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Wang D, Treede RD, Köhr G. Electrophysiological evidence that TRPM3 is a candidate in latent spinal sensitization of chronic low back pain. Neurosci Lett 2023; 816:137509. [PMID: 37802417 DOI: 10.1016/j.neulet.2023.137509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 09/19/2023] [Accepted: 10/03/2023] [Indexed: 10/10/2023]
Abstract
Latent spinal sensitization is one key mechanism developing at the early stage of chronic low back pain (LBP). TRPM3-mediated calcium transients of dorsal root ganglia (DRG) neurons are considered critical presynaptic signals involved in this latent sensitization. However, postsynaptic consequences in input laminae of the spinal cord have not been addressed so far. Here, by electrophysiological recordings in acute spinal cord slices from adult rats, we show that perfusion of the TRPM3 agonist pregnenolone sulfate (PregS) induced a significant increase in the frequency but not amplitude of spontaneous postsynaptic currents in lamina I and II neurons. This frequency increase started slowly during PregS perfusion but was reversible following washout. This result is consistent with a presynaptic action of the neurosteroid PregS, indicating the presynaptic expression of functional TRPM3 in the superficial dorsal horn of adult rats. Thus, PregS-induced TRPM3 activation enhances spinal synaptic strength, implying a mediating role of TRPM3 between neuroendocrine and nociceptive signaling, which might as well exist in chronic LBP primed by chronic stress that promotes the biosynthesis of PregS.
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Affiliation(s)
- Dan Wang
- Department of Anesthesiology, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China; Department of Neurophysiology, Mannheim Center for Translational Neurosciences, Heidelberg University, Mannheim, Germany
| | - Rolf-Detlef Treede
- Department of Neurophysiology, Mannheim Center for Translational Neurosciences, Heidelberg University, Mannheim, Germany; Deptartment of Psychiatry and Psychotherapy, Central Institute of Mental Health, Heidelberg University, Mannheim, Germany
| | - Georg Köhr
- Department of Neurophysiology, Mannheim Center for Translational Neurosciences, Heidelberg University, Mannheim, Germany; Physiology of Neural Networks, Central Institute of Mental Health, Heidelberg University, Mannheim, Germany.
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2
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Seljeset S, Liebowitz S, Bright DP, Smart TG. Pre- and postsynaptic modulation of hippocampal inhibitory synaptic transmission by pregnenolone sulphate. Neuropharmacology 2023; 233:109530. [PMID: 37037282 DOI: 10.1016/j.neuropharm.2023.109530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 03/28/2023] [Accepted: 03/31/2023] [Indexed: 04/12/2023]
Abstract
Neurosteroids are important endogenous modulators of GABAA receptor-mediated neurotransmission within the CNS and play a vital role in maintaining normal healthy brain function. Research has mainly focussed on neurosteroids such as allopregnanolone and tetrahydro-deoxycorticosterone (THDOC) which are allosteric potentiators of GABAA receptors, whilst the sulphated steroids, including pregnenolone sulphate (PS), which inhibit GABAA receptor function, have been relatively neglected. Importantly, a full description of PS effects on inhibitory synaptic transmission, at concentrations that are expected to inhibit postsynaptic GABAA receptors, is lacking. Here, we address this deficit by recording inhibitory postsynaptic currents (IPSCs) from rat hippocampal neurons both in culture and in acute brain slices and explore the impact of PS at micromolar concentrations. We reveal that PS inhibits postsynaptic GABAA receptors, evident from reductions in IPSC amplitude and decay time. Concurrently, PS also causes an increase in synaptic GABA release which we discover is due to the activation of presynaptic TRPM3 receptors located close to presynaptic GABA release sites. Pharmacological blockade of TRPM3 receptors uncovers a PS-evoked reduction in IPSC frequency. This second presynaptic effect is caused by PS activation of inwardly-rectifying Kir2.3 channels on interneurons, which act to depress synaptic GABA release. Overall, we provide a comprehensive characterisation of pre- and postsynaptic modulation by PS of inhibitory synaptic transmission onto hippocampal neurons which elucidates the diverse mechanisms by which this understudied neurosteroid can modulate brain function.
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Affiliation(s)
- Sandra Seljeset
- Department of Neuroscience, Physiology & Pharmacology, UCL, Gower Street, London, WC1E 6BT, UK
| | - Seth Liebowitz
- Department of Neuroscience, Physiology & Pharmacology, UCL, Gower Street, London, WC1E 6BT, UK
| | - Damian P Bright
- Department of Neuroscience, Physiology & Pharmacology, UCL, Gower Street, London, WC1E 6BT, UK.
| | - Trevor G Smart
- Department of Neuroscience, Physiology & Pharmacology, UCL, Gower Street, London, WC1E 6BT, UK.
