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Bengtsson SKS, Sjöstedt J, Malinina E, Das R, Doverskog M, Johansson M, Haage D, Bäckström T. Extra-Synaptic GABA A Receptor Potentiation and Neurosteroid-Induced Learning Deficits Are Inhibited by GR3027, a GABA A Modulating Steroid Antagonist. Biomolecules 2023; 13:1496. [PMID: 37892178 PMCID: PMC10604444 DOI: 10.3390/biom13101496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 10/01/2023] [Accepted: 10/03/2023] [Indexed: 10/29/2023] Open
Abstract
Objectives In Vitro: To study the effects of GR3027 (golexanolone) on neurosteroid-induced GABA-mediated current responses under physiological GABAergic conditions with recombinant human α5β3γ2L and α1β2γ2L GABAA receptors expressed in human embryonic kidney cells, using the response patch clamp technique combined with the Dynaflow™ application system. With α5β3γ2L receptors, 0.01-3 μM GR3027, in a concentration-dependent manner, reduced the current response induced by 200 nM THDOC + 0.3 µM GABA, as well as the THDOC-induced direct gated effect. GR3027 (1 μM) alone had no effect on the GABA-mediated current response or current in the absence of GABA. With α1β2γ2L receptors, GR3027 alone had no effect on the GABA-mediated current response or did not affect the receptor by itself. Meanwhile, 1-3 µM GR3027 reduced the current response induced by 200 nM THDOC + 30 µM GABA and 3 µM GR3027 that induced by 200 nM THDOC when GABA was not present. Objectives In Vivo: GR3027 reduces allopregnanolone (AP)-induced decreased learning and anesthesia in male Wistar rats. Rats treated i.v. with AP (2.2 mg/kg) or vehicle were given GR3027 in ratios of 1:0.5 to 1:5 dissolved in 10% 2-hydroxypropyl-beta-cyclodextrin. A dose ratio of AP:GR3027 of at least 1:2.5 antagonized the AP-induced decreased learning in the Morris Water Mase (MWM) and 1:7.5 antagonized the loss of righting reflex (LoR). GR3027 treatment did not change other functions in the rat compared to the vehicle group. Conclusions: GR3027 functions in vitro as an inhibitor of GABAA receptors holding α5β3γ2L and α1β2γ2L, in vivo, in the rat, as a dose-dependent inhibitor toward AP's negative effects on LoR and learning in the MWM.
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Affiliation(s)
- Sara K. S. Bengtsson
- Umeå Neurosteroid Research Center, Department of Clinical Sciences, Umeå University, SE-901 85 Umeå, Sweden
| | - Jessica Sjöstedt
- Umeå Neurosteroid Research Center, Department of Clinical Sciences, Umeå University, SE-901 85 Umeå, Sweden
| | - Evgenya Malinina
- Umeå Neurosteroid Research Center, Department of Clinical Sciences, Umeå University, SE-901 85 Umeå, Sweden
- Department of Integrative Medical Biology, Umeå University, SE-901 87 Umeå, Sweden
| | - Roshni Das
- Department of Integrative Medical Biology, Umeå University, SE-901 87 Umeå, Sweden
- Umecrine Cognition AB, SE-171 65 Solna, Sweden
| | | | - Maja Johansson
- Umeå Neurosteroid Research Center, Department of Clinical Sciences, Umeå University, SE-901 85 Umeå, Sweden
- Umecrine Cognition AB, SE-171 65 Solna, Sweden
| | - David Haage
- Umeå Neurosteroid Research Center, Department of Clinical Sciences, Umeå University, SE-901 85 Umeå, Sweden
- Department of Nursing Sciences, Mid Sweden University, AE-851 70 Sundsvall, Sweden
| | - Torbjörn Bäckström
- Umeå Neurosteroid Research Center, Department of Clinical Sciences, Umeå University, SE-901 85 Umeå, Sweden
- Umecrine Cognition AB, SE-171 65 Solna, Sweden
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Feng YH, Lim SW, Lin HY, Wang SA, Hsu SP, Kao TJ, Ko CY, Hsu TI. Allopregnanolone suppresses glioblastoma survival through decreasing DPYSL3 and S100A11 expression. J Steroid Biochem Mol Biol 2022; 219:106067. [PMID: 35114375 DOI: 10.1016/j.jsbmb.2022.106067] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 01/15/2022] [Accepted: 01/28/2022] [Indexed: 12/14/2022]
Abstract
Allopregnanolone (allo) is a physiological regulator of neuronal activity that treats multiple neurological disorders. Allo penetrates the blood-brain barrier with very high efficiency, implying that allo can treat CNS-related diseases, including glioblastoma (GBM), which always recurs after standard therapy. Hence, this study aimed to determine whether allo has a therapeutic effect on GBM. We found that allo enhanced temozolomide (TMZ)-suppressed cell survival and proliferation of TMZ-resistant cells. In particular, allo enhanced TMZ-inhibited cell migration and TMZ-induced apoptosis. Additionally, allo strongly induced DNA damage characterized by γH2Ax. Furthermore, quantitative proteomic analysis, iTRAQ, showed that allo significantly decreased the levels of DPYSL3, S100A11, and S100A4, reflecting the poor prognosis of patients with GBM confirmed by differential gene expression and survival analysis. Moreover, single-cell RNA-Seq revealed that S100A11, expressed in malignant cells, oligodendrocytes, and macrophages, was significantly associated with immune cell infiltration. Furthermore, overexpression of DPYSL3 or S100A11 prevented allo-induced cell death. In conclusion, allo suppresses GBM cell survival by decreasing DPYSL3/S100A11 expression and inducing DNA damage.
