In vitro and in vivo effect of chloropromazine, imipramine and lithium chloride on monoamine oxidase activity in rat brain mitochondria

Chloropromazine (CPZ) and imipramine at a concentration of 1×10−3 M inhibit rat brain mitochondrial monoamine oxidase activity in vitro by 70 and 55% respectively, while lithium, even at a concentration of 0.05 M, inhibits the activity of this enzyme very negligibly (4%). In vivo, these drugs at a dose level of 56 mg CPZ, 76 mg Jimipramine and 76 mg lithium chloride/Kg body wt., did not cause any observable variation from normal in brain mitochondrial monoamine oxidase activity.