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Smejkalova T, Korinek M, Krusek J, Hrcka Krausova B, Candelas Serra M, Hajdukovic D, Kudova E, Chodounska H, Vyklicky L. Endogenous neurosteroids pregnanolone and pregnanolone sulfate potentiate presynaptic glutamate release through distinct mechanisms. Br J Pharmacol 2021; 178:3888-3904. [PMID: 33988248 PMCID: PMC8518729 DOI: 10.1111/bph.15529] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 03/23/2021] [Accepted: 05/06/2021] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Neurosteroids influence neuronal function and have multiple promising clinical applications. Direct modulation of postsynaptic neurotransmitter receptors by neurosteroids is well characterized, but presynaptic effects remain poorly understood. Here, we report presynaptic glutamate release potentiation by neurosteroids pregnanolone and pregnanolone sulfate and compare their mechanisms of action to phorbol 12,13-dibutyrate (PDBu), a mimic of the second messenger DAG. EXPERIMENTAL APPROACH We use whole-cell patch-clamp electrophysiology and pharmacology in rat hippocampal microisland cultures and total internal reflection fluorescence (TIRF) microscopy in HEK293 cells expressing GFP-tagged vesicle priming protein Munc13-1, to explore the mechanisms of neurosteroid presynaptic modulation. KEY RESULTS Pregnanolone sulfate and pregnanolone potentiate glutamate release downstream of presynaptic Ca2+ influx, resembling the action of a phorbol ester PDBu. PDBu partially occludes the effect of pregnanolone, but not of pregnanolone sulfate. Calphostin C, an inhibitor that disrupts DAG binding to its targets, reduces the effect PDBu and pregnanolone, but not of pregnanolone sulfate, suggesting that pregnanolone might interact with a well-known DAG/phorbol ester target Munc13-1. However, TIRF microscopy experiments found no evidence of pregnanolone-induced membrane translocation of GFP-tagged Munc13-1, suggesting that pregnanolone may regulate Munc13-1 indirectly or interact with other DAG targets. CONCLUSION AND IMPLICATIONS We describe a novel presynaptic effect of neurosteroids pregnanolone and pregnanolone sulfate to potentiate glutamate release downstream of presynaptic Ca2+ influx. The mechanism of action of pregnanolone, but not of pregnanolone sulfate, partly overlaps with that of PDBu. Presynaptic effects of neurosteroids may contribute to their therapeutic potential in the treatment of disorders of the glutamate system.
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Affiliation(s)
- Tereza Smejkalova
- Institute of PhysiologyCzech Academy of SciencesPragueCzech Republic
| | - Miloslav Korinek
- Institute of PhysiologyCzech Academy of SciencesPragueCzech Republic
| | - Jan Krusek
- Institute of PhysiologyCzech Academy of SciencesPragueCzech Republic
| | | | | | | | - Eva Kudova
- Institute of Organic Chemistry and BiochemistryCzech Academy of SciencesPragueCzech Republic
| | - Hana Chodounska
- Institute of Organic Chemistry and BiochemistryCzech Academy of SciencesPragueCzech Republic
| | - Ladislav Vyklicky
- Institute of PhysiologyCzech Academy of SciencesPragueCzech Republic
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Ohashi K, Shibasaki K, Nakazawa H, Kunimasa R, Nagayasu K, Shirakawa H, Kaneko S. Transient Receptor Potential Melastatin 3 Is Functionally Expressed in Oligodendrocyte Precursor Cells and Is Upregulated in Ischemic Demyelinated Lesions. Biol Pharm Bull 2021; 44:181-187. [PMID: 33518671 DOI: 10.1248/bpb.b20-00510] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Oligodendrocyte precursor cells (OPCs) are glial cells that differentiate into oligodendrocytes and myelinate axons. The number of OPCs is reportedly increased in brain lesions in some demyelinating diseases and during ischemia; however, these cells also secrete cytokines and elicit both protective and deleterious effects in response to brain injury. The mechanism regulating the behaviors of OPCs in physiological and pathological conditions must be elucidated to control these cells and to treat demyelinating diseases. Here, we focused on transient receptor potential melastatin 3 (TRPM3), a Ca2+-permeable channel that is activated by the neurosteroid pregnenolone sulfate (PS) and body temperature. Trpm3+/Pdgfra+ OPCs were detected in the cerebral cortex (CTX) and corpus callosum (CC) of P4 and adult rats by in situ hybridization. Trpm3 expression was detected in primary cultured rat OPCs and was increased by treatment with tumor necrosis factor α (TNFα). Application of PS (30-100 µM) increased the Ca2+ concentration in OPCs and this effect was inhibited by co-treatment with the TRP channel blocker Gd3+ (100 µM) or the TRPM3 inhibitor isosakuranetin (10 µM). Stimulation of TRPM3 with PS (50 µM) did not affect the differentiation or migration of OPCs. The number of Trpm3+ OPCs was markedly increased in demyelinated lesions in an endothelin-1 (ET-1)-induced ischemic rat model. In conclusion, TRPM3 is functionally expressed in OPCs in vivo and in vitro and is upregulated in inflammatory conditions such as ischemic insults and TNFα treatment, implying that TRPM3 is involved in the regulation of specific behaviors of OPCs in pathological conditions.
