1
|
Maccioni P, Lorrai I, Carai MAM, Gessa GL, Colombo G. Blockade of the GABAB receptor suppressed alcohol self-administration in rats: an effect similar to that produced by GABAB receptor activation. Behav Pharmacol 2022; 33:51-60. [PMID: 34954712 DOI: 10.1097/fbp.0000000000000668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Literature data suggest that activation and blockade of the GABAB receptor may produce similar effects on several reward-related behaviours. Accordingly, the present study was designed to investigate whether treatment with the GABAB receptor antagonist, SCH 50911, reproduced the suppressing effect of the GABAB receptor agonist, baclofen, and several positive allosteric modulators of the GABAB receptor on operant oral alcohol self-administration in rats. To this end, Sardinian alcohol-preferring (sP) rats were trained to lever-respond for alcohol (15% v/v) under the fixed ratio (FR) 4 (FR4) schedule of reinforcement. Once lever-responding had stabilized, rats were exposed to test sessions preceded by treatment with SCH 50911 (0, 25, 50, and 100 mg/kg; i.p.). Two independent experiments were conducted, differing solely in the set of rats used. Selectivity of SCH 50911 effect on alcohol self-administration was assessed by evaluating the effect of SCH 50911 (0, 25, 50, and 100 mg/kg; i.p.) on self-administration of a sucrose solution (0.7% w/v) in sP rats exposed to the FR4 schedule. In both 'alcohol' experiments, treatment with SCH 50911 reduced lever-responding for alcohol and amount of self-administered alcohol. SCH 50911 effect was characterized by large interindividual variability, with several instances of dose-unrelated reductions, and frequent occurrence of complete suppression of lever-responding for alcohol. Similar data were collected in the 'sucrose' experiment. These results extend to alcohol self-administration with the notion that activation and blockade of GABAB receptor may produce unidirectional effects on reward-related behaviours; these similarities are discussed in terms of differential contribution of pre- and postsynaptic GABAB receptors.
Collapse
Affiliation(s)
- Paola Maccioni
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, Monserrato
| | - Irene Lorrai
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, Monserrato
| | | | - Gian Luigi Gessa
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, Monserrato
| | - Giancarlo Colombo
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, Monserrato
| |
Collapse
|
2
|
Amakhin DV, Soboleva EB, Chizhov AV, Zaitsev AV. Insertion of Calcium-Permeable AMPA Receptors during Epileptiform Activity In Vitro Modulates Excitability of Principal Neurons in the Rat Entorhinal Cortex. Int J Mol Sci 2021; 22:12174. [PMID: 34830051 PMCID: PMC8621524 DOI: 10.3390/ijms222212174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/05/2021] [Accepted: 11/07/2021] [Indexed: 12/19/2022] Open
Abstract
Epileptic activity leads to rapid insertion of calcium-permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (CP-AMPARs) into the synapses of cortical and hippocampal glutamatergic neurons, which generally do not express them. The physiological significance of this process is not yet fully understood; however, it is usually assumed to be a pathological process that augments epileptic activity. Using whole-cell patch-clamp recordings in rat entorhinal cortex slices, we demonstrate that the timing of epileptiform discharges, induced by 4-aminopyridine and gabazine, is determined by the shunting effect of Ca2+-dependent slow conductance, mediated predominantly by K+-channels. The blockade of CP-AMPARs by IEM-1460 eliminates this extra conductance and consequently increases the rate of discharge generation. The blockade of NMDARs reduced the additional conductance to a lesser extent than the blockade of CP-AMPARs, indicating that CP-AMPARs are a more significant source of intracellular Ca2+. The study's main findings were implemented in a mathematical model, which reproduces the shunting effect of activity-dependent conductance on the generation of discharges. The obtained results suggest that the expression of CP-AMPARs in principal neurons reduces the discharge generation rate and may be considered as a protective mechanism.
Collapse
Affiliation(s)
- Dmitry V. Amakhin
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
| | - Elena B. Soboleva
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
| | - Anton V. Chizhov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
- Ioffe Institute, Russian Academy of Sciences, Polytekhnicheskaya 26, 194021 Saint Petersburg, Russia
| | - Aleksey V. Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
| |
Collapse
|
3
|
Lin TY, Lu CW, Hsieh PW, Chiu KM, Lee MY, Wang SJ. Natural Product Isoliquiritigenin Activates GABA B Receptors to Decrease Voltage-Gate Ca 2+ Channels and Glutamate Release in Rat Cerebrocortical Nerve Terminals. Biomolecules 2021; 11:biom11101537. [PMID: 34680170 PMCID: PMC8534184 DOI: 10.3390/biom11101537] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/13/2021] [Accepted: 10/15/2021] [Indexed: 12/26/2022] Open
Abstract
Reduction in glutamate release is a key mechanism for neuroprotection and we investigated the effect of isoliquiritigenin (ISL), an active ingredient of Glycyrrhiza with neuroprotective activities, on glutamate release in rat cerebrocortical nerve terminals (synaptosomes). ISL produced a concentration-dependent inhibition of glutamate release and reduced the intraterminal [Ca2+] increase. The inhibition of glutamate release by ISL was prevented after removing extracellular Ca2+ or blocking P/Q-type Ca2+ channels. This inhibition was mediated through the γ-aminobutyric acid type B (GABAB) receptors because ISL was unable to inhibit glutamate release in the presence of baclofen (an GABAB agonist) or CGP3548 (an GABAB antagonist) and docking data revealed that ISL interacted with GABAB receptors. Furthermore, the ISL inhibition of glutamate release was abolished through the inhibition of Gi/o-mediated responses or Gβγ subunits, but not by 8-bromoadenosine 3′,5′-cyclic monophosphate or adenylate cyclase inhibition. The ISL inhibition of glutamate release was also abolished through the inhibition of protein kinase C (PKC), and ISL decreased the phosphorylation of PKC. Thus, we inferred that ISL, through GABAB receptor activation and Gβγ-coupled inhibition of P/Q-type Ca2+ channels, suppressed the PKC phosphorylation to cause a decrease in evoked glutamate release at rat cerebrocortical nerve terminals.
Collapse
Affiliation(s)
- Tzu-Yu Lin
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan; (T.-Y.L.); (C.-W.L.)
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Cheng-Wei Lu
- Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan; (T.-Y.L.); (C.-W.L.)
- Department of Mechanical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Pei-Wen Hsieh
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan;
- Graduate Institute of Natural Products, School of Traditional Chinese Medicine, and Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 33303, Taiwan
- Department of Anesthesiology, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan
| | - Kuan-Ming Chiu
- Division of Cardiovascular Surgery, Cardiovascular Center, Far-Eastern Memorial Hospital, New Taipei 22060, Taiwan; (K.-M.C.); (M.-Y.L.)
