Johansson
- Division of Psychiatry, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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Traish AM, Hassani J, Guay AT, Zitzmann M, Hansen ML. Adverse Side Effects of 5α‐Reductase Inhibitors Therapy: Persistent Diminished Libido and Erectile Dysfunction and Depression in a Subset of Patients. J Sex Med 2011; 8:872-84. [DOI: 10.1111/j.1743-6109.2010.02157.x] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Majeed Y, Agarwal AK, Naylor J, Seymour VAL, Jiang S, Muraki K, Fishwick CWG, Beech DJ. Cis-isomerism and other chemical requirements of steroidal agonists and partial agonists acting at TRPM3 channels. Br J Pharmacol 2011; 161:430-41. [PMID: 20735426 DOI: 10.1111/j.1476-5381.2010.00892.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND AND PURPOSE The transient receptor potential melastatin-3 (TRPM3) channel forms calcium-permeable, non-selective, cationic channels that are stimulated by pregnenolone sulphate (PregS). Here, we aimed to define chemical requirements of this acute steroid action and potentially reveal novel stimulators with physiological relevance. EXPERIMENTAL APPROACH We used TRPM3 channels over-expressed in HEK 293 cells, with intracellular calcium measurement and whole-cell patch-clamp recording techniques. KEY RESULTS The stimulation of TRPM3 channels was confined to PregS and closely related steroids and not mimicked by other major classes of steroids, including progesterone. Relatively potent stimulation of TRPM3-dependent calcium entry was observed. A sulphate group positioned at ring A was important for strong stimulation but more striking was the requirement for a cis (beta) configuration of the side group, revealing previously unrecognized stereo-selectivity and supporting existence of a specific binding site. A cis-oriented side group on ring A was not the only feature necessary for high activity because loss of the double bond in ring B reduced potency and loss of the acetyl group at ring D reduced efficacy and potency. Weak steroid stimulators of TRPM3 channels inhibited effects of PregS, suggesting partial agonism. In silico screening of chemical libraries for non-steroid modulators of TRPM3 channels revealed the importance of the steroid backbone for stimulatory effects. CONCLUSIONS AND IMPLICATIONS Our data defined some of the chemical requirements for acute stimulation of TRPM3 channels by steroids, supporting the existence of a specific and unique steroid binding site. Epipregnanolone sulphate was identified as a novel TRPM3 channel stimulator.
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Affiliation(s)
- Y Majeed
- Multidisciplinary Cardiovascular Research Centre and Institute of Membrane & Systems Biology, Faculties of Biological Sciences, University of Leeds, Leeds, UK
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Abstract
Neurosteroids represent a class of endogenous steroids that are synthesized in the brain, the adrenals, and the gonads and have potent and selective effects on the GABAA-receptor. 3α-hydroxy A-ring reduced metabolites of progesterone, deoxycorticosterone, and testosterone are positive modulators of GABA(A)-receptor in a non-genomic manner. Allopregnanolone (3α-OH-5α-pregnan-20-one), 5α-androstane-3α, 17α-diol (Adiol), and 3α5α-tetrahydrodeoxycorticosterone (3α5α-THDOC) enhance the GABA-mediated Cl(-) currents acting on a site (or sites) distinct from the GABA, benzodiazepine, barbiturate, and picrotoxin binding sites. 3α5α-P and 3α5α-THDOC potentiate synaptic GABA(A)-receptor function and activate δ-subunit containing extrasynaptic receptors that mediate tonic currents. On the contrary, 3β-OH pregnane steroids and pregnenolone sulfate (PS) are GABA(A)-receptor antagonists and induce activation-dependent inhibition of the receptor. The activities of neurosteroid are dependent on brain regions and types of neurons. In addition to the slow genomic action of the parent steroids, the non-genomic, and rapid actions of neurosteroids play a significant role in the GABA(A)-receptor function and shift in mood and memory function. This review describes molecular mechanisms underlying neurosteroid action on the GABA(A)-receptor, mood changes, and cognitive functions.
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Affiliation(s)
- Mingde Wang
- Section of Obstetrics and Gynecology, Department of Clinical Science, Umeå Neurosteroid Research Center, Umeå UniversityUmeå, Sweden
- *Correspondence: Mingde Wang, Section of Obstetrics and Gynecology, Department of Clinical Science, Umeå Neurosteroid Research Center, Umeå University, 901 85 Umeå, Sweden. e-mail:
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Magnaghi V. GABA and neuroactive steroid interactions in glia: new roles for old players? Curr Neuropharmacol 2010; 5:47-64. [PMID: 18615153 DOI: 10.2174/157015907780077132] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2006] [Revised: 04/24/2006] [Accepted: 07/27/2006] [Indexed: 02/06/2023] Open
Abstract
In recent years it has becoming clear that glial cells of the central and peripheral nervous system play a crucial role from the earliest stages of development throughout adult life. Glial cells are important for neuronal plasticity, axonal conduction and synaptic transmission. In this respect, glial cells are able to produce, uptake and metabolize many factors that are essential for neuronal physiology, including classic neurotransmitters and neuroactive steroids. In particular, neuroactive steroids, which are mainly synthesized by glial cells, are able to modulate some neurotransmitter receptors affecting both glia and neurons. Among the signaling systems that are specialized for neuron-glial communication, we can include neurotransmitter GABA.The main focus of this review is to illustrate the cross-talk between neurons and glial cells in terms of GABA neurotransmission and actions of neuroactive steroids. To this purpose, we will review the presence of the different GABA receptors in the glial cells of the central and peripheral nervous system. Then, we will discuss their modulation by some neuroactive steroids.
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Affiliation(s)
- Valerio Magnaghi
- Department of Endocrinology and Center of Excellence on Neurodegenerative Disease, University of Milan, Italy.
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Pharmacological characterization of a novel positive modulator at alpha 4 beta 3 delta-containing extrasynaptic GABA(A) receptors. Neuropharmacology 2010; 58:702-11. [PMID: 20060846 DOI: 10.1016/j.neuropharm.2009.12.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 11/30/2009] [Accepted: 12/23/2009] [Indexed: 01/25/2023]
Abstract
The in vitro and in vivo pharmacological effects of [2-amino-4-(2,4,6-trimethylbenzylamino)-phenyl]-carbamic acid ethyl ester (AA29504), which is a close analogue of retigabine, have been investigated. AA29504 induced a rightward shift of the activation threshold at cloned KCNQ2, 2/3 and 4 channels expressed in Xenopus oocytes, with a potency 3-4fold lower than retigabine. AA29504 (1 muM) had no agonist activity when tested at alpha(1)beta(3)gamma(2s) or alpha(4)beta(3)delta GABA(A) receptors expressed in Xenopus oocytes, but left-shifted the EC(50) for GABA and gaboxadol (THIP) at both receptors. The maximum GABA response at alpha(1)beta(3)gamma(2s) receptors was unchanged by AA29504 (1 muM), but increased 3-fold at alpha(4)beta(3)delta receptors. In slices prepared from the prefrontal cortex of adult rats AA29504 had no effect alone on the average IPSC or the tonic current in layer II/III pyramidal neurons, but potentiated the effect of gaboxadol on both phasic and tonic currents. Thus, the effects of gaboxadol could be positively modulated by AA29504. Systemic administration of AA29504 at doses relevant for modulating GABA transmission produced anxiolytic effects and reduced motor coordination consistent with activity at GABA(A) receptors. We conclude that AA29504 exerts a major action via alpha(4)beta(3)delta-containing GABA(A) receptors, which will be important for interpreting its effect in vivo.