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Affiliation(s)
- Kana Ohashi
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University
| | - Koji Shibasaki
- Division of Neurochemistry, Graduate School of Human Health Science, University of Nagasaki
| | - Hayaki Nakazawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University
| | - Ryotaro Kunimasa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University
| | - Kazuki Nagayasu
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University
| | - Hisashi Shirakawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University
| | - Shuji Kaneko
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University
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Xu Y, Zhang S, Sun Q, Wang XQ, Chai YN, Mishra C, Chandra SR, Ai J. Cholinergic Dysfunction Involvement in Chronic Cerebral Hypoperfusion-Induced Impairment of Medial Septum-dCA1 Neurocircuit in Rats. Front Cell Neurosci 2020; 14:586591. [PMID: 33132852 PMCID: PMC7550820 DOI: 10.3389/fncel.2020.586591] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Accepted: 08/31/2020] [Indexed: 11/13/2022] Open
Abstract
Chronic cerebral hypoperfusion (CCH) is considered a preclinical condition of mild cognitive impairment and thought to precede dementia. However, as the principal cholinergic source of hippocampus, whether the septo-hippocampal neurocircuit was impaired after CCH is still unknown. In this study, we established the CCH rat model by bilateral common carotid artery occlusion (2VO). Under anesthesia, the medial septum (MS) of rats was stimulated to evoke the field excitatory post-synaptic potential (fEPSP) in the pyramidal cell layer of dCA1. Consequently, we observed decreased amplitude of fEPSP and increased paired-pulse ratio (PPR) after 8-week CCH. After tail pinch, we also found decreased peak frequency and shortened duration of hippocampal theta rhythm in 2VO rats, indicating the dysfunction of septo-hippocampal neurocircuit. Besides, by intracerebroventricularly injecting GABAergic inhibitor (bicuculline) and cholinergic inhibitors (scopolamine and mecamylamine), we found that CCH impaired both the pre-synaptic cholinergic release and the post-synaptic nAChR function in MS-dCA1 circuits. These results gave an insight into the role of CCH in the impairment of cholinergic MS-dCA1 neurocircuits. These findings may provide a new idea about the CCH-induced neurodegenerative changes.
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Affiliation(s)
- Yi Xu
- Department of Pharmacology, The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, College of Pharmacy of Harbin Medical University, Harbin, China
| | - Shuai Zhang
- Department of Pharmacology, The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, College of Pharmacy of Harbin Medical University, Harbin, China
| | - Qiang Sun
- Department of Pharmacology, The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, College of Pharmacy of Harbin Medical University, Harbin, China
| | - Xu-Qiao Wang
- Department of Pharmacology, The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, College of Pharmacy of Harbin Medical University, Harbin, China
| | - Ya-Ni Chai
- Department of Pharmacology, The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, College of Pharmacy of Harbin Medical University, Harbin, China
| | - Chandan Mishra
- Department of Pharmacology, The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, College of Pharmacy of Harbin Medical University, Harbin, China
| | - Shah Ram Chandra
- Department of Pharmacology, The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, College of Pharmacy of Harbin Medical University, Harbin, China
| | - Jing Ai
- Department of Pharmacology, The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, College of Pharmacy of Harbin Medical University, Harbin, China
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6
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Wang R, Tu S, Zhang J, Shao A. Roles of TRP Channels in Neurological Diseases. Oxid Med Cell Longev 2020; 2020:7289194. [PMID: 32963700 DOI: 10.1155/2020/7289194] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 07/02/2020] [Indexed: 11/17/2022]
Abstract
Transient receptor potential (TRP) proteins consist of a superfamily of cation channels that have been involved in diverse physiological processes in the brain as well as in the pathogenesis of neurological disease. TRP channels are widely expressed in the brain, including neurons and glial cells, as well as in the cerebral vascular endothelium and smooth muscle. Members of this channel superfamily show a wide variety of mechanisms ranging from ligand binding to voltage, physical, and chemical stimuli, implying the promising therapeutic potential of TRP in neurological diseases. In this review, we focus on the physiological functions of TRP channels in the brain and the pathological roles in neurological disorders to explore future potential neuroprotective strategies.
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Webster CM, Tworig J, Caval-Holme F, Morgans CW, Feller MB. The Impact of Steroid Activation of TRPM3 on Spontaneous Activity in the Developing Retina. eNeuro 2020; 7:ENEURO.0175-19.2020. [PMID: 32238415 PMCID: PMC7177749 DOI: 10.1523/eneuro.0175-19.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 02/19/2020] [Accepted: 03/06/2020] [Indexed: 12/19/2022] Open
Abstract
In the central nervous system, melastatin transient receptor potential (TRPM) channels function as receptors for the neurosteroid pregnenolone sulfate (PregS). The expression and function of TRPM3 has been explored in adult retina, although its role during development is unknown. We found, during the second postnatal week in mice, TRPM3 immunofluorescence labeled distinct subsets of inner retinal neurons, including a subset of retinal ganglion cells (RGCs), similar to what has been reported in the adult. Labeling for a TRPM3 promoter-driven reporter confirmed expression of the TRPM3 gene in RGCs and revealed additional expression in nearly all Müller glial cells. Using two-photon calcium imaging, we show that PregS and the synthetic TRPM3 agonist CIM0216 (CIM) induced prolonged calcium transients in RGCs, which were mostly absent in TRPM3 knock-out (KO) mice. These prolonged calcium transients were not associated with strong membrane depolarizations but induced c-Fos expression. To elucidate the impact of PregS-activation of TRPM3 on retinal circuits we took two sets of physiological measurements. First, PregS induced a robust increase in the frequency but not amplitude of spontaneous postsynaptic currents (PSCs). This increase was absent in the TRPM3 KO mice. Second, PregS induced a small increase in cell participation and duration of retinal waves, but this modulation persisted in TRPM3 KO mice, indicating PregS was acting on wave generating circuits independent of TRPM3 channels. Though baseline frequency of retinal waves was slightly reduced in the TRPM3 KO mice, other properties of waves were indistinguishable from wildtype. Together, these results indicate that the presence of neurosteroids impact spontaneous synaptic activity and retinal waves during development via both TRPM3-dependent and independent mechanisms.