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Affiliation(s)
| | - Sher-Wei Lim
- Institute of Biomedical Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan; Department of Neurosurgery, Chi-Mei Medical Center, Tainan 722, Taiwan; Department of Nursing, Min-Hwei College of Health Care Management, Tainan 736, Taiwan
| | - Hong-Yi Lin
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan; The Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 110, Taiwan
| | - Shao-An Wang
- School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei 110, Taiwan
| | - Sung-Po Hsu
- Department of Physiology, School of Medicine, Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 110, Taiwan
| | - Tzu-Jen Kao
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan; The Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 110, Taiwan; Ph.D. Program in Medical Neuroscience, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 110, Taiwan; International Master Program in Medical Neuroscience, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 110, Taiwan; TMU Research Center of Neuroscience, Taipei Medical University, Taipei 110, Taiwan
| | - Chiung-Yuan Ko
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan; The Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 110, Taiwan; Ph.D. Program in Medical Neuroscience, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 110, Taiwan; International Master Program in Medical Neuroscience, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 110, Taiwan; TMU Research Center of Neuroscience, Taipei Medical University, Taipei 110, Taiwan.
| | - Tsung-I Hsu
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan; The Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 110, Taiwan; Ph.D. Program in Medical Neuroscience, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 110, Taiwan; International Master Program in Medical Neuroscience, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 110, Taiwan; TMU Research Center of Neuroscience, Taipei Medical University, Taipei 110, Taiwan; TMU Research Center of Cancer Translational Medicine, Taipei 110, Taiwan.
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3
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Bortolato M, Coffey BJ, Gabbay V, Scheggi S. Allopregnanolone: The missing link to explain the effects of stress on tic exacerbation? J Neuroendocrinol 2022; 34:e13022. [PMID: 34423500 PMCID: PMC8800948 DOI: 10.1111/jne.13022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/19/2021] [Accepted: 07/26/2021] [Indexed: 12/13/2022]
Abstract
The neurosteroid allopregnanolone (3α-hydroxy-5α-pregnan-20-one; AP) elicits pleiotropic effects in the central nervous system, ranging from neuroprotective and anti-inflammatory functions to the regulation of mood and emotional responses. Several lines of research show that the brain rapidly produces AP in response to acute stress to reduce the allostatic load and enhance coping. These effects not only are likely mediated by GABAA receptor activation but also result from the contributions of other mechanisms, such as the stimulation of membrane progesterone receptors. In keeping with this evidence, AP has been shown to exert rapid, potent antidepressant properties and has been recently approved for the therapy of moderate-to-severe postpartum depression. In addition to depression, emerging evidence points to the potential of AP as a therapy for other neuropsychiatric disorders, including anxiety, seizures, post-traumatic stress disorder and cognitive problems. Although this evidence has spurred interest in further therapeutic applications of AP, some investigations suggest that this neurosteroid may also be associated with adverse events in specific disorders. For example, our group has recently documented that AP increases tic-like manifestations in several animal models of tic disorders; furthermore, our results indicate that inhibiting AP synthesis and signalling reduces the exacerbation of tic severity associated with acute stress. Although the specific mechanisms of these effects remain partially elusive, our findings point to the possibility that the GABAergic activation by AP may also lead to disinhibitory effects, which could interfere with the ability of patients to suppress their tics. Future studies will be necessary to verify whether these mechanisms may apply to other externalising manifestations, such as impulse-control problems and manic symptoms.
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Affiliation(s)
- Marco Bortolato
- Department of Pharmacology and ToxicologyCollege of PharmacyUniversity of UtahSalt Lake CityUTUSA
- Research Consortium on NeuroEndocrine Causes of Tics (ReConNECT)
| | - Barbara J. Coffey
- Research Consortium on NeuroEndocrine Causes of Tics (ReConNECT)
- Department of Psychiatry and Behavioral ScienceMiller School of MedicineUniversity of MiamiMiamiFLUSA
| | - Vilma Gabbay
- Research Consortium on NeuroEndocrine Causes of Tics (ReConNECT)
- Department of Psychiatry and Behavioral SciencesAlbert Einstein College of MedicineBronxNYUSA
| | - Simona Scheggi
- Department of Molecular and Developmental MedicineSchool of MedicineUniversity of SienaSienaItaly
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Kalarani A, Vinodha V, Moses IR. Inter-relations of brain neurosteroids and monoamines towards reproduction in fish. REPRODUCTION AND BREEDING 2021. [DOI: 10.1016/j.repbre.2021.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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Horrell ND, Saltzman W, Hickmott PW. Plasticity of paternity: Effects of fatherhood on synaptic, intrinsic and morphological characteristics of neurons in the medial preoptic area of male California mice. Behav Brain Res 2019; 365:89-102. [PMID: 30802534 DOI: 10.1016/j.bbr.2019.02.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/16/2019] [Accepted: 02/16/2019] [Indexed: 12/28/2022]
Abstract
Parental care by fathers enhances offspring survival and development in numerous species. In the biparental California mouse, Peromyscus californicus, behavioral plasticity is seen during the transition into fatherhood: adult virgin males often exhibit aggressive or indifferent responses to pups, whereas fathers engage in extensive paternal care. In this species and other biparental mammals, the onset of paternal behavior is associated with increased neural responsiveness to pups in specific brain regions, including the medial preoptic area of the hypothalamus (MPOA), a region strongly implicated in both maternal and paternal behavior. To assess possible changes in neural circuit properties underlying this increased excitability, we evaluated synaptic, intrinsic, and morphological properties of MPOA neurons in adult male California mice that were either virgins or first-time fathers. We used standard whole-cell recordings in a novel in vitro slice preparation. Excitatory and inhibitory post-synaptic currents from MPOA neurons were recorded in response to local electrical stimulation, and input/output curves were constructed for each. Responses to trains of stimuli were also examined. We quantified intrinsic excitability by measuring voltage changes in response to square-pulse injections of both depolarizing and hyperpolarizing current. Biocytin was injected into neurons during recording, and their morphology was analyzed. Most parameters did not differ significantly between virgins and fathers. However, we document a decrease in synaptic inhibition in fathers. These findings suggest that the onset of paternal behavior in California mouse fathers may be associated with limited electrophysiological plasticity within the MPOA.
