Interleukin-1β fragment (163-171) modulates bovine granulosa cell proliferation in vitro:: dependence on size of follicle

The biological effects of IL-1 on ovarian function have been considered as an inflammatory-like reaction. The peptide fragment of IL-1 (163-171 aa), which belongs to the active site of the whole protein, has been shown to exert an immunostimulatory activity without inducing inflammatory effects. The aim of this study was to investigate whether IL 163-171, alone or associated with bFSH, modulates granulosa cell proliferation; in addition, we wanted to assess if IL 163-171 interferes with FSH binding to receptors. Bovine follicles were divided according to their size. Cell proliferation, assessed by [H-3]-thymidine uptake and [I-125]-FSH binding, were studied in cells treated with IL 163-171(0, 0.5, 5 and 20 ng/ml) with or without bFSH (100 ng/ml) for 24, 48 or 72 h. Basal incorporation of [H-3]-thymidine into granulosa cells from small follicles was always 3-fold higher (P < 0.01) than that by cells from large follicles. IL 163-171 did not show any effect in granulosa cells from large follicles but stimulated (P < 0.01) [H-3]-thymidine uptake into granulosa cells from small follicles; furthermore IL 163-171 interacted positively with bFSH (P < 0.01) after 48 and 72 h. IL 163-171 significantly reduced (P < 0.05) FSH binding in cells from small follicles after 24 h, but not after 48 and 72 h. This data demonstrates that: (1) Follicular size and cell proliferation are inversely related; (2) IL 163-171 modulates granulosa cell proliferation only in cells from small follicles; and (3) the interaction between IL 163-171 and FSH does not mainly occur at receptor level. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.