Interleukin-1 Stimulates Growth and Inhibits Progesterone Secretion in Cultures of Porcine Granulosa Cells*

Abstract

Interleukin-1 (IL-1) significantly inhibited basal progesterone secretion and influenced the cell number in high density cultures of porcine granulosa cells harvested from small (1-2 mm) or medium (3-5 mm) follicles. These two effects of IL-1 showed similar but inverse dose-response relationships: Significant effects were observed at concentrations higher than 50 pg/ml, and the maximal effective concentration was 5 ng/ml, which reduced progesterone secretion by 53.5 +/- 2.1%. In contrast, IL-1 neither inhibited progesterone secretion nor did it influence cell number in cultures of fully mature granulosa cells harvested from the largest (8-11 mm) follicles. The growth-promoting effect of IL-1 on granulosa cells was further examined in the low density cultures, which revealed that IL-1 significantly stimulated proliferation of the less mature granulosa cells at concentrations higher than 50 pg/ml, and that at a maximal stimulatory concentration (25 ng/ml) it increased cell number to 206 +/- 11% of control. Although IL-1 increased cell number and reduced progesterone secretion of fully mature granulosa cells after 5 days in low density cultures, it seemed that the proliferating population were not the cells with luteinized morphology and positive 3 beta-hydroxysteroid dehydrogenase staining. The proliferating population of cells appeared to have less mature morphology and were negative for 3 beta-hydroxysteroid dehydrogenase staining.