Dual regulation of 21-hydroxylase activity by sex steroid hormones in rat hepatocytes.
In the rat liver, cytochrome P450 catalyzes the hydroxylation of steroid hormones. The expression and activity of some P450 isozymes are regulated by sex steroid hormones. Steroid 21-hydroxylase activity in rat liver is provided mainly by CYP2C6. We studied the regulation of 21-hydroxylase activity by sex steroid hormones in rat primary hepatocyte culture. We added estrogens (estrone, estradiol, estriol) and androgens (testosterone, dihydrotestosterone), (ranging from 10(-9) to 10(-5)M) to the culture. The 21-hydroxylase activity was stimulated by estrogens and was suppressed slightly by androgen in a dose-related manner. The results of our studies demonstrated that sex steroid hormones act differently on 21-hydroxylase activity in rat hepatocytes and, thus, support the hypothesis that the extra-adrenal production of deoxycorticosterone from circulating progesterone is increased during pregnancy by the massive presence of estrogens.
Endoh
A
A
Department of Pediatrics, Hamamatsu University School of Medicine, Japan.
Natsume
H
H
Igarashi
Y
Y
D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D004967:Estrogens / Q000494:pharmacology*; D008099:Liver / Q000201:enzymology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013255:Steroid 21-Hydroxylase / Q000378:metabolism*
D000728:Androgens; D004967:Estrogens; D013255:Steroid 21-Hydroxylase