- Department of Nursing, Asia Eastern University of Science and Technology, New Taipei City 22060, Taiwan
- Department of Photonics Engineering, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Ming-Yi Lee
- Division of Cardiovascular Surgery, Cardiovascular Center, Far-Eastern Memorial Hospital, New Taipei 22060, Taiwan; (K.-M.C.); (M.-Y.L.)
| | - Su-Jane Wang
- Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan 33303, Taiwan;
- School of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan
- Correspondence: ; Tel.: +88-62-2905-3465; Fax: +88-62-2905-2096
| |
Collapse
|
4
|
Adkins JM, Lynch J, Gray M, Jasnow AM. Presynaptic GABA B receptor inhibition sex dependently enhances fear extinction and attenuates fear renewal. Psychopharmacology (Berl) 2021; 238:2059-2071. [PMID: 33855580 PMCID: PMC8295214 DOI: 10.1007/s00213-021-05831-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 03/22/2021] [Indexed: 12/11/2022]
Abstract
Anxiety and trauma-related disorders are highly prevalent worldwide, and are associated with altered associative fear learning. Despite the effectiveness of exposure therapy, which aims to reduce associative fear responses, relapse rates remain high. This is due, in part, to the context specificity of exposure therapy, which is a form of extinction. Many studies show that fear relapses when mice are tested outside the extinction context, and this is known as fear renewal. Using Pavlovian fear conditioning and extinction, we can study the mechanisms underlying extinction and renewal. The aim of the current experiment was to identify the role of presynaptic GABAB receptors in these two processes. Previous work from our lab showed that genetic deletion or pharmacological inhibition of GABAB(1a) receptors that provide presynaptic inhibition on glutamatergic terminals reduces context specificity and leads to generalization. We therefore hypothesized that inactivation of these presynaptic GABAB receptors could be used to reduce the context specificity associated with fear extinction training and suppress renewal when mice are tested outside of the extinction context. Using CGP 36216, an antagonist specific for presynaptic GABAB receptors, we blocked presynaptic GABAB receptors using intracerebroventricular injections during various time points of extinction learning in male and female mice. Results showed that blocking these receptors pre- and post-extinction training led to enhanced extinction learning in male mice only. We also found that post-extinction infusions of CGP reduced renewal rates in male mice when they were tested outside of the extinction context. In an attempt to localize the function of presynaptic GABAB receptors within regions of the extinction circuit, we infused CGP locally within the basolateral amygdala or dorsal hippocampus. We failed to reduce renewal when CGP was infused directly within these regions, suggesting that presynaptic inhibition within these regions per se may not be necessary for driving context specificity during extinction learning. Together, these results show an important sex-dependent role of presynaptic GABAB receptors in extinction and renewal processes and identify a novel receptor target that may be used to design pharmacotherapies to enhance the effectiveness of exposure therapy.
Collapse
Affiliation(s)
- Jordan M Adkins
- Department of Psychological Sciences, Kent State University, Kent, OH, 44242, USA
- Brain Health Research Institute, Kent State University, Kent, OH, 44242, USA
| | - Joseph Lynch
- Department of Psychological Sciences, Kent State University, Kent, OH, 44242, USA
- Brain Health Research Institute, Kent State University, Kent, OH, 44242, USA
| | - Michael Gray
- Department of Psychological Sciences, Kent State University, Kent, OH, 44242, USA
- Brain Health Research Institute, Kent State University, Kent, OH, 44242, USA
| | - Aaron M Jasnow
- Department of Psychological Sciences, Kent State University, Kent, OH, 44242, USA.
- Brain Health Research Institute, Kent State University, Kent, OH, 44242, USA.
- Department of Pharmacology, Physiology & Neuroscience, University of South Carolina School of Medicine, 6439 Garners Ferry Road, Columbia, SC, 29209, USA.
| |
Collapse
|
5
|
Amohashemi E, Reisi P, Alaei H. Lateral habenula electrical stimulation with different intensities in combination with GABA B receptor antagonist reduces acquisition and expression phases of morphine-induced CPP. Neurosci Lett 2021; 759:135996. [PMID: 34062194 DOI: 10.1016/j.neulet.2021.135996] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/21/2021] [Accepted: 05/25/2021] [Indexed: 12/12/2022]
Abstract
The lateral habenula (LHb) plays a principal role in response to aversive stimuli and negative emotional states. In this study, we have evaluated the effects of unilateral electrical stimulation (e-stim) of the LHb on morphine-conditioned place preference (CPP), before or after bilateral injections of Gamma-aminobutyric acid-B receptor (GABABR) antagonist, phaclofen, in male rats. Morphine (5 mg/kg; s.c.) induced a significant CPP, using a 5-day CPP paradigm. Intra-LHb microinjection of phaclofen or the LHb e-stim decreased only the acquisition of CPP. The 150 μA stimulation plus phaclofen significantly suppressed the expression phase but induced aversion in the acquisition of CPP, and an e-stim of 25 μA in combination with the antagonist, significantly prevented only the acquisition phase. The findings of this study confirm the possible role of GABABRs in the LHb on the acquisition and the expression of CPP. These results show that e-stim of LHb alone or plus phaclofen may change the GABA transmission, involving into CPP. Therefore, the GABAergic system, especially through GABABRs, may play a prominent role in the behavioral responses to morphine-induced CPP by LHb stimulation.
Collapse
Affiliation(s)
- Elahe Amohashemi
- Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Parham Reisi
- Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Hojjatallah Alaei
- Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
| |
Collapse
|
6
|
Khakpoor M, Vaseghi S, Mohammadi-Mahdiabadi-Hasani MH, Nasehi M. The effect of GABA-B receptors in the basolateral amygdala on passive avoidance memory impairment induced by MK-801 in rats. Behav Brain Res 2021; 409:113313. [PMID: 33891976 DOI: 10.1016/j.bbr.2021.113313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 04/17/2021] [Accepted: 04/18/2021] [Indexed: 11/19/2022]
Abstract
MK-801 (dizocilpine) is a potent non-competitive N-methyl-[D]-aspartate (NMDA) receptor antagonist that affects cognitive function, learning, and memory. As we know, NMDA receptors are significantly involved in memory function, as well as GABA (Gamma-Aminobutyric acid) receptors. In this study, we aimed to discover the effect of GABA-B receptors in the basolateral amygdala (BLA) on MK-801-induced memory impairment. We used 160 male Wistar rats. The shuttle box was used to evaluate passive avoidance memory and locomotion apparatus was used to evaluate locomotor activity. MK-801 (0.125, 0.25, and 0.5 μg/rat), baclofen (GABA-B agonist, 0.0001, 0.001, and 0.01 μg/rat) and phaclofen (GABA-B antagonist, 0.0001, 0.001, and 0.01 μg/rat) were injected intra-BLA, after the training. The results showed that MK-801 at the dose of 0.5 μg/rat, baclofen at the doses of 0.001 and 0.01 μg/rat, and phaclofen at the doses of 0.001 and 0.01 μg/rat, impaired passive avoidance memory. Locomotor activity did not alter in all groups. Furthermore, the subthreshold dose of both baclofen (0.0001 μg/rat) and phaclofen (0.0001 μg/rat) restored the impairment effect of MK-801 (0.5 μg/rat) on memory. Also, both baclofen (0.0001 μg/rat) potentiated the impairment effect of MK-801 (0.125 μg/rat) and phaclofen (0.0001 μg/rat) potentiated the impairment effect of MK-801 (0.125 and 0.25 μg/rat) on passive avoidance memory. In conclusion, our results indicated that BLA GABA-B receptors can alter the effect of NMDA inactivation on passive avoidance memory.
Collapse
Affiliation(s)
- Mitra Khakpoor
- Department of Basic Science, Farhangian University, Tehran, Iran; Department of Cognitive Neuroscience, Institute for Cognitive Science Studies (ICSS), Tehran, Iran
| | - Salar Vaseghi
- Cognitive and Neuroscience Research Center (CNRC), Amir-Almomenin Hospital, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran; Department of Cognitive Neuroscience, Institute for Cognitive Science Studies (ICSS), Tehran, Iran
| | | | - Mohammad Nasehi
- Cognitive and Neuroscience Research Center (CNRC), Amir-Almomenin Hospital, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran.