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Chesnoy-Marchais D. Progesterone and allopregnanolone enhance the miniature synaptic release of glycine in the rat hypoglossal nucleus. Eur J Neurosci 2009; 30:2100-11. [PMID: 19930400 DOI: 10.1111/j.1460-9568.2009.07013.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
It is well known that progesterone is synthesised and metabolised within the nervous system, and that one of its metabolites, allopregnanolone, potentiates the activity of GABA receptor anionic channels and modulates GABAergic neurotransmission. Progesterone is now under clinical trial for its neuroprotective properties, but its possible effects on neurotransmission have not yet been fully explored. The present study investigated acute effects of progesterone on the other major type of synaptic inhibition, glycinergic neurotransmission. Spontaneous glycinergic miniature currents were recorded in hypoglossal motoneurons, using the whole-cell patch-clamp technique in rat brainstem slices. A 20-min superfusion with progesterone (1 mum) triggered an increase in the frequency of glycinergic miniatures, whereas no effect of progesterone was observed after block with finasteride (5 mum) of 5alpha -reductase, the first enzymatic step leading from progesterone to allopregnanolone. The effect of progesterone could be mimicked by superfusion with allopregnanolone (0.3 mum), whereas no effect was induced by epiallopregnanolone. Thus, progesterone can increase the synaptic miniature release of glycine and this effect appears to be indirect, resulting from its metabolism into 5alpha-reduced derivatives, in particular into allopregnanolone. A low concentration of an exogenous GABA(A) agonist can also increase the frequency of inhibitory miniature currents in hypoglossal motoneurons. Thus, the effects of progesterone and allopregnanolone on glycine release can be at least partly explained by the potentiation of the activity of depolarizing presynaptic GABA receptor channels. The increase in the tonic synaptic release of a major inhibitory neurotransmitter should reduce the excitability of the neurons and contribute to their protection against excitotoxicity.
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Affiliation(s)
- Dominique Chesnoy-Marchais
- UMR 788 INSERM-University Paris-Sud 11 Steroids, neuroprotection and neuroregeneration, Bâtiment Grégory Pincus, 80 rue du Général Leclerc, 94276 Le Kremlin-Bicêtre Cedex, France.
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Charlet A, Lasbennes F, Darbon P, Poisbeau P. Fast non-genomic effects of progesterone-derived neurosteroids on nociceptive thresholds and pain symptoms. Pain 2008; 139:603-609. [PMID: 18614289 DOI: 10.1016/j.pain.2008.06.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Revised: 06/10/2008] [Accepted: 06/10/2008] [Indexed: 11/18/2022]
Abstract
Fast Inhibitory controls mediated by glycine (GlyRs) and GABAA receptors (GABAARs) play an important role to prevent the apparition of pathological pain symptoms of allodynia and hyperalgesia. The use of positive allosteric modulators of these receptors, specifically expressed in the spinal cord, may represent an interesting strategy to limit or block pain expression. In this study, we have used stereoisomers of progesterone metabolites, acting only via non-genomic effects, in order to evaluate the contribution of GlyRs and GABAARs for the reduction of mechanical and thermal heat hypernociception. We show that 3alpha neurosteroids were particularly efficient to elevate nociceptive thresholds in naive animal. It also reduced mechanical allodynia and thermal heat hyperalgesia in the carrageenan model of inflammatory pain. This effect is likely to be mediated by GABAA receptors since 3beta isomer was inefficient. More interestingly, 3alpha5beta neurosteroid was only efficient on mechanical allodynia while having no effect on thermal heat hyperalgesia. We characterized these paradoxical effects of 3alpha5beta neurosteroid using the strychnine and bicuculline models of allodynia. We clearly show that 3alpha5beta neurosteroid exerts an antinociceptive effect via a positive allosteric modulation of GABAARs but, at the same time, is pronociceptive by reducing GlyR function. This illustrates the importance of the inhibitory amino acid receptor channels and their allosteric modulators in spinal pain processing. Moreover, our results indicate that neurosteroids, which are synthesized in the dorsal horn of the spinal cord and have limited side effects, may be of significant interest in order to treat pathological pain symptoms.
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Affiliation(s)
- Alexandre Charlet
- Institut des Neurosciences Cellulaires et Intégratives, UMR 7168 Centre national de la Recherche Scientifique - Université Louis Pasteur, Department Nociception and Pain, 21 rue René Descartes, F-67084 Strasbourg Cedex, Strasbourg, France
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Étifoxine, neurostéroïdes et anxiété. Encephale 2008. [DOI: 10.1016/s0013-7006(08)71390-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Biggio G, Concas A, Follesa P, Sanna E, Serra M. Stress, ethanol, and neuroactive steroids. Pharmacol Ther 2007; 116:140-71. [PMID: 17555824 PMCID: PMC3000046 DOI: 10.1016/j.pharmthera.2007.04.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Accepted: 04/06/2007] [Indexed: 12/27/2022]
Abstract
Neurosteroids play a crucial role in stress, alcohol dependence and withdrawal, and other physiological and pharmacological actions by potentiating or inhibiting neurotransmitter action. This review article focuses on data showing that the interaction among stress, ethanol, and neuroactive steroids may result in plastic molecular and functional changes of GABAergic inhibitory neurotransmission. The molecular mechanisms by which stress-ethanol-neuroactive steroids interactions can produce plastic changes in GABA(A) receptors have been studied using different experimental models in vivo and in vitro in order to provide useful evidence and new insights into the mechanisms through which acute and chronic ethanol and stress exposure modulate the activity of GABAergic synapses. We show detailed data on a) the effect of acute and chronic stress on peripheral and brain neurosteroid levels and GABA(A) receptor gene expression and function; b) ethanol-stimulated brain steroidogenesis; c) plasticity of GABA(A) receptor after acute and chronic ethanol exposure. The implications of these new mechanistic insights to our understanding of the effects of ethanol during stress are also discussed. The understanding of these neurochemical and molecular mechanisms may shed new light on the physiopathology of diseases, such as anxiety, in which GABAergic transmission plays a pivotal role. These data may also lead to the need for new anxiolytic, hypnotic and anticonvulsant selective drugs devoid of side effects.
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Affiliation(s)
- Giovanni Biggio
- Department of Experimental Biology, Center of Excellence for the Neurobiology of Dependence, University of Cagliari, Cagliari, Italy.
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Ing T, Poulter MO. Diversity of GABA(A) receptor synaptic currents on individual pyramidal cortical neurons. Eur J Neurosci 2007; 25:723-34. [PMID: 17313570 DOI: 10.1111/j.1460-9568.2007.05331.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Miniature GABA(A) receptor-mediated inhibitory postsynaptic currents (mIPSCs) in cortical pyramidal neurons have previously been categorized into two types: small amplitude mIPSCs with a mono-exponential deactivation (mono-mIPSCs) and relatively larger mIPSCs with bi-exponential deactivation (bi-mIPSCs). The aim of this study was to determine if the GABA(A) channels that underlie these mIPSCSs are molecularly distinct. We found, using non-stationary noise analysis, that the difference in their amplitude could be not accounted for by their single channel conductance (both were 40 pS). Next, using alpha subunit selective GABA(A) receptor modulators, we examined the identity of the alpha subunits that may be expressed in the synapses that give rise to these mIPSCs. Zolpidem (100 and 500 nM, alpha1 selective) affected the deactivation of a subset of the mono-mIPSCs, indicating that alpha1 subunits are not highly expressed in these synapses. However, zolpidem (100 nM) prolonged the deactivation of all bi-mIPSCs, indicating a high abundance of alpha1 subunits in these synapses. SB-205384 (alpha3 selective) had no effect on the mono-mIPSCs but the bi-mIPSCs were prolonged. Furosemide (alpha4 selective) reduced the amplitude of only the mono-mIPSCs. L655,708 (alpha5 selective) reduced the amplitude of both populations and shortened the duration of the mono-mIPSCs. Finally, we found that the neuroactive steroid pregesterone sulphate reduced the amplitude of both mIPSC types. These results provide pharmacological evidence that synapses on cortical pyramidal neurons are molecularly distinct. The purpose of these different types of synapses may be to provide different inhibitory timing patterns on these cells.
