Regulation of hepatic sulfotransferase catalyzing the activation of N-hydroxyarylamide and N-hydroxyarylamine by growth hormone.

The regulatory mechanism of hepatic sulfation of N-hydroxyarylamine and N-hydroxyarylamide by endocrine factors has been studied in rats. The cytosolic sulfations of N-hydroxy-2-acetylaminofluorene (N-hydroxy-AAF) and 2-hydroxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (N-hydroxy-Glu-P-1), which were determined by the reductive formations of 2-acetylaminofluorene and Glu-P-1, were seven to nine times and three times higher, respectively, in male than female rats. Hypophysectomy of male rats decreased their activities to 23% and 41% of the levels of the untreated animals, respectively. Intermittent treatment of hypophysectomized male and female rats with human growth hormone (hGH) significantly increased their sulfating activities of both compounds. Infusion of hGH also enhanced the sulfating activity of N-hydroxy-AAF but not of N-hydroxy-Glu-P-1. The sulfating activity of N-hydroxy-AAF was also decreased by castration at neonate and was increased by the administration of testosterone propionate to gonadectomized male and female rats. Testosterone propionate and estradiol benzoate had no effect on hypophysectomized rats, but estradiol benzoate repressed the sulfating activities of N-hydroxy-AAF and N-hydroxy-Glu-P-1 in hGH-treated hypophysectomized male rats. These results indicate that sex steroids elicit their effects on the sulfations of N-hydroxyl-aryl compounds through modulating the action of growth hormone at hypothalamus-pituitary and hepatic levels in rat livers.