INFLUENCE OF ZINC ON 17-BETA ESTRADIOL AND PROGESTERONE RELEASE FROM DISPERSED RAT OVARIAN-CELLS

To test the hypothesis that Zn can affect ovarian steroidogenesis, the influence of dietary Zn levels (+Zn: 25 mu g Zn/g diet; -Zn: 0.5 mu g Zn/g diet) and medium Zn concentrations on in vivo and in vitro 17 be ta estradiol and progesterone release was examined. Maternal dietary t reatment (0.5 mu g Zn/g diet) was initiated on day 9 postnatal. Two da ys after injection with pregnant mare's serum gonadotropin, blood and ovaries were collected from immature rats (25-33 d old). Serum Zn, 17 beta estradiol, and progesterone were determined. Primary cultures of dispersed ovarian tissue were incubated in varying Zn concentrations ( 0.3, 5, 15, or 25 mu mol/l) for 24 h, and media were collected for det ermination of 17 beta estradiol and progesterone. Serum Zn concentrati ons were lower in -Zn than in +Zn rats (5.1 +/- 0.52 vs. 25.5 +/- 1.29 mu mol/l; P < .001). Serum concentrations of 17 beta estradiol (-Zn = 241 +/- 25 pg/ml; +Zn = 249 +/- 40 pg/ml; P>.05) and progesterone (-Z n = 8.49 +/- 3.99 ng/ml; +Zn = 9.72 +/- 3.22 ng/ml; P>.05) were simila r between groups. In vitro 17 beta estradiol and progesterone release were not influenced by either dietary or media Zn treatment (P>.05). ( C) 1993 Wiley-Liss, Inc.