Ontogeny and hormonal basis of female-dominant rat hepatic sulfotransferases

Female-dominant sulfotransferases (ST) are a group of enzymes catalyzing sulfation of steroid hormones, bile acids and exogenous carcinogens. To understand the regulation of these enzymes, developmental and hormonal regulation of three female-dominant ST was studied. The three ST, ST-20/21, ST-40/41 and ST-60, were differentiated by specific oligonucleotide probes, and their gene expression was examined by Northern-blot analyses. The three ST have different developmental patterns, as ST-20/21 and ST-60 were increased after puberty in female rats, although ST-40/41 was higher in immature rats. In addition, ST-20/21 and ST-60 expression reached a peak at 30 days of age in male rats, although ST-40/41 reached its highest value in male rats at 15 days of age. Estrogens and androgens did not appear to be major determinants of the developmental profiles. However, ST-20/21 was decreased in both male and female rats by hypophysectomy, and reversed by continuous infusion (female pattern) of growth hormone (GH). In contrast, hypophysectomy elevated ST-40/41 and ST-60 expression in males. The elevation in males was reversed by GH injection (male pattern). This study demonstrates that the three female-dominant sulfotransferases display two ontogenic patterns and are regulated by different mechanisms. Female GH secretory pattern appears to determine the high expression of ST-20/21 in postpubertal female rats, although male GH secretory pattern results in the low expression of ST-40/41 and ST-60 in mature male rats.