Benzodiazepine agonist and inverse agonist actions on GABA(A) receptor-operated chloride channels. II. Chronic effects of ethanol

Kari Buck, R. A. Harris

Research output: Contribution to journalArticle

140 Citations (Scopus)

Abstract

Mice were made tolerant to and dependent on ethanol by administration of a liquid diet. γ-Aminobutyric acid (GABA) receptor-dependent uptake of 36Cl- by mouse cortical microsacs was used to study the actions of benzodiazepine (BZ) agonists and inverse agonists. Chronic exposure to ethanol attenuated the ability of a BZ agonist, flunitrazepam, to augment muscimol stimulated uptake of 36Cl- and enhanced the actions of BZ inverse agonists, Ro15-4513 (ethyl-8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5a][1,4]- benzodiazepine-3-carboxylate) and DMCM (methyl-6,7-dimethoxy-4-ethyl-β-carboline-3-carboxylate), to inhibit GABA(A) receptor-operated chloride channels. Augmentation of chloride flux by pentobarbital was not reduced by chronic ethanol exposure. Attenuation of flunitrazepam efficacy was transient and returned to control levels within 6 to 24 hr after withdrawal from ethanol, but increased sensitivity to Ro15-4513 was observed as long as 8 days after withdrawal. Chronic exposure to ethanol did not alter [3H]SR 95531 ([2-(3'-carbethoxy-2'propyl)-3-amino-6-p-methoxyphenylpyridazinium bromide] binding to low-affinity GABA(A) receptors or muscimol stimulation of chloride flux; and did not alter [3H]Ro15-4513 or [3H]flunitrazepam binding to central BZ receptors or allosteric modulation of this binding by muscimol (i.e., muscimol-shift). These results suggest that chronic exposure to ethanol reduces coupling between BZ agonist sites and the chloride channel, and may be responsible for the development of cross-tolerance between ethanol and BZ agonists. In contrast, coupling between BZ inverse agonist sites and the chloride channel is increased. This action may be involved in the development of tolerance to or dependence on ethanol and could contribute to the anxiety and seizure susceptibility observed during ethanol withdrawal.

Original languageEnglish (US)
Pages (from-to)713-719
Number of pages7
JournalJournal of Pharmacology and Experimental Therapeutics
Volume253
Issue number2
StatePublished - 1990
Externally publishedYes

Fingerprint

Chloride Channels
GABA-A Receptors
Benzodiazepines
Ethanol
Muscimol
Flunitrazepam
Chlorides
Aminobutyrates
Carbolines
GABA Receptors
Pentobarbital
Bromides
Seizures
Anxiety
Diet

ASJC Scopus subject areas

  • Pharmacology

Cite this

@article{f5344fe32b4f4bfba6986c00380023ef,
title = "Benzodiazepine agonist and inverse agonist actions on GABA(A) receptor-operated chloride channels. II. Chronic effects of ethanol",
abstract = "Mice were made tolerant to and dependent on ethanol by administration of a liquid diet. γ-Aminobutyric acid (GABA) receptor-dependent uptake of 36Cl- by mouse cortical microsacs was used to study the actions of benzodiazepine (BZ) agonists and inverse agonists. Chronic exposure to ethanol attenuated the ability of a BZ agonist, flunitrazepam, to augment muscimol stimulated uptake of 36Cl- and enhanced the actions of BZ inverse agonists, Ro15-4513 (ethyl-8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5a][1,4]- benzodiazepine-3-carboxylate) and DMCM (methyl-6,7-dimethoxy-4-ethyl-β-carboline-3-carboxylate), to inhibit GABA(A) receptor-operated chloride channels. Augmentation of chloride flux by pentobarbital was not reduced by chronic ethanol exposure. Attenuation of flunitrazepam efficacy was transient and returned to control levels within 6 to 24 hr after withdrawal from ethanol, but increased sensitivity to Ro15-4513 was observed as long as 8 days after withdrawal. Chronic exposure to ethanol did not alter [3H]SR 95531 ([2-(3'-carbethoxy-2'propyl)-3-amino-6-p-methoxyphenylpyridazinium bromide] binding to low-affinity GABA(A) receptors or muscimol stimulation of chloride flux; and did not alter [3H]Ro15-4513 or [3H]flunitrazepam binding to central BZ receptors or allosteric modulation of this binding by muscimol (i.e., muscimol-shift). These results suggest that chronic exposure to ethanol reduces coupling between BZ agonist sites and the chloride channel, and may be responsible for the development of cross-tolerance between ethanol and BZ agonists. In contrast, coupling between BZ inverse agonist sites and the chloride channel is increased. This action may be involved in the development of tolerance to or dependence on ethanol and could contribute to the anxiety and seizure susceptibility observed during ethanol withdrawal.",
author = "Kari Buck and Harris, {R. A.}",
year = "1990",
language = "English (US)",
volume = "253",
pages = "713--719",
journal = "Journal of Pharmacology and Experimental Therapeutics",
issn = "0022-3565",
publisher = "American Society for Pharmacology and Experimental Therapeutics",
number = "2",

}

TY - JOUR

T1 - Benzodiazepine agonist and inverse agonist actions on GABA(A) receptor-operated chloride channels. II. Chronic effects of ethanol

AU - Buck, Kari

AU - Harris, R. A.

