1
|
Park SE, Neupane C, Noh C, Sharma R, Shin HJ, Pham TL, Lee GS, Park KD, Lee CJ, Kang DW, Lee SY, Kim HW, Park JB. Antiallodynic effects of KDS2010, a novel MAO-B inhibitor, via ROS-GABA inhibitory transmission in a paclitaxel-induced tactile hypersensitivity model. Mol Brain 2022; 15:41. [PMID: 35526002 PMCID: PMC9078011 DOI: 10.1186/s13041-022-00924-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 04/18/2022] [Indexed: 11/10/2022] Open
Abstract
Monoamine oxidase (MAO) inhibitors have been investigated for the treatment of neuropathic pain. Here, we assessed the antiallodynic effects of a novel MAO-B inhibitor, KDS2010, on paclitaxel (PTX)-induced mechanical hypersensitivity. Oral administration of KDS2010 effectively relieved PTX-induced mechanical hypersensitivity in a dose-dependent manner. KDS2010 (25 mg/Kg) significantly prevented and suppressed PTX-induced pain responses with minimal effects on the body weight, motor activity, and working memory. KDS2010 significantly reduced reactive astrocytosis and reactive oxygen species (ROS) level in the L4–L6 spinal cord of PTX-treated mice. Furthermore, KDS2010 reversed the attenuation of GABAergic spontaneous inhibitory postsynaptic current (sIPSC) frequency in spinal dorsal horn neurons, although it failed to restore the reduced tonic GABAA inhibition nor the increased GABA transporter 1 (GAT1) expression in PTX-treated mice. In addition, bath application of a reactive oxygen species (ROS) scavenger (PBN) restored the sIPSC frequency in PTX-treated mice but not in control and PTX + KDS2010-treated mice. These results indicated that the antiallodynic effect of KDS2010 is not due to a MAO-B-dependent GABA production. Finally, PBN alone also exerted a similar analgesic effect as KDS2010, but a co-treatment of PBN with KDS2010 showed no additive effect, suggesting that inhibition of MAO-B-dependent ROS production is responsible for the analgesic effect by KDS2010 on PTX-induced allodynia. Overall, KDS2010 attenuated PTX-induced pain behaviors by restoring the altered ROS level and GABAergic inhibitory signaling in the spinal cord, suggesting that KDS2010 is a promising therapeutic strategy for chemotherapy-induced peripheral neuropathy.
Collapse
Affiliation(s)
- Su Eun Park
- Department of Medical Sciences, Graduate School, Chungnam National University, Daejeon, 35015, Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, 35015, Korea
| | - Chiranjivi Neupane
- Department of Medical Sciences, Graduate School, Chungnam National University, Daejeon, 35015, Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, 35015, Korea.,Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea
| | - Chan Noh
- Department of Anesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon, 35015, South Korea
| | - Ramesh Sharma
- Department of Medical Sciences, Graduate School, Chungnam National University, Daejeon, 35015, Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, 35015, Korea.,Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea
| | - Hyun Jin Shin
- Department of Medical Sciences, Graduate School, Chungnam National University, Daejeon, 35015, Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, 35015, Korea
| | - Thuy Linh Pham
- Department of Medical Sciences, Graduate School, Chungnam National University, Daejeon, 35015, Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, 35015, Korea
| | - Gyu-Seung Lee
- Department of Medical Sciences, Graduate School, Chungnam National University, Daejeon, 35015, Korea.,Dong-Gu Health Promotion Center 301-01, 30 Bogeunso Avenue, Samseung-Dong, Dong-gu, Daejeon, South Korea
| | - Ki Duk Park
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, 02792, Korea
| | - C Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, 34126, Korea
| | - Dong-Wook Kang
- Department of Medical Sciences, Graduate School, Chungnam National University, Daejeon, 35015, Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, 35015, Korea
| | - So Yeong Lee
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea
| | - Hyun-Woo Kim
- Department of Medical Sciences, Graduate School, Chungnam National University, Daejeon, 35015, Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, 35015, Korea
| | - Jin Bong Park
- Department of Medical Sciences, Graduate School, Chungnam National University, Daejeon, 35015, Korea. .,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, 35015, Korea. .,Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea.