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Affiliation(s)
- Nathan D Horrell
- Graduate Program in Neuroscience, University of California, Riverside, CA, 92521, United States; Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, 92521, United States
| | - Wendy Saltzman
- Graduate Program in Neuroscience, University of California, Riverside, CA, 92521, United States; Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, 92521, United States.
| | - Peter W Hickmott
- Graduate Program in Neuroscience, University of California, Riverside, CA, 92521, United States; Department of Psychology, University of California, Riverside, CA, 92521, United States
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Johansson M, Strömberg J, Ragagnin G, Doverskog M, Bäckström T. GABAA receptor modulating steroid antagonists (GAMSA) are functional in vivo. J Steroid Biochem Mol Biol 2016; 160:98-105. [PMID: 26523675 DOI: 10.1016/j.jsbmb.2015.10.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 10/16/2015] [Accepted: 10/25/2015] [Indexed: 12/18/2022]
Abstract
GABAA receptor modulating steroid antagonists (GAMSA) selectively inhibit neurosteroid-mediated enhancement of GABA-evoked currents at the GABAA receptor. 3α-hydroxy-neurosteroids, notably allopregnanolone and tetrahydrodeoxycorticosterone (THDOC), potentiate GABAA receptor-mediated currents. On the contrary, various 3β-hydroxy-steroids antagonize this positive neurosteroid-mediated modulation. Importantly, GAMSAs are specific antagonists of the positive neurosteroid-modulation of the receptor and do not inhibit GABA-evoked currents. Allopregnanolone and THDOC have both negative and positive actions. Allopregnanolone can impair encoding/consolidation and retrieval of memories. Chronic administration of a physiological allopregnanolone concentration reduces cognition in mice models of Alzheimer's disease. In humans an allopregnanolone challenge impairs episodic memory and in hepatic encephalopathy cognitive deficits are accompanied by increased brain ammonia and allopregnanolone. Hippocampal slices react in vitro to ammonia by allopregnanolone synthesis in CA1 neurons, which blocks long-term potentiation (LTP). Thus, allopregnanolone may impair learning and memory by interfering with hippocampal LTP. Contrary, pharmacological treatment with allopregnanolone can promote neurogenesis and positively influence learning and memory of trace eye-blink conditioning in mice. In rat the GAMSA UC1011 inhibits an allopregnanolone-induced learning impairment and the GAMSA GR3027 restores learning and motor coordination in rats with hepatic encephalopathy. In addition, the GAMSA isoallopregnanolone antagonizes allopregnanolone-induced anesthesia in rats, and in humans it antagonizes allopregnanolone-induced sedation and reductions in saccadic eye velocity. 17PA is also an effective GAMSA in vivo, as it antagonizes allopregnanolone-induced anesthesia and spinal analgesia in rats. In vitro the allopregnanolone/THDOC-increased GABA-mediated GABAA receptor activity is antagonized by isoallopregnanolone, UC1011, GR3027 and 17PA, while the effect of GABA itself is not affected.
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Affiliation(s)
- Maja Johansson
- Umeå Neurosteroid research center, Obstetrics and Gynecology, Clinical Sciences at Umeå University, Building 6M, 4th floor at NUS, SE-901 85 Umeå, Sweden; Umecrine Cognition AB, Sweden.
| | - Jessica Strömberg
- Umeå Neurosteroid research center, Obstetrics and Gynecology, Clinical Sciences at Umeå University, Building 6M, 4th floor at NUS, SE-901 85 Umeå, Sweden
| | - Gianna Ragagnin
- Umeå Neurosteroid research center, Obstetrics and Gynecology, Clinical Sciences at Umeå University, Building 6M, 4th floor at NUS, SE-901 85 Umeå, Sweden
| | | | - Torbjörn Bäckström
- Umeå Neurosteroid research center, Obstetrics and Gynecology, Clinical Sciences at Umeå University, Building 6M, 4th floor at NUS, SE-901 85 Umeå, Sweden
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7
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Yelhekar TD, Druzin M, Karlsson U, Blomqvist E, Johansson S. How to Properly Measure a Current-Voltage Relation?-Interpolation vs. Ramp Methods Applied to Studies of GABAA Receptors. Front Cell Neurosci 2016; 10:10. [PMID: 26869882 PMCID: PMC4735409 DOI: 10.3389/fncel.2016.00010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 01/11/2016] [Indexed: 11/23/2022] Open
Abstract
The relation between current and voltage, I-V relation, is central to functional analysis of membrane ion channels. A commonly used method, since the introduction of the voltage-clamp technique, to establish the I-V relation depends on the interpolation of current amplitudes recorded at different steady voltages. By a theoretical computational approach as well as by experimental recordings from GABAA-receptor mediated currents in mammalian central neurons, we here show that this interpolation method may give reversal potentials and conductances that do not reflect the properties of the channels studied under conditions when ion flux may give rise to concentration changes. Therefore, changes in ion concentrations may remain undetected and conclusions on changes in conductance, such as during desensitization, may be mistaken. In contrast, an alternative experimental approach, using rapid voltage ramps, enable I-V relations that much better reflect the properties of the studied ion channels.