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Affiliation(s)
- Timothy Ing
- Neuroscience Research Institute, Department of Psychology, Carleton University, Ottawa, Ontario, Canada
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Herd MB, Belelli D, Lambert JJ. Neurosteroid modulation of synaptic and extrasynaptic GABA(A) receptors. Pharmacol Ther 2007; 116:20-34. [PMID: 17531325 DOI: 10.1016/j.pharmthera.2007.03.007] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Accepted: 03/29/2007] [Indexed: 02/04/2023]
Abstract
Certain naturally occurring pregnane steroids act in a nongenomic manner to potently and selectively enhance the interaction of the inhibitory neurotransmitter GABA with the GABA(A) receptor. Consequently such steroids exhibit anxiolytic, anticonvulsant, analgesic, sedative, hypnotic, and anesthetic properties. In both physiological and pathophysiological scenarios, the pregnane steroids may function as endocrine messengers (e.g., produced in the periphery and cross the blood-brain barrier) to influence behaviour. However, additionally "neurosteroids" can be synthesised in the brain and spinal cord to act in a paracrine or autocrine manner and thereby locally influence neuronal activity. Given the ubiquitous expression of the GABA(A) receptor throughout the mammalian central nervous system (CNS), physiological, pathophysiological, or drug-induced pertubations of neurosteroid levels may be expected to produce widespread changes in brain excitability. However, the neurosteroid/GABA(A) receptor interaction is brain region and indeed neuron specific. The molecular basis of this specificity will be reviewed here, including (1) the importance of the subunit composition of the GABA(A) receptor; (2) how protein phosphorylation may dynamically influence the sensitivity of GABA(A) receptors to neurosteroids; (3) the impact of local steroid metabolism; and (4) the emergence of extrasynaptic GABA(A) receptors as a neurosteroid target.
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Affiliation(s)
- Murray B Herd
- Neuroscience Institute, Ninewells Hospital and Medical School, Dundee University, Dundee DD19SY, Scotland, United Kingdom
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Steroid modulation of GABAA receptor-mediated transmission in the hypothalamus: effects on reproductive function. Neuropharmacology 2007; 52:1439-53. [PMID: 17433821 DOI: 10.1016/j.neuropharm.2007.01.022] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 01/30/2007] [Accepted: 01/31/2007] [Indexed: 10/23/2022]
Abstract
The hypothalamus, the seat of neuroendocrine control, is exquisitely sensitive to gonadal steroids. For decades it has been known that androgens, estrogens and progestins, acting through nuclear hormone receptors, elicit both organizational and activational effects in the hypothalamus and basal forebrain that are essential for reproductive function. While changes in gene expression mediated by these classical hormone pathways are paramount in governing both sexual differentiation and the neural control of reproduction, it is also clear that steroids impart critical control of neuroendocrine functions through non-genomic mechanisms. Specifically, endogenous neurosteroid derivatives of deoxycorticosterone, progesterone and testosterone, as well and synthetic anabolic androgenic steroids that are self-administered as drugs of abuse, elicit acute effects via allosteric modulation of gamma-aminobutyric acid type A receptors. GABAergic transmission within the hypothalamus and basal forebrain is a key regulator of pubertal onset, the expression of sexual behaviors, pregnancy and parturition. Summarized here are the known actions of steroid modulators on GABAergic transmission within the hypothalamus/basal forebrain, with a focus on the medial preoptic area and the supraoptic/paraventricular nuclei that are known to be central players in the control of reproduction.
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Kaura V, Ingram CD, Gartside SE, Young AH, Judge SJ. The progesterone metabolite allopregnanolone potentiates GABA(A) receptor-mediated inhibition of 5-HT neuronal activity. Eur Neuropsychopharmacol 2007; 17:108-15. [PMID: 16574382 DOI: 10.1016/j.euroneuro.2006.02.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 02/14/2006] [Indexed: 11/24/2022]
Abstract
The dorsal raphe nucleus (DRN) is the origin of much of the 5-HT innervation of the forebrain. The activity of DRN 5-HT neurons is regulated by a number of receptors including GABA(A) and 5-HT(1A) inhibitory receptors and by excitatory alpha(1)-adrenoceptors. Using in vitro electrophysiological recording we investigated the action of progesterone and its metabolite, allopregnanolone on receptor-mediated responses of DRN 5-HT neurons. Neither allopregnanolone nor progesterone affected the alpha(1)-adrenoceptor agonist-induced firing. Allopregnanolone also had no effect on the inhibitory response to 5-HT. However, allopregnanolone significantly potentiated the inhibitory responses to GABA(A) receptor agonists. Progesterone did not enhance GABA(A) receptor-meditated inhibitory responses. Thus, the neuroactive metabolite of progesterone, allopregnanolone, has the ability to cause potentiation of GABA(A)-mediated inhibition of DRN 5-HT neurons. This effect on 5-HT neurotransmission may have relevance for mood disorders commonly associated with reproductive hormone events, such as premenstrual dysphoric disorder and postpartum depression.
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Affiliation(s)
- Vikas Kaura
- Psychobiology Research Group, School of Neurology, Neurobiology and Psychiatry, The Medical School, University of Newcastle upon Tyne, NE2 4HH, UK
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Wang C, Marx CE, Morrow AL, Wilson WA, Moore SD. Neurosteroid modulation of GABAergic neurotransmission in the central amygdala: a role for NMDA receptors. Neurosci Lett 2007; 415:118-23. [PMID: 17275189 PMCID: PMC1892631 DOI: 10.1016/j.neulet.2007.01.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2006] [Revised: 11/01/2006] [Accepted: 01/03/2007] [Indexed: 11/25/2022]
Abstract
The neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one (allopregnanolone or ALLO) positively modulates GABA(A) receptors, an action that may contribute to the anxiolytic effects of ALLO. Recent evidence suggests that ALLO's anxiolytic effects appear to be mediated by the amygdala, a key neural structure for emotional and cognitive behaviors. However, little is known regarding ALLO effects on amygdala physiology. We therefore explored ALLO effects on GABA neurotransmission in the central nucleus (Ce) of the amygdala, a major output nucleus involved in fear and anxiety. We recorded evoked GABA(A) receptor-mediated inhibitory postsynaptic currents (IPSCs) in Ce neurons using whole-cell patch clamp techniques. We observed that ALLO significantly reduced the amplitude of evoked GABA(A) receptor-mediated IPSCs. However, the effect of ALLO was occluded by the NMDA receptor antagonist D-APV. D-APV alone also reduced evoked IPSCs in Ce neurons. These results suggest that ALLO-induced reduction of GABAergic transmission in Ce appears to depend on neural network activity, possibly involving an NMDA receptor-mediated mechanism. These ALLO effects on GABAergic transmission in the central amygdala may play a role in mediating its anxiolytic actions.