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Affiliation(s)
- Corey M Webster
- Department of Molecular and Cell Biology, University of California. Berkeley, Berkeley, CA 94720-3200
| | - Joshua Tworig
- Department of Molecular and Cell Biology, University of California. Berkeley, Berkeley, CA 94720-3200
| | - Franklin Caval-Holme
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720-3200
| | - Catherine W Morgans
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239
| | - Marla B Feller
- Department of Molecular and Cell Biology, University of California. Berkeley, Berkeley, CA 94720-3200
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720-3200
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8
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Abstract
Memory dysfunction is a symptomatic feature of many neurologic and neuropsychiatric disorders; however, the basic underlying mechanisms of memory and altered states of circuitry function associated with disorders of memory remain a vast unexplored territory. The initial discovery of endogenous neurosteroids triggered a quest to elucidate their role as neuromodulators in normal and diseased brain function. In this review, based on the perspective of our own research, the advances leading to the discovery of positive and negative neurosteroid allosteric modulators of GABA type-A (GABAA), NMDA, and non-NMDA type glutamate receptors are brought together in a historical and conceptual framework. We extend the analysis toward a state-of-the art view of how neurosteroid modulation of neural circuitry function may affect memory and memory deficits. By aggregating the results from multiple laboratories using both animal models for disease and human clinical research on neuropsychiatric and age-related neurodegenerative disorders, elements of a circuitry level view begins to emerge. Lastly, the effects of both endogenously active and exogenously administered neurosteroids on neural networks across the life span of women and men point to a possible underlying pharmacological connectome by which these neuromodulators might act to modulate memory across diverse altered states of mind.
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Chisari M, Wilding TJ, Brunwasser S, Krishnan K, Qian M, Benz A, Huettner JE, Zorumski CF, Covey DF, Mennerick S. Visualizing pregnenolone sulfate-like modulators of NMDA receptor function reveals intracellular and plasma-membrane localization. Neuropharmacology 2018; 144:91-103. [PMID: 30332607 DOI: 10.1016/j.neuropharm.2018.10.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 09/07/2018] [Accepted: 10/12/2018] [Indexed: 12/27/2022]
Abstract
Positive modulators of NMDA receptors are important candidates for therapeutic development to treat psychiatric disorders including autism and schizophrenia. Sulfated neurosteroids have been studied as positive allosteric modulators of NMDA receptors for years, but we understand little about the cellular fate of these compounds, an important consideration for drug development. Here we focus on a visualizable sulfated neurosteroid analogue, KK-169. As expected of a pregnenolone sulfate analogue, the compound strongly potentiates NMDA receptor function, is an antagonist of GABAA receptors, exhibits occlusion with pregnenolone sulfate potentiation, and requires receptor domains important for pregnenolone sulfate potentiation. KK-169 exhibits somewhat higher potency than the natural parent, pregnenolone sulfate. The analogue contains a side-chain alkyne group, which we exploited for retrospective click labeling of neurons. Although the anionic sulfate group is expected to hinder cell entry, we detected significant accumulation of KK-169 in neurons with even brief incubations. Adding a photolabile diazirine group revealed that the expected plasma membrane localization of KK-169 is likely lost during fixation. Overall, our studies reveal new facets of the structure-activity relationship of neurosteroids at NMDA receptors, and their intracellular distribution suggests that sulfated neurosteroids could have unappreciated targets in addition to plasma membrane receptors.
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Affiliation(s)
- Mariangela Chisari
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Timothy J Wilding
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Samuel Brunwasser
- Medical Scientist Training Program, Washington University School of Medicine, St. Louis, MO, USA
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Mingxing Qian
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Ann Benz
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - James E Huettner
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Charles F Zorumski
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA
| | - Douglas F Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA.
| | - Steven Mennerick
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA.
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Rebas E, Radzik T, Boczek T, Zylinska L. Calcium-engaged Mechanisms of Nongenomic Action of Neurosteroids. Curr Neuropharmacol 2017; 15:1174-1191. [PMID: 28356049 PMCID: PMC5725547 DOI: 10.2174/1570159x15666170329091935] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 01/01/1970] [Accepted: 03/25/2017] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Neurosteroids form the unique group because of their dual mechanism of action. Classically, they bind to specific intracellular and/or nuclear receptors, and next modify genes transcription. Another mode of action is linked with the rapid effects induced at the plasma membrane level within seconds or milliseconds. The key molecules in neurotransmission are calcium ions, thereby we focus on the recent advances in understanding of complex signaling crosstalk between action of neurosteroids and calcium-engaged events. METHODS Short-time effects of neurosteroids action have been reviewed for GABAA receptor complex, glycine receptor, NMDA receptor, AMPA receptor, G protein-coupled receptors and sigma-1 receptor, as well as for several membrane ion channels and plasma membrane enzymes, based on available published research. RESULTS The physiological relevance of neurosteroids results from the fact that they can be synthesized and accumulated in the central nervous system, independently from peripheral sources. Fast action of neurosteroids is a prerequisite for genomic effects and these early events can significantly modify intracellular downstream signaling pathways. Since they may exert either positive or negative effects on calcium homeostasis, their role in monitoring of spatio-temporal Ca2+ dynamics, and subsequently, Ca2+-dependent physiological processes or initiation of pathological events, is evident. CONCLUSION Neurosteroids and calcium appear to be the integrated elements of signaling systems in neuronal cells under physiological and pathological conditions. A better understanding of cellular and molecular mechanisms of nongenomic, calcium-engaged neurosteroids action could open new ways for therapeutic interventions aimed to restore neuronal function in many neurological and psychiatric diseases.
