Effect of estradiol-17 beta and luteinizing hormone on progesterone secretion by luteal cells from early pregnant, estradiol benzoate-treated and human chorionic gonadotropin-treated sows.

The present study was conducted to examine the effect of estradiol 17 beta (E2) and luteinizing hormone (LH) on progesterone (P4) secretion by luteal cells from early pregnant, estradiol benzoate (EB)-treated and hCG-treated sows and to compare the sensitivity of these cells to used exogenous hormones in vitro. Trypsin-dispersed luteal cells (5 X 10(4) cells/ml) were incubated with E2 (doses: 0.001, 0.01, 0.1, 1 and 5 micrograms/ml), with LH (doses: 0.01, 0.1 and 1 microgram/ml) and with E2 (1 microgram) plus LH (0.01, 0.1 and 1 microgram doses). Control cultures were incubated without exogenous hormones. The P4 level was estimated by radioimmunoassay after 1, 3 and 6 hour incubation. Luteal cells from hCG-treated sows released significantly more (P less than 0.05) P4 than the cells from EB-treated and pregnant pigs, the luteal cells from pregnant sows produced the least P4 amounts (P less than 0.05). The cells from pregnant pigs enhanced P4 secretion under influence of higher doses of LH and the cells from EB-treated sows under lower LH doses. The cells from hCG-treated animals did not respond to LH. E2 did not change P4 production by luteal cells from sows in the three investigated physiological stages, only the 0.01 microgram E2 dose stimulated (P less than 0.05) P4 release by the cells from pregnant pigs. E2 inhibited luteotropic LH action upon P4 secretion by luteal cells from pregnant and EB-treated sows. The results suggest that the luteal cells from early pregnant, EB-treated and hCG-treated sows differ from each other in steroidogenic potency and in the strength of reaction to E2 and LH.