2009 Volume 71 Issue 3 Pages 281-285
Previously we reported that androgen treatment reduced the extent of the increase in plasma cortisol (Cor) levels induced by adrenocorticotropic hormone (ACTH) administration in goats. In this study, we investigated the effect of androgen on the plasma levels of androstenedione and aldosterone. Four castrated male goats, which were treated with either 5α-dihydrotestosterone (DHT) or cholesterol (cho), were injected intravenously with 0.005, 0.02 or 0.1 mg of ACTH(1-24). Plasma Cor levels were increased significantly by all doses of ACTH injection, and these extents were lower in DHT-treated goats. Plasma androstenedione levels were also increased by ACTH injection, but DHT treatment seemed to little affect. Plasma aldosterone levels were also increased by ACTH injection, and there were no differences between cho- and DHT treated goats at 15 and 30 min after the ACTH injection. However, when goats were given the lower doses of ACTH (0.02 and 0.005 mg), plasma aldosterone levels were restored rapidly only in cho-treated goats, whereas those in DHT-treated goats were maintained throughout the 60 min experimental period. Consequently, plasma aldosterone levels in DHT-treated goats were higher than those in cho-treated goats at 45 and 60 min. One possible mechanism of the effect of DHT on the ACTH-induced increase in aldosterone synthesis may be the reduction of the activity of P450-17α, that is the enzyme to convert pregnenolone to 17α-OH-pregnenolone, and this mechanism may also be responsible to the suppressive effect of DHT on the ACTH-induced Cor synthesis.