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Affiliation(s)
- Tushar D Yelhekar
- Section for Physiology, Department of Integrative Medical Biology, Umeå University Umeå, Sweden
| | - Michael Druzin
- Section for Physiology, Department of Integrative Medical Biology, Umeå University Umeå, Sweden
| | - Urban Karlsson
- Section for Physiology, Department of Integrative Medical Biology, Umeå University Umeå, Sweden
| | - Erii Blomqvist
- Section for Physiology, Department of Integrative Medical Biology, Umeå University Umeå, Sweden
| | - Staffan Johansson
- Section for Physiology, Department of Integrative Medical Biology, Umeå University Umeå, Sweden
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8
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Chakrabarti S, Qian M, Krishnan K, Covey DF, Mennerick S, Akk G. Comparison of Steroid Modulation of Spontaneous Inhibitory Postsynaptic Currents in Cultured Hippocampal Neurons and Steady-State Single-Channel Currents from Heterologously Expressed α1β2γ2L GABA(A) Receptors. Mol Pharmacol 2016; 89:399-406. [PMID: 26769414 DOI: 10.1124/mol.115.102202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 01/13/2016] [Indexed: 12/18/2022] Open
Abstract
Neuroactive steroids are efficacious modulators of γ-aminobutyric acid type A receptor (GABA(A)) receptor function. The effects of steroids on the GABA(A) receptor are typically determined by comparing steady-state single-channel open probability or macroscopic peak responses elicited by GABA in the absence and presence of a steroid. Due to differences in activation conditions (exposure duration, concentration of agonist), it is not obvious whether modulation measured using typical experimental protocols can be used to accurately predict the effect of a modulator on native receptors under physiologic conditions. In the present study, we examined the effects of 14 neuroactive steroids and analogs on the properties of spontaneous inhibitory postsynaptic currents (sIPSCs) in cultured rat hippocampal neurons. The goal was to determine whether the magnitude of modulation of the decay time course of sIPSCs correlates with the extent of modulation and kinetic properties of potentiation as determined in previous single-channel studies. The steroids were selected to cover a wide range of efficacy on heterologously expressed rat α1β2γ2L GABA(A) receptors, ranging from essentially inert to highly efficacious (strong potentiators of single-channel and macroscopic peak responses). The data indicate a strong correlation between prolongation of the decay time course of sIPSCs and potentiation of single-channel open probability. Furthermore, changes in intracluster closed time distributions were the single best predictor of prolongation of sIPSCs. We infer that the information obtained in steady-state single-channel recordings can be used to forecast modulation of synaptic currents.
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Affiliation(s)
- Sampurna Chakrabarti
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Mingxing Qian
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Kathiresan Krishnan
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Douglas F Covey
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Steven Mennerick
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
| | - Gustav Akk
- Department of Anesthesiology (S.C., G.A.), Department of Developmental Biology (M.Q., K.K., D.F.C.), and Department of Psychiatry (S.M.), and the Taylor Family Institute for Innovative Psychiatric Research (D.F.C., S.M., G.A.), Washington University School of Medicine, St. Louis, Missouri
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10
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Karlsson U, Druzin M, Johansson S. Cl(-) concentration changes and desensitization of GABA(A) and glycine receptors. ACTA ACUST UNITED AC 2011; 138:609-26. [PMID: 22084415 PMCID: PMC3226965 DOI: 10.1085/jgp.201110674] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Desensitization of ligand-gated ion channels plays a critical role for the information transfer between neurons. The current view on γ-aminobutyric acid (GABA)A and glycine receptors includes significant rapid components of desensitization as well as cross-desensitization between the two receptor types. Here, we analyze the mechanism of apparent cross-desensitization between native GABAA and glycine receptors in rat central neurons and quantify to what extent the current decay in the presence of ligand is a result of desensitization versus changes in intracellular Cl− concentration ([Cl−]i). We show that apparent cross-desensitization of currents evoked by GABA and by glycine is caused by changes in [Cl−]i. We also show that changes in [Cl−]i are critical for the decay of current in the presence of either GABA or glycine, whereas changes in conductance often play a minor role only. Thus, the currents decayed significantly quicker than the conductances, which decayed with time constants of several seconds and in some cells did not decay below the value at peak current during 20-s agonist application. By taking the cytosolic volume into account and numerically computing the membrane currents and expected changes in [Cl−]i, we provide a theoretical framework for the observed effects. Modeling diffusional exchange of Cl− between cytosol and patch pipettes, we also show that considerable changes in [Cl−]i may be expected and cause rapidly decaying current components in conventional whole cell or outside-out patch recordings. The findings imply that a reevaluation of the desensitization properties of GABAA and glycine receptors is needed.
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Affiliation(s)
- Urban Karlsson
- Department of Neurosciences, CNSP iMed, AstraZeneca Research and Development, S-151 85 Södertälje, Sweden
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Abstract
Neurosteroids represent a class of endogenous steroids that are synthesized in the brain, the adrenals, and the gonads and have potent and selective effects on the GABAA-receptor. 3α-hydroxy A-ring reduced metabolites of progesterone, deoxycorticosterone, and testosterone are positive modulators of GABA(A)-receptor in a non-genomic manner. Allopregnanolone (3α-OH-5α-pregnan-20-one), 5α-androstane-3α, 17α-diol (Adiol), and 3α5α-tetrahydrodeoxycorticosterone (3α5α-THDOC) enhance the GABA-mediated Cl(-) currents acting on a site (or sites) distinct from the GABA, benzodiazepine, barbiturate, and picrotoxin binding sites. 3α5α-P and 3α5α-THDOC potentiate synaptic GABA(A)-receptor function and activate δ-subunit containing extrasynaptic receptors that mediate tonic currents. On the contrary, 3β-OH pregnane steroids and pregnenolone sulfate (PS) are GABA(A)-receptor antagonists and induce activation-dependent inhibition of the receptor. The activities of neurosteroid are dependent on brain regions and types of neurons. In addition to the slow genomic action of the parent steroids, the non-genomic, and rapid actions of neurosteroids play a significant role in the GABA(A)-receptor function and shift in mood and memory function. This review describes molecular mechanisms underlying neurosteroid action on the GABA(A)-receptor, mood changes, and cognitive functions.