| |
Collapse
|
7
|
Ramakrishna Y, Sadeghi SG. Activation of GABA B receptors results in excitatory modulation of calyx terminals in rat semicircular canal cristae. J Neurophysiol 2020; 124:962-972. [PMID: 32816581 PMCID: PMC7509296 DOI: 10.1152/jn.00243.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 12/15/2022] Open
Abstract
Previous studies have found GABA in vestibular end organs. However, existence of GABA receptors or possible GABAergic effects on vestibular nerve afferents has not been investigated. The current study was conducted to determine whether activation of GABAB receptors affects calyx afferent terminals in the central region of the cristae of semicircular canals. We used patch-clamp recording in postnatal day 13-18 (P13-P18) Sprague-Dawley rats of either sex. Application of GABAB receptor agonist baclofen inhibited voltage-sensitive potassium currents. This effect was blocked by selective GABAB receptor antagonist CGP 35348. Application of antagonists of small (SK)- and large-conductance potassium (BK) channels almost completely blocked the effects of baclofen. The remaining baclofen effect was blocked by cadmium chloride, suggesting that it could be due to inhibition of voltage-gated calcium channels. Furthermore, baclofen had no effect in the absence of calcium in the extracellular fluid. Inhibition of potassium currents by GABAB activation resulted in an excitatory effect on calyx terminal action potential firing. While in the control condition calyces could only fire a single action potential during step depolarizations, in the presence of baclofen they fired continuously during steps and a few even showed repetitive discharge. We also found a decrease in threshold for action potential generation and a decrease in first-spike latency during step depolarization. These results provide the first evidence for the presence of GABAB receptors on calyx terminals, showing that their activation results in an excitatory effect and that GABA inputs could be used to modulate calyx response properties.NEW & NOTEWORTHY Using in vitro whole cell patch-clamp recordings from calyx terminals in the vestibular end organs, we show that activation of GABAB receptors result in an excitatory effect, with decreased spike-frequency adaptation and shortened first-spike latencies. Our results suggest that these effects are mediated through inhibition of calcium-sensitive potassium channels.
Collapse
Affiliation(s)
- Yugandhar Ramakrishna
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, State University of New York at Buffalo, Buffalo, New York
- Department of Communication Disorders and Sciences, California State University, Northridge, Northridge, California
| | - Soroush G Sadeghi
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, State University of New York at Buffalo, Buffalo, New York
- Neuroscience Program, State University of New York at Buffalo, Buffalo, New York
| |
Collapse
|
8
|
Bizzozzero-Hiriart M, Di Giorgio NP, Libertun C, Lux-Lantos V. GABAergic input through GABA B receptors is necessary during a perinatal window to shape gene expression of factors critical to reproduction such as Kiss1. Am J Physiol Endocrinol Metab 2020; 318:E901-E919. [PMID: 32286880 DOI: 10.1152/ajpendo.00547.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Lack of GABAB receptors in GABAB1 knockout mice decreases neonatal ARC kisspeptin 1 (Kiss1) expression in the arcuate nucleus of the hypothalamus (ARC) in females, which show impaired reproduction as adults. Our aim was to selectively impair GABAB signaling during a short postnatal period to evaluate its impact on the reproductive system. Neonatal male and female mice were injected with the GABAB antagonist CGP 55845 (CGP, 1 mg/kg body wt sc) or saline from postnatal day 2 (PND2) to PND6, three times per day (8 AM, 1 PM, and 6 PM). One group was killed on PND6 for collection of blood samples (hormones by radioimmunoassay), brains for gene expression in the anteroventral periventricular nucleus-periventricular nucleus continuum (AVPV/PeN), and ARC micropunches [quantitative PCR (qPCR)] and gonads for qPCR, hormone contents, and histology. A second group of mice was injected with CGP (1 mg/kg body wt sc) or saline from PND2 to PND6, three times per day (8 AM, 1 PM, and 6 PM), and left to grow to adulthood. We measured body weight during development and parameters of sexual differentiation, puberty onset, and estrous cycles. Adult mice were killed, and trunk blood (hormones), brains for qPCR, and gonads for qPCR and hormone contents were obtained. Our most important findings on PND6 include the CGP-induced decrease in ARC Kiss1 and increase in neurokinin B (Tac2) in both sexes; the decrease in AVPV/PeN tyrosine hydroxylase (Th) only in females; the increase in gonad estradiol content in both sexes; and the increase in primordial follicles and decrease in primary and secondary follicles. Neonatally CGP-treated adults showed decreased ARC Kiss1 and ARC gonadotropin-releasing hormone (Gnrh1) and increased ARC glutamic acid decarboxylase 67 (Gad1) only in males; increased ARC GABAB receptor subunit 1 (Gabbr1) in both sexes; and decreased AVPV/PeN Th only in females. We demonstrate that ARC Kiss1 expression is chronically downregulated in males and that the normal sex difference in AVPV/PeN Th expression is abolished. In conclusion, neonatal GABAergic input through GABAB receptors shapes gene expression of factors critical to reproduction.
Collapse
MESH Headings
- Animals
- Animals, Newborn
- Arcuate Nucleus of Hypothalamus/drug effects
- Arcuate Nucleus of Hypothalamus/metabolism
- Estradiol/metabolism
- Female
- Follicle Stimulating Hormone/metabolism
- GABA-B Receptor Antagonists/pharmacology
- Gene Expression Regulation, Developmental/drug effects
- Gene Expression Regulation, Developmental/physiology
- Glutamate Decarboxylase/genetics
- Glutamate Decarboxylase/metabolism
- Gonadotropin-Releasing Hormone/genetics
- Gonadotropin-Releasing Hormone/metabolism
- Hypothalamus, Anterior/drug effects
- Hypothalamus, Anterior/metabolism
- Kisspeptins/genetics
- Kisspeptins/metabolism
- Luteinizing Hormone/metabolism
- Male
- Mice
- Ovary/drug effects
- Ovary/metabolism
- Phosphinic Acids/pharmacology
- Propanolamines/pharmacology
- Protein Precursors/genetics
- Protein Precursors/metabolism
- Puberty/drug effects
- Puberty/genetics
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Receptors, GABA-B/genetics
- Receptors, GABA-B/metabolism
- Receptors, Progesterone/genetics
- Receptors, Progesterone/metabolism
- Reproduction/drug effects
- Reproduction/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Sex Differentiation/drug effects
- Sex Differentiation/genetics
- Tachykinins/genetics
- Tachykinins/metabolism
- Testis/drug effects
- Testis/metabolism
- Testosterone/metabolism
- Tyrosine 3-Monooxygenase/genetics
- Tyrosine 3-Monooxygenase/metabolism
Collapse
Affiliation(s)
- Marianne Bizzozzero-Hiriart
- Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Noelia P Di Giorgio
- Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Carlos Libertun
- Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
- Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Argentina
| | - Victoria Lux-Lantos
- Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| |
Collapse
|
9
|
Liu Y, Yang XJ, Xia H, Tang CM, Yang K. GABA releases from parvalbumin-expressing and unspecific GABAergic neurons onto CA1 pyramidal cells are differentially modulated by presynaptic GABA B receptors in mouse hippocampus. Biochem Biophys Res Commun 2019; 520:449-452. [PMID: 31607482 DOI: 10.1016/j.bbrc.2019.10.044] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 10/03/2019] [Indexed: 12/31/2022]
Abstract
Hippocampus CA1 pyramidal cells receive γ-aminobutyric acid (GABA) release from multiple GABAergic interneurons. Combining optogenetic strategy and whole-cell recordings, we demonstrate that baclofen, a specific GABAB receptor agonist, depresses monosynaptic GABAA receptor-mediated transmission from parvalbumin (PV)-expressing interneuron terminals onto pyramidal cells with less efficacy than that from the unspecific GABAergic terminals. The depression from PV neuron terminals is mainly mediated by presynaptic P/N type calcium channels. The results suggest that GABAB receptors are widely expressed on GABAergic interneurons, where they exert inhibition onto pyramidal cells by GABA release with different efficacy. The data strengthen the proposal that diverse GABA neurons play different roles in modulating CA1 pyramidal cell excitability.
