The effect of ethanol on 35S-TBPS binding to mouse brain membranes in the presence of chloride.
The effect of in vitro and in vivo administration of ethanol on the binding of 35S-t-butyl-bicyclophosphorothionate (35S-TBPS) to cortical brain membranes of C57Bl mice was investigated using KCl (100 mM) containing assay media. The in vitro addition of ethanol produced a dose-dependent inhibition of basal 35S-TBPS binding. In the presence of chloride ions, GABA and pentobarbital had a biphasic action (stimulation followed by inhibition) on 35S-TBPS binding, whereas diazepam only stimulated the binding. Ethanol reduced the stimulatory effects of GABA and pentobarbital in a dose-dependent manner, but had no effect on the enhancement of 35S-TBPS binding produced by diazepam. 35S-TBPS binding to cortical brain membranes was inhibited by the putative Cl- channel blocking agent DIDS. This inhibitory action of DIDS was significantly, and dose-dependently reduced by ethanol (greater than or equal to 100 mM ethanol). Chronic ethanol ingestion in vivo, which produced tolerance to and physical dependence on ethanol in the animals, did not alter the stimulatory and inhibitory effects of GABA and pentobarbital on 35S-TBPS binding. The enhancement of 35S-TBPS binding produced by diazepam was slightly, but significantly, enhanced in brain membranes from animals which had undergone 24 hours of ethanol withdrawal. Chronic ethanol treatment did not change the potency of picrotoxin and of the peripheral BDZ-receptor ligand RO 5-4864 to competitively inhibit 35S-TBPS binding. Our results suggest that in vitro addition of ethanol alters the activity of the GABA/benzodiazepine (BDZ) receptor complex.(ABSTRACT TRUNCATED AT 250 WORDS)
Liljequist
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Laboratory for Studies of Neuroadaptive Processes, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD 20892.
Culp
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Tabakoff
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B
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001570:Benzodiazepinones / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D001643:Bridged Bicyclo Compounds / Q000494:pharmacology*; D019086:Bridged Bicyclo Compounds, Heterocyclic; D001952:Bridged-Ring Compounds / Q000494:pharmacology*; D002712:Chlorides / Q000378:metabolism; D003975:Diazepam / Q000494:pharmacology; D004361:Drug Tolerance; D000431:Ethanol / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010424:Pentobarbital / Q000494:pharmacology; D019966:Substance-Related Disorders / Q000378:metabolism; D013462:Sulfur Radioisotopes; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D001570:Benzodiazepinones; D001643:Bridged Bicyclo Compounds; D019086:Bridged Bicyclo Compounds, Heterocyclic; D001952:Bridged-Ring Compounds; D002712:Chlorides; D013462:Sulfur Radioisotopes; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; C028513:4'-chlorodiazepam; D000431:Ethanol; D005680:gamma-Aminobutyric Acid; C037476:tert-butylbicyclophosphorothionate; D010424:Pentobarbital; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D003975:Diazepam