Prolactin increases 17β-hydroxysteroid dehydrogenase activity in the testis

Dwarf male mice were treated with prolactin either by the implantation of a normal mouse pituitary under the kidney capsule or by sc injection. The testes were homogenized and the supernate from a 10, 000 × g centrifugation was assayed for 17β-hydroxy steroid dehydrogenase activity (17-HSD). The total activity of this enzyme was enhanced 244% above the controls by a grafted pituitary, in place for nine days. The subcutaneous injection of prolactin for a period of four days produced an enhancement of 186% above the controls. The results demonstrate an action of prolactin on the 17-HSD in dwarf mice and suggest the possible involvement of this hormone in sexual maturation. © 1972 by The Endocrine Society.