Collapse
Affiliation(s)
- Yingqian Liu
- Department of Anatomy, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, 212013, China; Research Center for Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang, Jiangsu, 212013, China
| | - Xingwu Jordan Yang
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Haiping Xia
- Department of Neurology, Zhenjiang Fourth People's Hospital Affiliated to Jiangsu University, Jiangsu, China
| | - Cha-Min Tang
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Kun Yang
- Department of Anatomy, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, 212013, China; Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
| |
Collapse
|
10
|
Coaviche-Yoval A, Luna H, Tovar-Miranda R, Soriano-Ursúa MA, Trujillo-Ferrara JG. Synthesis and Biological Evaluation of Novel 2,3-disubstituted Benzofuran Analogues of GABA as Neurotropic Agents. Med Chem 2019; 15:77-86. [PMID: 29792150 DOI: 10.2174/1573406414666180524091745] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Revised: 04/17/2018] [Accepted: 04/30/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND Benzofurans are heterocyclic compounds with neurotropic activity. Some have been developed for the treatment of acute and degenerative neuronal injuries. OBJECTIVE The study aimed to evaluate the in silico binding of some promising benzofurans on the GABA receptors, and the in vivo neurotropic activity of benzofuran analogues (BZF 6-10) of gamma-aminobutyric acid (GABA) on a seizure model. METHODS The ligands with the best physicochemical attributes were docked on two GABA receptors (the alpha-1 subunit of GABAA-R and GBR1 subunit of GABAB-R). Selected benzofuran derivatives were synthesized by a multistep procedure and characterized. To examine the neurotropic effects, mice were pretreated with different concentrations of the compounds prior to PTZ- or 4- AP-induced seizures. We assessed acute toxicity, motor behavior, and the effects on seizures. RESULTS The tested ligands that complied with Lipinski's rule of five were tested in silico with GABAA-R (ΔG = -5.51 to -5.84 kcal/mol) at the allosteric site for benzodiazepines. They bound to a similar cluster of residues as the reference compound (gaboxadol, ΔG = -5.51 kcal/mol). Synthesis was achieved with good overall yields (42-9.7%). Two compounds were selected for biological tests (BZF-7 and rac-BZF-10) on a mouse model of seizures, induced by pentylenetetrazol (PTZ) or 4-aminopyridine (4-AP). PTZ-induced seizures are associated with GABA receptors, and those 4-AP-induced with the blockage of the delayed rectifier-type potassium channel, which promotes the release of the NMDA-sensitive glutamatergic ionotropic receptor and other neurotransmitters. The biological assays demonstrated that BZF-7 and rac-BZF-10 do not protect against seizures. Indeed, BZF-7 increased the number of PTZ-induced seizures and decreased latency time. The 4-AP model apparently showed a potentiation of seizure effects after administration of the BZF-analogues, evidenced by the incidence and severity of the seizures and reduced latency time. CONCLUSION The results suggest that the test compounds are GABAergic antagonists with stimulatory activity on the CNS.
Collapse
Affiliation(s)
- Arturo Coaviche-Yoval
- Departamento de Sistemas Biologicos, Universidad Autonoma Metropolitana - Campus Xochimilco, Calzada del Hueso 1100, Col. Villa Quietud, Coyoacan, C.P. 04960, Mexico City, Mexico
| | - Héctor Luna
- Departamento de Sistemas Biologicos, Universidad Autonoma Metropolitana - Campus Xochimilco, Calzada del Hueso 1100, Col. Villa Quietud, Coyoacan, C.P. 04960, Mexico City, Mexico
| | - Ricardo Tovar-Miranda
- Instituto de Ciencias Basicas, Universidad Veracruzana, Av. Dr. Luis Castelazo Ayala s/n Col. Industrial Animas, 91190 Xalapa, Veracruz, Mexico
| | - Marvin A Soriano-Ursúa
- Escuela Superior de Medicina, Instituto Politecnico Nacional, Plan de San Luis y Díaz Mirón s/n Col. Casco de Santo Tomas, Del. Miguel Hidalgo, 11340, Mexico City, Mexico
| | - José G Trujillo-Ferrara
- Escuela Superior de Medicina, Instituto Politecnico Nacional, Plan de San Luis y Díaz Mirón s/n Col. Casco de Santo Tomas, Del. Miguel Hidalgo, 11340, Mexico City, Mexico
| |
Collapse
|
11
|
Bukia N, Butskhrikidze M, Machavariani L, Kekelia G, Svanidze M. POSSIBLE IMPLEMENTATION OF GABAERGIC AND GLUTAMATERGIC SYSTEMS IN REALIZATION OF ANTIEPILEPTIC EFFECTS OF ACOUSTIC RANGE ELECTRO - MAGNETIC FIELDS. Georgian Med News 2018:112-116. [PMID: 30204107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Seizure is a clinical manifestation of a hyperexcitable neuronal network, in which, the electrical balance underlying the normal neuronal activity is altered pathologically-excitation (Glutamatergic activity) predominates over inhibition (GABAergic activity). Arresting of seizure activity is carried out by restoration of neurotransmitter balance. This process has a direct relation with ion channel permeability in cell and ion transmembrane movement. Low frequency EMS may have a neurostimulating and neuromodulating effect that is based on electromagnetic induction of electric field in the brain. Under the conditions of certain amplitude, frequency and relaxation time low-frequency electromagnetic field (EMF) induces depolarization of separate neurons, and changes the total cortical excitability in case of repeatedly carried out procedures. It was shown that the exposure of acoustic range EMS in GEPRs treated with GABA-A or GABA-B receptors antagonists decreased behavior seizure activity in response to audiogenic stimuli. Injection of Glutamate receptor agonist on background EMS causes seizure activity, but seizure manifestations have less degree compared to non-stimulated rats. Thus, in response to electromagnetic stimulation, the reduction or complete cramping of seizures can be explained by a change in the activity of the neurotransmitter systems.
Collapse
Affiliation(s)
- N Bukia
- LEPL Beritashvili Center of Experimental Biomedicine, Tbilisi; I. Javakhishvili Tbilisi State University, Tbilisi, Georgia
| | - M Butskhrikidze
- LEPL Beritashvili Center of Experimental Biomedicine, Tbilisi; I. Javakhishvili Tbilisi State University, Tbilisi, Georgia
| | - L Machavariani
- LEPL Beritashvili Center of Experimental Biomedicine, Tbilisi; I. Javakhishvili Tbilisi State University, Tbilisi, Georgia
| | - G Kekelia
- LEPL Beritashvili Center of Experimental Biomedicine, Tbilisi; I. Javakhishvili Tbilisi State University, Tbilisi, Georgia
| | - M Svanidze
- LEPL Beritashvili Center of Experimental Biomedicine, Tbilisi; I. Javakhishvili Tbilisi State University, Tbilisi, Georgia
| |
Collapse
|
12
|
Varani AP, Pedrón VT, Aon AJ, Höcht C, Acosta GB, Bettler B, Balerio GN. Nicotine-induced molecular alterations are modulated by GABA B receptor activity. Addict Biol 2018; 23:230-246. [PMID: 28419642 DOI: 10.1111/adb.12506] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 02/22/2017] [Accepted: 02/23/2017] [Indexed: 12/22/2022]
Abstract
It has been demonstrated that GABAB receptors modulate nicotine (NIC) reward effect; nevertheless, the mechanism implicated is not well known. In this regard, we evaluated the involvement of GABAB receptors on the behavioral, neurochemical, biochemical and molecular alterations associated with the rewarding effects induced by NIC in mice, from a pharmacological and genetic approach. NIC-induced rewarding properties (0.5 mg/kg, subcutaneously, sc) were evaluated by conditioned place preference (CPP) paradigm. CPP has three phases: preconditioning, conditioning and postconditioning. GABAB receptor antagonist 2-hydroxysaclofen (0.25, 0.5 and 1 mg/kg; intraperitoneally, ip) or the GABAB receptor agonist baclofen (3 mg/kg; ip) was injected before NIC during the conditioning phase. GABAB1 knockout (GABAB1 KO) mice received NIC during the conditioning phase. Vehicle and wild-type controls were employed. Neurochemical (dopamine, serotonin and their metabolites), biochemical (nicotinic receptor α4β2, α4β2nAChRs) and molecular (c-Fos) alterations induced by NIC were analyzed after the postconditioning phase by high-performance liquid chromatography (HPLC), receptor-ligand binding assays and immunohistochemistry, respectively, in nucleus accumbens (Acb), prefrontal cortex (PFC) and ventral tegmental area (VTA). NIC induced rewarding effects in the CPP paradigm and increased dopamine levels in Acb and PFC, α4β2nAChRs density in VTA and c-Fos expression in Acb shell (AcbSh), VTA and PFC. We showed that behavioral, neurochemical, biochemical and molecular alterations induced by NIC were prevented by baclofen. However, in 2-hydroxysaclofen pretreated and GABAB1 KO mice, these alterations were potentiated, suggesting that GABAB receptor activity is necessary to control alterations induced by NIC-induced rewarding effects. Therefore, the present findings provided important contributions to the mechanisms implicated in NIC-induced rewarding effects.
