1
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Soedirdjo SDH, Chung YC, Dhaher YY. Sex hormone mediated change on flexion reflex. Front Neurosci 2023; 17:1263756. [PMID: 38188036 PMCID: PMC10768023 DOI: 10.3389/fnins.2023.1263756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 11/27/2023] [Indexed: 01/09/2024] Open
Abstract
It has been shown that estrogen and progesterone receptors are expressed in the spinal cord; therefore, fluctuation in their concentrations may affect the spinal network and modulate the control of movement. Herein, we assessed the neuro-modulatory effect of sex hormones on the polysynaptic spinal network by using a flexion reflex network as a model system. Twenty-four healthy eumenorrheic women (age 21-37 years) were tested every other day for one menstrual cycle. Serum estradiol and progesterone were acquired at the time of testing. The flexion reflex of the tibialis anterior was elicited by sending an innocuous electrical stimulus directly to the posterior tibial nerve or plantar cutaneous afferent. Analyses were performed for each menstrual cycle phase: the follicular phase and the luteal phase. Increases in estradiol or progesterone concentrations were not associated with reflex duration or root mean squared (RMS) amplitude in either the follicular or luteal phases. In the luteal phase, an increase in the estradiol concentration was associated with a longer latency of the reflex (b = 0.23, p = 0.038). The estradiol × progesterone interaction was found towards significance (b = -0.017, p = 0.081). These results highlight the potential synergistic effect of estradiol and progesterone and may provide indirect confirmatory evidence of the observed modulatory effect.
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Affiliation(s)
- Subaryani D. H. Soedirdjo
- Department of Physical Medicine and Rehabilitation, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Yu-Chen Chung
- Department of Physical Medicine and Rehabilitation, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Yasin Y. Dhaher
- Department of Physical Medicine and Rehabilitation, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Biomedical Engineering, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States
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2
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Sun C, Zhu H, Clark S, Gouaux E. Cryo-EM structures reveal native GABA A receptor assemblies and pharmacology. Nature 2023; 622:195-201. [PMID: 37730991 PMCID: PMC10550821 DOI: 10.1038/s41586-023-06556-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 08/21/2023] [Indexed: 09/22/2023]
Abstract
Type A γ-aminobutyric acid receptors (GABAARs) are the principal inhibitory receptors in the brain and the target of a wide range of clinical agents, including anaesthetics, sedatives, hypnotics and antidepressants1-3. However, our understanding of GABAAR pharmacology has been hindered by the vast number of pentameric assemblies that can be derived from 19 different subunits4 and the lack of structural knowledge of clinically relevant receptors. Here, we isolate native murine GABAAR assemblies containing the widely expressed α1 subunit and elucidate their structures in complex with drugs used to treat insomnia (zolpidem (ZOL) and flurazepam) and postpartum depression (the neurosteroid allopregnanolone (APG)). Using cryo-electron microscopy (cryo-EM) analysis and single-molecule photobleaching experiments, we uncover three major structural populations in the brain: the canonical α1β2γ2 receptor containing two α1 subunits, and two assemblies containing one α1 and either an α2 or α3 subunit, in which the single α1-containing receptors feature a more compact arrangement between the transmembrane and extracellular domains. Interestingly, APG is bound at the transmembrane α/β subunit interface, even when not added to the sample, revealing an important role for endogenous neurosteroids in modulating native GABAARs. Together with structurally engaged lipids, neurosteroids produce global conformational changes throughout the receptor that modify the ion channel pore and the binding sites for GABA and insomnia medications. Our data reveal the major α1-containing GABAAR assemblies, bound with endogenous neurosteroid, thus defining a structural landscape from which subtype-specific drugs can be developed.
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Affiliation(s)
- Chang Sun
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Hongtao Zhu
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Sarah Clark
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, USA
| | - Eric Gouaux
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA.
- Howard Hughes Medical Institute, Oregon Health and Science University, Portland, OR, USA.
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3
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Perucca E, Bialer M, White HS. New GABA-Targeting Therapies for the Treatment of Seizures and Epilepsy: I. Role of GABA as a Modulator of Seizure Activity and Recently Approved Medications Acting on the GABA System. CNS Drugs 2023; 37:755-779. [PMID: 37603262 PMCID: PMC10501955 DOI: 10.1007/s40263-023-01027-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/06/2023] [Indexed: 08/22/2023]
Abstract
γ-Aminobutyric acid (GABA) is the most prevalent inhibitory neurotransmitter in the mammalian brain and has been found to play an important role in the pathogenesis or the expression of many neurological diseases, including epilepsy. Although GABA can act on different receptor subtypes, the component of the GABA system that is most critical to modulation of seizure activity is the GABAA-receptor-chloride (Cl-) channel complex, which controls the movement of Cl- ions across the neuronal membrane. In the mature brain, binding of GABA to GABAA receptors evokes a hyperpolarising (anticonvulsant) response, which is mediated by influx of Cl- into the cell driven by its concentration gradient between extracellular and intracellular fluid. However, in the immature brain and under certain pathological conditions, GABA can exert a paradoxical depolarising (proconvulsant) effect as a result of an efflux of chloride from high intracellular to lower extracellular Cl- levels. Extensive preclinical and clinical evidence indicates that alterations in GABAergic inhibition caused by drugs, toxins, gene defects or other disease states (including seizures themselves) play a causative or contributing role in facilitating or maintaning seizure activity. Conversely, enhancement of GABAergic transmission through pharmacological modulation of the GABA system is a major mechanism by which different antiseizure medications exert their therapeutic effect. In this article, we review the pharmacology and function of the GABA system and its perturbation in seizure disorders, and highlight how improved understanding of this system offers opportunities to develop more efficacious and better tolerated antiseizure medications. We also review the available data for the two most recently approved antiseizure medications that act, at least in part, through GABAergic mechanisms, namely cenobamate and ganaxolone. Differences in the mode of drug discovery, pharmacological profile, pharmacokinetic properties, drug-drug interaction potential, and clinical efficacy and tolerability of these agents are discussed.
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Affiliation(s)
- Emilio Perucca
- Department of Medicine (Austin Health), The University of Melbourne, Melbourne, VIC, Australia.
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia.
- Melbourne Brain Centre, 245 Burgundy Street, Heidelberg, VIC, 3084, Australia.
| | - Meir Bialer
- Institute of Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- David R. Bloom Center for Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - H Steve White
- Department of Pharmacy, School of Pharmacy, University of Washington, Seattle, WA, USA
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4
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Sun C, Zhu H, Clark S, Gouaux E. Regulated assembly and neurosteroid modulation constrain GABA A receptor pharmacology in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.16.528867. [PMID: 36824901 PMCID: PMC9949137 DOI: 10.1101/2023.02.16.528867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Type A GABA receptors (GABA A Rs) are the principal inhibitory receptors in the brain and the target of a wide range of clinical agents, including anesthetics, sedatives, hypnotics, and antidepressants. However, our understanding of GABA A R pharmacology has been hindered by the vast number of pentameric assemblies that can be derived from a total 19 different subunits and the lack of structural knowledge of clinically relevant receptors. Here, we isolate native murine GABA A R assemblies containing the widely expressed α 1 subunit, and elucidate their structures in complex with drugs used to treat insomnia (zolpidem and flurazepam) and postpartum depression (the neurosteroid allopregnanolone). Using cryo-EM analysis and single-molecule photobleaching experiments, we uncover only three structural populations in the brain: the canonical α 1 β2γ 2 receptor containing two α 1 subunits and two unanticipated assemblies containing one α 1 and either an α 2 , α 3 or α 5 subunit. Both of the noncanonical assemblies feature a more compact arrangement between the transmembrane and extracellular domains. Interestingly, allopregnanolone is bound at the transmembrane α/β subunit interface, even when not added to the sample, revealing an important role for endogenous neurosteroids in modulating native GABA A Rs. Together with structurally engaged lipids, neurosteroids produce global conformational changes throughout the receptor that modify both the pore diameter and binding environments for GABA and insomnia medications. Together, our data reveal that GABA A R assembly is a strictly regulated process that yields a small number of structurally distinct complexes, defining a structural landscape from which subtype-specific drugs can be developed.
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5
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Boychuk JA, Butler CR, Smith KC, Halmos MB, Smith BN. Zolpidem Profoundly Augments Spared Tonic GABAAR Signaling in Dentate Granule Cells Ipsilateral to Controlled Cortical Impact Brain Injury in Mice. Front Syst Neurosci 2022; 16:867323. [PMID: 35694044 PMCID: PMC9178240 DOI: 10.3389/fnsys.2022.867323] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/05/2022] [Indexed: 11/18/2022] Open
Abstract
Type A GABA receptors (GABAARs) are pentameric combinations of protein subunits that give rise to tonic (ITonicGABA) and phasic (i.e., synaptic; ISynapticGABA) forms of inhibitory GABAAR signaling in the central nervous system. Remodeling and regulation of GABAAR protein subunits are implicated in a wide variety of healthy and injury-dependent states, including epilepsy. The present study undertook a detailed analysis of GABAAR signaling using whole-cell patch clamp recordings from mouse dentate granule cells (DGCs) in coronal slices containing dorsal hippocampus at 1–2 or 8–13 weeks after a focal, controlled cortical impact (CCI) or sham brain injury. Zolpidem, a benzodiazepine-like positive modulator of GABAARs, was used to test for changes in GABAAR signaling of DGCs due to its selectivity for α1 subunit-containing GABAARs. Electric charge transfer and statistical percent change were analyzed in order to directly compare tonic and phasic GABAAR signaling and to account for zolpidem’s ability to modify multiple parameters of GABAAR kinetics. We observed that baseline ITonicGABA is preserved at both time-points tested in DGCs ipsilateral to injury (Ipsi-DGCs) compared to DGCs contralateral to injury (Contra-DGCs) or after sham injury (Sham-DGCs). Interestingly, application of zolpidem resulted in modulation of ITonicGABA across groups, with Ipsi-DGCs exhibiting the greatest responsiveness to zolpidem. We also report that the combination of CCI and acute application of zolpidem profoundly augments the proportion of GABAAR charge transfer mediated by tonic vs. synaptic currents at both time-points tested, whereas gene expression of GABAAR α1, α2, α3, and γ2 subunits is unchanged at 8–13 weeks post-injury. Overall, this work highlights the shift toward elevated influence of tonic inhibition in Ipsi-DGCs, the impact of zolpidem on all components of inhibitory control of DGCs, and the sustained nature of these changes in inhibitory tone after CCI injury.