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Affiliation(s)
- Chunsheng Wang
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center
- Division of Psychiatry, Durham Veterans Affairs Medical Center Durham, North Carolina
| | - Christine E. Marx
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center
- Division of Psychiatry, Durham Veterans Affairs Medical Center Durham, North Carolina
- VISN 6 Mental Illness Research, Education and Clinical Center, Durham, N.C. 27705
| | - A. Leslie Morrow
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, U.S.A
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, U.S.A
| | - Wilkie A. Wilson
- Department of Pharmacology and Cancer Biology, Duke University Medical Center
- Division of Neurology Research, Durham Veterans Affairs Medical Center Durham, North Carolina
- VISN 6 Mental Illness Research, Education and Clinical Center, Durham, N.C. 27705
| | - Scott D. Moore
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center
- Division of Psychiatry, Durham Veterans Affairs Medical Center Durham, North Carolina
- VISN 6 Mental Illness Research, Education and Clinical Center, Durham, N.C. 27705
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Havlíková H, Hill M, Kancheva L, Vrbíková J, Pouzar V, Cerny I, Kancheva R, Stárka L. Serum profiles of free and conjugated neuroactive pregnanolone isomers in nonpregnant women of fertile age. J Clin Endocrinol Metab 2006; 91:3092-9. [PMID: 16720657 DOI: 10.1210/jc.2005-2785] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Pregnanolone isomers (PI) with a hydroxy group in the 3alpha-position are neuroinhibitors operating via positive modulation of GABA(A) receptors. The 3beta-PI and sulfates of PI and pregnenolone exert the opposite effect. In addition to the brain's in situ synthesis, some circulating steroids can penetrate the blood-brain barrier. METHODS To assess the physiological impact of peripheral endogenous neuroactive pregnanolone isomers and their polar conjugates in women, serum allopregnanolone (P3alpha5alpha), isopregnanolone (P3beta5alpha), pregnanolone (P3alpha5beta), epipregnanolone (P3beta5beta), pregnenolone, estradiol (including their polar conjugates), and additional steroids were measured in 16 women in the follicular and luteal phases of the menstrual cycle using gas chromatography/mass spectrometry and RIA for the analysis. Linear models and Spearman's correlations were used for data evaluation. RESULTS AND DISCUSSION The levels of conjugated PI were from one to almost three orders of magnitude higher in comparison with the free steroids. The results indicate that a substantial proportion of the progesterone is metabolized in the sequence progesterone-->5beta-dihydroprogesterone-->P3alpha5beta-->conjugated P3alpha5beta. The sulfation of PI and particularly of P3alpha5beta moderates the levels of free PI and restrains estradiol biosynthesis via progesterone degradation. PI including the conjugates reflected changing progesterone formation during the menstrual cycle. In the follicular phase, the positive correlation with conjugated pregnenolone, the independence of progesterone, and the negative age relationships of PI indicate their adrenal origin. The dependence on progesterone and the independence of conjugated pregnenolone suggest a gonadal source of PI in the luteal phase. The neuroactivating PI prevailed over neuroinhibiting PI.
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Affiliation(s)
- Helena Havlíková
- Institute of Endocrinology, Národní trida 8, CZ 116 94 Prague 1, Czech Republic
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Schlichter R, Keller AF, De Roo M, Breton JD, Inquimbert P, Poisbeau P. Fast nongenomic effects of steroids on synaptic transmission and role of endogenous neurosteroids in spinal pain pathways. J Mol Neurosci 2006; 28:33-51. [PMID: 16632874 DOI: 10.1385/jmn:28:1:33] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Revised: 11/30/1999] [Accepted: 06/28/2005] [Indexed: 11/11/2022]
Abstract
Steroids exert long-term modulatory effects on numerous physiological functions by acting at intracellular/nuclear receptors influencing gene transcription. Steroids and neurosteroids can also rapidly modulate membrane excitability and synaptic transmission by interacting with ion channels, that is, ionotropic neurotransmitter receptors or voltage-dependent Ca2+ or K+ channels. More recently, the cloning of a plasma membrane-located G protein-coupled receptor for progestins in various species has suggested that steroids/neurosteroids could also influence second-messenger pathways by directly interacting with specific membrane receptors. Here we review the experimental evidence implicating steroids/neurosteroids in the modulation of synaptic transmission and the evidence for a role of endogenously produced neurosteroids in such modulatory effects. We present some of our recent results concerning inhibitory synaptic transmission in lamina II of the spinal cord and show that endogenous 5alpha-reduced neurosteroids are produced locally in lamina II and modulate synaptic gamma-aminobutyric acid A(GABAA) receptor function during development, as well as during inflammatory pain. The production of 5alpha-reduced neurosteroids is controlled by the endogenous activation of the peripheral benzodiazepine receptor (PBR), which initiates the first step of neurosteroidogenesis by stimulating the translocation of cholesterol across the inner mitochondrial membrane. Tonic neurosteroidogenesis observed in immature animals was decreased during postnatal development, resulting in an acceleration of GABAA receptor-mediated miniature inhibitory postsynaptic current (mIPSC) kinetics observed in the adult. Stimulation of the PBR resulted in a prolongation of GABAergic mIPSCs at all ages and was observed during inflammatory pain. Neurosteroidogenesis might play an important role in the control of nociception at least at the spinal cord level.
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Affiliation(s)
- Rémy Schlichter
- Institut des Neurosciences Cellulaires et Intégratives-Centre National de la Recherche Scientifique (CNRS), Université Louis Pasteur, 67084 Strasbourg Cedex, France.
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Poisbeau P, Patte-Mensah C, Keller AF, Barrot M, Breton JD, Luis-Delgado OE, Freund-Mercier MJ, Mensah-Nyagan AG, Schlichter R. Inflammatory pain upregulates spinal inhibition via endogenous neurosteroid production. J Neurosci 2006; 25:11768-76. [PMID: 16354935 PMCID: PMC6726017 DOI: 10.1523/jneurosci.3841-05.2005] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Inhibitory synaptic transmission in the dorsal horn (DH) of the spinal cord plays an important role in the modulation of nociceptive messages because pharmacological blockade of spinal GABAA receptors leads to thermal and mechanical pain symptoms. Here, we show that during the development of thermal hyperalgesia and mechanical allodynia associated with inflammatory pain, synaptic inhibition mediated by GABAA receptors in lamina II of the DH was in fact markedly increased. This phenomenon was accompanied by an upregulation of the endogenous production of 5alpha-reduced neurosteroids, which, at the spinal level, led to a prolongation of GABAA receptor-mediated synaptic currents and to the appearance of a mixed GABA/glycine cotransmission. This increased inhibition was correlated with a selective limitation of the inflammation-induced thermal hyperalgesia, whereas mechanical allodynia remained unaffected. Our results show that peripheral inflammation activates an endogenous neurosteroid-based antinociceptive control, which discriminates between thermal and mechanical hyperalgesia.
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Affiliation(s)
- Pierrick Poisbeau
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique/Université Louis Pasteur, F-67084 Strasbourg, France.
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Weiner JL, Valenzuela CF. Ethanol modulation of GABAergic transmission: the view from the slice. Pharmacol Ther 2006; 111:533-54. [PMID: 16427127 DOI: 10.1016/j.pharmthera.2005.11.002] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Accepted: 11/16/2005] [Indexed: 10/25/2022]
Abstract
For almost three decades now, the GABAergic synapse has been the focus of intense study for its putative role in mediating many of the behavioral consequences associated with acute and chronic ethanol exposure. Although it was initially thought that ethanol interacted solely with the postsynaptic GABAA receptors that mediate the majority of fast synaptic inhibition in the mammalian central nervous system (CNS), a number of recent studies have identified novel pre- and postsynaptic mechanisms that may contribute to the acute and long-term effects of ethanol on GABAergic synaptic inhibition. These mechanisms appear to differ in a brain region specific manner and may also be influenced by a variety of endogenous neuromodulatory factors. This article provides a focused review of recent evidence, primarily from in vitro brain slice electrophysiological studies, that offers new insight into the mechanisms through which acute and chronic ethanol exposures modulate the activity of GABAergic synapses. The implications of these new mechanistic insights to our understanding of the behavioral and cognitive effects of ethanol are also discussed.
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Affiliation(s)
- J L Weiner
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1083, USA.