Collapse
Affiliation(s)
- Andres P Varani
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Valeria T Pedrón
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Amira J Aon
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Christian Höcht
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Cátedra de Farmacología, Buenos Aires, Argentina
| | - Gabriela B Acosta
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Bernhard Bettler
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, University of Basel, Switzerland
| | - Graciela N Balerio
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Cátedra de Farmacología, Buenos Aires, Argentina
| |
Collapse
|
13
|
Tian J, Dang H, Hu A, Xu W, Kaufman DL. Repurposing Lesogaberan to Promote Human Islet Cell Survival and β-Cell Replication. J Diabetes Res 2017; 2017:6403539. [PMID: 29018828 PMCID: PMC5605788 DOI: 10.1155/2017/6403539] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 07/26/2017] [Indexed: 12/15/2022] Open
Abstract
The activation of β-cell's A- and B-type gamma-aminobutyric acid receptors (GABAA-Rs and GABAB-Rs) can promote their survival and replication, and the activation of α-cell GABAA-Rs promotes their conversion into β-cells. However, GABA and the most clinically applicable GABA-R ligands may be suboptimal for the long-term treatment of diabetes due to their pharmacological properties or potential side-effects on the central nervous system (CNS). Lesogaberan (AZD3355) is a peripherally restricted high-affinity GABAB-R-specific agonist, originally developed for the treatment of gastroesophageal reflux disease (GERD) that appears to be safe for human use. This study tested the hypothesis that lesogaberan could be repurposed to promote human islet cell survival and β-cell replication. Treatment with lesogaberan significantly enhanced replication of human islet cells in vitro, which was abrogated by a GABAB-R antagonist. Immunohistochemical analysis of human islets that were grafted into immune-deficient mice revealed that oral treatment with lesogaberan promoted human β-cell replication and islet cell survival in vivo as effectively as GABA (which activates both GABAA-Rs and GABAB-Rs), perhaps because of its more favorable pharmacokinetics. Lesogaberan may be a promising drug candidate for clinical studies of diabetes intervention and islet transplantation.
Collapse
Affiliation(s)
- Jide Tian
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Hoa Dang
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Angela Hu
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Willem Xu
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| | - Daniel L. Kaufman
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, USA
| |
Collapse
|
14
|
Gillani Q, Ali M, Iqbal F. Effect of GABA B receptor antagonists (CGP 35348 and CGP 55845) on serum interleukin 6 and 18 concentrations in albino mice following neonatal hypoxia ischemia insult. Pak J Pharm Sci 2016; 29:1503-1508. [PMID: 27731803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Interleukin (IL) 6 and 18 plays an important role in inflammatory response following hypoxia ischemia encephalopathy (HIE). Present study was designed to demonstrate the effect of two GABAB receptor antagonists (CGP 35348 and 55845), respectively, on the serum IL6 and IL 18 concentrations in albino mice. Albino mice pups (of both genders) were subjected to Murine model of hypoxia-ischemia encephalopathy on postnatal day 10 (right common carotid artery was ligated followed by 8% hypoxia for 25 minutes). After neonatal brain damage and following weaning, mice were divided in three groups, in gender specific manner, and fed on normal rodent diet till they were 13 week old. At this time point, group 1 received intraperitonial saline solution (control group), group 2 was supplemented with CGP 35348 (1mg/ml solvent/Kg body weight) and group 3 with CGP 55845 (1mg/ml solvent/Kg body weight), intraperitonially, for 12 days and IL 6 and 18 concentrations were determined in serum by ELISA. It was observed that CGP 35348 supplementation resulted in reduced interlukin-6 and interlukin-18 concentrations in male albino mice. While CGP 55845 supplementation increased IL-6 and IL-18 concentrations in female albino mice following HIE. Our results are indicating that GABAB receptor antagonist's supplementation affects IL concentrations in albino mice in a gender specific manner following neonatal brain damage and can be further explored for the treatments of hypoxia ischemia associated neurological ailments.
Collapse
Affiliation(s)
- Quratulane Gillani
- Institute of Pure and Applied Biology, Zoology Division, Bahauddin Zakariya University, Multan, Pakistan
| | - Muhammad Ali
- Institute of Molecular Biology and Biotechnology, Bahauddin Zakariya University Multan, Pakistan
| | - Furhan Iqbal
- Institute of Pure and Applied Biology, Zoology Division, Bahauddin Zakariya University, Multan, Pakistan
| |
Collapse
|
15
|
Maccioni P, Lorrai I, Carai MAM, Riva A, Morazzoni P, Mugnaini C, Corelli F, Gessa GL, Colombo G. Reducing effect of saikosaponin A, an active ingredient of Bupleurum falcatum, on alcohol self-administration in rats: Possible involvement of the GABAB receptor. Neurosci Lett 2016; 621:62-67. [PMID: 27080427 DOI: 10.1016/j.neulet.2016.04.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 03/25/2016] [Accepted: 04/09/2016] [Indexed: 11/18/2022]
Abstract
Recent studies demonstrated that treatment with saikosaponin A (SSA) - an active ingredient of the medicinal herb, Bupleurum falcatum L. - selectively suppressed, likely via a GABAB receptor-mediated mechanism, intravenous self-administration of morphine and cocaine in rats [Yoon et al., 2012; 2013]. The present study was designed to investigate whether the capacity of SSA to suppress morphine and cocaine self-administration extends to oral alcohol self-administration. To this end, selectively bred Sardinian alcohol-preferring (sP) rats were trained to lever-respond on a Fixed Ratio (FR) 4 (FR4) schedule of reinforcement for alcohol (15%, v/v) in daily 30-min sessions. Once responding had stabilized, rats were tested under the FR4 (measure of alcohol reinforcing properties) and Progressive Ratio (PR; measure of alcohol motivational properties) schedules of reinforcement. The possible involvement of the GABAB receptor system was investigated testing the effect of (a) pretreatment with the GABAB receptor antagonist, SCH50911, and (b) combined treatment with the positive allosteric modulator of the GABAB receptor, GS39783. Treatment with SSA (0, 0.25, 0.5, and 1mg/kg, i.p.) markedly reduced lever-responding for alcohol, amount of self-administered alcohol, and breakpoint for alcohol (defined as the lowest response requirement not achieved in the PR experiment). Pretreatment with 2mg/kg SCH50911 (i.p.) resulted in a partial blockade of the reducing effect of 0.5mg/kg SSA on lever-responding for alcohol and amount of self-administered alcohol. Combination of per se ineffective doses of GS39783 (5mg/kg, i.g.) and SSA (0.1mg/kg, i.p.) reduced lever-responding for alcohol and amount of self-administered alcohol. These results (a) extend to alcohol self-administration the capacity of SSA to suppress morphine and cocaine self-administration in rats and (b) suggest that the GABAB receptor system is likely part of the neural substrate underlying the reducing effect of SSA on alcohol self-administration.