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Affiliation(s)
- Mingde Wang
- Section of Obstetrics and Gynecology, Department of Clinical Science, Umeå Neurosteroid Research Center, Umeå UniversityUmeå, Sweden
- *Correspondence: Mingde Wang, Section of Obstetrics and Gynecology, Department of Clinical Science, Umeå Neurosteroid Research Center, Umeå University, 901 85 Umeå, Sweden. e-mail:
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12
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Baker C, Sturt BL, Bamber BA. Multiple roles for the first transmembrane domain of GABAA receptor subunits in neurosteroid modulation and spontaneous channel activity. Neurosci Lett 2010; 473:242-7. [PMID: 20193738 DOI: 10.1016/j.neulet.2010.02.058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 01/26/2010] [Accepted: 02/23/2010] [Indexed: 01/02/2023]
Abstract
Neurosteroids exert potent physiological effects by allosterically modulating synaptic and extrasynaptic GABA(A) receptors. Some endogenous neurosteroids, such as 3alpha, 21-dihydroxy-5beta-pregnan-20-one (5alpha, 3alpha-THDOC), potentiate GABA(A) receptor function by interacting with a binding pocket defined by conserved residues in the first and fourth transmembrane (TM) domains of alpha subunits. Others, such as pregnenolone sulfate (PS), inhibit GABA(A) receptor function through as-yet unidentified binding sites. Here we investigate the mechanisms of PS inhibition of mammalian GABA(A) receptors, based on studies of PS inhibition of the UNC-49 GABA receptor, a GABA(A)-like receptor from Caenorhabditis elegans. In UNC-49, a 19 residue segment of TM1 can be mutated to increase or decrease PS sensitivity over a 20-fold range. Surprisingly, substituting these UNC-49 sequences into mammalian alpha(1), beta(2), and gamma(2) subunits did not produce the corresponding effects on PS sensitivity of the resulting chimeric receptors. Therefore, it is unlikely that a conserved PS binding pocket is formed at this site. However we observed several interesting unexpected effects. First, chimeric gamma2 subunits caused increased efficacy of 5alpha, 3alpha-THDOC potentiation; second, spontaneous gating of alpha(6)beta(2)delta receptors was blocked by PS, and reduced by chimeric beta(2) subunits; and third, direct activation of alpha(6)beta(2)delta receptors by 5alpha, 3alpha-THDOC was reduced by chimeric beta(2) subunits. These results reveal novel roles for non-alpha subunits in neurosteroid modulation and direct activation, and show that the beta subunit TM1 domain is important for spontaneous activity of extrasynaptic GABA(A) receptors.
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Affiliation(s)
- Carrie Baker
- Department of Bioengineering, University of Toledo, 2801 W Bancroft Street, Toledo, OH 43606, United States
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The effect of the neuroactive steroid 5beta-pregnane-3beta, 20(R)-diol on the time course of GABA evoked currents is different to that of pregnenolone sulphate. Eur J Pharmacol 2009; 605:78-86. [PMID: 19168059 DOI: 10.1016/j.ejphar.2008.12.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 12/02/2008] [Accepted: 12/18/2008] [Indexed: 01/19/2023]
Abstract
The endogenous progesterone metabolite allopregnanolone has a number of properties including anesthetic, sedative, antiepileptic, anxiolytic, impaired memory function and negative mood symptoms. Allopregnanolone is a potent positive GABA(A) receptor function modulators. In contrast, 3beta-hydroxy-steroids (3beta-steroids) usually modulate the GABA(A) receptor negatively. They have attracted some interest for their possible use as therapeutic agents that could counteract the negative symptoms induced by allopregnanolone. Two hypotheses for the action of 3beta-steroids have been proposed: 1) 3beta-steroids act in a similar way to pregnenolone sulphate, which non-competitively reduces GABA(A) receptor activity. 2) 3beta-steroids specifically antagonize the effect of allopregnanolone. We have therefore tried to clarify this issue by comparing the effect of pregnenolone sulphate and 5beta-pregnane-3beta, 20(R)-diol on the GABA-evoked currents by the patch clamp technique on neurons from the medial preoptic nucleus. Both pregnenolone sulphate and 5beta-pregnane-3beta, 20(R)-diol increase the desensitization rate of the current response evoked by a 2 s GABA application. However, their effects on other parameters of the GABA evoked currents differed in degree and sometimes even in direction. The actions of pregnenolone sulphate and 5beta-pregnane-3beta, 20(R)-diol were not altered in the presence of allopregnanolone, which indicates that they do not directly interact with allopregnanolone. In addition, when 5beta-pregnane-3beta, 20(R)-diol was tested on spontaneous inhibitory postsynaptic currents (sIPSCs), it dramatically reduced the allopregnanolone-induced prolongation of the decay time constant but it had no effect on the decay under control conditions. In conclusion, the effect of 5beta-pregnane-3beta, 20(R)-diol on GABA-evoked currents is different to that of pregnenolone sulphate in medial preoptic nucleus neurons.
