In vivo effects of GnRH on expression of interleukin 1 (IL-1) system members in bovine preovulatory follicles and the influence of IL-1β on cumulus-oocyte complexes cultured in vitro

The purpose of this study was to determine the effects of in vivo GnRH treatment on mRNA expression of IL-1β system in bovine granulosa cells from preovulatory follicles and to analyze the in vitro effect of gonadotropins on the IL-1β system gene expression in cumulus cells. Moreover, the additive effect of IL-1β on cumulus expansion, gene expression and ultrastructural integrity of COCs cultured in vitro was evaluated. In vivo studies in granulosa cells demonstrated that IL-1RA mRNA levels were increased after 24 h of GnRH treatment. Similarly, the presence of gonadotropins increased the levels of mRNAs for IL-1R1 and IL-1RA in cumulus cells after 24 h of culture in vitro. The presence of IL-1β in culture medium did not influence cumulus expansion, but it increased the expression of mRNAs for IL-1β, IL-1RA, HAS2 and iNOS after COC culture. In addition, the ultrastructure of COCs cultured in vitro in the presence of IL-1β was maintained. In conclusion, IL-1RA mRNA is upregulated in granulosa cells at later stages of the ovulatory process in cattle. In cumulus cells, mRNA expression of IL-1RI and IL-1RA is induced by gonadotropins and IL-1β maintains the ultrastructure of COC cultured in vitro.