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Affiliation(s)
- Elzbieta Rebas
- Department of Molecular Neurochemistry, Faculty of Health Sciences, Medical University of Lodz, Poland
| | - Tomasz Radzik
- Department of Molecular Neurochemistry, Faculty of Health Sciences, Medical University of Lodz, Poland
| | - Tomasz Boczek
- Department of Molecular Neurochemistry, Faculty of Health Sciences, Medical University of Lodz, Poland
- Boston Children’s Hospital and Harvard Medical School, Boston, USA
| | - Ludmila Zylinska
- Department of Molecular Neurochemistry, Faculty of Health Sciences, Medical University of Lodz, Poland
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Vyklicky V, Smejkalova T, Krausova B, Balik A, Korinek M, Borovska J, Horak M, Chvojkova M, Kleteckova L, Vales K, Cerny J, Nekardova M, Chodounska H, Kudova E, Vyklicky L. Preferential Inhibition of Tonically over Phasically Activated NMDA Receptors by Pregnane Derivatives. J Neurosci 2016; 36:2161-75. [PMID: 26888927 DOI: 10.1523/JNEUROSCI.3181-15.2016] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Postsynaptic N-methyl-d-aspartate receptors (NMDARs) phasically activated by presynaptically released glutamate are critical for synaptic transmission and plasticity. However, under pathological conditions, excessive activation of NMDARs by tonically increased ambient glutamate contributes to excitotoxicity associated with various acute and chronic neurological disorders. Here, using heterologously expressed GluN1/GluN2A and GluN1/GluN2B receptors and rat autaptic hippocampal microisland cultures, we show that pregnanolone sulfate inhibits NMDAR currents induced by a prolonged glutamate application with a higher potency than the NMDAR component of EPSCs. For synthetic pregnanolone derivatives substituted with a carboxylic acid moiety at the end of an aliphatic chain of varying length and attached to the steroid skeleton at C3, the difference in potency between tonic and phasic inhibition increased with the length of the residue. The steroid with the longest substituent, pregnanolone hemipimelate, had no effect on phasically activated receptors while inhibiting tonically activated receptors. In behavioral tests, pregnanolone hemipimelate showed neuroprotective activity without psychomimetic symptoms. These results provide insight into the influence of steroids on neuronal function and stress their potential use in the development of novel therapeutics with neuroprotective action. SIGNIFICANCE STATEMENT Synaptic activation of N-methyl-d-aspartate receptors (NMDARs) plays a key role in synaptic plasticity, but excessive tonic NMDAR activation mediates excitotoxicity associated with many neurological disorders. Therefore, there is much interest in pharmacological agents capable of selectively blocking tonically activated NMDARs while leaving synaptically activated NMDARs intact. Here, we show that an endogenous neurosteroid pregnanolone sulfate is more potent at inhibiting tonically than synaptically activated NMDARs. Further, we report that a novel synthetic analog of pregnanolone sulfate, pregnanolone hemipimelate, inhibits tonic NMDAR currents without inhibiting the NMDAR component of the EPSC and shows neuroprotective activity in vivo without inducing psychomimetic side effects. These results suggest steroids may have a clinical advantage over other known classes of NMDAR inhibitors.
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Kumar A, Kumari S, Majhi RK, Swain N, Yadav M, Goswami C. Regulation of TRP channels by steroids: Implications in physiology and diseases. Gen Comp Endocrinol 2015; 220:23-32. [PMID: 25449179 DOI: 10.1016/j.ygcen.2014.10.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Revised: 10/09/2014] [Accepted: 10/10/2014] [Indexed: 01/26/2023]
Abstract
While effects of different steroids on the gene expression and regulation are well established, it is proven that steroids can also exert rapid non-genomic actions in several tissues and cells. In most cases, these non-genomic rapid effects of steroids are actually due to intracellular mobilization of Ca(2+)- and other ions suggesting that Ca(2+) channels are involved in such effects. Transient Receptor Potential (TRP) ion channels or TRPs are the largest group of non-selective and polymodal ion channels which cause Ca(2+)-influx in response to different physical and chemical stimuli. While non-genomic actions of different steroids on different ion channels have been established to some extent, involvement of TRPs in such functions is largely unexplored. In this review, we critically analyze the literature and summarize how different steroids as well as their metabolic precursors and derivatives can exert non-genomic effects by acting on different TRPs qualitatively and/or quantitatively. Such effects have physiological repercussion on systems such as in sperm cells, immune cells, bone cells, neuronal cells and many others. Different TRPs are also endogenously expressed in diverse steroid-producing tissues and thus may have importance in steroid synthesis as well, a process which is tightly controlled by the intracellular Ca(2+) concentrations. Tissue and cell-specific expression of TRP channels are also regulated by different steroids. Understanding of the crosstalk between TRP channels and different steroids may have strong significance in physiological, endocrinological and pharmacological context and in future these compounds can also be used as potential biomedicine.