| |
Collapse
|
2
|
Pandit S, Neupane C, Woo J, Sharma R, Nam MH, Lee GS, Yi MH, Shin N, Kim DW, Cho H, Jeon BH, Kim HW, Lee CJ, Park JB. Bestrophin1-mediated tonic GABA release from reactive astrocytes prevents the development of seizure-prone network in kainate-injected hippocampi. Glia 2019; 68:1065-1080. [PMID: 31833596 DOI: 10.1002/glia.23762] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/25/2019] [Accepted: 11/28/2019] [Indexed: 12/22/2022]
Abstract
Tonic extrasynaptic GABAA receptor (GABAA R) activation is under the tight control of tonic GABA release from astrocytes to maintain the brain's excitation/inhibition (E/I) balance; any slight E/I balance disturbance can cause serious pathological conditions including epileptic seizures. However, the pathophysiological role of tonic GABA release from astrocytes has not been tested in epileptic seizures. Here, we report that pharmacological or genetic intervention of the GABA-permeable Bestrophin-1 (Best1) channel prevented the generation of tonic GABA inhibition, disinhibiting CA1 pyramidal neuronal firing and augmenting seizure susceptibility in kainic acid (KA)-induced epileptic mice. Astrocyte-specific Best1 over-expression in KA-injected Best1 knockout mice fully restored the generation of tonic GABA inhibition and effectively suppressed seizure susceptibility. We demonstrate for the first time that tonic GABA from reactive astrocytes strongly contributes to the compensatory shift of E/I balance in epileptic hippocampi, serving as a good therapeutic target against altered E/I balance in epileptic seizures.
Collapse
Affiliation(s)
- Sudip Pandit
- Department of Medical Science, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea
| | - Chiranjivi Neupane
- Department of Medical Science, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea
| | - Junsung Woo
- Center for Glia-Neuron Interaction and Neuroscience, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
| | - Ramesh Sharma
- Department of Medical Science, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea
| | - Min-Ho Nam
- Center for Glia-Neuron Interaction and Neuroscience, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
| | - Gyu-Seung Lee
- Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea
| | - Min-Hee Yi
- Department of Anatomy, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea
| | - Nara Shin
- Department of Medical Science, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea.,Department of Anatomy, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea
| | - Dong Woon Kim
- Department of Medical Science, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea.,Department of Anatomy, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea
| | - Hyunsill Cho
- Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea
| | - Byeong Hwa Jeon
- Department of Medical Science, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea
| | - Hyun-Woo Kim
- Department of Medical Science, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea
| | - C Justin Lee
- Center for Glia-Neuron Interaction and Neuroscience, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science, Daejeon, Republic of Korea
| | - Jin Bong Park
- Department of Medical Science, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea.,Department of Physiology, College of Medicine and Brain Research Institute, Chungnam National University, Daejeon, Republic of Korea
| |
Collapse
|
3
|
Pai YH, Lim CS, Park KA, Cho HS, Lee GS, Shin YS, Kim HW, Jeon BH, Yoon SH, Park JB. Facilitation of AMPA receptor-mediated steady-state current by extrasynaptic NMDA receptors in supraoptic magnocellular neurosecretory cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2016; 20:425-32. [PMID: 27382359 PMCID: PMC4930911 DOI: 10.4196/kjpp.2016.20.4.425] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 06/06/2016] [Accepted: 06/09/2016] [Indexed: 01/02/2023]
Abstract
In addition to classical synaptic transmission, information is transmitted between cells via the activation of extrasynaptic receptors that generate persistent tonic current in the brain. While growing evidence supports the presence of tonic NMDA current (INMDA) generated by extrasynaptic NMDA receptors (eNMDARs), the functional significance of tonic INMDA in various brain regions remains poorly understood. Here, we demonstrate that activation of eNMDARs that generate INMDA facilitates the α-amino-3-hydroxy-5-methylisoxazole-4-proprionate receptor (AMPAR)-mediated steady-state current in supraoptic nucleus (SON) magnocellular neurosecretory cells (MNCs). In low-Mg2+ artificial cerebrospinal fluid (aCSF), glutamate induced an inward shift in Iholding (IGLU) at a holding potential (Vholding) of –70 mV which was partly blocked by an AMPAR antagonist, NBQX. NBQX-sensitive IGLU was observed even in normal aCSF at Vholding of –40 mV or –20 mV. IGLU was completely abolished by pretreatment with an NMDAR blocker, AP5, under all tested conditions. AMPA induced a reproducible inward shift in Iholding (IAMPA) in SON MNCs. Pretreatment with AP5 attenuated IAMPA amplitudes to ~60% of the control levels in low-Mg2+ aCSF, but not in normal aCSF at Vholding of –70 mV. IAMPA attenuation by AP5 was also prominent in normal aCSF at depolarized holding potentials. Memantine, an eNMDAR blocker, mimicked the AP5-induced IAMPA attenuation in SON MNCs. Finally, chronic dehydration did not affect IAMPA attenuation by AP5 in the neurons. These results suggest that tonic INMDA, mediated by eNMDAR, facilitates AMPAR function, changing the postsynaptic response to its agonists in normal and osmotically challenged SON MNCs.