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Affiliation(s)
- Jeffery A Boychuk
- Department of Physiology, University of Kentucky, Lexington, KY, United States
- Department of Cellular and Integrative Physiology, UT Health San Antonio, San Antonio, TX, United States
| | - Corwin R Butler
- Department of Physiology, University of Kentucky, Lexington, KY, United States
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR, United States
| | - Katalin Cs Smith
- Department of Physiology, University of Kentucky, Lexington, KY, United States
- Department of Neuroscience, University of Kentucky, Lexington, KY, United States
| | - Miklos B Halmos
- Department of Psychology, Georgia State University, Atlanta, GA, United States
| | - Bret N Smith
- Department of Physiology, University of Kentucky, Lexington, KY, United States
- Department of Neuroscience, University of Kentucky, Lexington, KY, United States
- Spinal Cord and Brain Injury Research Center (SCoBIRC), University of Kentucky, Lexington, KY, United States
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
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6
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Wang L, Covey DF, Akk G, Evers AS. Neurosteroid Modulation of GABA A Receptor Function by Independent Action at Multiple Specific Binding Sites. Curr Neuropharmacol 2022; 20:886-890. [PMID: 34856904 PMCID: PMC9881108 DOI: 10.2174/1570159x19666211202150041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 11/28/2021] [Accepted: 11/28/2021] [Indexed: 11/22/2022] Open
Abstract
Neurosteroids are endogenous modulators of GABAA receptors that mediate anxiety, pain, mood and arousal. The 3-hydroxyl epimers, allopregnanolone (3α-OH) and epiallopregnanolone (3β-OH) are both prevalent in the mammalian brain and produce opposite effects on GABAA receptor function, acting as positive and negative allosteric modulators, respectively. This Perspective provides a model to explain the actions of 3α-OH and 3β-OH neurosteroids. The model is based on evidence that the neurosteroid epimers bind to an overlapping subset of specific sites on GABAA receptors, with their net functional effect on channel gating being the sum of their independent effects at each site.
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Affiliation(s)
- Lei Wang
- Department of Anesthesiology (LW, DFC, GA, ASE),,Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Douglas F. Covey
- Department of Anesthesiology (LW, DFC, GA, ASE),,Department of Developmental Biology (Pharmacology);,Department of Psychiatry (DFC) and
| | - Gustav Akk
- Department of Anesthesiology (LW, DFC, GA, ASE),,The Taylor Institute for Innovative Psychiatric Research (DFC, GA, ASE), Washington University School of Medicine, St. Louis, MO63110; U.S.A
| | - Alex S. Evers
- Department of Anesthesiology (LW, DFC, GA, ASE),,Department of Developmental Biology (Pharmacology);,The Taylor Institute for Innovative Psychiatric Research (DFC, GA, ASE), Washington University School of Medicine, St. Louis, MO63110; U.S.A,Address correspondence to this author at the Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave, Box # 8054, St. Louis, MO 63110, USA; Tel: +1 314-362-8557; E-mail:
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7
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Electrophysiology of ionotropic GABA receptors. Cell Mol Life Sci 2021; 78:5341-5370. [PMID: 34061215 PMCID: PMC8257536 DOI: 10.1007/s00018-021-03846-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/02/2021] [Accepted: 04/23/2021] [Indexed: 10/30/2022]
Abstract
GABAA receptors are ligand-gated chloride channels and ionotropic receptors of GABA, the main inhibitory neurotransmitter in vertebrates. In this review, we discuss the major and diverse roles GABAA receptors play in the regulation of neuronal communication and the functioning of the brain. GABAA receptors have complex electrophysiological properties that enable them to mediate different types of currents such as phasic and tonic inhibitory currents. Their activity is finely regulated by membrane voltage, phosphorylation and several ions. GABAA receptors are pentameric and are assembled from a diverse set of subunits. They are subdivided into numerous subtypes, which differ widely in expression patterns, distribution and electrical activity. Substantial variations in macroscopic neural behavior can emerge from minor differences in structure and molecular activity between subtypes. Therefore, the diversity of GABAA receptors widens the neuronal repertoire of responses to external signals and contributes to shaping the electrical activity of neurons and other cell types.
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8
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Abstract
Migraine is considered mostly a woman’s complaint, even if it affects also men. Epidemiological data show a higher incidence of the disease in women, starting from puberty throughout life. The sex-related differences of migraine hold clinical relevance too. The frequency, duration, and disability of attacks tend to be higher in women. Because of this, probably, they also consult specialists more frequently and take more prescription drugs than men. Different mechanisms have been evaluated to explain these differences. Hormonal milieu and its modulation of neuronal and vascular reactivity is probably one of the most important aspects. Estrogens and progesterone regulate a host of biological functions through two mechanisms: nongenomic and genomic. They influence several neuromediators and neurotransmitters, and they may cause functional and structural differences in several brain regions, involved in migraine pathogenesis. In addition to their central action, sex hormones exert rapid modulation of vascular tone. The resulting specific sex phenotype should be considered during clinical management and experimental studies.
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9
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Biosynthesis and signalling functions of central and peripheral nervous system neurosteroids in health and disease. Essays Biochem 2021; 64:591-606. [PMID: 32756865 PMCID: PMC7517341 DOI: 10.1042/ebc20200043] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/09/2020] [Accepted: 07/14/2020] [Indexed: 02/07/2023]
Abstract
Neurosteroids are steroid hormones synthesised de novo in the brain and peripheral nervous tissues. In contrast to adrenal steroid hormones that act on intracellular nuclear receptors, neurosteroids directly modulate plasma membrane ion channels and regulate intracellular signalling. This review provides an overview of the work that led to the discovery of neurosteroids, our current understanding of their intracellular biosynthetic machinery, and their roles in regulating the development and function of nervous tissue. Neurosteroids mediate signalling in the brain via multiple mechanisms. Here, we describe in detail their effects on GABA (inhibitory) and NMDA (excitatory) receptors, two signalling pathways of opposing function. Furthermore, emerging evidence points to altered neurosteroid function and signalling in neurological disease. This review focuses on neurodegenerative diseases associated with altered neurosteroid metabolism, mainly Niemann-Pick type C, multiple sclerosis and Alzheimer disease. Finally, we summarise the use of natural and synthetic neurosteroids as current and emerging therapeutics alongside their potential use as disease biomarkers.
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10
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Pati GK, Kar C, Narayan J, Uthansingh K, Behera M, Sahu MK, Mishra D, Singh A. Irritable Bowel Syndrome and the Menstrual Cycle. Cureus 2021; 13:e12692. [PMID: 33614302 PMCID: PMC7883586 DOI: 10.7759/cureus.12692] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Introduction: Irritable bowel syndrome (IBS) is a common gastrointestinal (GI) disorder. Female patients with bowel disease commonly report worsening of symptoms in the menstrual cycle. However, there is a paucity of data regarding IBS presentations' variation during different phases of the menstrual cycle. The current study aimed to evaluate the same in female IBS patients. Materials and Methods: Consecutive premenopausal female patients with the diagnosis of IBS attending the outdoor (OPD) of Department of Gastroenterology and Gynaecology; IMS and SUM Hospital, Bhubaneswar, Odisha from June 2019 to December 2019 were included in the study and evaluated by a set of questionnaires regarding various presentations during all the three phases of the menstrual cycle. Results: Consecutive 102 cases with the diagnosis of IBS were included in the study and evaluated. The mean age of presentation was in mid-30s. Most of the subjects suffered from IBS mixed (IBS-M) type. More patients significantly suffered from constipation (27.27%) during the luteal phase of their menstrual cycles than the menstrual period of their cycles (p - 0.009). More than 50% of all the cases suffered from abdominal bloating during all phases of the menstrual cycle, which was quite disturbing and affected the quality of life. These IBS patients were more symptomatic with more significant limitation of daily activities, suffered from low quality of life, and obtained physician consultation during the menstrual phase as compared to other cycle stages. Conclusion: Premenopausal female patients with IBS become much more symptomatic during the menstrual phase of the cycle than other stages of the cycle.
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Affiliation(s)
- Girish K Pati
- Gastroenterology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, IND
| | - Chinmayee Kar
- Obstetrics and Gynecology, SUM Ultimate Medicare, Siksha 'O' Anusandhan University, Bhubaneswar, IND
| | - Jimmy Narayan
- Gastroenterology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, IND
| | - Kanishka Uthansingh
- Gastroenterology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, IND
| | - Manas Behera
- Gastroenterology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, IND
| | - Manoj K Sahu
- Gastroenterology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, IND
| | - Debakanta Mishra
- Gastroenterology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, IND
| | - Ayaskanta Singh
- Gastroenterology, Institute of Medical Sciences and SUM Hospital, SUM Ultimate Medicare, Siksha 'O' Anusundhan University, Bhubaneswar, IND
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11
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Castellano D, Shepard RD, Lu W. Looking for Novelty in an "Old" Receptor: Recent Advances Toward Our Understanding of GABA ARs and Their Implications in Receptor Pharmacology. Front Neurosci 2021; 14:616298. [PMID: 33519367 PMCID: PMC7841293 DOI: 10.3389/fnins.2020.616298] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 12/14/2020] [Indexed: 12/16/2022] Open
Abstract
Diverse populations of GABAA receptors (GABAARs) throughout the brain mediate fast inhibitory transmission and are modulated by various endogenous ligands and therapeutic drugs. Deficits in GABAAR signaling underlie the pathophysiology behind neurological and neuropsychiatric disorders such as epilepsy, anxiety, and depression. Pharmacological intervention for these disorders relies on several drug classes that target GABAARs, such as benzodiazepines and more recently neurosteroids. It has been widely demonstrated that subunit composition and receptor stoichiometry impact the biophysical and pharmacological properties of GABAARs. However, current GABAAR-targeting drugs have limited subunit selectivity and produce their therapeutic effects concomitantly with undesired side effects. Therefore, there is still a need to develop more selective GABAAR pharmaceuticals, as well as evaluate the potential for developing next-generation drugs that can target accessory proteins associated with native GABAARs. In this review, we briefly discuss the effects of benzodiazepines and neurosteroids on GABAARs, their use as therapeutics, and some of the pitfalls associated with their adverse side effects. We also discuss recent advances toward understanding the structure, function, and pharmacology of GABAARs with a focus on benzodiazepines and neurosteroids, as well as newly identified transmembrane proteins that modulate GABAARs.
