Estrone sulfate sulfohydrolase in the developing brain and pituitary of rat, mouse and guinea pig

Steroid sulfatase in mouse liver and testis: Characterization, ontogeny and localization

Steroid hormones often circulate in the plasma as inactive sulfated forms, such as estrone sulfate and dehydroepiandrosterone sulfate. The enzyme steroid sulfatase (STS) converts these steroids into active forms, mainly estrogens, in peripheral tissues. STS is present in most tissues, but it occurs at higher levels in certain organs, notably liver and placenta. In this study, we examined the tissue distribution of STS in a prominent laboratory model, the house mouse (Mus musculus). Tissues included were heart, liver, small intestine, skeletal muscle, and gonads of both sexes. An 3H-estrone-sulfate conversion assay was used to measure STS activity in tissue homogenates and extracts. STS activities were high for hepatic tissue homogenates of both genders. Testicular STS levels were similar to those of liver, while STS activities of ovary, small intestine, heart, and muscle were considerably lower. The specific STS inhibitors, EMATE and STX-64 virtually eliminated STS activity in hepatic microsomes and cytosols, verifying that the observed enzyme activity was due to STS. Enzyme kinetic assays showed Km values of 8.6 µM for liver and 9.1 µM for testis, using E1S as substrate. Hepatic and testicular STS activities, measured in CHAPS-extracted microsome, were low up to 5 weeks of age and were higher through 56 weeks. Western blotting, with a specific STS antibody, confirmed the presence of STS protein (65 Da) in both liver and testis. Immunofluorescence of tissue sections detected the presence of STS protein in hepatocytes, in testicular Leydig cells and in seminiferous tubules (Leydig cells and developing germ cells). These results suggest that STS may have a significant role in testicular function.

Ovine fetal estrogen sulfotransferase in brain regions important for hypothalamus-pituitary-adrenal axis control

Ovine parturition is initiated by increases in fetal hypothalamus-pituitary-adrenal (HPA) axis activity which, in turn, increase placental estrogen biosynthesis and ultimately increase uterine contractility. In addition to their action in the uterus, estrogens in fetal plasma augment fetal corticotropin (ACTH) secretion. In late gestation, estrone sulfate is more abundant in fetal plasma than unconjugated estrone and it is possible that there is interconversion of sulfoconjugated and unconjugated steroids within the fetal brain. We studied hypothalamus and brainstem tissue from fetal, neonatal, and adult sheep to test the hypothesis that the ovine brain contains estrogen sulfotransferase. Although no significant ontogenic pattern was revealed, the presence of estrogen sulfotransferase within the hypothalamus and brainstem was detectable. Immunohistochemistry revealed the presence of estrogen sulfotransferase in the paraventricular nucleus of the hypothalamus, the nucleus of the tractus solatarius, and the rostral ventral lateral medulla. We conclude that ovine fetal hypothalamus and brainstem contain estrogen sulfotransferase in brain regions important for HPA axis control.

Ontogeny of estrogen sulfatase activity in ovine fetal hypothalamus, hippocampus, and brain stem

Ovine parturition is initiated by increases in fetal hypothalamus-pituitary-adrenal (HPA) axis activity, which in turn increase placental estrogen biosynthesis and ultimately increase uterine contractility. In addition to the action in the uterus, estrogens augment fetal ACTH secretion. In late gestation, estrone sulfate is more abundant in fetal plasma than is unconjugated estrone. We studied hypothalamus, hippocampus, and brain stem tissue from fetal, neonatal, and adult sheep to test the hypothesis that the ovine brain contains estrogen sulfatase activity. We found that the activity in the hippocampus was significantly increased in late-gestation fetuses compared with both younger and older animals. No significant change in either hypothalamus or brain stem was revealed; however, the activity in all brain areas was high. Immunohistochemistry revealed the presence of estrogen sulfatase in the paraventricular nucleus of the hypothalamus, the nucleus of the solitary tract, and the rostral ventrolateral medulla. We conclude that ovine fetal hypothalamus, hippocampus, and brain stem contain estrogen sulfatase activity and that the activity in the hippocampus is developmentally regulated.

Estrone sulfatase activity in rat brain and pituitary: effects of gonadectomy and the estrous cycle

Estrone sulfatase activity was characterized in microsomal preparations from rat brain and anterior pituitary. No differences in apparent Km were found in hypothalamic-preoptic area between male (7.5 microM) and female (7.4 microM) rats. Apparent Km's of anterior pituitaries from males (14.5 microM) and females (22.5 microM) were higher than those found in brain. Estrone sulfatase activity was equally inhibited by estradiol-17 beta-3-sulfate, dehydroepiandrosterone-3-sulfate and estrone-3-sulfate indicating a broad range of substrate specificity for this enzyme. Sulfatase activity in female anterior pituitary was found to be twice that of male. Sulfatase activity was distributed similarly in brain tissues between sexes with cerebellum greater than or equal to medial basal hypothalamus greater than preoptic area = cortex. Following gonadectomy, sulfatase activity in anterior pituitary of males was significantly greater than activity found in intact animals (P less than 0.05). This increase in activity, however, was unaffected by treatment with testosterone, dihydrotestosterone or estradiol-17 beta. Gonadectomy did not change sulfatase activity in brains of males or females or in pituitaries of females. However, sulfatase activity in pituitary glands of females changed significantly (P less than 0.05) with stages of the estrous cycle (metestrus less than diestrus less than proestrus less than estrus). These data indicate sulfatase activity in rat anterior pituitary gland may be controlled by gonadal factors while sulfatase activity in brain is regulated differently.