Effect of in vitro administration of LH, prolactin separately and LH and prolactin in mixture, on cultured Leydig cells from mouse testes: I. Changes of delta 5, 3 beta-hydroxysteroid dehydrogenase during postnatal life.

Activity of delta 5, 3 beta-hydroxysteroid dehydrogenase in cultured Leydig cells isolated from mouse testes of various age was quantitatively investigated. Activity of delta 5, 3 beta-HSD was low in testes after birth and increased in 21 day old mouse, and then decreased in Leydig cells of 28 day old animals. Maximum activity of dehydrogenase within Leydig cells was observed in 60 day old mice and then gradually declined simultaneously with ageing process. Significant increase of enzymes activity was observed in Leydig cells cultured in medium containing a mixture of 100 ng LH and 100 ng PRL/ml. Doses of either 100 ng LH alone or 100 ng PRL alone showed higher stimulation than lower doses of 10 ng. Changes of activity were statistically significant.