title: Disulfiram lowers Ca2+, Mg(2+)-ATPase activity of rat brain synaptosomes.
abstract: The chronic administration of disulfiram (DS) to rats resulted in significant decrease of synaptosomal Ca2+, Mg(2+)-ATPase activity. In vitro studies indicated that DS (ID50 = 20 microM) produced a dose-dependent inhibition of Ca2+, Mg(2+)-ATPase. However, diethyldithio-carbamate, a metabolite of DS, failed to modify Ca2+, Mg(2+)-ATPase activity, implying that the decrease in ATPase activity in DS administered rats was due to the effect of parent compound. The DS-mediated inhibition (48%) of ATPase activity was comparable with a similar degree of inhibition (49%) achieved by treating the synaptosomal membranes with N-ethylmaleimide (ID50 = 20 microM) in vitro. Furthermore, the inhibition by DS was neither altered by washing the membranes with EGTA nor reversed by treatment with sulfhydryl reagents such as GSH or dithiothreitol. About 74% and 68% decrease of synaptosomal Ca2+, Mg(2+)-ATPase specific activity was observed when treated with DS (30 microM) and EGTA (100 microM) respectively. The remaining 25-30% of total activity is suggested to be of Mg(2+)-dependent ATPase activity. This indicates that both these drugs may act on a common target, calmodulin component that represents 70-75% of total Ca2+, Mg(2+)-ATPase activity. Therefore, DS-mediated modulation of synaptosomal Ca2+, Mg(2+)-ATPase activity could affect its function of maintaining intracellular Ca2+ concentration. This could contribute to the deleterious effects on CNS.
authors.affiliation: Dept. of Neurochemistry, National Institute of Mental Health and Neurosciences, Bangalore, India.
authors.forename: S N
authors.initials: SN
authors.lastname: Nagendra
authors.forename: K M
authors.initials: KM
authors.lastname: Rao
authors.forename: M N
authors.initials: MN
authors.lastname: Subhash
authors.forename: K T
authors.initials: KT
authors.lastname: Shetty
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D004221:Disulfiram / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D004229:Dithiothreitol / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D005978:Glutathione / Q000494:pharmacology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013574:Synaptosomes / Q000187:drug effects / Q000201:enzymology*
chemical_list: D004533:Egtazic Acid; D017301:Ca(2+) Mg(2+)-ATPase; D005978:Glutathione; D005033:Ethylmaleimide; D004229:Dithiothreitol; D004221:Disulfiram