Effects of interleukin-1β fragment (163-171) on progesterone and estradiol-17β release by bovine granulosa cells from different size follicles

Recent studies indicate that interleukin-1β may play a role in ovarian function. To explore this possibility, we examined the effects of a fragment of interleukin-1β (163-171 aa) on progesterone and estradiol-17β production by bovine granulosa cells from small (< 5 mm) and large (> 8 mm) follicles; in addition we investigated the distribution of monocytes/macrophages, a possible source of interleukin-1β in the follicles, to determine a possible relationship between production of the cytokine and its activity. Bovine follicles were divided according to the size, granulosa cells were obtained by aspiration and plated at a density of 105 cells/well; then different concentrations of interleukin-1β fragment (0, 0.5, 5, 20 ng/ml) with or without bFSH were added for 24 h. Progesterone (P4) and estradiol-17β (E2) concentrations in media were evaluated by validated RIAs. Interleukin-1β (0.5 and 5 ng/ml) stimulated (P < 0.05) P4 output in both small and large follicles, while FSH-induced P4 output was reduced (P < 0.05) in large but not in small follicles by all the concentrations of peptide. FSH-induced E2 output was reduced (P < 0.05) in large, but not in small follicles. Immunohisto- and cytochemistry revealed a higher number of monocytes/macrophages in large follicles. It appears from our data that: (1) interleukin-1β fragment may modulate steroidogenesis in bovine granulosa cells depending on the stage of development of the follicle, and (2) the presence of monocytes/macrophages is related to this modulation.