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Affiliation(s)
- David Castellano
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Ryan David Shepard
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Wei Lu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
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12
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Serratto GM, Pizzi E, Murru L, Mazzoleni S, Pelucchi S, Marcello E, Mazzanti M, Passafaro M, Bassani S. The Epilepsy-Related Protein PCDH19 Regulates Tonic Inhibition, GABA AR Kinetics, and the Intrinsic Excitability of Hippocampal Neurons. Mol Neurobiol 2020; 57:5336-5351. [PMID: 32880860 PMCID: PMC7541378 DOI: 10.1007/s12035-020-02099-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 08/25/2020] [Indexed: 12/19/2022]
Abstract
PCDH19 encodes for protocadherin-19 (PCDH19), a cell-adhesion molecule of the cadherin superfamily preferentially expressed in the brain. PCDH19 mutations cause a neurodevelopmental syndrome named epileptic encephalopathy, early infantile, 9 (EIEE9) characterized by seizures associated with cognitive and behavioral deficits. We recently reported that PCDH19 binds the alpha subunits of GABAA receptors (GABAARs), modulating their surface availability and miniature inhibitory postsynaptic currents (mIPSCs). Here, we investigated whether PCDH19 regulatory function on GABAARs extends to the extrasynaptic receptor pool that mediates tonic current. In fact, the latter shapes neuronal excitability and network properties at the base of information processing. By combining patch-clamp recordings in whole-cell and cell-attached configurations, we provided a functional characterization of primary hippocampal neurons from embryonic rats of either sex expressing a specific PCDH19 short hairpin (sh)RNA. We first demonstrated that PCDH19 downregulation reduces GABAAR-mediated tonic current, evaluated by current shift and baseline noise analysis. Next, by single-channel recordings, we showed that PCDH19 regulates GABAARs kinetics without altering their conductance. In particular, GABAARs of shRNA-expressing neurons preferentially exhibit brief openings at the expense of long ones, thus displaying a flickering behavior. Finally, we showed that PCDH19 downregulation reduces the rheobase and increases the frequency of action potential firing, thus indicating neuronal hyperexcitability. These findings establish PCDH19 as a critical determinant of GABAAR-mediated tonic transmission and GABAARs gating, and provide the first mechanistic insights into PCDH19-related hyperexcitability and comorbidities.
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Affiliation(s)
| | - Erika Pizzi
- Department of Bioscience, University of Milan, 20133, Milan, Italy
| | - Luca Murru
- Institute of Neuroscience, CNR, 20129, Milan, Italy.,NeuroMI Milan Center for Neuroscience, University of Milano-Bicocca, 20126, Milan, Italy
| | - Sara Mazzoleni
- Institute of Neuroscience, CNR, 20129, Milan, Italy.,Department of Medical Biotechnology and Translational Medicine, University of Milan, 20129, Milan, Italy
| | - Silvia Pelucchi
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133, Milan, Italy
| | - Elena Marcello
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133, Milan, Italy
| | - Michele Mazzanti
- Department of Bioscience, University of Milan, 20133, Milan, Italy
| | - Maria Passafaro
- Institute of Neuroscience, CNR, 20129, Milan, Italy.,NeuroMI Milan Center for Neuroscience, University of Milano-Bicocca, 20126, Milan, Italy
| | - Silvia Bassani
- Institute of Neuroscience, CNR, 20129, Milan, Italy. .,NeuroMI Milan Center for Neuroscience, University of Milano-Bicocca, 20126, Milan, Italy.
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13
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Littlejohn EL, Espinoza L, Lopez MM, Smith BN, Boychuk CR. GABA A receptor currents in the dorsal motor nucleus of the vagus in females: influence of ovarian cycle and 5α-reductase inhibition. J Neurophysiol 2019; 122:2130-2141. [PMID: 31596653 PMCID: PMC6879959 DOI: 10.1152/jn.00039.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 09/23/2019] [Accepted: 10/07/2019] [Indexed: 11/22/2022] Open
Abstract
The dorsal motor nucleus of the vagus (DMV) contains the preganglionic motor neurons important in the regulation of glucose homeostasis and gastrointestinal function. Despite the role of sex in the regulation of these processes, few studies examine the role of sex and/or ovarian cycle in the regulation of synaptic neurotransmission to the DMV. Since GABAergic neurotransmission is critical to normal DMV function, the present study used in vitro whole cell patch-clamping to investigate whether sex differences exist in GABAergic neurotransmission to DMV neurons. It additionally investigated whether the ovarian cycle plays a role in those sex differences. The frequency of phasic GABAA receptor-mediated inhibitory postsynaptic currents in DMV neurons from females was lower compared with males, and this effect was TTX sensitive and abolished by ovariectomy (OVX). Amplitudes of GABAergic currents (both phasic and tonic) were not different. However, females demonstrated significantly more variability in the amplitude of both phasic and tonic GABAA receptor currents. This difference was eliminated by OVX in females, suggesting that these differences were related to reproductive hormone levels. This was confirmed for GABAergic tonic currents by comparing females in two ovarian stages, estrus versus diestrus. Female mice in diestrus had larger tonic current amplitudes compared with those in estrus, and this increase was abolished after administration of a 5α-reductase inhibitor but not modulation of estrogen. Taken together, these findings demonstrate that DMV neurons undergo GABAA receptor activity plasticity as a function of sex and/or sex steroids.NEW & NOTEWORTHY Results show that GABAergic signaling in dorsal vagal motor neurons (DMV) demonstrates sex differences and fluctuates across the ovarian cycle in females. These findings are the first to demonstrate that female GABAA receptor activity in this brain region is modulated by 5α-reductase-dependent hormones. Since DMV activity is critical to both glucose and gastrointestinal homeostasis, these results suggest that sex hormones, including those synthesized by 5α-reductase, contribute to visceral, autonomic function related to these physiological processes.
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Affiliation(s)
- Erica L Littlejohn
- Department of Cellular and Integrative Physiology, College of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Liliana Espinoza
- Department of Cellular and Integrative Physiology, College of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Monica M Lopez
- Department of Cellular and Integrative Physiology, College of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Bret N Smith
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky
- Department of Neuroscience, College of Medicine, University of Kentucky, Lexington, Kentucky
| | - Carie R Boychuk
- Department of Cellular and Integrative Physiology, College of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
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14
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Joshi S, Kapur J. Neurosteroid regulation of GABA A receptors: A role in catamenial epilepsy. Brain Res 2019; 1703:31-40. [PMID: 29481795 PMCID: PMC6107446 DOI: 10.1016/j.brainres.2018.02.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 09/08/2017] [Accepted: 02/20/2018] [Indexed: 12/31/2022]
Abstract
The female reproductive hormones progesterone and estrogen regulate network excitability. Fluctuations in the circulating levels of these hormones during the menstrual cycle cause frequent seizures during certain phases of the cycle in women with epilepsy. This seizure exacerbation, called catamenial epilepsy, is a dominant form of drug-refractory epilepsy in women of reproductive age. Progesterone, through its neurosteroid derivative allopregnanolone, increases γ-aminobutyric acid type-A receptor (GABAR)-mediated inhibition in the brain and keeps seizures under control. Catamenial seizures are believed to be a neurosteroid withdrawal symptom, and it was hypothesized that exogenous administration of progesterone to maintain its levels high during luteal phase will treat catamenial seizures. However, in a multicenter, double-blind, phase III clinical trial, progesterone treatment did not suppress catamenial seizures. The expression of GABARs with reduced neurosteroid sensitivity in epileptic animals may explain the failure of the progesterone clinical trial. The expression of neurosteroid-sensitive δ subunit-containing GABARs is reduced, and the expression of α4γ2 subunit-containing GABARs is upregulated, which alters the inhibition of dentate granule cells in epilepsy. These changes reduce the endogenous neurosteroid control of seizures and contribute to catamenial seizures.
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Affiliation(s)
- Suchitra Joshi
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States.
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States; Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, United States
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15
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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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16
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Gielen M, Corringer P. The dual-gate model for pentameric ligand-gated ion channels activation and desensitization. J Physiol 2018; 596:1873-1902. [PMID: 29484660 PMCID: PMC5978336 DOI: 10.1113/jp275100] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 01/17/2018] [Accepted: 01/17/2018] [Indexed: 12/15/2022] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) mediate fast neurotransmission in the nervous system. Their dysfunction is associated with psychiatric, neurological and neurodegenerative disorders such as schizophrenia, epilepsy and Alzheimer's disease. Understanding their biophysical and pharmacological properties, at both the functional and the structural level, thus holds many therapeutic promises. In addition to their agonist-elicited activation, most pLGICs display another key allosteric property, namely desensitization, in which they enter a shut state refractory to activation upon sustained agonist binding. While the activation mechanisms of several pLGICs have been revealed at near-atomic resolution, the structural foundation of desensitization has long remained elusive. Recent structural and functional data now suggest that the activation and desensitization gates are distinct, and are located at both sides of the ion channel. Such a 'dual gate mechanism' accounts for the marked allosteric effects of channel blockers, a feature illustrated herein by theoretical kinetics simulations. Comparison with other classes of ligand- and voltage-gated ion channels shows that this dual gate mechanism emerges as a common theme for the desensitization and inactivation properties of structurally unrelated ion channels.
