Sex hormones metabolism in the brain: influence of central acting drugs on 5 alpha-reduction in rat diencephalon.

Rats after adrenalectomy-testectomy showed a gradual increase in diencephalon 3-oxo-5 alpha-steroid: (acceptor) delta4-oxidoreductase (5 alpha-reductase) activity for 3 days. The activity then returned near to the normal range on the 4th postoperative day. When rats were given testosterone propionate (TP) 3 days after adrenalectomy-testectomy, diencephalon 5 alpha-reductase activity returned to the preoperative range 2 hr after TP administration. Diencephalon 5 alpha-reductase activity showed a highly significant increase (p less than 0.01) after a single administration of carbamazepine, reserpine, diazepam, phenytoin, phenobarbital or disulfiram. A significant increase (p less than 0.05) was also found after a single administration of methylphenidate, caffeine or methamphetamine. Plasma testosterone decreased concurrently after administration of all these agents, except diazepam. Diencephalon enzyme activity decreased significantly after repeated disulfiram administrations (p less than 0.01) but increased significantly after methamphetamine administrations (p less than 0.05). Plasma testosterone showed a tendency to decrease after repeated methamphetamine administrations but tended to increase after repeated disulfiram administrations.