Induction of porcine uterine estrogen sulfotransferase activity by progesterone.
Studies have been carried out which were designed to examine the hormonal requirement for the appearance of estrogen sulfotransferase activity in porcine uteri. Mature, ovariectomized (OVX) gilts were housed for 3 weeks before being treated with various regimens of estradiol-17 beta (E2) and progesterone (P). Uteri were then removed, minced, incubated for 2 h with [3H] E2 (10(-8) M) and Na2 35SO4 (10(-4) M) and the labeled metabolic products were extracted and analyzed. Endometrial samples were also taken for the determination of E2 and P cytoplasmic and nuclear receptors (R). It was found that 4 daily injections of 250 micrograms of E2 was sufficient to bring plasma E2 concentrations to that representative of a normal estrous cycle (approx. 30 pg/ml) and to induce cytoplasmic PR to high levels (7000--19000 fmol/mg DNA). Estrogen sulfotransferase activity, which was negligible in OVX and E2-treated pigs, increased to near normal secretory levels (4 pmol product/h per 0.4 g tissue) only in pigs primed with E2 and subsequently treated with E2 and P (25--250 mg/day, 3 days). This treatment also brought about the translocation of PR to the nuclear compartment. The steroid alcohol sulfotransferase activity in these tissues decreased upon ovariectomy and remained unaffected by the hormone treatments. Endometria from treated and untreated pigs were cultured for a period up to 7 days. During this time E2 (10(-8) M) induced and/or maintained PR and P (10(-6) M) was shown to stimulate estrogen sulfurylation concomitant with the translocation of PR to the nucleus. These studies have demonstrated that, in OVX pigs and endometrial cultures, P stimulated uterine estrogen sulfotransferase activity to a level normally found in secretory uteri. In order for P to bring about elevated levels of estrogen sulfurylation it was necessary that the endometrium contain adequate concentrations of cytoplasmic PR (which required E2 priming of the system) and the P receptor complex must display nuclear translocation.[1]References
- Induction of porcine uterine estrogen sulfotransferase activity by progesterone. Meyers, S.A., Lozon, M.M., Corombos, J.D., Saunders, D.E., Hunter, K., Christensen, C., Brooks, S.C. Biol. Reprod. (1983) [Pubmed]
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