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Wang MD, Borra VB, Strömberg J, Lundgren P, Haage D, Bäckström T. Neurosteroids 3beta, 20 (R/S)-pregnandiols decrease offset rate of the GABA-site activation at the recombinant GABA A receptor. Eur J Pharmacol 2008; 586:67-73. [PMID: 18374329 DOI: 10.1016/j.ejphar.2008.02.063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2007] [Revised: 02/07/2008] [Accepted: 02/20/2008] [Indexed: 10/22/2022]
Abstract
Neurosteroids directly modulate ligand gated ion channels such as GABA A receptors. Two such molecules, 3beta-OH A-ring reduced pregnane steroids and pregnenolone sulfate (PS), inhibit recombinant GABA A receptor. Using a two-electrode voltage-clamp technique, we compared the effect of 5alpha-pregnan-3beta,20(S)-diol (UC1019), 5beta-pregnan-3beta, 20(R)-diol (UC1020) and PS on the activation onset and offset times of the recombinant GABA A receptor (rat alpha1beta2gamma2L) in Xenopus oocytes. Rapid solution changes allowed the kinetic analysis of GABA-evoked currents. Steroids were co-applied with 30 microM GABA for 10 s, followed by a 80 s washout period. PS (> ir =0.3 microM) moderately increased the slow onset rate (k(on-S)) of GABA-response. PS had no significant effects on the fast onset rate (k(on-F)). UC1019 and UC1020 decreased the k(on-S) of the GABA-response in a concentration-dependent manner with no significant effects on the k(on-F). Like PS, UC1019 and UC1020 decreased the slow offset rates (k(off-S)). In addition, PS increased the fast offset rate (k(off-F)) in a concentration-dependent manner, while UC1019 and UC1020 decreased k(off-F). The EC50 of PS to increase k(off-F) was calculated as 0.47+/-0.1 microM. The corresponding IC50 values of UC1019 and UC1020 to decrease k(off-F) were 5.0+/-0.5 microM and 8.4+/-0.9 microM, respectively. These results suggest differential actions of PS and 3beta, 20(R/S)-pregnandiols on the offset time course of GABA-site activation.
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Affiliation(s)
- Ming-De Wang
- Umeå Neurosteroid Research Center, Department of Clinical Science, Obstetrics and Gynecology, Sweden.
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15
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Herd MB, Belelli D, Lambert JJ. Neurosteroid modulation of synaptic and extrasynaptic GABA(A) receptors. Pharmacol Ther 2007; 116:20-34. [PMID: 17531325 DOI: 10.1016/j.pharmthera.2007.03.007] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Accepted: 03/29/2007] [Indexed: 02/04/2023]
Abstract
Certain naturally occurring pregnane steroids act in a nongenomic manner to potently and selectively enhance the interaction of the inhibitory neurotransmitter GABA with the GABA(A) receptor. Consequently such steroids exhibit anxiolytic, anticonvulsant, analgesic, sedative, hypnotic, and anesthetic properties. In both physiological and pathophysiological scenarios, the pregnane steroids may function as endocrine messengers (e.g., produced in the periphery and cross the blood-brain barrier) to influence behaviour. However, additionally "neurosteroids" can be synthesised in the brain and spinal cord to act in a paracrine or autocrine manner and thereby locally influence neuronal activity. Given the ubiquitous expression of the GABA(A) receptor throughout the mammalian central nervous system (CNS), physiological, pathophysiological, or drug-induced pertubations of neurosteroid levels may be expected to produce widespread changes in brain excitability. However, the neurosteroid/GABA(A) receptor interaction is brain region and indeed neuron specific. The molecular basis of this specificity will be reviewed here, including (1) the importance of the subunit composition of the GABA(A) receptor; (2) how protein phosphorylation may dynamically influence the sensitivity of GABA(A) receptors to neurosteroids; (3) the impact of local steroid metabolism; and (4) the emergence of extrasynaptic GABA(A) receptors as a neurosteroid target.
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Affiliation(s)
- Murray B Herd
- Neuroscience Institute, Ninewells Hospital and Medical School, Dundee University, Dundee DD19SY, Scotland, United Kingdom
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16
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Steroid modulation of GABAA receptor-mediated transmission in the hypothalamus: effects on reproductive function. Neuropharmacology 2007; 52:1439-53. [PMID: 17433821 DOI: 10.1016/j.neuropharm.2007.01.022] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 01/30/2007] [Accepted: 01/31/2007] [Indexed: 10/23/2022]
Abstract
The hypothalamus, the seat of neuroendocrine control, is exquisitely sensitive to gonadal steroids. For decades it has been known that androgens, estrogens and progestins, acting through nuclear hormone receptors, elicit both organizational and activational effects in the hypothalamus and basal forebrain that are essential for reproductive function. While changes in gene expression mediated by these classical hormone pathways are paramount in governing both sexual differentiation and the neural control of reproduction, it is also clear that steroids impart critical control of neuroendocrine functions through non-genomic mechanisms. Specifically, endogenous neurosteroid derivatives of deoxycorticosterone, progesterone and testosterone, as well and synthetic anabolic androgenic steroids that are self-administered as drugs of abuse, elicit acute effects via allosteric modulation of gamma-aminobutyric acid type A receptors. GABAergic transmission within the hypothalamus and basal forebrain is a key regulator of pubertal onset, the expression of sexual behaviors, pregnancy and parturition. Summarized here are the known actions of steroid modulators on GABAergic transmission within the hypothalamus/basal forebrain, with a focus on the medial preoptic area and the supraoptic/paraventricular nuclei that are known to be central players in the control of reproduction.
