Hormonal regulation of activities of 4-ene-5β- and 5α-reductases and 17β-hydroxy-dehydrogenase in immature golden hamster testis

Abstract

We have reported [1–3] in immature golden hamster testis that 5β-reductase is localized in the tubular nongerm cells, while 5α-reductase is present in the interstitial tissue and that the 17β-hydroxy-dehydrogenase activity is found predominantly in the tubular nongerm cells. Hormonal regulation of these enzyme activities was examined in the present study. Male golden hamsters were hypophysectomized on day 22 after birth. The hypophysectomized hamsters in groups of 3–8 were injected daily with 10 μg NIH-LH-S19, 50 μg NIAMD-Rat-FSH-B-1, 8 or 16 μg NIAMD-oFSH-13, 8 μg NIAMD-oFSH-13 plus 5 or 10 μg NIH-LH-S19, 1 mg testosterone propionate or saline for 5 days starting from day 23. Testicular homogenates of the treated hamsters and intact hamsters on day 28 were incubated with [ 14C]4-androstene-3,17-dione and NADPH, and enzyme activity (nmol/testes/h) was estimated. The activities of 5β- and 5α-reductases and 17β-hydroxy-dehydrogenase decreased significantly 6 days after hypophysectomy. In the hypophysectomized hamster testis, a distinct response to FSH but not to LH in the activities of 5β-reductase and 17β-hydroxy-dehydrogenase was found. The injection of LH in addition to FSH showed no significant additive effects on these enzyme activities. The 5α-reductase activity was stimulated significantly by LH plus FSH but not by LH alone, FSH alone or androgen. These results show that 5β -reduction of 4-ene-3-ketosteroids takes place in the Sertoli cells under the influence of FSH while 5α-reduction occurs in the interstitial cells under the influence of LH and FSH in immature hamster testis.