Collapse
Affiliation(s)
- Yoon Hyoung Pai
- Department of Physiology, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon 35015, Korea
| | - Chae Seong Lim
- Department of Anesthesiology & Pain Medicine, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon 35015, Korea
| | - Kyung-Ah Park
- Department of Physiology, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon 35015, Korea
| | - Hyun Sil Cho
- Department of Physiology, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon 35015, Korea
| | - Gyu-Seung Lee
- Department of Physiology, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon 35015, Korea
| | - Yong Sup Shin
- Department of Anesthesiology & Pain Medicine, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon 35015, Korea
| | - Hyun-Woo Kim
- Department of Physiology, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon 35015, Korea
| | - Byeong Hwa Jeon
- Department of Physiology, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon 35015, Korea
| | - Seok Hwa Yoon
- Department of Anesthesiology & Pain Medicine, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon 35015, Korea
| | - Jin Bong Park
- Department of Physiology, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon 35015, Korea
| |
Collapse
|
4
|
Pandit S, Jo JY, Lee SU, Lee YJ, Lee SY, Ryu PD, Lee JU, Kim HW, Jeon BH, Park JB. Enhanced astroglial GABA uptake attenuates tonic GABAA inhibition of the presympathetic hypothalamic paraventricular nucleus neurons in heart failure. J Neurophysiol 2015; 114:914-26. [PMID: 26063771 DOI: 10.1152/jn.00080.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 06/03/2015] [Indexed: 01/08/2023] Open
Abstract
γ-Aminobutyric acid (GABA) generates persistent tonic inhibitory currents (Itonic) and conventional inhibitory postsynaptic currents in the hypothalamic paraventricular nucleus (PVN) via activation of GABAA receptors (GABAARs). We investigated the pathophysiological significance of astroglial GABA uptake in the regulation of Itonic in the PVN neurons projecting to the rostral ventrolateral medulla (PVN-RVLM). The Itonic of PVN-RVLM neurons were significantly reduced in heart failure (HF) compared with sham-operated (SHAM) rats. Reduced Itonic sensitivity to THIP argued for the decreased function of GABAAR δ subunits in HF, whereas similar Itonic sensitivity to benzodiazepines argued against the difference of γ2 subunit-containing GABAARs in SHAM and HF rats. HF Itonic attenuation was reversed by a nonselective GABA transporter (GAT) blocker (nipecotic acid, NPA) and a GAT-3 selective blocker, but not by a GAT-1 blocker, suggesting that astroglial GABA clearance increased in HF. Similar and minimal Itonic responses to bestrophin-1 blockade in SHAM and HF neurons further argued against a role for astroglial GABA release in HF Itonic attenuation. Finally, the NPA-induced inhibition of spontaneous firing was greater in HF than in SHAM PVN-RVLM neurons, whereas diazepam induced less inhibition of spontaneous firing in HF than in SHAM neurons. Overall, our results showed that combined with reduced GABAARs function, the enhanced astroglial GABA uptake-induced attenuation of Itonic in HF PVN-RVLM neurons explains the deficit in tonic GABAergic inhibition and increased sympathetic outflow from the PVN during heart failure.