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34
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Hill M, Popov P, Havlikova H, Kancheva L, Vrbikova J, Meloun M, Kancheva R, Cibula D, Pouzar V, Cerny I, Starka L. Reinstatement of serum pregnanolone isomers and progesterone during alcohol detoxification therapy in premenopausal women. Alcohol Clin Exp Res 2005; 29:1010-7. [PMID: 15976527 DOI: 10.1097/01.alc.0000167953.97205.0a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Alcohol abuse is associated with menstrual irregularities related to the inhibition of progesterone secretion involved in regulation of the menstrual cycle. Reduced progesterone metabolites, including pregnanolone isomers (PIs), are efficient neuromodulators. The authors attempted to evaluate whether levels of PIs reflect impairment in progesterone biosynthesis in premenopausal women treated for alcohol addiction and whether alcohol detoxification therapy contributes to the restoration of their reproductive functions and psychosomatic stability by influencing steroid biosynthesis. METHODS Serum allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one; P3alpha5alpha), pregnanolone (P3alpha5beta), isopregnanolone (P3beta5alpha), epipregnanolone (P3beta5beta), progesterone, pregnanolone sulfate (PregS), pregnanolone, and estradiol were measured in 20 women during therapy (at start, three days, 14 days, one month, and four months) by gas chromatography-mass spectrometry or radioimmunoassay. The results were evaluated by a linear mixed model for longitudinal data, with stage of the treatment and subject as categorical factors, phase of the menstrual cycle as a time-varying covariate, and age of the subject as a covariate and by regression in individual stages of the menstrual cycle. RESULTS During detoxification treatment, progesterone increased in the luteal phase. P3alpha5alpha, P3beta5alpha, and P3beta5beta rose in both phases of the menstrual cycle. DISCUSSION Given the similar mechanism in the effects of alcohol and steroids in activating gamma-aminobutyric acid A receptors, the restoration of progesterone and PIs during therapy could be explained by an adaptation to increasing requests for gamma-aminobutyric acid A-receptor activating substances owing to the cessation of alcohol intake or by the regeneration of progesterone formation. In conclusion, the reinstatement of progesterone, P3alpha5alpha, and P3beta5beta serum levels demonstrates the favorable effect of detoxification therapy on both reproductive functions and the psychosomatic stability of premenopausal women treated for alcohol addiction.
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Affiliation(s)
- Martin Hill
- Institute of EndocrinologyCharles University, Prague, Czech Republic.
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35
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Schwabe K, Gavrilovici C, McIntyre DC, Poulter MO. Neurosteroids exhibit differential effects on mIPSCs recorded from normal and seizure prone rats. J Neurophysiol 2005; 94:2171-81. [PMID: 15928052 DOI: 10.1152/jn.01233.2004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the perirhinal cortex of seizure prone (SP) rats, GABA(A)-mediated miniature inhibitory postsynaptic currents (mIPSCs) are smaller in amplitude but have longer deactivation phases than mIPSCs recorded in normal control (NC; outbred) rats. These differences in mIPSCs are correlated to the relatively higher alpha1 subunit expression in the NC rat strains and the higher alpha2, alpha3, and alpha5 subunit expression in the SP strain. Using patch-clamp recording, we investigated how the neurosteroids tetrahydrodeoxcorticosterone (THDOC) and allopregnanolone at physiological and pharmacological concentrations may differentially affect the mIPSCs in the perirhinal cortex of brain slices isolated from SP and NC rats. We found that 100 nM THDOC prolonged the time course and increased the amplitude of both the mono- and biphasic mIPSCs in the SP rats, but these effects were smaller in the NC rats. By comparison, allopregnanolone (100 nM) had small effects in both the NC and SP rats. At 1.0 microM, THDOC enhanced mIPSCs in both strains, but this effect was not greater in the SP rat than it was at 100 nM. By contrast, allopregnanolone (500 nM) enhanced the time course of the mIPSCs in both strains but it reduced mIPSC amplitudes as well. THDOC (100 nM) was much more effective than 100 nM allopregnanolone in inducing a tonic current in SP and NC rats. These data show that neurosteroids modulate synaptic activity at synapses having different biophysical behaviors. As differing GABA(A) receptors are targeted by subsets of interneurons, these data suggest these neurosteroids may selectively modulate one inhibitory input over another.
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Affiliation(s)
- Kerstin Schwabe
- Neuroscience Research Institute, Department of Psychology, Carleton University, 1125 Colonel By Dr., Ottawa Ontario, K1S 5B6 Canada
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36
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Haage D, Bäckström T, Johansson S. Interaction between allopregnanolone and pregnenolone sulfate in modulating GABA-mediated synaptic currents in neurons from the rat medial preoptic nucleus. Brain Res 2005; 1033:58-67. [PMID: 15680340 DOI: 10.1016/j.brainres.2004.11.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2004] [Indexed: 12/29/2022]
Abstract
The two neurosteroids 3alpha-hydroxy-5alpha-pregnane-20-one (allopregnanolone; AlloP) and pregnenolone sulfate (PregS) affect neuronal GABA(A) receptors differently. While AlloP mainly potentiates the currents through GABA(A) receptors, PregS reduces such currents. The present study aimed at clarifying the interaction of AlloP and PregS at GABA(A) receptors in neurons from the medial preoptic nucleus of male rat. AlloP has previously been shown to dramatically prolong GABA-mediated spontaneous inhibitory postsynaptic currents (sIPSCs) in these neurons. Here, by recording sIPSCs under voltage-clamp conditions with the perforated-patch technique, it was shown that PregS by itself did not significantly affect the amplitude or time course of such currents. However, PregS, in a concentration-dependent manner, reduced the AlloP-evoked prolongation of sIPSC decay when the two neurosteroids were applied together. In contrast to sIPSC amplitude and time course, sIPSC frequency was significantly reduced by 10 microM PregS alone. Further, although 1.0 microM AlloP alone induced a clear increase in sIPSC frequency, the frequency was not significantly different from control when 1.0 microM AlloP was applied in combination with 10 microM PregS. In addition to the effects on sIPSC parameters, PregS reduced the baseline current evoked by 1.0 microM AlloP in the absence of GABA application or synaptic activity. PregS by itself did not significantly affect the baseline current. The main effects of AlloP and PregS on the sIPSC time course were mimicked by a simplified model with AlloP assumed to reduce the rate of GABA unbinding from the receptor and PregS assumed to increase the rate of desensitization.
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Affiliation(s)
- David Haage
- Department of Clinical Sciences, Obstetrics and Gynecology, Umeå Neurosteroid Research Center, Umeå University Hospital, SE-901 85 Umeå, Sweden
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Paul CA, Boegle AK, Maue RA. Before the loss: neuronal dysfunction in Niemann-Pick Type C disease. Biochim Biophys Acta Mol Cell Biol Lipids 2004; 1685:63-76. [PMID: 15465427 DOI: 10.1016/j.bbalip.2004.08.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Niemann-Pick Type C (NPC) disease is an autosomal recessive disorder caused by mutations in either the NPC1 or HE1 genes. Hallmarks of this presently incurable disease include abnormal intracellular accumulation of cholesterol and glycosphingolipids, progressive neuropathology and neurodegeneration, and premature death. There have been increased efforts to understand the effects of NPC disease on neurons of the brain, in part due to the recent development of improved research tools and reagents, and in part due to the rapidly growing appreciation of the importance of cholesterol and lipoproteins in the brain during neuronal development, function, and degeneration. Here, we highlight fundamental aspects of neurons that appear to be affected by NPC disease, including their morphology, metabolism, intracellular transport, electrical signaling, and response to environmental factors, and suggest other potentially important areas for future investigation. This provides a framework for acquiring additional insight to this disorder and shaping new therapeutic approaches to NPC disease.
