Effect of Estradiol-17β and Luteinizing Hormone on Progesterone Secretion by Luteal Cells from Early Pregnant, Estradiol Benzoate-Treated and Human Chorionic Gonadotropin-Treated Sows

Summary

The present study was conducted to examine the effect of estradiol 17β (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 X10⁴ cells/ml) were incubated with E₂ (doses: 0.001, 0.01, 0.1, 1 and 5 μg/ml), with LH (doses: 0.01, 0.1 and 1 μg/ml) and with E₂ (1 μg) plus LH (0.01, 0.1 and 1 μg 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 < 0.05) P₄ than the cells from EB-treated and pregnant pigs, the luteal cells frompregnant sows produced the least P₄ amounts (P < 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 μg E₂ dose stimulated (P < 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.

Key words

Estradiol 17β - LH - Luteal cells - Progesterone - Sow