Collapse
Affiliation(s)
- Sudip Pandit
- Department of Physiology, School of Medicine, Chungnam National University, Daejeon, Republic of Korea
| | - Ji Yoon Jo
- Department of Physiology, School of Medicine, Chungnam National University, Daejeon, Republic of Korea
| | - Sang Ung Lee
- Department of Anesthesiology and Pain Medicine, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon, Republic of Korea; and
| | - Young Jae Lee
- Department of Anesthesiology and Pain Medicine, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon, Republic of Korea; and
| | - So Yeong Lee
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute of Veterinary Science, Seoul National University, Seoul, Republic of Korea
| | - Pan Dong Ryu
- Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute of Veterinary Science, Seoul National University, Seoul, Republic of Korea
| | - Jung Un Lee
- Department of Anesthesiology and Pain Medicine, Brain Research Institute, School of Medicine, Chungnam National University, Daejeon, Republic of Korea; and
| | - Hyun-Woo Kim
- Department of Physiology, School of Medicine, Chungnam National University, Daejeon, Republic of Korea
| | - Byeong Hwa Jeon
- Department of Physiology, School of Medicine, Chungnam National University, Daejeon, Republic of Korea
| | - Jin Bong Park
- Department of Physiology, School of Medicine, Chungnam National University, Daejeon, Republic of Korea;
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Reis WL, Biancardi VC, Son S, Antunes-Rodrigues J, Stern JE. Carbon monoxide and nitric oxide interactions in magnocellular neurosecretory neurones during water deprivation. J Neuroendocrinol 2015; 27:111-22. [PMID: 25494574 DOI: 10.1111/jne.12245] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 11/13/2014] [Accepted: 12/07/2014] [Indexed: 12/21/2022]
Abstract
Nitric oxide (NO) and carbon monoxide (CO) are diffusible gas messengers in the brain. Previously, we have shown their independent involvement in central fluid/electrolyte homeostasis control. In the present study, we investigated a possible functional interaction between NO/CO in the regulation of vasopressin (VP) and oxytocin (OT) magnocellular neurosecretory cells (MNCs) activity in euhydrated (EU) and dehydrated [48-h water-deprived (48WD)] rats. Using brain slices from EU and 48WD rats, we measured, by immunohistochemistry, the expression of neuronal NO synthase (nNOS, which synthesises NO) and haeme-oxygenase (HO-1, which synthesises CO) in the hypothalamic supraoptic nucleus (SON). In addition, we used patch-clamp electrophysiology to investigate whether regulation of SON MNC firing activity by endogenous CO was dependent on NO bioavailability and GABAergic inhibitory synaptic function. We found a proportion of OT and VP SON MNCs in EU rats to co-express both of HO-1 and nNOS (33.2 ± 2.9% and 15.3 ± 1.4%, respectively), which was increased in 48WD rats (55.5 ± 0.9% and 21.0 ± 1.7%, respectively, P < 0.05 for both). Inhibition of endogenous HO activity [chromium mesoporphyrin IX chloride (CrMP) 20 μm] induced MNC membrane hyperpolarisation and decreased firing activity, and these effects were blunted by previous blockade of endogenous NOS activity (l-NAME, 2 mm) or blockade of inhibitory GABA function [Picrotoxin (Sigma-Aldrich, St Louis, MO, USA), 50 μm]. No significant changes in SON NO bioavailability (4,5 diaminofluorescein diacetate fluorescence) were observed after CrMP treatment. Taken together, our results support a state-dependent functional inter-relationship between NO and CO in MNCs, in which CO acts as an excitatory gas molecule, whose effects are largely dependent on interactions with the inhibitory SON signals NO and GABA.
Collapse
Affiliation(s)
- W L Reis
- Department of Physiology, Georgia Regents University, Augusta, GA, USA; Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | | | | | | | | |
Collapse
|
7
|
Abstract
Since their introduction in the 1960s, benzodiazepines (BZs) remain one of the most commonly prescribed medications, acting as potent sedatives, hypnotics, anxiolytics, anticonvulsants, and muscle relaxants. The primary neural action of BZs and related compounds is augmentation of inhibitory transmission, which occurs through allosteric modulation of the gamma-aminobutyric acid (GABA)-induced current at the gamma-aminobutyric acid receptor (GABAAR). The discovery of the BZ-binding site on GABAARs encouraged many to speculate that the brain produces its own endogenous ligands to this site (Costa & Guidotti, 1985). The romanticized quest for endozepines, endogenous ligands to the BZ-binding site, has uncovered a variety of ligands that might fulfill this role, including oleamides (Cravatt et al., 1995), nonpeptidic endozepines (Rothstein et al., 1992), and the protein diazepam-binding inhibitor (DBI) (Costa & Guidotti, 1985). Of these ligands, DBI, and affiliated peptide fragments, is the most extensively studied endozepine. The quest for the "brain's Valium" over the decades has been elusive as mainly negative allosteric modulatory effects have been observed (Alfonso, Le Magueresse, Zuccotti, Khodosevich, & Monyer, 2012; Costa & Guidotti, 1985), but recent evidence is accumulating that DBI displays regionally discrete endogenous positive modulation of GABA transmission through activation of the BZ receptor (Christian et al., 2013). Herein, we review the literature on this topic, focusing on identification of the endogenous molecule and its region-specific expression and function.
