Estrogen-Induced 16-Hydroxysteroid Dehydrogenase Activity in Rat Kidney

Abstract

The activity of an enzyme system which readily converts estriol to 16-ketoestradiol is present only in the kidneys of mature female rats and is absent in the kidneys of male rats and immature rats of either sex. The full enzyme activity occurs in kidneys of rats of either sex at any stage of maturity after administration of estradiol for 2 weeks. The time course of the appearance and disappearance of the enzyme, the absence of detectable inhibitors and activators, and evaluation of cofactor requirements suggest that this may be an example of enzyme induction by the hormone. Furthermore, the enzyme activity itself represents a metabolic pathway for estriol metabolism whose potential quantitative significance has not heretofore been recognized.