EFFECTS OF OXYTOCIN, VASOPRESSIN AND VASOTOCIN AND THEIR AGONISTS ON STEROID-SECRETION BY BOVINE GRANULOSA-CELLS

The effects of oxytocin and vasopressin and their agonists on the secr etion of progesterone and oestradiol-17 beta by bovine luteinised gran ulosa cells cultured in a serum-supplemented medium were analysed. The effects of oxytocin (OT), its long-acting agonist 2-O-methyl-tyrosin( deamino-karba)-oxytocin (DK-OT), arginine-8-vasopressin (AVP), 1-desam ino-arginine-8-vasopressin (D-AVP, a vasopressin analogue with high an tidiuretic and without vasopressor properties) and arginine-8-vasotoci n (AVT) were investigated. It was found that OT and DK-OT had a stimul atory effect on progesterone release, while AVP, D-AVP and AVT had an inhibitory effect. All peptide hormones investigated significantly inc reased oestradiol-17 beta secretion. The results suggest the involveme nt of nonapeptide hormones of both oxytocin and vasopressin groups in the regulation of steroidogenesis by granulosa cells from bovine ovari an follicles.