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Affiliation(s)
- Marc Gielen
- Channel Receptors UnitInstitut PasteurCNRS UMR 3571ParisFrance
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17
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Clossen BL, Reddy DS. Novel therapeutic approaches for disease-modification of epileptogenesis for curing epilepsy. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1519-1538. [PMID: 28179120 PMCID: PMC5474195 DOI: 10.1016/j.bbadis.2017.02.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/31/2017] [Accepted: 02/03/2017] [Indexed: 11/16/2022]
Abstract
This article describes the recent advances in epileptogenesis and novel therapeutic approaches for the prevention of epilepsy, with a special emphasis on the pharmacological basis of disease-modification of epileptogenesis for curing epilepsy. Here we assess animal studies and human clinical trials of epilepsy spanning 1982-2016. Epilepsy arises from a number of neuronal factors that trigger epileptogenesis, which is the process by which a brain shifts from a normal physiologic state to an epileptic condition. The events precipitating these changes can be of diverse origin, including traumatic brain injury, cerebrovascular damage, infections, chemical neurotoxicity, and emergency seizure conditions such as status epilepticus. Expectedly, the molecular and system mechanisms responsible for epileptogenesis are not well defined or understood. To date, there is no approved therapy for the prevention of epilepsy. Epigenetic dysregulation, neuroinflammation, and neurodegeneration appear to trigger epileptogenesis. Targeted drugs are being identified that can truly prevent the development of epilepsy in at-risk people. The promising agents include rapamycin, COX-2 inhibitors, TRK inhibitors, epigenetic modulators, JAK-STAT inhibitors, and neurosteroids. Recent evidence suggests that neurosteroids may play a role in modulating epileptogenesis. A number of promising drugs are under investigation for the prevention or modification of epileptogenesis to halt the development of epilepsy. Some drugs in development appear rational for preventing epilepsy because they target the initial trigger or related signaling pathways as the brain becomes progressively more prone to seizures. Additional research into the target validity and clinical investigation is essential to make new frontiers in curing epilepsy.
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Affiliation(s)
- Bryan L Clossen
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807, USA
| | - Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807, USA.
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18
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Filatova E, Kasian A, Kolomin T, Rybalkina E, Alieva A, Andreeva L, Limborska S, Myasoedov N, Pavlova G, Slominsky P, Shadrina M. GABA, Selank, and Olanzapine Affect the Expression of Genes Involved in GABAergic Neurotransmission in IMR-32 Cells. Front Pharmacol 2017; 8:89. [PMID: 28293190 PMCID: PMC5328971 DOI: 10.3389/fphar.2017.00089] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 02/13/2017] [Indexed: 11/13/2022] Open
Abstract
Clinical studies have shown that Selank had an anxiolytic effect comparable to that of classical benzodiazepine drugs, which can enhance the inhibitory effect of GABA by allosteric modulation of GABAA receptors. These data suggest that the molecular mechanism of the effect of Selank may also be related to its ability to affect the performance of the GABAergic system. To test this hypothesis, we studied the changes in expression of 84 genes involved in the functioning of the GABAergic system and in the processes of neurotransmission in the culture of neuroblastoma IMR-32 cells using qPCR method. As test substances, in addition to Selank, we selected the major GABAA receptor ligand, GABA, the atypical antipsychotic, olanzapine, and combinations of these compounds (Selank and GABA; Selank and olanzapine). We found no changes in the mRNA levels of the genes studied under the effect of Selank. The combined effect of GABA and Selank led to nearly complete suppression of changes in expression of genes in which mRNA levels changed under the effect of GABA. When Selank was used in conjunction with olanzapine, the expression alterations of more genes were observed compared with olanzapine alone. The data obtained indicate that Selank has no direct effect on the mRNA levels of the GABAergic system genes in neuroblastoma IMR-32 cells. At the same time, our results partially confirm the hypothesis that the peptide may affect the interaction of GABA with GABAA receptors. Our data also suggest that Selank may enhance the effect of olanzapine on the expression of the genes studied.
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Affiliation(s)
- Elena Filatova
- Department of Molecular Basis of Human Genetics, Institute of Molecular Genetics, Russian Academy of Sciences Moscow, Russia
| | - Anastasiya Kasian
- Department of Molecular Basis of Human Genetics, Institute of Molecular Genetics, Russian Academy of Sciences Moscow, Russia
| | - Timur Kolomin
- Department of Molecular Basis of Human Genetics, Institute of Molecular Genetics, Russian Academy of Sciences Moscow, Russia
| | - Ekaterina Rybalkina
- Laboratory of Tumor Cells Genetics, Blokhin Russian Cancer Research Center, Ministry of Health of the Russian Federation Moscow, Russia
| | - Anelya Alieva
- Department of Molecular Basis of Human Genetics, Institute of Molecular Genetics, Russian Academy of Sciences Moscow, Russia
| | - Lyudmila Andreeva
- Department of Chemistry of Physiologically Active Compounds, Institute of Molecular Genetics, Russian Academy of Sciences Moscow, Russia
| | - Svetlana Limborska
- Department of Molecular Basis of Human Genetics, Institute of Molecular Genetics, Russian Academy of Sciences Moscow, Russia
| | - Nikolay Myasoedov
- Department of Chemistry of Physiologically Active Compounds, Institute of Molecular Genetics, Russian Academy of Sciences Moscow, Russia
| | - Galina Pavlova
- Group of Neurogenetics and Developmental Genetics, Institute of Gene Biology, Russian Academy of Sciences Moscow, Russia
| | - Petr Slominsky
- Department of Molecular Basis of Human Genetics, Institute of Molecular Genetics, Russian Academy of Sciences Moscow, Russia
| | - Maria Shadrina
- Department of Molecular Basis of Human Genetics, Institute of Molecular Genetics, Russian Academy of Sciences Moscow, Russia
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19
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MacKenzie G, Maguire J. Neurosteroids and GABAergic signaling in health and disease. Biomol Concepts 2015; 4:29-42. [PMID: 25436563 DOI: 10.1515/bmc-2012-0033] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 10/12/2012] [Indexed: 11/15/2022] Open
Abstract
Endogenous neurosteroids such as allopregnanolone, allotetrahydrodeoxycorticosterone, and androstanediol are synthesized either de novo in the brain from cholesterol or are generated from the local metabolism of peripherally derived progesterone or corticosterone. Fluctuations in neurosteroid concentrations are important in the regulation of a number of physiological responses including anxiety and stress, reproductive, and sexual behaviors. These effects are mediated in part by the direct binding of neurosteroids to γ-aminobutyric acid type-A receptors (GABAARs), resulting in the potentiation of GABAAR-mediated currents. Extrasynaptic GABAARs containing the δ subunit, which contribute to the tonic conductance, are particularly sensitive to low nanomolar concentrations of neurosteroids and are likely their preferential target. Considering the large charge transfer generated by these persistently open channels, even subtle changes in neurosteroid concentrations can have a major impact on neuronal excitability. Consequently, aberrant levels of neurosteroids have been implicated in numerous disorders, including, but not limited to, anxiety, neurodegenerative diseases, alcohol abuse, epilepsy, and depression. Here we review the modulation of GABAAR by neurosteroids and the consequences for health and disease.
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20
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Taubøll E, Heuser K, Sveberg L, Svalheim S. Experimental models for the study of hormonal changes in epilepsy. ZEITSCHRIFT FUR EPILEPTOLOGIE 2015. [DOI: 10.1007/s10309-015-0001-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Iacovides S, Avidon I, Baker F. Does pain vary across the menstrual cycle? A review. Eur J Pain 2015; 19:1389-405. [DOI: 10.1002/ejp.714] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2015] [Indexed: 02/06/2023]
Affiliation(s)
- S. Iacovides
- Wits Dial-a-bed Sleep Laboratory; Brain Function Research Group; School of Physiology; Faculty of Health Sciences; University of the Witwatersrand; Johannesburg South Africa
| | - I. Avidon
- Exercise Physiology Laboratory; School of Physiology; Faculty of Health Sciences; University of the Witwatersrand; Johannesburg South Africa
| | - F.C. Baker
- Wits Dial-a-bed Sleep Laboratory; Brain Function Research Group; School of Physiology; Faculty of Health Sciences; University of the Witwatersrand; Johannesburg South Africa
- Human Sleep Research Program; SRI International; San Francisco USA
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22
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Puia G, Ravazzini F, Castelnovo LF, Magnaghi V. PKCε and allopregnanolone: functional cross-talk at the GABAA receptor level. Front Cell Neurosci 2015; 9:83. [PMID: 25852476 PMCID: PMC4365694 DOI: 10.3389/fncel.2015.00083] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 02/23/2015] [Indexed: 11/13/2022] Open
Abstract
Changes in GABAergic inhibition occur during physiological processes, during response to drugs and in various pathologies. These changes can be achieved through direct allosteric modifications at the γ-amino butyric acid (GABA) type A (GABAA) receptor protein level, or by altering the synthesis, trafficking and stability of the receptor. Neurosteroids (NSs) and protein kinase C (PKC) are potent modulators of GABAA receptors and their effects are presumably intermingled, even though evidence for this hypothesis is only partially explored. However, several PKC isoforms are able to phosphorylate the GABAA receptor, producing different functional effects. We focused on the ε isoform, that has been correlated to the sensitivity of the GABAA receptor to allosteric modulators and whose expression may be regulated in peripheral sensory neurons by NSs. The cross-talk between PKC-ε and NSs, leading to changes in GABAA receptor functionality, is considered and discussed in this perspective.
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Affiliation(s)
- Giulia Puia
- Department of Life Science, University of Modena and Reggio Emilia Modena, Italy
| | - Federica Ravazzini
- Department of Life Science, University of Modena and Reggio Emilia Modena, Italy
| | - Luca Franco Castelnovo
- Department of Pharmacological and Biomolecular Sciences, University of Milan Milan, Italy
| | - Valerio Magnaghi
- Department of Pharmacological and Biomolecular Sciences, University of Milan Milan, Italy
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23
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Bharadwaj S, Barber MD, Graff LA, Shen B. Symptomatology of irritable bowel syndrome and inflammatory bowel disease during the menstrual cycle. Gastroenterol Rep (Oxf) 2015; 3:185-93. [PMID: 25788484 PMCID: PMC4527267 DOI: 10.1093/gastro/gov010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 02/03/2015] [Indexed: 12/17/2022] Open
Abstract
Gender-related physiological variations in gastrointestinal (GI) symptomatology have been observed in women of reproductive age. Many women experience cyclical changes in GI symptomatology during their menstrual cycle, particularly alteration in their bowel habits. Physiological studies of healthy women during the menstrual cycle showed a prolonged GI transit time during the luteal phase, either in the oro-cecum route or in the colon. Worsened GI symptoms, such as abdominal pain, bloating or diarrhea are observed in patients with irritable bowel syndrome (IBS) during menses. This may be due to elevated prostaglandin levels during menses, with an enhanced perception of viscera-somatic stimuli resulting in nausea, abdominal distension and pain. Also patients with IBS or IBD demonstrate a cyclical pattern more closely related to their bowel habits than healthy controls. Women with inflammatory bowel disease (IBD) also have exacerbated symptoms during menses; however, it is unclear whether this relates to physiological variation or disease exacerbation in IBS or IBD. Studies examining the association of the menstrual cycle and GI symptomatology in patients with IBS or IBD, have not yet clarified the underlying mechanisms. Moreover medications—such as non-steroidal anti-inflammatory drugs and oral contraceptive pills used for dysmenorrhea and menstrual migraine in those patients have not well been controlled for in the previous studies, which can contribute to further bias. Understanding changes in GI symptomatology during the menstrual cycle may help to determine the true extent of disease exacerbation and proper management strategy.
