Effects of hyperprolactinemia on FSH- or LH-induced activities of 17 beta-oxidoreductase, 5 alpha-reductase, and 17-hydroxylase in hypophysectomized rat testes.
Two pituitaries from 7-week-old female rats (Sprague-Dawley strain) were grafted under the capsule of the left kidney of a 49-day old male rat. The pituitary grafted and sham-operated rats were hypophysectomized at 56 days of age. The hypophysectomized rats were given daily injections of NIAMDD-oFSH-13 (20 micrograms/0.5 ml saline), NIAMDD-oLH-23 (9 micrograms/0.5 ml saline) or saline for 4 days starting from day 58. The treated rats and normal male rats were killed at 61 days of age. Testicular homogenates were incubated with [14C]4-androstene-3, 17-dione or [3H] progesterone, and enzyme activities per testes were estimated. Hypophysectomy caused significant decreases in activities of testicular 17 beta-oxidoreductase and 17-hydroxylase. The decreased activity of 17 beta-oxidoreductase was significantly stimulated by FSH or LH treatment, whereas the decreased 17-hydroxylase activity was stimulated only by LH treatment. Although pituitary grafts alone showed little or no effect on these enzyme activities in the hypophysectomized rats, the grafts significantly inhibited FSH-stimulated 17 beta-oxidoreductase activity and the LH-stimulated 17 beta-oxidoreductase and 17-hydroxylase activities but enhanced LH-induced 5 alpha-reductase activity. The present results confirm previous findings that an excess of prolactin directly inhibits LH-stimulated 17-hydroxylase activity but enhances LH-induced 5 alpha-reductase activity in the rat testis. The present results also demonstrate that the same grafts directly inhibit FSH-stimulated 17 beta-oxidoreductase activity but have no effect on FSH-induced 5 alpha-reductase activity.
D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000378:metabolism; D000818:Animals; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D006966:Hyperprolactinemia / Q000201:enzymology*; D007016:Hypophysectomy; D007986:Luteinizing Hormone / Q000494:pharmacology; D008297:Male; D006899:Mixed Function Oxygenases / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*; D010902:Pituitary Gland / Q000637:transplantation; D051381:Rats; D011919:Rats, Inbred Strains; D013737:Testis / Q000201:enzymology*
D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase