[Hormonal regulation of 5 alpha-reductase activity in anterior pituitary gland microsomes of the male rat].

It was previously shown that the microsomal 5 alpha-reductase activity in the male rat pituitary was increased by castration. Subcutaneous administration of androgens to castrated rats prevented the rise in 5 alpha-reductase activity. Their relative efficiency was as follows: 5 alpha-dihydrotestosterone greater than 5 alpha-androstane-3 alpha, 17 beta-diol greater than testosterone. Under our experimental conditions 5 alpha-androstane-3 beta, 17 beta-diol and estrogens were inefficient. The rise in 5 alpha-reductase activity following castration is exclusively located in hypophysis and it is probably due to an increased of the enzyme biosynthesis.