ENDOTOXIN-INDUCED APOPTOSIS IN OVARIAN FOLLICLES IS PARTIALLY BLOCKEDBY 2-METHYLTHIOATP OR 2-CHLOROATP

The purposes of this study were to determine how early in time endotox in can trigger apoptosis of bovine ovarian follicles in vitro, and to further characterize if these inductions are mediated via adenine nucl eotides and the P2 purinergic receptors. Healthy preantral and early a ntral follicles (400 and 700 mu m) isolated from bovine ovaries were s andwiched between two layers of collagen gel and incubated (39 degrees C, 5% CO2, 95% air) for various time periods up to 72 hr, floating in complete medium with either 2-MethylThioATP or with 2-ChloroATP, or w ith or without LPS (10 or 50 mu g/ml), or with combinations of LPS wit h 2-MethylThioATP or 2-ChloroATP, Data from histological examination, and in situ detection of apoptotic DNA cleavage, showed that by 2 hr f rom start of incubation, both doses of LPS had triggered apoptosis of granulosa cells (P < 0.001), and simultaneously decreased estradiol co ncentrations to nondetectable levels (P < 0.001), but progesterone val ues increased (P < 0.001) with time of incubation. Both 2-MethylThioAT P and 2-ChloroATP inhibited (P < 0.001) LPS (10 and 50 mu g/ml)-induce d apoptosis by 30% to 100%. We concluded that adenine nucleotides play a fundamental role in endotoxin-induced apoptosis/atresia of bovine f ollicles, probably via the P2 purinergic receptors. It is possible tha t during the first 2 hr of incubation, the apoptotic events associated with LPS-induced follicular atresia might not be detectable with the procedures used in this study. (C) 1996 Wiley-Liss, Inc.