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Affiliation(s)
- Shishira Bharadwaj
- Departments of Gastroenterology/Hepatology, the Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Matthew D Barber
- Department of Obstetrics and Gynecology, the Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Lesley A Graff
- Department of Clinical Health Psychology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Bo Shen
- Departments of Gastroenterology/Hepatology, the Cleveland Clinic Foundation, Cleveland, OH, USA
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24
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Romo-Parra H, Blaesse P, Sosulina L, Pape HC. Neurosteroids increase tonic GABAergic inhibition in the lateral section of the central amygdala in mice. J Neurophysiol 2015; 113:3421-31. [PMID: 25787948 DOI: 10.1152/jn.00045.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/12/2015] [Indexed: 01/12/2023] Open
Abstract
Neurosteroids are formed de novo in the brain and can modulate both inhibitory and excitatory neurotransmission. Recent evidence suggests that the anxiolytic effects of neurosteroids are mediated by the amygdala, a key structure for emotional and cognitive behaviors. Tonic inhibitory signaling via extrasynaptic type A γ-aminobutyric acid receptors (GABA(A)Rs) is known to be crucially involved in regulating network activity in various brain regions including subdivisions of the amygdala. Here we provide evidence for the existence of tonic GABAergic inhibition generated by the activation of δ-subunit-containing GABA(A)Rs in neurons of the lateral section of the mouse central amygdala (CeAl). Furthermore, we show that neurosteroids play an important role in the modulation of tonic GABAergic inhibition in the CeAl. Taken together, these findings provide new mechanistic insights into the effects of pharmacologically relevant neurosteroids in the amygdala and might be extrapolated to the regulation of anxiety.
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Affiliation(s)
- H Romo-Parra
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - P Blaesse
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - L Sosulina
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - H-C Pape
- Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany
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25
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Taubøll E, Sveberg L, Svalheim S. Interactions between hormones and epilepsy. Seizure 2015; 28:3-11. [PMID: 25765693 DOI: 10.1016/j.seizure.2015.02.012] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 02/08/2015] [Accepted: 02/12/2015] [Indexed: 11/18/2022] Open
Abstract
There is a complex, bidirectional interdependence between sex steroid hormones and epilepsy; hormones affect seizures, while seizures affect hormones thereby disturbing reproductive endocrine function. Both female and male sex steroid hormones influence brain excitability. For the female sex steroid hormones, progesterone and its metabolites are anticonvulsant, while estrogens are mainly proconvulsant. The monthly fluctuations in hormone levels of estrogen and progesterone are the basis for catamenial epilepsy described elsewhere in this issue. Androgens are mainly anticonvulsant, but the effects are more varied, probably because of its metabolism to, among others, estradiol. The mechanisms for the effects of sex steroid hormones on brain excitability are related to both classical, intracellularly mediated effects, and non-classical membrane effects due to binding to membrane receptors. The latter are considered the most important in relation to epilepsy. The different sex steroids can also be further metabolized within the brain to different neurosteroids, which are even more potent with regard to their effect on excitability. Estrogens potentiate glutamate responses, primarily by potentiating NMDA receptor activity, but also by affecting GABA-ergic mechanisms and altering brain morphology by increasing dendritic spine density. Progesterone and its main metabolite 5α-pregnan-3α-ol-20-one (3α-5α-THP) act mainly to enhance postsynaptic GABA-ergic activity, while androgens enhance GABA-activated currents. Seizures and epileptic discharges also affect sex steroid hormones. There are close anatomical connections between the temporolimbic system and the hypothalamus controlling the endocrine system. Several studies have shown that epileptic activity, especially mediated through the amygdala, alters reproductive function, including reduced ovarian cyclicity in females and altered sex steroid hormone levels in both genders. Furthermore, there is an asymmetric activation of the hypothalamus with unilateral amygdala seizures. This may, again, be the basis for the occurrence of different reproductive endocrine disorders described for patients with left-sided or right-sided temporal lobe epilepsy.
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Affiliation(s)
- Erik Taubøll
- Department of Neurology, Oslo University Hospital - Rikshospitalet, Oslo, Norway; Faculty of Medicine, University of Oslo, Oslo, Norway.
| | - Line Sveberg
- Department of Neurology, Oslo University Hospital - Rikshospitalet, Oslo, Norway
| | - Sigrid Svalheim
- Department of Neurology, Oslo University Hospital - Rikshospitalet, Oslo, Norway
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26
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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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27
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Comenencia-Ortiz E, Moss SJ, Davies PA. Phosphorylation of GABAA receptors influences receptor trafficking and neurosteroid actions. Psychopharmacology (Berl) 2014; 231:3453-65. [PMID: 24847959 PMCID: PMC4135009 DOI: 10.1007/s00213-014-3617-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 05/02/2014] [Indexed: 01/06/2023]
Abstract
RATIONALE Gamma-aminobutyric acid type A receptors (GABAARs) are the principal mediators of inhibitory transmission in the mammalian central nervous system. GABAARs can be localized at post-synaptic inhibitory specializations or at extrasynaptic sites. While synaptic GABAARs are activated transiently following the release of GABA from presynaptic vesicles, extrasynaptic GABAARs are typically activated continuously by ambient GABA concentrations and thus mediate tonic inhibition. The tonic inhibitory currents mediated by extrasynaptic GABAARs control neuronal excitability and the strength of synaptic transmission. However, the mechanisms by which neurons control the functional properties of extrasynaptic GABAARs had not yet been explored. OBJECTIVES We review GABAARs, how they are assembled and trafficked, and the role phosphorylation has on receptor insertion and membrane stabilization. Finally, we review the modulation of GABAARs by neurosteroids and how GABAAR phosphorylation can influence the actions of neurosteroids. CONCLUSIONS Trafficking and stability of functional channels to the membrane surface are critical for inhibitory efficacy. Phosphorylation of residues within GABAAR subunits plays an essential role in the assembly, trafficking, and cell surface stability of GABAARs. Neurosteroids are produced in the brain and are highly efficacious allosteric modulators of GABAAR-mediated current. This allosteric modulation by neurosteroids is influenced by the phosphorylated state of the GABAAR which is subunit dependent, adding temporal and regional variability to the neurosteroid response. Possible links between neurosteroid actions, phosphorylation, and GABAAR trafficking remain to be explored, but potential novel therapeutic targets may exist for numerous neurological and psychological disorders which are linked to fluctuations in neurosteroid levels and GABAA subunit expression.
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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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Neurosteroids and their role in sex-specific epilepsies. Neurobiol Dis 2014; 72 Pt B:198-209. [PMID: 24960208 DOI: 10.1016/j.nbd.2014.06.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Revised: 05/11/2014] [Accepted: 06/14/2014] [Indexed: 01/21/2023] Open
Abstract
Neurosteroids are involved in sex-specific epilepsies. Allopregnanolone and related endogenous neurosteroids in the brain control excessive neuronal excitability and seizure susceptibility. Neurosteroids activate GABA-A receptors, especially extrasynaptic αγδ-GABA-A receptor subtypes that mediate tonic inhibition and thus dampen network excitability. Our studies over the past decade have shown that neurosteroids are broad-spectrum anticonvulsants and confer seizure protection in various animal models. Neurosteroids also exert antiepileptogenic effects. There is emerging evidence on a critical role for neurosteroids in the pathophysiology of the sex-specific forms of epilepsies such as catamenial epilepsy, a menstrual cycle-related seizure disorder in women. Catamenial epilepsy is a neuroendocrine condition in which seizures are clustered around specific points in the menstrual cycle, most often around the perimenstrual or periovulatory period. Apart from ovarian hormones, fluctuations in neurosteroid levels could play a critical role in this gender-specific epilepsy. Neurosteroids also regulate the plasticity of synaptic and extrasynaptic GABA-A receptors in the hippocampus and other regions involved in epilepsy pathology. Based on these studies, we proposed a neurosteroid replacement therapy for catamenial epilepsy. Thus, neurosteroids are novel drug targets for pharmacotherapy of epilepsy.
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Carver CM, Reddy DS. Neurosteroid interactions with synaptic and extrasynaptic GABA(A) receptors: regulation of subunit plasticity, phasic and tonic inhibition, and neuronal network excitability. Psychopharmacology (Berl) 2013; 230:151-88. [PMID: 24071826 PMCID: PMC3832254 DOI: 10.1007/s00213-013-3276-5] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 08/29/2013] [Indexed: 12/25/2022]
Abstract
RATIONALE Neurosteroids are steroids synthesized within the brain with rapid effects on neuronal excitability. Allopregnanolone, allotetrahydrodeoxycorticosterone, and androstanediol are three widely explored prototype endogenous neurosteroids. They have very different targets and functions compared to conventional steroid hormones. Neuronal γ-aminobutyric acid (GABA) type A (GABA(A)) receptors are one of the prime molecular targets of neurosteroids. OBJECTIVE This review provides a critical appraisal of recent advances in the pharmacology of endogenous neurosteroids that interact with GABA(A) receptors in the brain. Neurosteroids possess distinct, characteristic effects on the membrane potential and current conductance of the neuron, mainly via potentiation of GABA(A) receptors at low concentrations and direct activation of receptor chloride channel at higher concentrations. The GABA(A) receptor mediates two types of inhibition, now characterized as synaptic (phasic) and extrasynaptic (tonic) inhibition. Synaptic release of GABA results in the activation of low-affinity γ2-containing synaptic receptors, while high-affinity δ-containing extrasynaptic receptors are persistently activated by the ambient GABA present in the extracellular fluid. Neurosteroids are potent positive allosteric modulators of synaptic and extrasynaptic GABA(A) receptors and therefore enhance both phasic and tonic inhibition. Tonic inhibition is specifically more sensitive to neurosteroids. The resulting tonic conductance generates a form of shunting inhibition that controls neuronal network excitability, seizure susceptibility, and behavior. CONCLUSION The growing understanding of the mechanisms of neurosteroid regulation of the structure and function of the synaptic and extrasynaptic GABA(A) receptors provides many opportunities to create improved therapies for sleep, anxiety, stress, epilepsy, and other neuropsychiatric conditions.
