The effects of LH on progesterone production by cell subpopulations isolated from early and late luteal phase goat corpora lutea

The objective of this study was to investigate the complementary effects of luteinizing hormone (LH) on cell subpopulations. Corpora lutea were collected on days 5 and 15 of the cycle. The luteal tissues were treated with collagenase for cell dissociation. Percoll density-gradient centrifugation was performed to separate cells into 2 distinct subpopulations. Luteal cells (5 x 104 cells/well) were cultured with and without 22(R)-hydroxycholesterol (22R-HC, 10 mu g/mL) and LH (10 and 100 ng/mL) alone, and also with 22R-HC (10 mu g/mL) plus LH (10 and 100 ng/mL), in a serum-free culture medium for 6 days of incubation. Untreated cells isolated from luteal tissue collected on day 15 of the estrous cycle produced more steroids than those collected on day 5. Treatment of the cells with LH resulted in a significant (P < 0.05) increase in steroid synthesis on both days 5 and 15 of the cycle. Throughout the 7 days of incubation, 22R-HC caused a significant increase in progesterone production compared to untreated controls and to the LH treatments (P < 0.01). As a result, it appears that LH is mainly effective on small luteal cells in both the early and late luteal stages in goats.