Collapse
|
8
|
Lee V, Maguire J. The impact of tonic GABAA receptor-mediated inhibition on neuronal excitability varies across brain region and cell type. Front Neural Circuits 2014; 8:3. [PMID: 24550784 PMCID: PMC3909947 DOI: 10.3389/fncir.2014.00003] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 01/08/2014] [Indexed: 01/19/2023] Open
Abstract
The diversity of GABAA receptor (GABAAR) subunits and the numerous configurations during subunit assembly give rise to a variety of receptors with different functional properties. This heterogeneity results in variations in GABAergic conductances across numerous brain regions and cell types. Phasic inhibition is mediated by synaptically-localized receptors with a low affinity for GABA and results in a transient, rapidly desensitizing GABAergic conductance; whereas, tonic inhibition is mediated by extrasynaptic receptors with a high affinity for GABA and results in a persistent GABAergic conductance. The specific functions of tonic versus phasic GABAergic inhibition in different cell types and the impact on specific neural circuits are only beginning to be unraveled. Here we review the diversity in the magnitude of tonic GABAergic inhibition in various brain regions and cell types, and highlight the impact on neuronal excitability in different neuronal circuits. Further, we discuss the relevance of tonic inhibition in various physiological and pathological contexts as well as the potential of targeting these receptor subtypes for treatment of diseases, such as epilepsy.
Collapse
Affiliation(s)
- Vallent Lee
- Medical Scientist Training Program and Graduate Program in Neuroscience, Sackler School of Graduate Biomedical Sciences, Tufts University Boston, MA, USA
| | - Jamie Maguire
- Department of Neuroscience, Tufts University School of Medicine Boston, MA, USA
| |
Collapse
|
9
|
Brunton PJ, Russell JA, Hirst JJ. Allopregnanolone in the brain: protecting pregnancy and birth outcomes. Prog Neurobiol 2014; 113:106-36. [PMID: 24012715 DOI: 10.1016/j.pneurobio.2013.08.005] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 08/12/2013] [Accepted: 08/25/2013] [Indexed: 01/09/2023]
Abstract
A successful pregnancy requires multiple adaptations in the mother's brain that serve to optimise foetal growth and development, protect the foetus from adverse prenatal programming and prevent premature delivery of the young. Pregnancy hormones induce, organise and maintain many of these adaptations. Steroid hormones play a critical role and of particular importance is the progesterone metabolite and neurosteroid, allopregnanolone. Allopregnanolone is produced in increasing amounts during pregnancy both in the periphery and in the maternal and foetal brain. This review critically examines a role for allopregnanolone in both the maternal and foetal brain during pregnancy and development in protecting pregnancy and birth outcomes, with particular emphasis on its role in relation to stress exposure at this time. Late pregnancy is associated with suppressed stress responses. Thus, we begin by considering what is known about the central mechanisms in the maternal brain, induced by allopregnanolone, that protect the foetus(es) from exposure to harmful levels of maternal glucocorticoids as a result of stress during pregnancy. Next we discuss the central mechanisms that prevent premature secretion of oxytocin and consider a role for allopregnanolone in minimising the risk of preterm birth. Allopregnanolone also plays a key role in the foetal brain, where it promotes development and is neuroprotective. Hence we review the evidence about disruption to neurosteroid production in pregnancy, through prenatal stress or other insults, and the immediate and long-term adverse consequences for the offspring. Finally we address whether progesterone or allopregnanolone treatment can rescue some of these deficits in the offspring.