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Affiliation(s)
- Ashutosh Kumar
- School of Biology, National Institute of Science Education and Research, Sachivalaya Marg, Bhubaneswar, Orissa 751005, India
| | - Shikha Kumari
- School of Biology, National Institute of Science Education and Research, Sachivalaya Marg, Bhubaneswar, Orissa 751005, India
| | - Rakesh Kumar Majhi
- School of Biology, National Institute of Science Education and Research, Sachivalaya Marg, Bhubaneswar, Orissa 751005, India
| | - Nirlipta Swain
- School of Biology, National Institute of Science Education and Research, Sachivalaya Marg, Bhubaneswar, Orissa 751005, India
| | - Manoj Yadav
- School of Biology, National Institute of Science Education and Research, Sachivalaya Marg, Bhubaneswar, Orissa 751005, India
| | - Chandan Goswami
- School of Biology, National Institute of Science Education and Research, Sachivalaya Marg, Bhubaneswar, Orissa 751005, India.
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Emnett CM, Eisenman LN, Mohan J, Taylor AA, Doherty JJ, Paul SM, Zorumski CF, Mennerick S. Interaction between positive allosteric modulators and trapping blockers of the NMDA receptor channel. Br J Pharmacol 2015; 172:1333-47. [PMID: 25377730 DOI: 10.1111/bph.13007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 10/27/2014] [Accepted: 10/29/2014] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE Memantine and ketamine are clinically used, open-channel blockers of NMDA receptors exhibiting remarkable pharmacodynamic similarities despite strikingly different clinical profiles. Although NMDA channel gating constitutes an important difference between memantine and ketamine, it is unclear how positive allosteric modulators (PAMs) might affect the pharmacodynamics of these NMDA blockers. EXPERIMENTAL APPROACH We used two different PAMs: SGE-201, an analogue of an endogenous oxysterol, 24S-hydroxycholesterol, along with pregnenolone sulphate (PS), to test on memantine and ketamine responses in single cells (oocytes and cultured neurons) and networks (hippocampal slices), using standard electrophysiological techniques. KEY RESULTS SGE-201 and PS had no effect on steady-state block or voltage dependence of a channel blocker. However, both PAMs increased the actions of memantine and ketamine on phasic excitatory post-synaptic currents, but neither revealed underlying pharmacodynamic differences. SGE-201 accelerated the re-equilibration of blockers during voltage jumps. SGE-201 also unmasked differences among the blockers in neuronal networks - measured either by suppression of activity in multi-electrode arrays or by neuroprotection against a mild excitotoxic insult. Either potentiating NMDA receptors while maintaining the basal activity level or increasing activity/depolarization without potentiating NMDA receptor function is sufficient to expose pharmacodynamic blocker differences in suppressing network function and in neuroprotection. CONCLUSIONS AND IMPLICATIONS Positive modulation revealed no pharmacodynamic differences between NMDA receptor blockers at a constant voltage, but did expose differences during spontaneous network activity. Endogenous modulator tone of NMDA receptors in different brain regions may underlie differences in the effects of NMDA receptor blockers on behaviour.
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Affiliation(s)
- Christine M Emnett
- Graduate Program in Neuroscience, Washington University, St Louis, MO, USA; Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
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Zhang E, Liao P. Brain transient receptor potential channels and stroke. J Neurosci Res 2014; 93:1165-83. [PMID: 25502473 DOI: 10.1002/jnr.23529] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/10/2014] [Accepted: 11/04/2014] [Indexed: 02/06/2023]
Abstract
Transient receptor potential (TRP) channels have been increasingly implicated in the pathological mechanisms of CNS disorders. TRP expression has been detected in neurons, astrocytes, oligodendrocytes, microglia, and ependymal cells as well as in the cerebral vascular endothelium and smooth muscle. In stroke, TRPC3/4/6, TRPM2/4/7, and TRPV1/3/4 channels have been found to participate in ischemia-induced cell death, whereas other TRP channels, in particular those expressed in nonneuronal cells, have been less well studied. This review summarizes the current knowledge on the expression and functions of the TRP channels in various cell types in the brain and our current understanding of TRP channels in stroke pathophysiology. In an aging society, the occurrence of stroke is expected to increase steadily, and there is an urgent requirement to improve the current stroke management strategy. Therefore, elucidating the roles of TRP channels in stroke could shed light on the development of novel therapeutic strategies and ultimately improve stroke outcome.
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Affiliation(s)
- Eric Zhang
- Calcium Signalling Laboratory, National Neuroscience Institute, Singapore
| | - Ping Liao
- Calcium Signalling Laboratory, National Neuroscience Institute, Singapore.,Duke-NUS Graduate Medical School Singapore, Singapore
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Abstract
RATIONALE The neurosteroid pregnenolone sulfate (PregS) acts as a cognitive enhancer and modulator of neurotransmission, yet aligning its pharmacological and physiological effects with reliable measurements of endogenous local concentrations and pharmacological and therapeutic targets has remained elusive for over 20 years. OBJECTIVES New basic and clinical research concerning neurosteroid modulation of the central nervous system (CNS) function has emerged over the past 5 years, including important data involving pregnenolone and various neurosteroid precursors of PregS that point to a need for a critical status update. RESULTS Highly specific actions of PregS affecting excitatory N-methyl-D-aspartate receptor (NMDAR)-mediated synaptic transmission and the pharmacological effects of PregS on various receptors and ion channels are discussed. The discovery of a high potency (nanomolar) signal transduction pathway for PregS-induced NMDAR trafficking to the cell surface via a Ca(2+)- and G protein-coupled receptor (GPCR)-dependent mechanism and a potent (EC50 ~ 2 pM) direct enhancement of intracellular Ca(2+) levels is discussed in terms of its agonist effects on long-term potentiation (LTP) and memory. Lastly, preclinical and clinical studies assessing the promnestic effects of PregS and pregnenolone toward cognitive dysfunction in schizophrenia, and altered serum levels in epilepsy and alcohol dependence, are reviewed. CONCLUSIONS PregS is present in human and rodent brain at physiologically relevant concentrations and meets most of the criteria for an endogenous neurotransmitter/neuromodulator. PregS likely plays a significant role in modulation of glutamatergic excitatory synaptic transmission underlying learning and memory, yet the molecular target(s) for its action awaits identification.