Collapse
Affiliation(s)
- Paola Maccioni
- Neuroscience Institute, National Research Council of Italy, Section of Cagliari, I-09042 Monserrato, CA, Italy
| | - Irene Lorrai
- Neuroscience Institute, National Research Council of Italy, Section of Cagliari, I-09042 Monserrato, CA, Italy
| | - Mauro A M Carai
- Cagliari Pharmacological Research s.r.l., I-09127 Cagliari, CA, Italy
| | | | | | - Claudia Mugnaini
- Department of Biotechnologies, Chemistry and Pharmacy, University of Siena, I-53100, Siena, SI, Italy
| | - Federico Corelli
- Department of Biotechnologies, Chemistry and Pharmacy, University of Siena, I-53100, Siena, SI, Italy
| | - Gian Luigi Gessa
- Neuroscience Institute, National Research Council of Italy, Section of Cagliari, I-09042 Monserrato, CA, Italy
| | - Giancarlo Colombo
- Neuroscience Institute, National Research Council of Italy, Section of Cagliari, I-09042 Monserrato, CA, Italy.
| |
Collapse
|
16
|
Mareš P, Kubová H. GABAB, not GABAA receptors play a role in cortical postictal refractoriness. Neuropharmacology 2014; 88:99-102. [PMID: 25229720 DOI: 10.1016/j.neuropharm.2014.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/30/2014] [Accepted: 09/04/2014] [Indexed: 11/17/2022]
Abstract
Postictal refractoriness may be taken as an expression of lasting activity of inhibitory systems arresting seizures. We tested drugs interfering with GABAergic inhibitory system in pairs of cortical epileptic afterdischarges induced with 1-min interval in rats. Under control conditions the second stimulation failed to elicit an afterdischarge. This postictal refractoriness was not affected by antagonists of GABAA receptors acting at three binding sites (bicuculline, picrotoxin, benzodiazepine inverse agonist Ro 19-4603) as well as by a less specific antagonist pentetrazol. In contrast, antagonist of GABAB receptors CGP35348 partially blocked the refractoriness. Cooperation of different inhibitory systems is probably necessary to abolish postictal refractoriness in neocortex. This article is part of the Special Issue entitled 'GABAergic Signaling in Health and Disease'.
Collapse
Affiliation(s)
- Pavel Mareš
- Department of Developmental Epileptology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
| | - Hana Kubová
- Department of Developmental Epileptology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
| |
Collapse
|
17
|
Stratton MS, Staros M, Budefeld T, Searcy BT, Nash C, Eitel C, Carbone D, Handa RJ, Majdic G, Tobet SA. Embryonic GABA(B) receptor blockade alters cell migration, adult hypothalamic structure, and anxiety- and depression-like behaviors sex specifically in mice. PLoS One 2014; 9:e106015. [PMID: 25162235 PMCID: PMC4146593 DOI: 10.1371/journal.pone.0106015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 07/27/2014] [Indexed: 11/18/2022] Open
Abstract
Neurons of the paraventricular nucleus of the hypothalamus (PVN) regulate the hypothalamic- pituitary-adrenal (HPA) axis and the autonomic nervous system. Females lacking functional GABAB receptors because of a genetic disruption of the R1 subunit have altered cellular characteristics in and around the PVN at birth. The genetic disruption precluded appropriate assessments of physiology or behavior in adulthood. The current study was conducted to test the long term impact of a temporally restricting pharmacological blockade of the GABAB receptor to a 7-day critical period (E11–E17) during embryonic development. Experiments tested the role of GABAB receptor signaling in fetal development of the PVN and later adult capacities for adult stress related behaviors and physiology. In organotypic slices containing fetal PVN, there was a female specific, 52% increase in cell movement speeds with GABAB receptor antagonist treatment that was consistent with a sex-dependent lateral displacement of cells in vivo following 7 days of fetal exposure to GABAB receptor antagonist. Anxiety-like and depression-like behaviors, open-field activity, and HPA mediated responses to restraint stress were measured in adult offspring of mothers treated with GABAB receptor antagonist. Embryonic exposure to GABAB receptor antagonist resulted in reduced HPA axis activation following restraint stress and reduced depression-like behaviors. There was also increased anxiety-like behavior selectively in females and hyperactivity in males. A sex dependent response to disruptions of GABAB receptor signaling was identified for PVN formation and key aspects of physiology and behavior. These changes correspond to sex specific prevalence in similar human disorders, namely anxiety disorders and hyperactivity.
Collapse
Affiliation(s)
- Matthew S. Stratton
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Michelle Staros
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Tomaz Budefeld
- Center for Animal Genomics, Veterinary Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Brian T. Searcy
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Connor Nash
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Chad Eitel
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - David Carbone
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, Arizona, United States of America
| | - Robert J. Handa
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, Arizona, United States of America
| | - Gregor Majdic
- Center for Animal Genomics, Veterinary Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Stuart A. Tobet
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- School of Biomedical Engineering, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail:
| |
Collapse
|
18
|
Gillani Q, Ali M, Iqbal F. CGP 35348, GABA B receptor antagonist, has a potential to improve neuromuscular coordination and spatial learning in albino mouse following neonatal brain damage. Biomed Res Int 2014; 2014:295215. [PMID: 24804211 PMCID: PMC3997133 DOI: 10.1155/2014/295215] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 03/04/2014] [Accepted: 03/10/2014] [Indexed: 01/14/2023]
Abstract
To study the effect of CGP 35348 on learning and memory in albino mice following hypoxia ischemia insult, 10 days old albino mice were subjected to right common carotid artery ligation followed by 8% hypoxia for 25 minutes. Following brain damage, mice were fed on normal rodent diet till they were 13 week old. At this time point, mice were divided into two groups. Group 1 received saline and group 2 intrapertoneally CGP 35348 (1 mg/mL solvent/Kg body weight) for 12 days. A battery of tests used to assess long term neurofunction (Morris water maze, Rota rod and open field) along with brain infarct measurement. Overall CGP 35348 has improved the motor function in male and female albino mice but effects were more pronounced in female albino mice. In open field, CGP 35348 treated female albino mice had demonstrated poor exploratory behavior. During Morris water maze test, gender specific effects were observed as CGP 35348 had improved spatial learning and memory and swimming speed in male albino mice but had no effect in female albino mice following hypoxia ischemia encephalopathy (HIE). We concluded that GABAB receptor antagonists CGP 35348 can be used to improve gender based spatial memory.
Collapse
Affiliation(s)
- Q. Gillani
- Zoology Division, Institute of Pure and Applied Biology, Bahauddin Zakariya University, Multan 60800, Pakistan
| | - M. Ali
- Institute of Molecular Biology and Biotechnology, Bahauddin Zakariya University, Multan 60800, Pakistan
| | - F. Iqbal
- Zoology Division, Institute of Pure and Applied Biology, Bahauddin Zakariya University, Multan 60800, Pakistan
| |
Collapse
|
19
|
Bañuelos C, Beas BS, McQuail JA, Gilbert RJ, Frazier CJ, Setlow B, Bizon JL. Prefrontal cortical GABAergic dysfunction contributes to age-related working memory impairment. J Neurosci 2014; 34:3457-66. [PMID: 24599447 PMCID: PMC3942567 DOI: 10.1523/jneurosci.5192-13.2014] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/15/2014] [Accepted: 01/20/2014] [Indexed: 12/12/2022] Open
Abstract
Working memory functions supported by the prefrontal cortex decline in normal aging. Disruption of corticolimbic GABAergic inhibitory circuits can impair working memory in young subjects; however, relatively little is known regarding how aging impacts prefrontal cortical GABAergic signaling and whether such changes contribute to cognitive deficits. The current study used a rat model to evaluate the effects of aging on expression of prefrontal GABAergic synaptic proteins in relation to working memory decline, and to test whether pharmacological manipulations of prefrontal GABAergic signaling can improve working memory abilities in aged subjects. Results indicate that in aged medial prefrontal cortex (mPFC), expression of the vesicular GABA transporter VGAT was unchanged; however, there was a significant increase in expression of the GABA synthesizing enzyme GAD67, and a significant decrease in the primary neuronal GABA transporter GAT-1 and in both subunits of the GABA(B) receptor (GABA(B)R). Expression of VGAT, GAD67, and GAT-1 was not associated with working memory ability. In contrast, among aged rats, GABA(B)R expression was significantly and negatively associated with working memory performance, such that lower GABA(B)R expression predicted better working memory. Subsequent experiments showed that systemic administration of a GABA(B)R antagonist, CGP55845, dose-dependently enhanced working memory in aged rats. This enhancing effect of systemic CGP55845 was reproduced by direct intra-mPFC administration. Together, these data suggest that age-related dysregulation of GABAergic signaling in prefrontal cortex may play a causal role in impaired working memory and that targeting GABA(B)Rs may provide therapeutic benefit for age-related impairments in executive functions.