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Affiliation(s)
- Colleen A Paul
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755, USA
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Feng HJ, Bianchi MT, Macdonald RL. Pentobarbital Differentially Modulates α1β3δ and α1β3γ2L GABAA Receptor Currents. Mol Pharmacol 2004; 66:988-1003. [PMID: 15247320 DOI: 10.1124/mol.104.002543] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
GABAA receptors are modulated by a variety of compounds, including the neurosteroids and barbiturates. Although the effects of barbiturates on alphabetagamma isoforms, thought to dominate phasic (synaptic) GABAergic inhibition, have been extensively studied, the effects of pentobarbital on kinetic properties of alphabetadelta GABAA receptors, thought to mediate tonic (extra- or perisynaptic) inhibition, are unknown. Using ultrafast drug delivery and single channel recording techniques, we demonstrate isoform-specific pentobarbital modulation of low-efficacy, minimally desensitizing alpha1beta3 currents and high-efficacy, rapidly desensitizing alpha1beta3gamma2L currents. Specifically, with saturating concentrations of GABA, pentobarbital substantially potentiated peak alpha1beta3delta receptor currents but failed to potentiate peak alpha1beta3gamma2L receptor currents. Also, pentobarbital had opposite effects on the desensitization of alpha1beta3delta (increased) and alpha1beta3gamma2L (decreased) receptor currents evoked by saturating GABA. Pentobarbital increased steady-state alpha1beta3delta receptor single channel open duration primarily by introducing a longer duration open state, whereas for alpha1beta3gamma2L receptor channels, pentobarbital increased mean open duration by increasing the proportion and duration of the longest open state. The data support previous suggestions that GABA may be a partial agonist at alphabetadelta isoforms, which may render them particularly sensitive to allosteric modulation. The remarkable increase in gating efficacy of alpha1beta3delta receptors suggests that alphabetadelta isoforms, and by inference tonic forms of inhibition, may be important targets for barbiturates.
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Affiliation(s)
- Hua-Jun Feng
- Department of Neurology, Vanderbilt University, Nashville, TN, USA
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Brussaard AB, Koksma JJ. Conditional regulation of neurosteroid sensitivity of GABAA receptors. Ann N Y Acad Sci 2004; 1007:29-36. [PMID: 14993037 DOI: 10.1196/annals.1286.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Nongenomic gonadal steroid feedback to oxytocin containing neurons in the supraoptic nucleus of the hypothalamus is mediated via the neurosteroid allopregnanolone (3alpha-OH-DHP) that acts as an allosteric modulator of the postsynaptic GABA(A) receptors. We found evidence to support the idea that neurosteroids not only potentiate GABA(A) receptor function but also prevent its suppression by PKC. In addition, we found that neurosteroid sensitivity of GABA(A) receptor itself is dependent on the balance between endogenous phosphatase and PKC activity and not, as previously suggested, on subunit composition changes of the GABA(A) receptor. These data imply that native GABA(A) receptors are only sensitive to 3alpha-OH-DHP if there is endogenous phosphatase activity. In contrast, when, due to endogenous release of oxytocin in the hypothalamus, the intracellular balance is shifted from high phosphatase activity toward a higher level of PKC-dependent phosphorylation, this leads to 3alpha-OH-DHP-insensitivity of the GABA(A) receptors. How the regulatory mechanisms of the GABA(A) receptor physiology for the hypothalamus may also account for alterations in GABA transmission observed in other brain areas is discussed.
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Affiliation(s)
- Arjen B Brussaard
- Department of Experimental Neurophysiology, Research Institute for Neurosciences, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, the Netherlands.
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Henderson LP, Jorge JC. Steroid modulation of GABAA receptors:from molecular mechanisms to CNS roles in reproduction, dysfunction and drug abuse. MOLECULAR INSIGHTS INTO ION CHANNEL BIOLOGY IN HEALTH AND DISEASE 2004. [DOI: 10.1016/s1569-2558(03)32010-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Mtchedlishvili Z, Kapur J. A presynaptic action of the neurosteroid pregnenolone sulfate on GABAergic synaptic transmission. Mol Pharmacol 2003; 64:857-64. [PMID: 14500742 DOI: 10.1124/mol.64.4.857] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The endogenous neurosteroid pregnenolone sulfate (PS) is known to enhance memory and cognitive function at nanomolar concentrations. However, the effect of these low concentrations on synaptic transmission has not been previously studied. The effects of PS on GABAA receptor-mediated inhibitory postsynaptic currents were studied in cultured hippocampal pyramidal neurons. Concentrations of PS similar to those endogenous in the hippocampus (10-30 nM) reduced the frequency of both action potential-dependent (spontaneous inhibitory postsynaptic current) and -independent (miniature inhibitory postsynaptic current; mIPSC) inhibitory postsynaptic currents. This effect of PS was mimicked by the selective sigma1 receptor agonist [2S-(2alpha,6alpha,11R]-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2,6-methano-3-benzazocin-8-ol hydrochloride [(+)-SKF 10047] and blocked the specific sigma1 receptor antagonists 1-[2-(3,4-dichlorophenyl)ethyl]-4-methylpiperazine dihydrochloride (BD-1063) and haloperidol and by pertussis toxin. The GABAB antagonist baclofen and the metabotropic glutamate receptor antagonist (R,S)-a-cyclopropyl-4-phosphonophenylglycine had no effect on the PS-mediated inhibition of mIPSC frequency. The postsynaptic effects of PS occurred at micromolar concentrations but not at nanomolar concentrations. A comparison of the pre- and postsynaptic effects of PS demonstrated that it was 100-fold more potent in inhibiting presynaptic GABAergic synaptic mechanisms than GABAA receptors. These studies demonstrate that concentrations of PS, similar to those endogenous in the hippocampus, inhibit GABAergic synaptic transmission by a presynaptic effect. PS causes specific activation of G protein-coupled sigma1 receptors, resulting in modulation of both action potential-dependent and -independent IPSCs. These findings improve our understanding of the physiological function of PS.
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Affiliation(s)
- Zakaria Mtchedlishvili
- Department of Neurology, Box 800394, University of Virginia-HSC Charlottesville, VA 22908-0394, USA
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Abstract
Certain metabolites of progesterone and deoxycorticosterone are established as potent and selective positive allosteric modulators of the gamma-aminobutyric acid type A (GABA(A)) receptor. Upon administration these steroids exhibit clear behavioural effects that include anxiolysis, sedation and analgesia, they are anticonvulsant and at high doses induce a state of general anaesthesia, a profile consistent with an action to enhance neuronal inhibition. Physiologically, peripherally synthesised pregnane steroids derived from endocrine glands such as the adrenals and ovaries function as hormones by crossing the blood brain barrier to influence neuronal signalling. However, the demonstration that certain neurons and glial cells within the central nervous system (CNS) can synthesize these steroids either de novo, or from peripherally derived progesterone, has led to the proposal that these steroids (neurosteroids) can additionally function in a paracrine manner, to locally influence GABAergic transmission. Steroid levels are known to change dynamically, for example in stress and during pregnancy. Given that GABA(A) receptors are ubiquitously expressed throughout the central nervous system, such changes in steroid levels would be predicted to cause a global enhancement of inhibitory neurotransmission throughout the brain, a scenario that would seem incompatible with a physiological role as a selective neuromodulator. Here, we will review emerging evidence that the GABA-modulatory actions of the pregnane steroids are highly selective, with their actions being brain region and indeed neuron dependent. Furthermore, the sensitivity of GABA(A) receptors is not static but can dynamically change. The molecular mechanisms underpinning this neuronal specificity will be discussed with particular emphasis being given to the role of GABA(A) receptor isoforms, protein phosphorylation and local steroid metabolism and synthesis.
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Affiliation(s)
- Jeremy J Lambert
- The Department of Pharmacology and Neuroscience, The Neuroscience Institute, Ninewells Hospital and Medical School, Dundee University, Dundee DD1 9SY, Scotland, UK.