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Affiliation(s)
- Conor C. Smith
- Laboratory of Molecular Neurobiology, Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, 72 East Concord St., Boston, MA 02118, USA
| | - Terrell T. Gibbs
- Laboratory of Molecular Neurobiology, Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, 72 East Concord St., Boston, MA 02118, USA
| | - David H. Farb
- Laboratory of Molecular Neurobiology, Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, 72 East Concord St., Boston, MA 02118, USA
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Harteneck C. Pregnenolone sulfate: from steroid metabolite to TRP channel ligand. Molecules 2013; 18:12012-28. [PMID: 24084011 DOI: 10.3390/molecules181012012] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 09/20/2013] [Accepted: 09/21/2013] [Indexed: 01/16/2023] Open
Abstract
Pregnenolone sulfate is a steroid metabolite with a plethora of actions and functions. As a neurosteroid, pregnenolone sulfate modulates a variety of ion channels, transporters, and enzymes. Interestingly, as a sulfated steroid, pregnenolone sulfate is not the final- or waste-product of pregnenolone being sulfated via a phase II metabolism reaction and renally excreted, as one would presume from the pharmacology textbook knowledge. Pregnenolone sulfate is also the source and thereby the starting point for subsequent steroid synthesis pathways. Most recently, pregnenolone sulfate has been functionally “upgraded” from modulator of ion channels to an activating ion channel ligand. This review will focus on molecular aspects of the neurosteroid, pregnenolone sulfate, its metabolism, concentrations in serum and tissues and last not least will summarize the functional data.
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Hong JS, Cho JH, Choi IS, Lee MG, Jang IS. Pregnenolone sulfate modulates glycinergic transmission in rat medullary dorsal horn neurons. Eur J Pharmacol 2013; 712:30-8. [PMID: 23665111 DOI: 10.1016/j.ejphar.2013.04.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 04/19/2013] [Accepted: 04/26/2013] [Indexed: 11/20/2022]
Abstract
The neurosteroid pregnenolone sulfate (PS), a representative excitatory neuromodulator, has a variety of neuropharmacological actions, such as memory enhancement and convulsant effects. In this study, the effects of PS on glycinergic transmission, such as glycinergic spontaneous miniature inhibitory postsynaptic currents (mIPSCs), were investigated in acutely isolated medullary dorsal horn neurons by use of a conventional whole-cell patch-clamp technique. PS significantly increased the frequency but decreased the amplitude of glycinergic mIPSCs in a concentration-dependent manner. PS also accelerated the decay time constant of glycinergic mIPSCs. The PS-induced decrease in mIPSC amplitude was due to the direct postsynaptic inhibition of glycine receptors because PS inhibited the glycine-induced Cl(-) currents in a noncompetitive manner. The PS-induced increase in mIPSC frequency was not due to the activation of α7 nicotinic acetylcholine, NMDA, σ1 receptors and voltage-dependent Ca(2+) channels, which are known to be molecular targets of PS. On the other hand, the PS-induced increase in mIPSC frequency was completely attenuated either in the Ca(2+)-free external solution or in the presence of transient receptor potential (TRP) channel blockers, suggesting that PS elicits an increase in Ca(2+) concentration within glycinergic nerve terminals via the activation of putative TRP channels. The PS-mediated modulation of glycinergic synaptic transmission, such as the enhancement of presynaptic glycine release and direct inhibition of postsynaptic glycine receptors, might have a broad impact on the excitability of medullary dorsal horn neurons and therefore affect the processing of nociceptive transmission from orofacial tissues.
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McEwen AM, Burgess DTA, Hanstock CC, Seres P, Khalili P, Newman SC, Baker GB, Mitchell ND, Khudabux-Der J, Allen PS, LeMelledo JM. Increased glutamate levels in the medial prefrontal cortex in patients with postpartum depression. Neuropsychopharmacology 2012; 37:2428-35. [PMID: 22805604 PMCID: PMC3442339 DOI: 10.1038/npp.2012.101] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 04/24/2012] [Accepted: 05/17/2012] [Indexed: 12/21/2022]
Abstract
The medial prefrontal cortex (MPFC) is a key brain area in depressive symptomatology; specifically, glutamate (Glu) has been reported to play a significant role in major depression (MD) in this area. MPFC Glu levels are sensitive to ovarian hormone fluctuations and pregnancy and the postpartum period are associated with the most substantial physiological alterations of female hormones. It is therefore logical to measure MPFC Glu levels in women with postpartum depression (PPD). Using in vivo magnetic resonance spectroscopy (MRS) at a field strength of 3 T, we acquired single-voxel spectra from the MPFC of 12 women with PPD and 12 healthy controls (HCs) matched for postpartum scan timing. Water-referenced MPFC Glu levels were measured using a MRS technique that allowed us to be specific for Glu with very little glutamine contamination. The concentrations of other water-quantified brain metabolites such as glycerophosphorylcholine plus phosphorylcholine, N-acetylaspartate (NAA), and creatine plus phosphocreatine were measured in the same MR spectra. MPFC Glu levels were higher in women with PPD (7.21±1.20) compared to matched HCs (6.04±1.21). There were no differences between groups for other brain metabolites measured. These findings suggest an association between Glu dysregulation in the MPFC and PPD. Whether the pathophysiology of PPD differs from the pathophysiology of MD remains to be determined. Further investigations are needed to determine the chronological associations between the occurrence of symptoms of PPD and the onset of changes in MPFC Glu levels.
