The effect of ethanol consumption on the sensitivity of rat brain monoamine oxidases to the inhibition by pargyline in vivo and in vitro.

The effect of ethanol consumption on the sensitivity of rat brain mitochondrial monoamine oxidases to the inhibition by pargyline in vivo and in vitro was investigated. Administration of pargyline (10 mg/kg, s.c.) produced significantly higher inhibition of MAO-A in alcoholised rats, whereas MAO-B inhibition did not differ from that observed in control animals. The concentration-response curve for the inhibition of brain mitochondrial MAO-A and MAO-B by pargyline in vitro did not reveal higher sensitivity of MAO from alcoholised rats to pargyline. This probably means that more pronounced inhibition by pargyline of brain MAO-A in alcoholised rats in vivo can be attributed to decreased content of compounds reversibly interacting with the its catalytic site. Taking into consideration some ethanol-induced decrease of brain tribulin content we suggest that the reduced level of endogenous inhibitors (tribulin components?) may have some importance in the development of alcoholism.