The stimulating effects of ethanol consumption on synthesis of rat brain monoamine oxidases and their sensitivity to the irreversible inhibitor, pargyline.

Administration of a large dose of pargyline (60 mg/kg) caused total irreversible inhibition of brain monoamine oxidases (MAOs) in both control and alcoholised rats. During the first 50 h the recovery of brain MAO-A (but not MAO-B) activity occurred faster in the alcoholised rats. A low dose of pargyline (10 mg/kg) produced significantly higher inhibition of MAO-A in the alcoholised rats, whereas the degree of MAO-B inhibition was the same in both groups. Brain MAOs of control and alcoholised rats exhibited similar sensitivity to pargyline in vitro. Since chronic ethanol feeding reduced the content of reversible endogenous MAO inhibitor, tribulin, higher pargyline-induced inhibition of MAO-A in alcoholised rats may stem from a tribulin deficit. The data obtained suggest that chronic ethanol consumption increases turnover of MAO-A molecules in the brain and reduces the content of endogenous MAO(A) inhibitors.