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Wang MD, Rahman M, Zhu D, Bäckström T. Pregnenolone sulphate and Zn2+ inhibit recombinant rat GABA(A) receptor through different channel property. Acta Physiol (Oxf) 2006; 188:153-62. [PMID: 17054655 DOI: 10.1111/j.1748-1716.2006.01617.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
AIMS We compared the antagonistic effects of state-dependent gamma-aminobutyric acid A (GABA(A)) receptor blockers picrotoxin, Zn(2+) and pregnenolone sulphate (PS) on GABA- and pentobarbital-activated currents in recombinant rat GABA(A) receptors in Xenopus oocytes. METHODS Experiments were performed with wild type rat alpha1 beta2 gamma2L and alpha1beta2 receptors, mutants alpha1V256S beta2 gamma2L and alpha1beta2A252Sgamma2L receptors by the two-electrode voltage-clamp technique. RESULTS In contrast to respective 3840- and 56-fold increases in Zn(2+) potencies to inhibit GABA- and pentobarbital-activated currents in the alpha1beta2 receptor, the corresponding potencies of PS remained unchanged in comparison with the alpha1 beta2 gamma2L receptor. A homologous mutation of the residue at 2' position closest to the cytoplasmic end of the M(2) helix to serine on both alpha1 and beta2 subunit, alpha1V256S and beta2A252S, abolished the inhibition of GABA(A) receptor by PS. In comparison with the wild type alpha1beta2gamma2L receptor, mutants alpha1V256S beta2 gamma2L and alpha1beta2 A252S gamma2L receptors did not affect the Zn(2+) inhibition. Furthermore, a significant increase in GABA potency was observed in the mutant alpha1V256S beta2 gamma2L receptor (P < 0.05), but not the mutant alpha1beta2 A252S gamma2L receptor compared with the wild type receptor. CONCLUSIONS Pregnenolone sulphate was a gamma2-subunit independent inhibitor in the GABA(A) receptor, whereas the Zn(2+) antagonism was profoundly influenced by the gamma2-subunit. It is likely that the 2' residue closest to the N-terminus of the protein at M(2) helix on both alpha1 and beta2 subunit are critical to the inhibitory actions of PS and the function of Cl(-) channels. These results are consistent with the hypothesis that PS behaves as a Cl(-) channel blocker that does not share with Zn(2+), the coincident channel property in the GABA(A) receptors.
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Affiliation(s)
- M-D Wang
- Department of Clinical Science, Obstetrics and Gynecology, Umeå Neurosteroid Research Center, Umeå University, Umeå, Sweden.
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Gibbs TT, Russek SJ, Farb DH. Sulfated steroids as endogenous neuromodulators. Pharmacol Biochem Behav 2006; 84:555-67. [PMID: 17023038 DOI: 10.1016/j.pbb.2006.07.031] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2006] [Revised: 07/12/2006] [Accepted: 07/17/2006] [Indexed: 11/18/2022]
Abstract
Central nervous system function is critically dependent upon an exquisitely tuned balance between excitatory synaptic transmission, mediated primarily by glutamate, and inhibitory synaptic transmission, mediated primarily by GABA. Modulation of either excitation or inhibition would be expected to result in altered functionality of finely tuned synaptic pathways and global neural systems, leading to altered nervous system function. Administration of positive or negative modulators of ligand-gated ion channels has been used extensively and successfully in CNS therapeutics, particularly for the induction of sedation and treatment of anxiety, seizures, insomnia, and pain. Excessive activation of excitatory glutamate receptors, such as in cerebral ischemia, can result in neuronal damage via excitotoxic mechanisms. The discovery that neuroactive steroids exert rapid, direct effects upon the function of both excitatory and inhibitory neurotransmitter receptors has raised the possibility that endogenous neurosteroids may play a regulatory role in synaptic transmission by modulating the balance between excitatory and inhibitory neurotransmission. The sites to which neuroactive steroids bind may also serve as targets for the discovery of therapeutic neuromodulators.
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Affiliation(s)
- Terrell T Gibbs
- Laboratory of Molecular Neurobiology, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, United States
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Devaud LL, Risinger FO, Selvage D. Impact of the Hormonal Milieu on the Neurobiology of Alcohol Dependence and Withdrawal. The Journal of General Psychology 2006; 133:337-56. [PMID: 17128955 DOI: 10.3200/genp.133.4.337-356] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Alcoholism, or alcohol dependence, is a complex disorder with withdrawal symptoms that are often problematic for those trying to recover from their dependence. As researchers attempt to elucidate the neurobiological underpinnings of alcohol dependence and withdrawal, it is becoming clear that numerous factors, including the hormonal environment, impact the manifestations of this disorder. Of particular interest is the observation that women have fewer and less severe withdrawal symptoms than do men even though they tend to suffer greater physiological harm from excessive alcohol consumption. In this article, the authors present an overview of their understanding of how gonadal and stress hormones interact with alcohol, which results in differential neurobiological responses between males and females. Thus far, data generated from representative animal models have shown significant differences between the sexes in behavioral responses and neuroadaptations to chronic alcohol consumption and withdrawal. Accumulating evidence suggests that treatment of alcoholism, including withdrawal, should be tailored to the patient's gender and hormonal status.
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Affiliation(s)
- Leslie L Devaud
- Department of Pharmaceutical Sciences, Idaho State University, Pocatello, ID 83209, USA.
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Strömberg J, Haage D, Taube M, Bäckström T, Lundgren P. Neurosteroid modulation of allopregnanolone and GABA effect on the GABA-A receptor. Neuroscience 2006; 143:73-81. [PMID: 16938407 DOI: 10.1016/j.neuroscience.2006.07.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 07/06/2006] [Accepted: 07/23/2006] [Indexed: 11/22/2022]
Abstract
The neurosteroid allopregnanolone (ALLO) or 3alpha-OH-5alpha-pregnane-20-one interacts with the GABA type A receptor chloride ion channel complex and enhances the effect of GABA. Animal and human studies suggest that ALLO plays an important role in several disorders including premenstrual syndrome, anxiety, and memory impairment. In contrast to ALLO, steroids with a hydroxy group in the 3beta position usually exert a reducing effect and have recently attracted interest due to their suggested role in counteracting the negative action of ALLO. In this study, five different 3beta-steroids were tested for their ability to modulate GABA-mediated chloride ion uptake in the absence and presence of ALLO in rat brain microsacs preparations. In addition, the effects of the 3beta-steroids and their interaction with ALLO were investigated by patch-clamp recordings of spontaneous inhibitory postsynaptic currents (sIPSCs) in rat hypothalamic neurons from the medial preoptic nucleus (MPN). All tested 3beta-steroids reduced the ALLO-enhanced GABA response in cerebral cortex, in hippocampus and in MPN. In cerebellum, only one had this effect. However, in the absence of ALLO, two of the 3beta-steroids potentiated GABA-evoked chloride ion uptake and prolonged the sIPSCs decay time, whereas the others had little or no effect. Therefore, it is possible that at least some 3beta-steroids can act as positive GABA(A) receptor modulators as well as negative modulators depending on whether or not ALLO is present. Finally, these results suggest that the 3beta-steroids could be of interest as pharmacological agents that could counteract the negative effects of ALLO.
