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 secretion of progesterone and oestradiol-17β by bovine luteinised granulosa cells cultured in a serum-supplemented medium were analysed. The effects of oxytocin (OT), its long-acting agonist 2-0-methyl-tyrosin (deamino-karba)-oxytocin (DK-OT), arginine-8-vasopressin (AVP), 1-desamino-arginine-8-vasopressin (D-AVP, a vasopressin analogue with high antidiuretic and without vasopressor properties) and arginine-8-vasotocin (AVT) were investigated. It was found that OT and DK-OT had a stimulatory effect on progesterone release, while AVP, D-AVP and AVT had an inhibitory effect. All peptide hormones investigated significantly increased oestradiol-17β secretion. The results suggest the involvement of nonapeptide hormones of both oxytocin and vasopressin groups in the regulation of steroidogenesis by granulosa cells from bovine ovarian follicles.