BRAIN GABA-TRANSAMINASE AND MONOAMINE-OXIDASE AFTER CHRONIC ETHANOL TREATMENT IN RATS

The activities of gamma-aminobutyrate aminotransferase (GABA-T) and mo noamine oxidase (MAO-A and -B) were estimated in various brain regions of rats exposed to ethanol for 90 weeks. During the first period (wee ks 1-58), the rats had access to both ethanol (10% w/v) and water duri ng a 24-hr interval at the end of each week. At this point, the animal s were given either a saline injection (intraperitoneally, group 1) or an ethanol injection (2.0 g/kg ip, group 2). During the second period (weeks 59-90), the rats In groups 1 and 2 had continuous access to bo th ethanol and water. The third group was composed of untreated contro l rats. Compared with controls, there was an increase of 20-45% in the mean brain GABA-T activity in both groups of ethanol-treated rats. Ho wever, analysis of the data for the individual ethanol-treated rats re vealed a considerable difference in brain GABA-T activity. Thus, simil ar to 30% of the ethanol-treated rats showed approximately twice the a ctivity of rats in the exposed groups and in the control group. There was no connection between ethanol intake, water intake, or body weight and GABA-T activity in any of the brain regions examined. There was n o effect of ethanol In vitro on the activity of GABA-T in the brain co rtex in concentrations of 20-100 mM, whereas acetaldehyde inhibited th e activity by 15% at these concentrations. The present results suggest that there is a bimodal distribution with respect to the effect of et hanol on rat brain GABA-T activity. With regard to MAO, the activities (both forms) in the brain remained unaffected after 90 weeks of ethan ol treatment.