The Stimulatory Effect of Corticotrophin on Testicular Testosterone Release in Male Rabbits

Summary

Intravenous injection of 1—24 ACTH synthetic analogue (10 μg/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.

Key words

ACTH - testosterone - male rabbit