Collapse
Affiliation(s)
- Paula J Brunton
- Division of Neurobiology, The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Scotland, UK.
| | - John A Russell
- Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, Scotland, UK
| | - Jonathan J Hirst
- Mothers and Babies Research Centre, School of Biomedical Sciences, University of Newcastle, Newcastle, N.S.W., Australia
| |
Collapse
|
10
|
Bali A, Jaggi AS. Multifunctional aspects of allopregnanolone in stress and related disorders. Prog Neuropsychopharmacol Biol Psychiatry 2014; 48:64-78. [PMID: 24044974 DOI: 10.1016/j.pnpbp.2013.09.005] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 09/05/2013] [Accepted: 09/05/2013] [Indexed: 12/22/2022]
Abstract
Allopregnanolone (3α-hydroxy-5α-pregnan-20-one) is a major cholesterol-derived neurosteroid in the central nervous system and is synthesized from progesterone by steroidogenic enzymes, 5α-reductase (the rate-limiting enzyme) and 3α-hydroxysteroid dehydrogenase. The pathophysiological role of allopregnanolone in neuropsychiatric disorders has been highlighted in several investigations. The changes in neuroactive steroid levels are detected in stress and stress-related disorders including anxiety, panic and depression. The changes in allopregnanolone in response to acute stressor tend to restore the homeostasis by dampening the hyper-activated HPA axis. However, long standing stressors leading to development of neuropsychiatric disorders including depression and anxiety are associated with decrease in the allopregnanolone levels. GABAA receptor complex has been considered as the primary target of allopregnanolone and majority of its inhibitory actions are mediated through GABA potentiation or direct activation of GABA currents. The role of progesterone receptors in producing the late actions of allopregnanolone particularly in lordosis facilitation has also been described. Moreover, recent studies have also described the involvement of other multiple targets including brain-derived neurotrophic factor (BDNF), glutamate, dopamine, opioids, oxytocin, and calcium channels. The present review discusses the various aspects of allopregnanolone in stress and stress-related disorders including anxiety, depression and panic.
Collapse
Affiliation(s)
- Anjana Bali
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University Patiala, 147002, India
| | | |
Collapse
|
11
|
Pandit S, Song JG, Kim YJ, Jeong JA, Jo JY, Lee GS, Kim HW, Jeon BH, Lee JU, Park JB. Attenuated benzodiazepine-sensitive tonic GABAA currents of supraoptic magnocellular neuroendocrine cells in 24-h water-deprived rats. J Neuroendocrinol 2014; 26:26-34. [PMID: 24313753 DOI: 10.1111/jne.12123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 11/05/2013] [Accepted: 12/01/2013] [Indexed: 11/26/2022]
Abstract
In supraoptic nucleus (SON) magnocellular neurosecretory cells (MNCs), γ-GABA, via activation of GABAA receptors (GABAA Rs), mediates persistent tonic inhibitory currents (Itonic ), as well as conventional inhibitory postsynaptic currents (IPSCs, Iphasic ). In the present study, we examined the functional significance of Itonic in SON MNCs challenged by 24-h water deprivation (24WD). Although the main characteristics of spontaneous IPSCs were similar in 24WD compared to euhydrated (EU) rats, Itonic , measured by bicuculline (BIC)-induced Iholding shifts, was significantly smaller in 24WD compared to EU rats (P < 0.05). Propofol and diazepam prolonged IPSC decay time to a similar extent in both groups but induced less Itonic in 24WD compared to EU rats, suggesting a selective decrease in GABAA receptors mediating Itonic over Iphasic in 24WD rats. THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol), a preferential δ subunit agonist, and L-655,708, a GABAA receptor α5 subunit selective imidazobenzodiazepine, caused a significantly smaller inward and outward shift in Iholding , respectively, in 24WD compared to EU rats (P < 0.05 in both cases), suggesting an overall decrease in the α5 subunit-containing GABAA Rs and the δ subunit-containing receptors mediating Itonic in 24WD animals. Consistent with a decrease in 24WD Itonic , bath application of GABA induced significantly less inhibition of the neuronal firing activity in 24WD compared to EU SON MNCs (P < 0.05). Taken together, the results of the present study indicate a selective decrease in GABAA Rs functions mediating Itonic as opposed to those mediating Iphasic in SON MNCs, demonstrating the functional significance of Itonic with respect to increasing neuronal excitability and hormone secretion in 24WD rats.