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Affiliation(s)
- Chase Matthew Carver
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, 2008 Medical Research and Education Building, 8447 State Highway 47, Bryan, TX, 77807-3260, USA
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Greenfield LJ. Molecular mechanisms of antiseizure drug activity at GABAA receptors. Seizure 2013; 22:589-600. [PMID: 23683707 PMCID: PMC3766376 DOI: 10.1016/j.seizure.2013.04.015] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 04/16/2013] [Accepted: 04/17/2013] [Indexed: 02/09/2023] Open
Abstract
The GABAA receptor (GABAAR) is a major target of antiseizure drugs (ASDs). A variety of agents that act at GABAARs s are used to terminate or prevent seizures. Many act at distinct receptor sites determined by the subunit composition of the holoreceptor. For the benzodiazepines, barbiturates, and loreclezole, actions at the GABAAR are the primary or only known mechanism of antiseizure action. For topiramate, felbamate, retigabine, losigamone and stiripentol, GABAAR modulation is one of several possible antiseizure mechanisms. Allopregnanolone, a progesterone metabolite that enhances GABAAR function, led to the development of ganaxolone. Other agents modulate GABAergic "tone" by regulating the synthesis, transport or breakdown of GABA. GABAAR efficacy is also affected by the transmembrane chloride gradient, which changes during development and in chronic epilepsy. This may provide an additional target for "GABAergic" ASDs. GABAAR subunit changes occur both acutely during status epilepticus and in chronic epilepsy, which alter both intrinsic GABAAR function and the response to GABAAR-acting ASDs. Manipulation of subunit expression patterns or novel ASDs targeting the altered receptors may provide a novel approach for seizure prevention.
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Affiliation(s)
- L John Greenfield
- Dept. of Neurology, University of Arkansas for Medical Sciences, 4301W. Markham St., Slot 500, Little Rock, AR 72205, United States.
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Iacovides S, Baker FC, Avidon I, Bentley A. Women With Dysmenorrhea Are Hypersensitive to Experimental Deep Muscle Pain Across the Menstrual Cycle. THE JOURNAL OF PAIN 2013; 14:1066-76. [PMID: 23769507 DOI: 10.1016/j.jpain.2013.04.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 03/26/2013] [Accepted: 04/08/2013] [Indexed: 10/26/2022]
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Reddy DS. Role of hormones and neurosteroids in epileptogenesis. Front Cell Neurosci 2013; 7:115. [PMID: 23914154 PMCID: PMC3728472 DOI: 10.3389/fncel.2013.00115] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 07/01/2013] [Indexed: 12/03/2022] Open
Abstract
This article describes the emerging evidence of hormonal influence on epileptogenesis, which is a process whereby a brain becomes progressively epileptic due to an initial precipitating event of diverse origin such as brain injury, stroke, infection, or prolonged seizures. The molecular mechanisms underlying the development of epilepsy are poorly understood. Neuroinflammation and neurodegeneration appear to trigger epileptogenesis. There is an intense search for drugs that truly prevent the development of epilepsy in people at risk. Hormones play an important role in children and adults with epilepsy. Corticosteroids, progesterone, estrogens, and neurosteroids have been shown to affect seizure activity in animal models and in clinical studies. However, the impact of hormones on epileptogenesis has not been investigated widely. There is emerging new evidence that progesterone, neurosteroids, and endogenous hormones may play a role in regulating the epileptogenesis. Corticosterone has excitatory effects and triggers epileptogenesis in animal models. Progesterone has disease-modifying activity in epileptogenic models. The antiepileptogenic effect of progesterone has been attributed to its conversion to neurosteroids, which binds to GABA-A receptors and enhances phasic and tonic inhibition in the brain. Neurosteroids are robust anticonvulsants. There is pilot evidence that neurosteroids may have antiepileptogenic properties. Future studies may generate new insight on the disease-modifying potential of hormonal agents and neurosteroids in epileptogenesis.
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Affiliation(s)
- Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center Bryan, TX, USA
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Abstract
This review describes the neuroendocrinological aspects of catamenial epilepsy, a menstrual cycle-related seizure disorder in women with epilepsy. Catamenial epilepsy is a multifaceted neuroendocrine condition in which seizures are clustered around specific points in the menstrual cycle, most often around perimenstrual or periovulatory period. Three types of catamenial seizures (perimenstrual, periovulatory and inadequate luteal) have been identified. The molecular pathophysiology of catamenial epilepsy remains unclear. Cyclical changes in the circulating levels of estrogens and progesterone (P) play a central role in the development of catamenial epilepsy. Endogenous neurosteroids such as allopregnanolone (AP) and allotetrahydrodeoxycorticosterone (THDOC) that modulate seizure susceptibility could play a critical role in catamenial epilepsy. In addition, plasticity in GABA-A receptor subunits could play a role in the enhanced seizure susceptibility in catamenial epilepsy. P-derived neurosteroids such as AP and THDOC potentiate synaptic GABA-A receptor function and also activate extrasynaptic GABA-A receptors in the hippocampus and thus may represent endogenous regulators of catamenial seizure susceptibility. Experimental studies have shown that neurosteroids confer greater seizure protection in animal models of catamenial epilepsy, especially without evident tolerance to their actions during chronic therapy. In the recently completed NIH-sponsored, placebo controlled phase 3 clinical trial, P therapy proved to be beneficial only in women with perimenstrual catamenial epilepsy but not in non-catamenial subjects. Neurosteroid analogs with favorable profile may be useful in the treatment of catamenial epilepsy.
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Affiliation(s)
- Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M Health Science Center, 8447 State Highway 47, MREB Building, Bryan, TX 77807, USA.
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Eikermann-Haerter K, Can A, Ayata C. Pharmacological targeting of spreading depression in migraine. Expert Rev Neurother 2012; 12:297-306. [PMID: 22364328 PMCID: PMC3321647 DOI: 10.1586/ern.12.13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Migraine, particularly with aura, is a genetically heterogeneous disorder of ion channels, pumps or transporters associated with increased cortical excitability. Spreading depression, as one reflection of hyperexcitability, is the electrophysiological event underlying aura symptoms and a trigger for headache. Endogenous (e.g., genes and hormones) and exogenous factors (e.g., drugs) modulating migraine susceptibility have also been shown to modulate spreading depression susceptibility concordantly, suggesting that spreading depression can be a relevant therapeutic target in migraine. In support of this, several migraine prophylactic drugs used in clinical practice have been shown to suppress spreading depression susceptibility as a probable mechanism of action, despite belonging to widely different pharmacological classes. Hence, susceptibility to spreading depression can be a useful preclinical model with good positive and negative predictive value for drug screening.
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Affiliation(s)
- Katharina Eikermann-Haerter
- Neurovascular Research Laboratory, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 149 13th Street, Charleston, MA 02129, USA.
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Aoki C, Sabaliauskas N, Chowdhury T, Min JY, Colacino AR, Laurino K, Barbarich-Marsteller NC. Adolescent female rats exhibiting activity-based anorexia express elevated levels of GABA(A) receptor α4 and δ subunits at the plasma membrane of hippocampal CA1 spines. Synapse 2012; 66:391-407. [PMID: 22213233 DOI: 10.1002/syn.21528] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 12/06/2011] [Accepted: 12/14/2011] [Indexed: 12/26/2022]
Abstract
Activity-based anorexia (ABA) is an animal model for anorexia nervosa that has revealed genetic links to anxiety traits and neurochemical characteristics within the hypothalamus. However, few studies have used this animal model to investigate the biological basis for vulnerability of pubertal and adolescent females to ABA, even though the great majority of the anorexia nervosa cases are females exhibiting the first symptoms during puberty. GABAergic inhibition of the hippocampus strongly regulates anxiety as well as plasticity throughout life. We recently showed that the hippocampal CA1 of female mice undergo a dramatic change at puberty onset--from expressing virtually none of the nonsynaptic α4βδ GABA(A) receptors (GABARs) prepubertally to expressing these GABARs at ~7% of the CA1 dendritic spine membranes at puberty onset. Furthermore, we showed that this change underlies the enhanced modulation of anxiety, neuronal excitability, and NMDA receptor-dependent synaptic plasticity in the hippocampus by the stress neurosteroid, THP (3α-OH-5α[β]-pregnan-20-one or [allo]pregnanolone). Here, we used quantitative electron microscopy to determine whether ABA induction in female rats during adolescence also elevates the expression of α4 and δ subunits of α4βδ GABARs, as was observed at puberty onset for mice. Our analysis revealed that rats also exhibit a rise of α4 and δ subunits of α4βδ GABARs at puberty onset, in that these subunits are detectable at ~6% of the dendritic spine membranes of CA1 pyramidal cells at puberty onset (postnatal day 32-36; P32-36) but this drops to about 2% by P40-P44. The levels of α4 and δ subunits at the CA1 spines remained low following exposure of females to either of the two environmental factors needed to generate ABA--food restriction and access to a running wheel for 4 days--from P40 to P44. This pattern contrasted greatly from those of ABA animals, for which the two environmental factors were combined. Within the hippocampus of ABA animals, 12% of the spine profiles were labeled for α4, reflecting a sixfold increase, relative to hippocampi of age-matched (P44) control females (p < 0.005). Concurrently, 7% of the spine profiles were labeled for δ, reflecting a 130% increase from the control values of 3% (p = 0.01). No measurable change was detected for spine size. The observed magnitude of increase in the α4 and δ subunits at spines is sufficient to increase both tonic inhibition of hippocampus and anxiety during stress, thereby likely to exacerbate hyperactivity and weight loss.
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Affiliation(s)
- Chiye Aoki
- Center for Neural Science, New York University, New York, New York 10003, USA.