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Hansen SL, Fjalland B, Jackson MB. Modulation of GABAA receptors and neuropeptide secretion by the neurosteroid allopregnanolone in posterior and intermediate pituitary. PHARMACOLOGY & TOXICOLOGY 2003; 93:91-7. [PMID: 12899671 DOI: 10.1034/j.1600-0773.2003.930206.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A number of neurosteroids bind to GABAA receptors and alter their responsiveness to neurotransmitters. Considerable effort has been devoted to understanding how this form of receptor modulation alters inhibitory synaptic function. Neurosteroid-sensitive GABAA receptors have also been demonstrated in many endocrine cells, but little is known about how neurosteroids modulate the release of hormones. Here, the action of allopregnanolone, a neurosteroid that enhances GABAA receptor-mediated responses, was investigated in posterior pituitary nerve terminals and intermediate pituitary endocrine cells. Patch clamp recordings showed that GABA-evoked currents were enhanced to similar degrees and with similar concentration dependences in both locations. An organ bath preparation of the neurointermediate lobe was used to investigate drug effects on secretion of vasopressin and alpha-melanocyte stimulating hormone. GABA increased the basal release of vasopressin and alpha-melanocyte stimulating hormone from the posterior and intermediate pituitary lobe, respectively, an effect that could be blocked by picrotoxinin. Vasopressin release evoked by electrical stimulation was also examined, and a small statistically significant inhibition by 5 microM GABA was observed. Allopregnanolone increased the basal release of vasopressin, and this effect was blocked by the GABAA receptor antagonist picrotoxinin. Allopregnanolone had no effect in conjunction with GABA. In contrast to the posterior lobe, allopregnanolone had no effect on release from the intermediate lobe. Thus, allopregnanolone in physiological relevant concentrations modulates GABAA receptors in both the posterior and intermediate lobes, but only affects hormone release in the posterior lobe.
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Affiliation(s)
- Suzanne L Hansen
- Department of Pharmacology, The Danish University of Pharmaceutical Sciences, 2 Universitetsparken, 2100 Copenhagen, Denmark
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Haage D, Druzin M, Johansson S. Allopregnanolone modulates spontaneous GABA release via presynaptic Cl- permeability in rat preoptic nerve terminals. Brain Res 2002; 958:405-13. [PMID: 12470877 DOI: 10.1016/s0006-8993(02)03704-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The endogenous neurosteroid 3alpha-hydroxy-5alpha-pregnane-20-one (allopregnanolone) affects presynaptic nerve terminals and thereby increases the frequency of spontaneous GABA release. The present study aimed at clarifying the mechanisms underlying this presynaptic neurosteroid action, by recording the frequency of spontaneous GABA-mediated inhibitory postsynaptic currents (sIPSCs) in neurons from the medial preoptic nucleus (MPN) of rat. Acutely dissociated neurons with functional adhering nerve terminals were studied by perforated-patch recording under voltage-clamp conditions. It was shown that the sIPSC frequency increased with the external K(+) concentration ([K(+)](o)). Further, the effect of allopregnanolone on the sIPSC frequency was strongly dependent on [K(+)](o). In a [K(+)](o) of 5 mM, 2.0 microM allopregnanolone caused a clear increase in sIPSC frequency. However, the effect declined rapidly with increased [K(+)](o) and at high [K(+)](o) allopregnanolone reduced the sIPSC frequency. The effect of allopregnanolone was also strongly dependent on the external Cl(-) concentration ([Cl(-)](o)). In a reduced [Cl(-)](o) (40 mM, but with a standard [K(+)](o) of 5 mM), the effect on sIPSC frequency was larger than that in the standard [Cl(-)](o) of 146 mM. The dependence of the effect of allopregnanolone on [K(+)](o) and on estimated presynaptic membrane potential was also altered by the reduction in [Cl(-)](o). As in standard [Cl(-)](o), the effect in low [Cl(-)](o) declined when [K(+)](o) was raised, but reversed at a higher [K(+)](o). The GABA(A) receptor agonist muscimol also potentiated the sIPSC frequency. Altogether, the results suggest that allopregnanolone exerts its presynaptic effect by increasing the presynaptic Cl(-) permeability, most likely via GABA(A) receptors.
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Affiliation(s)
- David Haage
- Department of Integrative Medical Biology, Section for Physiology, Umeå University, S-901 87 Umeå, Sweden
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Brussaard AB, Koksma JJ. Short-term modulation of GABAA receptor function in the adult female rat. PROGRESS IN BRAIN RESEARCH 2002; 139:31-42. [PMID: 12436924 DOI: 10.1016/s0079-6123(02)39005-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Oxytocin neurons in the supraoptic nucleus (SON) exhibit marked neuronal plasticity during each reproductive cycle. We have previously shown that this neuronal plasticity includes GABAA receptor subunit switching around the time of parturition. Here we focus on addition plasticity in short-term regulatory mechanisms of postsynaptic receptor function before and after parturition, i.e. alterations in metabotropic and allosteric modulation of GABAA receptor activity. Both short- and long-term regulation of the GABAA receptor function affects the electrical behaviour of the oxytocin neurons (Brussaard and Herbison, 2000); however, their causal linkage until recently remained unclear. Non-genomic gonadal steroid feedback to oxytocin neurons is mediated via the neurosteroid allopregnanolone (3 alpha-OH-DHP) that is an allosteric modulator of postsynaptic GABAA receptors. We recently found evidence to support the idea that (1) neurosteroids not only potentiate GABAA receptor function but also prevent its suppression by PKC (Brussaard et al., 2000), and (2) that neurosteroid sensitivity of GABAA receptor is not regulated by subunit switching, but instead, is dependent on the balance between endogenous phosphatase and PKC activity (Koksma et al., 2002). Thus, before pregnancy, the GABAA receptors are sensitive to 3 alpha-OH-DHP, due to a constitutively high level of phosphatase activity. At parturition, endogenous release of oxytocin within the SON shifts the intracellular balance towards a higher level of phosphorylation, leading to 3 alpha-OH-DHP insensitivity of the GABAA receptors. Here we discuss the putative mechanisms underlying these changes in receptor physiology, their causal relations and the functional significance for the hormonal output.
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Affiliation(s)
- Arjen B Brussaard
- Department of Experimental Neurophysiology, Vrije Universiteit Amsterdam, Research Institute Neurosciences, Centre for Neurogenomics and Cognitive Research, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands.
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Uchida S, Noda E, Kakazu Y, Mizoguchi Y, Akaike N, Nabekura J. Allopregnanolone enhancement of GABAergic transmission in rat medial preoptic area neurons. Am J Physiol Endocrinol Metab 2002; 283:E1257-65. [PMID: 12424107 DOI: 10.1152/ajpendo.00049.2002] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gamma-aminobutyric acid (GABA)-mediated transmission in the medial preoptic area (MPOA) of the hypothalamus plays an important role in functions such as sex steroid hormone dynamics and control of body temperature. The action of allopregnanolone, the primary metabolite of progesterone, on GABAergic transmission was investigated by employing patch clamp whole cell recording on acutely dissociated rat MPOA neurons with the functional connection of presynaptic terminals. Allopregnanolone enhanced spontaneous GABA release on the MPOA neurons and induced prolonged decay of miniature GABAergic-inhibitory postsynaptic currents (mIPSCs). The facilitation of GABA release from the presynaptic terminals by allopregnanolone disappeared in Ca2+-free extracellular solution. The presynaptic action of this neurosteroid was also blocked by bumetanide, a blocker of cation-Cl- cotransporters, and by removal of extracellular Na+. The results suggest that allopregnanolone enhances GABAergic transmission at the MPOA neurons by pre- and postsynaptic mechanisms. The enhancement of GABA release by allopregnanolone might require a high Cl- concentration in the presynaptic terminal maintained by Na+-dependent, bumetanide-sensitive mechanisms (e.g., Na+-K+-Cl- cotransporter) and might be mediated by Ca2+ influx into presynaptic terminal.