PY - 1990

Y1 - 1990

N2 - Mice were made tolerant to and dependent on ethanol by administration of a liquid diet. γ-Aminobutyric acid (GABA) receptor-dependent uptake of 36Cl- by mouse cortical microsacs was used to study the actions of benzodiazepine (BZ) agonists and inverse agonists. Chronic exposure to ethanol attenuated the ability of a BZ agonist, flunitrazepam, to augment muscimol stimulated uptake of 36Cl- and enhanced the actions of BZ inverse agonists, Ro15-4513 (ethyl-8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5a][1,4]- benzodiazepine-3-carboxylate) and DMCM (methyl-6,7-dimethoxy-4-ethyl-β-carboline-3-carboxylate), to inhibit GABA(A) receptor-operated chloride channels. Augmentation of chloride flux by pentobarbital was not reduced by chronic ethanol exposure. Attenuation of flunitrazepam efficacy was transient and returned to control levels within 6 to 24 hr after withdrawal from ethanol, but increased sensitivity to Ro15-4513 was observed as long as 8 days after withdrawal. Chronic exposure to ethanol did not alter [3H]SR 95531 ([2-(3'-carbethoxy-2'propyl)-3-amino-6-p-methoxyphenylpyridazinium bromide] binding to low-affinity GABA(A) receptors or muscimol stimulation of chloride flux; and did not alter [3H]Ro15-4513 or [3H]flunitrazepam binding to central BZ receptors or allosteric modulation of this binding by muscimol (i.e., muscimol-shift). These results suggest that chronic exposure to ethanol reduces coupling between BZ agonist sites and the chloride channel, and may be responsible for the development of cross-tolerance between ethanol and BZ agonists. In contrast, coupling between BZ inverse agonist sites and the chloride channel is increased. This action may be involved in the development of tolerance to or dependence on ethanol and could contribute to the anxiety and seizure susceptibility observed during ethanol withdrawal.

AB - Mice were made tolerant to and dependent on ethanol by administration of a liquid diet. γ-Aminobutyric acid (GABA) receptor-dependent uptake of 36Cl- by mouse cortical microsacs was used to study the actions of benzodiazepine (BZ) agonists and inverse agonists. Chronic exposure to ethanol attenuated the ability of a BZ agonist, flunitrazepam, to augment muscimol stimulated uptake of 36Cl- and enhanced the actions of BZ inverse agonists, Ro15-4513 (ethyl-8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5a][1,4]- benzodiazepine-3-carboxylate) and DMCM (methyl-6,7-dimethoxy-4-ethyl-β-carboline-3-carboxylate), to inhibit GABA(A) receptor-operated chloride channels. Augmentation of chloride flux by pentobarbital was not reduced by chronic ethanol exposure. Attenuation of flunitrazepam efficacy was transient and returned to control levels within 6 to 24 hr after withdrawal from ethanol, but increased sensitivity to Ro15-4513 was observed as long as 8 days after withdrawal. Chronic exposure to ethanol did not alter [3H]SR 95531 ([2-(3'-carbethoxy-2'propyl)-3-amino-6-p-methoxyphenylpyridazinium bromide] binding to low-affinity GABA(A) receptors or muscimol stimulation of chloride flux; and did not alter [3H]Ro15-4513 or [3H]flunitrazepam binding to central BZ receptors or allosteric modulation of this binding by muscimol (i.e., muscimol-shift). These results suggest that chronic exposure to ethanol reduces coupling between BZ agonist sites and the chloride channel, and may be responsible for the development of cross-tolerance between ethanol and BZ agonists. In contrast, coupling between BZ inverse agonist sites and the chloride channel is increased. This action may be involved in the development of tolerance to or dependence on ethanol and could contribute to the anxiety and seizure susceptibility observed during ethanol withdrawal.

UR - http://www.scopus.com/inward/record.url?scp=0025295401&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025295401&partnerID=8YFLogxK

M3 - Article

C2 - 2160008

AN - SCOPUS:0025295401

VL - 253

SP - 713

EP - 719

JO - Journal of Pharmacology and Experimental Therapeutics

JF - Journal of Pharmacology and Experimental Therapeutics

SN - 0022-3565

IS - 2

ER -