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Michopoulos V, Berga SL, Wilson ME. Estradiol and progesterone modify the effects of the serotonin reuptake transporter polymorphism on serotonergic responsivity to citalopram. Exp Clin Psychopharmacol 2011; 19:401-8. [PMID: 21843009 PMCID: PMC3253022 DOI: 10.1037/a0025008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Individual vulnerability to psychopathologies is linked to a number of genetic polymorphisms including the serotonin transporter (5HTT) promoter polymorphic region (5HTTLPR). A single copy of the short variant (s-variant) allele of 5HTTLPR confers increased susceptibility to anxiety disorders and depression and decreased efficacy of serotonin-releasing agents in pharmacotherapy compared to the homozygous long 5HTTLPR variant (l/L). The data suggesting that the 5HTTLPR polymorphism modulates the efficacy of serotonin-releasing agents in pharmacotherapy is inconsistent. Other factors such as age, gender, and hormonal status could interact with 5HTTLPR genotype to affect individual physiological and behavioral responses to serotonin reuptake inhibitors such as citalopram. Indeed, estradiol and progesterone, the primary female steroid hormones, exert an array of effects on the serotonergic system, including 5HTT expression. The present study used ovariectomized female rhesus monkeys to determine the interaction between the 5HTTLPR polymorphism and the effects of midfollicular levels of estradiol and luteal levels of progesterone on serotonergic responsivity to acute citalopram administration. The increase in serum prolactin, a surrogate measure of serotonin activity, following citalopram administration was significantly larger in l/L females than in s-variant females over the course of two hours during concurrent estradiol and progesterone hormone replacement only. These data suggest that ovarian function and the 5HTTLPR polymorphism interact to gate serotonergic reactivity in females, suggesting that clinicians should be aware of the ovarian status and 5HTTLPR genotype of women when considering serotonergic pharmacotherapy in women.
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Affiliation(s)
- Vasiliki Michopoulos
- Division of Psychobiology, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA.
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A mutant residue in the third transmembrane region of the GABA(A) alpha1 subunit causes increased agonistic neurosteroid responses. Neurochem Int 2011; 58:794-803. [PMID: 21397651 DOI: 10.1016/j.neuint.2011.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 03/02/2011] [Accepted: 03/05/2011] [Indexed: 11/24/2022]
Abstract
Pregnane derived steroids have agonistic and antagonistic actions at GABA(A) receptors. Putative binding sites for agonistic neurosteroids are located within the transmembrane (TM) regions. A mutation within the rat α(1) TM3 region, S299C, caused the expressed receptors to have unusual and extreme sensitivity to agonistic neurosteroids. For mutant α1S299C receptors, with wild type β and γ subunits, expressed in Xenopus oocytes, steroids activated the GABA(A) receptors in the absence of GABA. Maximal steroid induced currents were about half of maximal GABA currents. The steroid activation was biphasic with EC(50)'s much lower than wild type, in subnanomolar and nanomolar concentrations, while the wild type had only one activation peak with near micromolar EC(50). These currents could be blocked by both picrotoxin and an antagonist neurosteroid. The steroids did not seem to potentiate significantly submaximal GABA currents. The α1S299C mutation did not affect responses to the extracellularly acting partial agonist piperidine-4-sulfate. Substituted cysteine experiments indicate that this mutant can be modified by pCMBS(-) when the sulfhydryl reagent is added with the higher steroid concentration for activation but not the lower steroid concentration. The pCMBS(-) will also immediately block the high concentration steroid current. Taken together the data suggest that α1S299 is important in at least the in transduction of the steroid binding to the rest of the receptor.
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Reddy DS. Role of anticonvulsant and antiepileptogenic neurosteroids in the pathophysiology and treatment of epilepsy. Front Endocrinol (Lausanne) 2011; 2:38. [PMID: 22654805 PMCID: PMC3356070 DOI: 10.3389/fendo.2011.00038] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 09/06/2011] [Indexed: 02/05/2023] Open
Abstract
This review highlights the role of major endogenous neurosteroids in seizure disorders and the promise of neurosteroid replacement therapy in epilepsy. Neurosteroids are endogenous modulators of seizure susceptibility. Neurosteroids such as allopregnanolone (3α-hydroxy-5α-pregnane-20-one) and allotetrahydrodeoxycorticosterone (3α,21-dihydroxy-5α-pregnan-20-one) are positive modulators of GABA-A receptors. Aside from peripheral tissues, neurosteroids are synthesized within the brain, mostly in principal neurons. Neurosteroids potentiate synaptic GABA-A receptor function and also activate δ-subunit-containing extrasynaptic GABA-A receptors that mediate tonic currents and thus may play an important role in neuronal network excitability and seizure susceptibility. Our studies over the past decade have shown that neurosteroids are broad-spectrum anticonvulsants and confer seizure protection in various animal models. They protect against seizures induced by GABA-A receptor antagonists, 6-Hz model, pilocarpine-induced limbic seizures, and seizures in kindled animals. Unlike benzodiazepines, tolerance does not occur to their actions during chronic administration. Our recent studies provide compelling evidence that neurosteroids may have antiepileptogenic properties. There is emerging evidence that endogenous neurosteroids may play a key role in the pathophysiology of catamenial epilepsy, stress-sensitive seizure conditions, temporal lobe epilepsy, and alcohol-withdrawal seizures. It is suggested that neurosteroid replacement with natural or synthetic neurosteroids may be useful in the treatment of epilepsy. Synthetic analogs of neurosteroids that are devoid of hormonal side effects show promise in the treatment of diverse seizure disorders. Agents that stimulate endogenous production of neurosteroids may also be useful for treatment of epilepsy.
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Affiliation(s)
- Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M Health Science CenterCollege Station, TX, USA
- *Correspondence: Doodipala Samba Reddy, Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M Health Science Center, 228 Reynolds Medical Building, College Station, TX 77843, USA. e-mail:
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Body weight decreases induced by estradiol in female rhesus monkeys are dependent upon social status. Physiol Behav 2010; 102:382-8. [PMID: 21130792 DOI: 10.1016/j.physbeh.2010.11.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 11/25/2010] [Accepted: 11/29/2010] [Indexed: 11/22/2022]
Abstract
Gonadal steroids regulate appetite and thus body weight. In addition, continuous exposure to stressors negatively influences appetite through circuits likely distinct from those of gonadal steroids. The occurrence of adverse metabolic consequences due to chronic exposure to psychosocial stressors is twice as frequent in women as men, implicating a role for ovarian hormones, estradiol (E2) and progesterone (P4), in modulating stress-induced changes in appetite. Using social subordination in female macaques as a model of social stress, the current study tested the hypothesis that subordinate females would lose more weight during E2 treatment and gain less weight during P4 administration than dominant females. Because polymorphisms in the gene encoding the serotonin transporter (5HTT; SCL6A4) are known to alter responsivity to stress, we hypothesized that weight loss during E2 administration would be greatest in females with the short variant (s-variant) allele of 5HTT. Dominant females were significantly heavier than subordinate animals throughout the study, a result consistent with previous accounts of food intake when animals are fed a low-fat, high-fiber diet. Females with the s-variant 5HTT genotype weighed significantly less than l/l animals. Dominant animals lost significantly more weight than subordinate animals during E2 treatment. Administration of P4 blocked the weight-reducing effects of E2 in all females, regardless of social status. These data provide evidence that social subordination modulates the influence of ovarian steroid hormones on body weight in female rhesus monkeys independent of 5HTT genotype. Given the prosocial effects of these steroids, future studies are necessary to determine whether status differences in E2-induced weight loss are due to diminished food intake and or increases in energy expenditure and how the change in energy availability during E2 treatments relates to a female's motivation to interact with conspecifics.
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Rajasekaran K, Joshi S, Sun C, Mtchedlishvilli Z, Kapur J. Receptors with low affinity for neurosteroids and GABA contribute to tonic inhibition of granule cells in epileptic animals. Neurobiol Dis 2010; 40:490-501. [PMID: 20682339 DOI: 10.1016/j.nbd.2010.07.016] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 07/22/2010] [Accepted: 07/26/2010] [Indexed: 01/24/2023] Open
Abstract
Neurosteroid sensitivity of GABA(A) receptor mediated inhibition of the hippocampal dentate granule cells (DGCs) is reduced in animal models of temporal lobe epilepsy. However, the properties and subunit composition of GABA(A) receptors mediating tonic inhibition in DGCs of epileptic animals have not been described. In the DGCs of epileptic animals, allopregnanolone and L-655708 sensitivity of holding current was diminished and δ subunit was retained in the endoplasmic reticulum and its surface expression was decreased the in the hippocampus. Ro15-4513 and lanthanum had distinct effects on holding current recorded from DGCs of control and epileptic animals suggesting that the pharmacological properties of GABA(A) receptors maintaining tonic inhibition in DGCs of epileptic animals were similar to those containing the α4βxγ2 subunits. Furthermore, surface expression of the α4 subunit increased and a larger fraction of the subunit co-immunoprecipitated with theγ2 subunit in hippocampi of epileptic animals. Together, these studies revealed that functional α4βxδ and α5βxγ2 receptors were reduced in the hippocampi of epileptic animals and that novel α4bxγ2 receptors contributed to the maintenance of tonic inhibition. The presence of α4βxγ2 receptors resulted in low GABA affinity and neurosteroid sensitivity of tonic currents in the DGCs of epileptic animals that could potentially increase seizure vulnerability. These receptors may represent a novel therapeutic target for anticonvulsant drugs without sedative actions.