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Affiliation(s)
- Soko Uchida
- Cellular and System Physiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812 - 8582, Japan
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Hill M, Parízek A, Klak J, Hampl R, Sulcová J, Havlíková H, Lapcík O, Bicíková M, Fait T, Kancheva R, Cibula D, Pouzar V, Meloun M, Stárka L. Neuroactive steroids, their precursors and polar conjugates during parturition and postpartum in maternal and umbilical blood: 3.3beta-hydroxy-5-ene steroids. J Steroid Biochem Mol Biol 2002; 82:241-50. [PMID: 12477491 DOI: 10.1016/s0960-0760(02)00188-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Five 3beta-hydroxy-5-ene steroids involved in the metabolic route from pregnenolone sulfate to dehydroepiandrosterone and its sulfate, of which three are known allosteric modulators of neurotransmitter receptors, were monitored in the serum of 20 women around parturition. In addition, their levels in maternal and umbilical serum were compared at delivery. On the basis of these data, a scheme of steroid biosynthesis in maternal organism during the critical stages around parturition is proposed. In maternal serum, all the steroids except dehydroepiandrosterone sulfate decreased during labor and even first day after delivery, although their changes were less distinct the more distant from pregnenolone sulfate (PregS) in the metabolic pathway. Calculation of product/immediate precursor ratios in maternal serum over all stages around parturition enabled identification of the respective changes in the activities of the relevant enzymes. The ratio of 17-hydroxypregnenolone/pregnenolone did not change significantly, while that of dehydroepiandrosterone/17-hydroxypregnenolone grew, indicating increased C17,20 side chain cleavage on the account of C17-hydroxylation both catalyzed by C17-hydroxylase-C17,20-lyase. As was shown by factor analysis, the changes in the maternal steroids were associated with a single common factor, which strongly correlated with all the steroids except dehydroepiandrosterone sulfate. The lack of change in the pregnenolone sulfate/pregnenolone ratio and a marked increase of the ratio dehydroepiandrosterone sulfate to unconjugated dehydroepiandrosterone indicate a different means of formation of both steroid sulfates. On the basis of these data, a scheme of steroid biosynthesis in maternal organism during the critical stages around parturition is proposed.
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Affiliation(s)
- M Hill
- Institute of Endocrinology, Národní trída 8, Prague, Czech Republic.
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Abstract
Endogenous neurosteroids have rapid actions on ion channels, particularly GABA(A) receptors, which are potentiated by nanomolar concentrations of 3alpha-hydroxypregnane neurosteroids. Previous evidence suggests that 3beta-hydroxypregnane steroids may competitively antagonize potentiation induced by their 3alpha diastereomers. Because of the potential importance of antagonists as experimental and clinical tools, we characterized the functional effect of 3beta-hydroxysteroids. Although 3beta-hydroxysteroids reduced the potentiation induced by 3alpha-hydroxysteroids, 3beta-hydroxysteroids acted noncompetitively with respect to potentiating steroids and inhibited the largest degrees of potentiation most effectively. Potentiation by high concentrations of barbiturates was also reduced by 3beta-hydroxysteroids. 3beta-Hydroxysteroids are also direct, noncompetitive GABA(A) receptor antagonists. 3beta-Hydroxysteroids coapplied with GABA significantly inhibited responses to > or =15 microm GABA. The profile of block was similar to that exhibited by sulfated steroids, known blockers of GABA(A) receptors. This direct, noncompetitive effect of 3beta-hydroxysteroids was sufficient to account for the apparent antagonism of potentiating steroids. Mutated receptors exhibiting decreased sensitivity to sulfated steroid block were insensitive to both the direct effects of 3beta-hydroxysteroids on GABA(A) responses and the reduction of potentiating steroid effects. At concentrations that had little effect on GABAergic synaptic currents, 3beta-hydroxysteroids and low concentrations of sulfated steroids significantly reversed the potentiation of synaptic currents induced by 3alpha-hydroxysteroids. We conclude that 3beta-hydroxypregnane steroids are not direct antagonists of potentiating steroids but rather are noncompetitive, likely state-dependent, blockers of GABA(A) receptors. Nevertheless, these steroids may be useful functional blockers of potentiating steroids when used at concentrations that do not affect baseline neurotransmission.
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Smith SS. Withdrawal properties of a neuroactive steroid: implications for GABA(A) receptor gene regulation in the brain and anxiety behavior. Steroids 2002; 67:519-28. [PMID: 11960630 DOI: 10.1016/s0039-128x(01)00170-2] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Early work in the field established that the 5 alpha-reduced metabolite of progesterone 3 alpha-OH-5 alpha-pregnan-20-one (allopregnanolone or 3 alpha,5 alpha-THP) is a potent positive modulator of the GABA(A) receptor (GABAR), the receptor mediating the effects of the primary inhibitory transmitter in the brain. This steroid acts in a manner similar to sedative drugs, such as the barbiturates, both in terms of potentiating GABA-induced inhibition in vitro and in behavioral assays, by reducing anxiety and seizure susceptibility. Because sedative compounds exhibit withdrawal properties that result in behavioral hyperexcitability, our laboratory has more recently investigated the effect of prolonged application and rapid removal (i.e. 'withdrawal') of this steroid, administered in vivo to female rats. Withdrawal from 3 alpha,5 alpha-THP produces a state of increased anxiety and lowered seizure threshold, similar to withdrawal from other GABA-modulatory drugs such as the benzodiazepines and alcohol. Hormone withdrawal also produced increases in the alpha 4-containing GABAR, an effect correlated with insensitivity of the GABAR to modulation by the benzodiazepine class of tranquilizers, as would normally occur under control conditions. In addition, changes in intrinsic channel properties, including a marked acceleration in the decay rate was also observed as a result of declining levels of 3 alpha,5 alpha-THP. Such a change would result in less inhibitory total current, and the resulting increase in neuronal excitability could then underlie the observed behavioral excitability following hormone withdrawal. These results suggest that actions of this steroid on a traditional transmitter receptor in the brain lead to alterations in GABAR subunit composition that result in changes in the intrinsic channel properties of the receptor and behavioral excitability. These results may have implications for endogenous fluctuations in this hormone which may accompany premenstrual dysphoric disorder.
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Affiliation(s)
- Sheryl S Smith
- Deppartment of Physiology and Pharmacology, SUNY Health Science Center at Brooklyn, 450 Clarkson Ave., Brooklyn, NY 11203, USA.
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Jorge JC, McIntyre KL, Henderson LP. The function and the expression of forebrain GABA(A) receptors change with hormonal state in the adult mouse. JOURNAL OF NEUROBIOLOGY 2002; 50:137-49. [PMID: 11793360 DOI: 10.1002/neu.10021] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Neurotransmission mediated by gamma-aminobutyric acid type A (GABA(A)) receptors in the mammalian medial preoptic area (mPOA) plays a pivotal role in the expression of hormone-sensitive behaviors. Hand in hand with GABAergic control of reproduction, hormone treatments that activate gonadal steroid signaling pathways in gonadectomized rats are known to regulate the expression of specific GABA(A) receptor subunit mRNAs. While the effects of exogenous hormone treatments have been well documented, little information is available as to how GABA(A) receptor-mediated transmission in the mPOA is altered by endogenous changes in hormonal state in gonadally-intact adult animals or if those changes can be ascribed to hormone-dependent changes in receptor subunit composition. In the present study, we found that both the peak amplitudes of GABA(A) receptor-mediated synaptic currents in the mPOA, as well as the ability of the endogenous neurosteroids to modulate those currents, varied as a function of the estrous cycle. Moreover, we found that the degree of neurosteroid modulation was also significantly different between wild-type and the androgen-insensitive testicular feminization (Tfm) mutant male mice. Semiquantitative RT-PCR analysis performed to assess levels of GABA(A) receptor subunit mRNAs indicated that levels of specific subunits varied over the course of the estrous cycle and between wild-type and Tfm male mice. The variations in GABA(A) receptor expression and function in the mPOA that are associated with differences in gonadal steroid signaling may contribute to the dynamic nature of GABAergic control of neuroendocrine pathways.
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Affiliation(s)
- Juan Carlos Jorge
- Department of Anatomy, Medical Sciences Campus, University of Puerto Rico, San Juan, Puerto Rico
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