Collapse
Affiliation(s)
- S Pandit
- Department of Physiology, School of Medicine, Brain Research Institute, Chungnam National University, Jung-gu, Daejeon, Korea
| | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Pandit S, Jeong JA, Jo JY, Cho HS, Kim DW, Kim JM, Ryu PD, Lee SY, Kim HW, Jeon BH, Park JB. Dual mechanisms diminishing tonic GABAA inhibition of dentate gyrus granule cells in Noda epileptic rats. J Neurophysiol 2013; 110:95-102. [PMID: 23576696 DOI: 10.1152/jn.00727.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The Noda epileptic rat (NER), a Wistar colony mutant, spontaneously has tonic-clonic convulsions with paroxysmal discharges. In the present study, we measured phasic and tonic γ-aminobutyric acid A (GABAA) current (I tonic) in NER hippocampal dentate gyrus granule cells and compared the results with those of normal parent strain Wistar rats (WIS). I tonic, revealed by a bicuculline-induced outward shift in holding current, was significantly smaller in NER than in WIS (P < 0.01). The frequency of inhibitory postsynaptic currents (IPSCs) was also significantly lower in NER than in WIS (P < 0.05), without significant differences in the IPSC amplitude or decay time between WIS and NER. I tonic attenuation in NER was further confirmed in the presence of GABA transporter blockers, NO-711 and nipecotic acid, with no difference in neuronal GABA transporter expression between WIS and NER. I tonic responses to extrasynaptic GABAA receptor agonists (THIP and DS-2) were significantly reduced in NER compared with WIS (P < 0.05). Allopregnanolone caused less I tonic increase in NER than in WIS, while it prolonged the IPSC decay time to a similar rate in the two groups. Expression of the GABAA receptor δ-subunit was decreased in the dentate gyrus of NER relative to that of WIS. Taken together, our results showed that a combination of attenuated presynaptic GABA release and extrasynaptic GABAA receptor expression reduced I tonic amplitude and its sensitivity to neurosteroids, which likely diminishes the gating function of dentate gyrus granule cells and renders NER more susceptible to seizure propagation.
Collapse
Affiliation(s)
- Sudip Pandit
- Department of Physiology, School of Medicine and Brain Research Institute, Chungnam National University, Daejeon, South Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Puia G, Gullo F, Dossi E, Lecchi M, Wanke E. Novel modulatory effects of neurosteroids and benzodiazepines on excitatory and inhibitory neurons excitability: a multi-electrode array recording study. Front Neural Circuits 2012; 6:94. [PMID: 23233835 PMCID: PMC3516127 DOI: 10.3389/fncir.2012.00094] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2012] [Accepted: 11/08/2012] [Indexed: 01/26/2023] Open
Abstract
The balance between glutamate- and GABA-mediated neurotransmission in the brain is fundamental in the nervous system, but it is regulated by the “tonic” release of a variety of endogenous factors. One such important group of molecules are the neurosteroids (NSs) which, similarly to benzodiazepines (BDZs), enhance GABAergic neurotransmission. The purpose of our work was to investigate, at in vivo physiologically relevant concentrations, the effects of NSs and BDZs as GABA modulators on dissociated neocortical neuron networks grown in long-term culture. We used a multi-electrode array (MEA) recording technique and a novel analysis that was able to both identify the action potentials of engaged excitatory and inhibitory neurons and to detect drug-induced network up-states (burst). We found that the NSs tetrahydrodeoxycorticosterone (THDOC) and allopregnanolone (ALLO) applied at low nanomolar concentrations, produced different modulatory effects on the two neuronal clusters. Conversely, at high concentrations (1 μM), both NSs, decreased excitatory and inhibitory neuron cluster excitability; however, even several hours after wash-out, the excitability of inhibitory neurons continued to be depressed, leading to a network long-term depression (LTD). The BDZs clonazepam (CLZ) and midazolam (MDZ) also decreased the network excitability, but only MDZ caused LTD of inhibitory neuron cluster. To investigate the origin of the LTD after MDZ application, we tested finasteride (FIN), an inhibitor of endogenous NSs synthesis. FIN did not prevent the LTD induced by MDZ, but surprisingly induced it after application of CLZ. The significance and possible mechanisms underlying these LTD effects of NSs and BDZs are discussed. Taken together, our results not only demonstrate that ex vivo networks show a sensitivity to NSs and BDZs comparable to that expressed in vivo, but also provide a new global in vitro description that can help in understanding their activity in more complex systems.
Collapse
Affiliation(s)
- Giulia Puia
- Department of Biomedical Sciences, University of Modena and Reggio Emilia Modena, Italy
| | | | | | | | | |
Collapse
|