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Affiliation(s)
- J Strömberg
- Umeå Neurosteroid Research Center, Obstetrics and Gynecology, Department of Clinical Science, Umeå University, Norrland University Hospital, Building 5B level 5, SE 901 85 Umeå, Sweden.
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Rahman M, Lindblad C, Johansson IM, Bäckström T, Wang MD. Neurosteroid modulation of recombinant rat alpha5beta2gamma2L and alpha1beta2gamma2L GABA(A) receptors in Xenopus oocyte. Eur J Pharmacol 2006; 547:37-44. [PMID: 16934248 DOI: 10.1016/j.ejphar.2006.07.039] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 07/17/2006] [Accepted: 07/19/2006] [Indexed: 11/28/2022]
Abstract
GABA(A) receptors containing alpha(5)-subunit have an important role in cognitive function. As the agonistic effect of 3alpha-hydroxy ring-A reduced steroids depends on subunit combinations of the GABA(A) receptor, the antagonistic effect of pregnenolone sulfate and 3beta-hydroxypregnane steroids may vary between alpha(5)-subunit and alpha(1)-subunit containing receptors. We investigated the effect of agonist and antagonist steroids in the recombinant rat alpha(1)beta(2)gamma(2L) and alpha(5)beta(2)gamma(2L) receptors expressed in Xenopus oocytes using a two electrodes voltage-clamp technique. We did not find any significant difference in potency and efficacy of GABA response between alpha(1)beta(2)gamma(2L) and alpha(5)beta(2)gamma(2L) receptors. Compared to the alpha(1)beta(2)gamma(2L) receptor, a significantly lower degree of desensitization was observed in the alpha(5)beta(2)gamma(2L) receptor. In addition, the potencies of 3alpha-OH-5alpha-pregnan-20-one (3alpha5alphaP), 5alpha-pregnan-3alpha,21-diol-20-one (3alpha5alphaTHDOC) and 5alpha-androstane-3alpha,17beta-diol (3alpha5alphaADL) to enhance GABA response were significantly higher in the alpha(5)beta(2)gamma(2L) receptor, whereas their efficacies remained unchanged between two receptors. In either receptor, the efficacy of 3alpha5alphaTHDOC was significantly higher than 3alpha5alphaP and 3alpha5alphaADL. The efficacies of 5beta-pregnan-3beta,21-diol-20-one(UC1015) and 5alpha-pregnan-3beta,20alpha-diol(UC1019) to inhibit 30 microM GABA response, and the efficacies of 3beta-OH-5beta-pregnan-20-one (UC1014) and 5beta-pregnan-3beta, 20beta-diol (UC1020) to inhibit 3 microM 3alpha5alphaTHDOC+3 microM GABA response were higher in the alpha(5)beta(2)gamma(2L) receptor compared to the alpha(1)beta(2)gamma(2L) receptor. The potencies of pregnenolone sulfate and 3beta-hydroxypregnane steroids to inhibit the GABA response and the 3alpha5alphaTHDOC+GABA response did not vary between two receptors. Interestingly, the potencies and efficacies of pregnenolone sulfate and 3beta-hydroxypregnane steroids to inhibit the GABA response were positively correlated to their potencies and efficacies to inhibit the 3alpha5alphaTHDOC+GABA response. Results from the current study revealed a different modulation pattern by neurosteroids between the alpha(1)beta(2)gamma(2L) and alpha(5)beta(2)gamma(2L) receptor.
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Affiliation(s)
- Mozibur Rahman
- Umeå Neurosteroid Research Center, Department of Clinical Science, Obstetrics and Gynecology, Umeå University, S-901 85 Umeå, Sweden
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Miller JE, Levine RB. Steroid hormone activation of wandering in the isolated nervous system of Manduca sexta. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2006; 192:1049-62. [PMID: 16788816 DOI: 10.1007/s00359-006-0143-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 05/17/2006] [Accepted: 05/21/2006] [Indexed: 02/02/2023]
Abstract
Steroid hormones modulate motor circuits in both vertebrates and invertebrates. The insect Manduca sexta, with its well-characterized developmental and endocrinological history, is a useful model system in which to study these effects. Wandering is a stage-specific locomotor behavior triggered by the steroid hormone 20-hydroxyecdysone (20E), consisting of crawling and burrowing movements as the animal searches for a pupation site. This study was undertaken to determine whether the wandering motor pattern is activated by direct action of 20E on the CNS. 20E acts on the isolated larval nervous system to induce a fictive motor pattern showing features of crawling and burrowing. The latency of the response to 20E is long, suggestive of a genomic mechanism of action. The abdominal motoneurons or segmental pattern generating circuits are unlikely to be the primary targets of 20E action in inducing fictive wandering. Exposure of the segmental ganglia alone to hormone did not evoke fictive wandering. Therefore, as suggested by an earlier study, the likely site of 20E action is within the brain.
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Affiliation(s)
- Julie E Miller
- Division of Neurobiology, University of Arizona, Tucson, AZ 85721, USA.
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