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Affiliation(s)
- Alyssa M McEwen
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Denee T A Burgess
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | | | - Peter Seres
- Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada
| | - Panteha Khalili
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Stephen C Newman
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Glen B Baker
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | | | | | - Peter S Allen
- Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada
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Abstract
This review will highlight a variety of mechanisms by which neurosteroids affect sensitivity to ethanol, including physiological states associated with activity of the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes, and the effects of chronic exposure to ethanol, in addition to behavioral implications. To date, γ-aminobutyric acid (GABA(A)) receptor mechanisms are a major focus of the modulation of ethanol effects by neuroactive steroids. While NMDA receptor mechanisms are gaining prominence in the literature, these complex data would be best discussed separately. Accordingly, GABA(A) receptor mechanisms are emphasized in this review with brief mention of some NMDA receptor mechanisms to point out contrasting neuroactive steroid pharmacology. Overall, the data suggest that neurosteroids are virtually ubiquitous modulators of inhibitory neurotransmission. Neurosteroids appear to affect sensitivity to ethanol in specific brain regions and, consequently, specific behavioral tests, possibly related to the efficacy and potency of ethanol to potentiate the release of GABA and increase neurosteroid concentrations. Although direct interaction of ethanol and neuroactive steroids at common receptor binding sites has been suggested in some studies, this proposition is still controversial. It is currently difficult to assign a specific mechanism by which neuroactive steroids could modulate the effects of ethanol in particular behavioral tasks.
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Affiliation(s)
- Christa M. Helms
- Division of Neuroscience, Oregon National Primate Research CenterBeaverton, OR, USA
- *Correspondence: Christa M. Helms, Division of Neuroscience, Oregon National Primate Research Center, L-584, 505 North-West 185th Avenue, Beaverton, OR 97006, USA. e-mail:
| | - David J. Rossi
- Department of Behavioral Neuroscience, Oregon Health and Science UniversityPortland, OR, USA
| | - Kathleen A. Grant
- Division of Neuroscience, Oregon National Primate Research CenterBeaverton, OR, USA
- Department of Behavioral Neuroscience, Oregon Health and Science UniversityPortland, OR, USA
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Abstract
The Transient receptor potential (TRP) family of cation channels is a large protein family, which is mainly structurally uniform. Proteins consist typically of six transmembrane domains and mostly four subunits are necessary to form a functional channel. Apart from this, TRP channels display a wide variety of activation mechanisms (ligand binding, G-protein coupled receptor dependent, physical stimuli such as temperature, pressure, etc.) and ion selectivity profiles (from highly Ca(2+) selective to non-selective for cations). They have been described now in almost every tissue of the body, including peripheral and central neurons. Especially in the sensory nervous system the role of several TRP channels is already described on a detailed level. This review summarizes data that is currently available on their role in the central nervous system. TRP channels are involved in neurogenesis and brain development, synaptic transmission and they play a key role in the development of several neurological diseases.
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Zamudio-Bulcock PA, Everett J, Harteneck C, Valenzuela CF. Activation of steroid-sensitive TRPM3 channels potentiates glutamatergic transmission at cerebellar Purkinje neurons from developing rats. J Neurochem 2011; 119:474-85. [PMID: 21955047 DOI: 10.1111/j.1471-4159.2011.07441.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The functional implications of transient receptor potential melastatin 3 (TRPM3) activation, the most recently described member of the melastatin subfamily of cation permeable TRP channels, have begun to be elucidated in recent years. The discovery of TRPM3 activation by the steroid pregnenolone sulfate (PregS) has shed new light on the physiological role of this channel. For example, TRPM3 activation enhances insulin secretion from β pancreatic cells, induces contraction of vascular smooth muscle, and is also involved in the detection of noxious heat. Although TRPM3 expression has been detected in several regions of the developing and mature brain, little is known about the roles of TRPM3 in brain physiology. In this study, we demonstrate the abundant expression of TRPM3 steroid-sensitive channels in the developing cerebellar cortex. We also show that TRPM3-like channels are expressed at glutamatergic synapses in neonatal Purkinje cells. We recently showed that PregS potentiates spontaneous glutamate release onto neonatal Purkinje cells during a period of active glutamatergic synapse formation; we now show that this effect of PregS is mediated by TRPM3-like channels. Mefenamic acid, a recently discovered TRPM3 antagonist, blocked the effect of PregS on glutamate release. The PregS effect on glutamate release was mimicked by other TRPM3 agonists (nifedipine and epipregnanolone sulfate) but not by a TRMP3-inactive steroid (progesterone). Our findings identify TRPM3 channels as novel modulators of glutamatergic transmission in the developing brain.
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Affiliation(s)
- Paula A Zamudio-Bulcock
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131-0001, USA
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