Collapse
Affiliation(s)
| | | | | | | | - Charles J. Frazier
- Department of Neuroscience
- Department of Pharmacodynamics, University of Florida, Gainesville, Florida 32610
| | - Barry Setlow
- Department of Neuroscience
- Department of Psychiatry
| | - Jennifer L. Bizon
- Department of Neuroscience
- Department of Psychiatry
- McKnight Brain Institute, and
| |
Collapse
|
20
|
Abstract
Human GABA(B) (γ-aminobutyric acid class B) receptor is a G-protein-coupled receptor central to inhibitory neurotransmission in the brain. It functions as an obligatory heterodimer of the subunits GBR1 and GBR2. Here we present the crystal structures of a heterodimeric complex between the extracellular domains of GBR1 and GBR2 in the apo, agonist-bound and antagonist-bound forms. The apo and antagonist-bound structures represent the resting state of the receptor; the agonist-bound complex corresponds to the active state. Both subunits adopt an open conformation at rest, and only GBR1 closes on agonist-induced receptor activation. The agonists and antagonists are anchored in the interdomain crevice of GBR1 by an overlapping set of residues. An antagonist confines GBR1 to the open conformation of the inactive state, whereas an agonist induces its domain closure for activation. Our data reveal a unique activation mechanism for GABA(B) receptor that involves the formation of a novel heterodimer interface between subunits.
Collapse
Affiliation(s)
- Yong Geng
- Department of Pharmacology, Columbia University, New York, New York 10032, USA
| | - Martin Bush
- Department of Pharmacology, Columbia University, New York, New York 10032, USA
| | - Lidia Mosyak
- Department of Pharmacology, Columbia University, New York, New York 10032, USA
| | - Feng Wang
- Department of Pharmacology, Columbia University, New York, New York 10032, USA
| | - Qing R Fan
- 1] Department of Pharmacology, Columbia University, New York, New York 10032, USA [2] Department of Pathology & Cell Biology, Columbia University, New York, New York 10032, USA
| |
Collapse
|
21
|
Kanat O, Bagdas D, Ozboluk HY, Gurun MS. Preclinical evidence for the antihyperalgesic activity of CDP-choline in oxaliplatin-induced neuropathic pain. J BUON 2013; 18:1012-1018. [PMID: 24344031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
PURPOSE This study was designed to evaluate the antihyperalgesic effect of CDP-choline (cytidine-5'-diphosphate- choline; citicoline) in a rat model of neuropathic pain produced by oxaliplatin (OXA). METHODS A single administration of OXA (6 mg/kg intraperitoneally/ ip) was used for induction of neuropathy. We assessed the antihyperalgesic effect of intracerebroventricularly (icv) administered CDP-choline (0.5, 1.0 and 2.0 μmol) using the rat paw pressure test (Randall-Selitto). RESULTS CDP-choline significantly reduced OXA-induced mechanical hyperalgesia, in a dose- and time-dependent manner. The antihyperalgesic effect of CDP-choline was blocked by the neuronal high affinity choline uptake inhibitor hemicholinium-3 (1 μg; icv), the nonselective nicotinic receptor antagonist mecamylamine (50 μg; icv), the α7 selective nicotinic acetylcholine receptor antagonist α-bungarotoxin (2 μg; icv), and the gamma-amino butyric acid (GABA)-B receptor antagonist CGP-35348 (20 μg; icv), but not by the nonselective opioid receptor antagonist naloxone (10 μg; icv) and the nonselective muscarinic receptor antagonist atropine (10 μg; icv). CONCLUSION These findings indicate that CDP-choline exerts an antihyperalgesic effect in OXA-induced neuropatic pain and it can be tested in clinical trials.
Collapse
|
22
|
Sinchak K, Dewing P, Ponce L, Gomez L, Christensen A, Berger M, Micevych P. Modulation of the arcuate nucleus-medial preoptic nucleus lordosis regulating circuit: a role for GABAB receptors. Horm Behav 2013; 64:136-43. [PMID: 23756153 PMCID: PMC3742545 DOI: 10.1016/j.yhbeh.2013.06.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 05/29/2013] [Accepted: 06/02/2013] [Indexed: 12/20/2022]
Abstract
Estradiol rapidly activates a microcircuit in the arcuate nucleus of the hypothalamus (ARH) that is needed for maximal female sexual receptivity. Membrane estrogen receptor-α complexes with and signals through the metabotropic glutamate receptor-1a stimulating NPY release within the ARH activating proopiomelanocortin (POMC) neurons. These POMC neurons project to the medial preoptic nucleus (MPN) and release β-endorphin. Estradiol treatment induces activation/internalization of MPN μ-opioid receptors (MOR) to inhibit lordosis. Estradiol membrane action modulates ARH gamma-aminobutyric acid receptor-B (GABAB) activity. We tested the hypothesis that ARH GABAB receptors mediate estradiol-induced MOR activation and facilitation of sexual receptivity. Double-label immunohistochemistry revealed expression of GABAB receptors in NPY, ERα and POMC expressing ARH neurons. Approximately 70% of POMC neurons expressed GABAB receptors. Because estradiol initially activates an inhibitory circuit and maintains activation of this circuit, the effects of blocking GABAB receptors were evaluated before estradiol benzoate (EB) treatment and after at the time of lordosis testing. Bilateral infusions of the GABAB receptor antagonist, CGP52432, into the ARH prior to EB treatment of ovariectomized rats prevented estradiol-induced activation/internalization of MPN MOR, and the rats remained unreceptive. However, in EB-treated rats, bilateral CGP52432 infusions 30 min before behavior testing attenuated MOR internalization and facilitated lordosis. These results indicated that GABAB receptors were located within the lordosis-regulating ARH microcircuit and are necessary for activation and maintenance of the estradiol inhibition of lordosis behavior. Although GABAB receptors positively influence estradiol signaling, they negatively regulate lordosis behavior since GABAB activity maintains the estradiol-induced inhibition.
