The stimulatory effect of corticotrophin on testicular testosterone release in male rabbits.
Intravenous injection of 1-24 ACTH synthetic analogue (10 micrograms/kg body weight 1-24 ACTH) via permanent indwelling jugular catheters to intact male rabbits, resulted in a rapid rise of plasma corticosteroid (C) and plasma testosterone (T) levels. Mean C levels were significantly elevated during the period between 10 and 100 min after ACTH administration whereas mean T concentrations showed a significant rise at 20 min after the 1-24 ACTH administration. On the other hand a significant suppression of plasma T levels was observed 120 min p.i., indicating a biphasic effect of 1-24 ACTH on plasma T levels. Castrated animals reacted to 1-24 ACTH with mean C levels, comparable to concentrations in intact rabbits, whereas their lowered plasma T concentrations showed no changes. When 1-24 ACTH was administered to intact animals 96 h after pretreatment with HCG, plasma T levels were significantly elevated at 20 min after 1-24 ACTH injection whereas a second HCG injection was ineffective in modifying T concentrations. From these results we concluded, that exogenously applied 1-24 ACTH can effectively stimulate the testicular T release in adult male rabbits and that such release is independent of the LH receptors in Leydig cells.
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D008297:Male; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000187:drug effects; D011974:Receptors, LH; D013268:Stimulation, Chemical; D013737:Testis / Q000187:drug effects* / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism*
D006063:Chorionic Gonadotropin; D011956:Receptors, Cell Surface; D011974:Receptors, LH; D013739:Testosterone; D000324:Adrenocorticotropic Hormone