Corticosteroid secretion after the soy extract application to orchidectomized adult male rats

Abstract

Herein, we have tested the effects of application of commercial soy extract, rich in estrogen-like isoflavones, to orchidectomized adult rats (the model of mild andropause), on the corticosteroid secretion. Exploited animal model provides the opportunity to examine the potential effects of steroid-like compounds in the hormonal milieu deprived of endogenous sex steroids along with preserved hippocampal and hypothalamic regulation of the adrenal gland function. The experimental groups included sham-operated (SO), orchidectomized (Orx) and soy extract-treated orchidectomized (Orx + Soy; 30 mg/kg b.m. s.c., for 3 weeks) rats. Plasma level of ACTH and serum levels of aldosterone, corticosterone and DHEA were determined by the immunoassays. Orchidectomy caused the increase (P<0.05) of circulating ACTH, aldosterone and DHEA by 57.0%. 2.6 and 2.0 folds respectively, compared to SO group. In Orx + Soy group, blood levels of ACTH and corticosterone were higher (P<0.05) by 99.5% and 79.6% respectively, in comparison with SO group. Also, the treatment of orchidectomized rats with soy extract elevated (P<0.05) the systemic levels of ACTH, aldosterone and corticosterone by 26.9 %, 2.7 folds and 56.4% respectively, while the circulating DHEA level was decreased (65.6%; P<0.05), all compared to the corresponding parameters in Orx rats. Summarily, soy extract raised the ACTH level which has stimulatory influence on the mineralocorticoid and glucocorticoid output, while the adrenal androgens consequently fallen, in the rat model of mild andropause. The data support impression of a beneficial effect of soy isoflavone mixture on the homeostatic response to stress, but also call for precautions in the case of cardiovascular issue presence.