Immunoreactivity for Gonadotropin-Releasing Hormone in Microdialyzed Perfusates of Bovine Mature Follicles In Vitro

The presence of gonadotropin-releasing hormone (GnRH)-like protein has been previously demonstrated in the bovine folicle. This GnRH-like protein was purified and concluded to be histone H2A. However. neither GnRH peptide nor specific GnRH-immunoreactivity (GnRH IR) has been demonstrated in the bovine folicIe 50 far. Thus. this study focused 00 the detection of specific GnRH-IR using the second-antibody enzyme immunoassay in isolated bovine mature follicles, and 00 an examination of the direct effect of luteinizing hormone (LH). endothelin-l (ET1), and cytokines on the GnRH-IR using an in vitro microdialysis system (MDS). We further examined a cross-reactivity of the GnRH antibody with bovine histone H2A. GnRH:-IR was detected in microdialyzed perfusate from isolated bovine mature folic1es at 4ιo :t 0.35 pg/m1 (mean士SEM).Bovine histone H2A showed no GnRH-IR at all. Heat treatment of the extract (100 C for 10 min) did not affect the GnRH.IR. Sing1e infusion of LH. ET-l. or cytokines into the MDS did not affect the GnR~-IR. However, infusion of ET-l after LH exposure iocreased the GnRH-IR These results demonstrate the presence of specific GnRH-IR,出atis different from histone H2A, in microdialyzed perfusate of isolated bovine mature follicles in vitro, suggesting that the GnRH-IR may reflect a role of GnRH-like peptide or some peptide structurally similar to GnRH in the local regulation of mature folic1es