Collapse
MESH Headings
- Animals
- Arcuate Nucleus of Hypothalamus/drug effects
- Arcuate Nucleus of Hypothalamus/physiology
- Estradiol/pharmacology
- Estrogen Receptor alpha/metabolism
- Female
- GABA-B Receptor Antagonists/pharmacology
- Image Processing, Computer-Assisted
- Immunohistochemistry
- Male
- Nerve Net/drug effects
- Nerve Net/physiology
- Neuropeptide Y/metabolism
- Ovariectomy
- Preoptic Area/drug effects
- Preoptic Area/physiology
- Pro-Opiomelanocortin/metabolism
- Rats
- Rats, Long-Evans
- Receptors, GABA-B/drug effects
- Receptors, GABA-B/physiology
- Receptors, Opioid, mu/drug effects
- Receptors, Opioid, mu/physiology
- Sexual Behavior, Animal/drug effects
- Sexual Behavior, Animal/physiology
Collapse
Affiliation(s)
- Kevin Sinchak
- Biol. Sci., California State University, Long Beach, Long Beach, CA, USA.
| | | | | | | | | | | | | |
Collapse
|
23
|
Fawley JA, Peters JH, Andresen MC. GABA(B)-mediated inhibition of multiple modes of glutamate release in the nucleus of the solitary tract. J Neurophysiol 2011; 106:1833-40. [PMID: 21734101 PMCID: PMC3191834 DOI: 10.1152/jn.00476.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 07/01/2011] [Indexed: 01/06/2023] Open
Abstract
In the caudal portions of the solitary tract (ST) nucleus, primary sensory afferents fall into two broad classes based on the expression of transient receptor potential vanilloid type 1 (TRPV1) receptors. Both afferent classes (TRPV1+/-) have indistinguishable glutamate release mechanisms for ST-evoked excitatory postsynaptic currents (EPSCs). However, TRPV1+ terminals release additional glutamate from a unique, TRPV1-operated vesicle pool that is temperature sensitive and facilitated by ST activity to generate asynchronous EPSCs. This study tested whether presynaptic γ-aminobutyric acid (GABA)(B) receptors inhibit both the evoked and TRPV1-operated release mechanisms on second-order ST nucleus neurons. In horizontal slices, shocks activated single ST axons and evoked the time-invariant (latency jitter <200 μs), glutamatergic EPSCs, which identified second-order neurons. Gabazine eliminated GABA(A) responses in all recordings. The GABA(B) agonist baclofen inhibited the amplitude of ST-EPSCs from both TRPV1+ and TRPV1- afferents with a similar EC(50) (∼1.2 μM). In TTX, GABA(B) activation decreased miniature EPSC (mEPSC) rates but not amplitudes, suggesting presynaptic actions downstream from terminal excitability. With calcium entry through voltage-activated calcium channels blocked by cadmium, baclofen reduced mEPSC frequency, indicating that GABA(B) reduced vesicle release by TRPV1-dependent calcium entry. GABA(B) activation also reduced temperature-evoked increases in mEPSC frequency, which relies on TRPV1. Our studies indicate that GABA(B) G protein-coupled receptors are uniformly distributed across all ST primary afferent terminals and act at multiple stages of the excitation-release cascades to suppress both action potential-triggered and TRPV1-coupled glutamate transmission pathways. Moreover, the segregated release cascades within TRPV1+ ST primary afferents represent independent, potential targets for differential modulation.
Collapse
Affiliation(s)
- Jessica A Fawley
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, USA.
| | | | | |
Collapse
|
24
|
Karamian OA, Polina IA, Chmykhova NM, Veselkin NP. [Convergence of modulating influences of presynaptic metabotropic glutamate and GABAB receptors]. Zh Evol Biokhim Fiziol 2011; 47:411-413. [PMID: 22145324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
|
25
|
Vlachou S, Paterson NE, Guery S, Kaupmann K, Froestl W, Banerjee D, Finn MG, Markou A. Both GABA(B) receptor activation and blockade exacerbated anhedonic aspects of nicotine withdrawal in rats. Eur J Pharmacol 2011; 655:52-8. [PMID: 21262222 DOI: 10.1016/j.ejphar.2011.01.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 12/07/2010] [Accepted: 01/07/2011] [Indexed: 01/19/2023]
Abstract
Nicotine dependence is maintained by the aversive, depression-like effects of nicotine withdrawal and the rewarding effects of acute nicotine. GABA(B) receptor antagonists exhibit antidepressant-like effects in rodents, whereas GABA(B) receptor agonists attenuate the rewarding effects of nicotine. Recent studies with GABA(B) receptor positive modulators showed that these compounds represent potentially improved medications for the treatment of nicotine dependence because of fewer side-effects than GABA(B) receptor agonists. Thus, GABA(B) receptor agonists and antagonists, and GABA(B) receptor positive modulators may have efficacy as smoking cessation aids by targeting different aspects of nicotine dependence and withdrawal. The present study assessed the effects of the GABA(B) receptor agonist CGP44532, the GABA(B) receptor antagonist CGP56433A, and the GABA(B) receptor positive modulator BHF177 on the anhedonic aspects of nicotine withdrawal. Rats were prepared with stimulating electrodes in the posterior lateral hypothalamus. After establishing stable intracranial self-stimulation (ICSS) thresholds, rats were prepared with subcutaneous osmotic minipumps delivering either nicotine or saline for 7 or 14days. ICSS thresholds were assessed 6h post-pump removal. Thirty hours after pump removal, CGP44532, CGP56433A, and BHF177 were administered 30min prior to ICSS testing. Both GABA(B) receptor activation (CGP44532 and BHF177) and blockade (CGP56433A) elevated ICSS thresholds in all groups, resulting in exacerbated effects of nicotine withdrawal in the nicotine-treated groups. These similar effects of GABA(B) receptor activation and blockade on the anhedonic depression-like aspects of nicotine withdrawal were surprising and perhaps reflect differential efficacy of these compounds at presynaptic hetero- and autoreceptors, as well as postsynaptic, GABA(B) receptors.
Collapse
Affiliation(s)
- Styliani Vlachou
- Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, CA 92093-0603, USA
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Heskin-Sweezie R, Titley HK, Baizer JS, Broussard DM. Type B GABA receptors contribute to the restoration of balance during vestibular compensation in mice. Neuroscience 2010; 169:302-14. [PMID: 20394801 PMCID: PMC2910079 DOI: 10.1016/j.neuroscience.2010.04.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Revised: 03/23/2010] [Accepted: 04/05/2010] [Indexed: 10/19/2022]
Abstract
Following unilateral vestibular damage (UVD), vestibular compensation restores both static and dynamic vestibular reflexes. The cerebellar cortex provides powerful GABAergic inhibitory input to the vestibular nuclei which is necessary for compensation. Metabotropic GABA type B (GABA(B)) receptors in the vestibular nuclei are thought to be involved. However, the contribution of GABA(B) receptors may differ between static and dynamic compensation. We tested static and dynamic postural reflexes and gait in young mice, while they compensated for UVD caused by injection of air into the vestibular labyrinth. The effects of an agonist (baclofen), an antagonist (CGP56433A) and a positive allosteric modulator (CGP7930) of the GABA(B) receptor were evaluated during compensation. Static postural reflexes recovered very rapidly in our model, and baclofen slightly accelerated recovery. However, CGP56433A significantly impaired static compensation. Dynamic reflexes were evaluated by balance-beam performance and by gait; both showed significant decrements following UVD and performance improved over the next 2 days. Both CGP56433A and baclofen temporarily impaired the ability to walk on a balance beam after UVD. Two days later, there were no longer any significant effects of drug treatments on balance-beam performance. Baclofen slightly accelerated the recovery of stride length on a flat surface, but CGP7930 worsened the gait impairment following UVD. Using immunohistochemistry, we confirmed that GABA(B) receptors are abundantly expressed on the vestibulospinal neurons of Deiters in mice. Our results suggest that GABA(B) receptors contribute to the compensation of static vestibular reflexes following unilateral peripheral damage. We also conclude that impairment of the first stage of compensation, static recovery, does not necessarily result in an impairment of dynamic recovery in the long term.
Collapse
Affiliation(s)
| | | | - Joan S. Baizer
- Department of Physiology and Biophysics, University at Buffalo
| | - Dianne M. Broussard
- Department of Physiology, University of Toronto
- Division of Neurology, Department of Medicine, University of Toronto
- Division of Fundamental Neurobiology, Toronto Western Research Institute, University Health Network, Toronto
| |
Collapse
|