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Affiliation(s)
- Karthik Rajasekaran
- Department of Neurology, University of Virginia, Health Sciences Center, Charlottesville, VA 22908-0394, USA
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Palmitoylethanolamide modulates pentobarbital-evoked hypnotic effect in mice: involvement of allopregnanolone biosynthesis. Eur Neuropsychopharmacol 2010; 20:195-206. [PMID: 19864116 DOI: 10.1016/j.euroneuro.2009.09.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 09/17/2009] [Accepted: 09/28/2009] [Indexed: 01/28/2023]
Abstract
Palmitoylethanolamde (PEA) is an endogenous lipid neuromodulator that mediates a broad spectrum of pharmacological effects by activation of peroxisome proliferator-activated receptor alpha (PPAR-alpha). Detectable or high levels of PEA in the CNS have been found, but the specific function of this lipid remains to be clarified. Here we report evidence that PEA, activating PPAR-alpha receptor and involving neurosteroids de novo synthesis, modulates pentobarbital-evoked hypnotic effect. A single i.c.v. administration of PEA (1-5microg) increases pentobarbital induced loss of righting reflex (LORR) duration in mice. This effect is mimicked by GW7647 (3microg), a synthetic PPAR-alpha agonist, and disappears in PPAR-alpha knockout mice. Antagonism experiments strongly support the engaging of neurosteroidogenic pathway in the increase of LORR duration induced by PEA. This effect disappeared using two inhibitors blocking the key steps of neurosteroids synthesis, aminogluthetimide and finasteride. Moreover, we demonstrated that in brainstem PEA increased the expression of steroidogenic acute regulatory protein (StAR) and cytochrome P450 side-chain cleavage (P450scc), both involved in neurosteroidogenesis. Accordingly, allopregnanolone (ALLO) levels were in turn higher in brainstem of PEA and pentobarbital treated mice vs pentobarbital alone, as revealed by quantitative analysis using gas chromatography-mass spectrometry. A Our results demonstrate that exogenous administration of PEA, through a PPAR-alpha-dependent mechanism, modulates neurosteroids formation increasing ALLO levels and leading to a positive modulation of GABA(A) receptor. These data further strengthen our previous data on the role of PPAR-alpha in PEA's actions and could provide a new framework to understand its role in the CNS.
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Abstract
This chapter provides an overview of neurosteroids, especially their impact on the brain, sex differences and their therapeutic potentials. Neurosteroids are synthesized within the brain and rapidly modulate neuronal excitability. They are classified as pregnane neurosteroids, such as allopregnanolone and allotetrahydrodeoxycorticosterone, androstane neurosteroids, such as androstanediol and etiocholanolone, and sulfated neurosteroids such as pregnenolone sulfate. Neurosteroids such as allopregnanolone are positive allosteric modulators of GABA-A receptors with powerful anti-seizure activity in diverse animal models. Neurosteroids increase both synaptic and tonic inhibition. They are endogenous regulators of seizure susceptibility, anxiety, and stress. Sulfated neurosteroids such as pregnenolone sulfate, which are negative GABA-A receptor modulators, are memory-enhancing agents. Sex differences in susceptibility to brain disorders could be due to neurosteroids and sexual dimorphism in specific structures of the human brain. Synthetic neurosteroids that exhibit better bioavailability and efficacy and drugs that enhance neurosteroid synthesis have therapeutic potential in anxiety, epilepsy, and other brain disorders. Clinical trials with the synthetic neurosteroid analog ganaxolone in the treatment of epilepsy have been encouraging. Neurosteroidogenic agents that lack benzodiazepine-like side effects show promise in the treatment of anxiety and depression.
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Affiliation(s)
- Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M Health Science Center, College Station, TX, USA.
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Ziegler E, Bodusch M, Song Y, Jahn K, Wolfes H, Steinlechner S, Dengler R, Bufler J, Krampfl K. Interaction of androsterone and progesterone with inhibitory ligand-gated ion channels: a patch clamp study. Naunyn Schmiedebergs Arch Pharmacol 2009; 380:277-91. [DOI: 10.1007/s00210-009-0440-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2008] [Accepted: 07/20/2009] [Indexed: 10/20/2022]
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Frye CA, Paris JJ. Infusions of bicuculline to the ventral tegmental area attenuates sexual, exploratory, and anti-anxiety behavior of proestrous rats. Pharmacol Biochem Behav 2009; 93:474-81. [PMID: 19576238 DOI: 10.1016/j.pbb.2009.06.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 06/19/2009] [Accepted: 06/23/2009] [Indexed: 10/20/2022]
Abstract
Actions of 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP), in the midbrain ventral tegmental area (VTA) modulate sexual receptivity of female rats. Actions of 3alpha,5alpha-THP at GABAergic substrates in the VTA are known to modulate consummatory aspects of sexual behavior among rodents, such as lordosis. However, the extent to which GABA(A) receptors in the VTA are important for appetitive (exploratory, anti-anxiety, social) aspects of sexual receptivity is not well-understood. Proestrous rats were bilaterally-infused with saline or bicuculline (100 ng), a GABA(A) receptor antagonist, to the VTA or missed control sites. Rats were assessed for exploratory/anti-anxiety (open field/elevated plus maze), social (social interaction), and sexual (paced-mating) behavior. Compared to saline or missed site controls, intra-VTA bicuculline significantly reduced the number of central entries in an open field, time spent on the open arms of an elevated plus maze, frequency and intensity of lordosis, anti-aggression towards a male, pacing of sexual contacts, and 3alpha,5alpha-THP concentrations in midbrain and hippocampus. Bicuculline-infused rats also displayed less affiliation with a novel conspecific, fewer sexual solicitations, and had lower 3alpha,5alpha-THP concentrations in diencephalon and cortex, albeit these were not significant differences. Thus, actions at GABA(A) receptors in the midbrain VTA are essential for appetitive and consummatory aspects of sexual receptivity among rats.
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Affiliation(s)
- Cheryl A Frye
- Department of Psychology, The University at Albany-SUNY, NY 12222, USA.
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Stastna E, Chodounska H, Pouzar V, Kapras V, Borovska J, Cais O, Vyklicky L. Synthesis of C3, C5, and C7 pregnane derivatives and their effect on NMDA receptor responses in cultured rat hippocampal neurons. Steroids 2009; 74:256-63. [PMID: 19071149 DOI: 10.1016/j.steroids.2008.11.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Revised: 10/31/2008] [Accepted: 11/15/2008] [Indexed: 01/16/2023]
Abstract
The synthesis of several novel 5alpha- and 5beta-20-oxo-pregnane derivatives substituted in the position 3 and 7 of the steroid skeleton is described. Activity of synthesized compounds was studied in voltage-clamped cultured rat hippocampal neurons. Substituted derivatives inhibited NMDA-elicited neuronal activity. The relationship between biological activity and structure is discussed.
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Affiliation(s)
- Eva Stastna
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i.,166 10 Prague 6, Czech Republic
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Frye CA. Hormonal influences on seizures: basic neurobiology. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2009; 83:27-77. [PMID: 18929075 DOI: 10.1016/s0074-7742(08)00003-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
There are sex differences and effects of steroid hormones, such as androgens, estrogens, and progestogens, that influence seizures. Androgens exert early organizational and later activational effects that can amplify sex/gender differences in the expression of some seizure disorders. Female-typical sex steroids, such as estrogen (E2) and progestins, can exert acute activational effects to reduce convulsive seizures and these effects are mediated in part by the actions of steroids in the hippocampus. Some of these anticonvulsive effects of sex steroids are related to their formation of ligands which have agonist-like actions at gamma-aminobutyric acid (GABAA) receptors or antagonist actions at glutamatergic receptors. Differences in stress, developmental phase, reproductive status, endocrine status, and treatments, such as anti-epileptic drugs (AEDs), may alter levels of these ligands and/or the function of target sites, which may mitigate differences in sensitivity to, and/or tolerance of, steroids among some individuals. The evidence implicating sex steroids in differences associated with hormonal, reproductive, developmental, stress, seizure type, and/or therapeutics are discussed.
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Affiliation(s)
- Cheryl A Frye
- Department of Psychology, The University at Albany-State University of New York, New York 12222, USA
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Ovarian hormones and pain response: A review of clinical and basic science studies. ACTA ACUST UNITED AC 2009; 6 Suppl 2:168-92. [DOI: 10.1016/j.genm.2009.03.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2008] [Indexed: 12/18/2022]
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Fernandez F, Esposito T, Lea RA, Colson NJ, Ciccodicola A, Gianfrancesco F, Griffiths LR. Investigation of gamma-aminobutyric acid (GABA) A receptors genes and migraine susceptibility. BMC MEDICAL GENETICS 2008; 9:109. [PMID: 19087248 PMCID: PMC2615754 DOI: 10.1186/1471-2350-9-109] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2008] [Accepted: 12/16/2008] [Indexed: 11/19/2022]
Abstract
BACKGROUND Migraine is a neurological disorder characterized by recurrent attacks of severe headache, affecting around 12% of Caucasian populations. It is well known that migraine has a strong genetic component, although the number and type of genes involved is still unclear. Prior linkage studies have reported mapping of a migraine gene to chromosome Xq 24-28, a region containing a cluster of genes for GABA A receptors (GABRE, GABRA3, GABRQ), which are potential candidate genes for migraine. The GABA neurotransmitter has been implicated in migraine pathophysiology previously; however its exact role has not yet been established, although GABA receptors agonists have been the target of therapeutic developments. The aim of the present research is to investigate the role of the potential candidate genes reported on chromosome Xq 24-28 region in migraine susceptibility. In this study, we have focused on the subunit GABA A receptors type epsilon (GABRE) and type theta (GABRQ) genes and their involvement in migraine. METHODS We have performed an association analysis in a large population of case-controls (275 unrelated Caucasian migraineurs versus 275 controls) examining a set of 3 single nucleotide polymorphisms (SNPs) in the coding region (exons 3, 5 and 9) of the GABRE gene and also the I478F coding variant of the GABRQ gene. RESULTS Our study did not show any association between the examined SNPs in our test population (P>0.05). CONCLUSION Although these particular GABA receptor genes did not show positive association, further studies are necessary to consider the role of other GABA receptor genes in migraine susceptibility.
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Affiliation(s)
- Francesca Fernandez
- Genomics Research Centre, Griffith Institute for Health and Medical Research, Griffith University, Gold Coast, Queensland, Australia
| | - Teresa Esposito
- Institute of Genetics and Biophysics, Adriano Buzzati-Traverso, CNR, Naples, Italy
| | - Rod A Lea
- Genomics Research Centre, Griffith Institute for Health and Medical Research, Griffith University, Gold Coast, Queensland, Australia
- Institute of Environmental Science and Research, Wellington, New Zealand
| | - Natalie J Colson
- Genomics Research Centre, Griffith Institute for Health and Medical Research, Griffith University, Gold Coast, Queensland, Australia
| | - Alfredo Ciccodicola
- Institute of Genetics and Biophysics, Adriano Buzzati-Traverso, CNR, Naples, Italy
| | | | - Lyn R Griffiths
- Genomics Research Centre, Griffith Institute for Health and Medical Research, Griffith University, Gold Coast, Queensland, Australia
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