Animal Reproduction Science39 ( 1995) 81-87 Effects of oxytocin, vasopressin and vasotocin and their agonists on steroid secretion by bovine granulosa cells Alexander V . Sirotkin”* * , Josef Nitray”, Larisa W. Tarasenkob, Pave1 Uhrin”, Jozef LaurinEik”, Jozef Bulla” “ Research Institute of Animal Production. Hlohovska 2, 949 92 Nitra, Slovak Republic ‘Kiev Research Institute of Endocrinology and Metabolism, Kiev 252114, Ukraine Accepted 5 January 1995 Abstract The effects of oxytocin and vasopressin and their agonists on the secretion of progesterone and oestradiol-17/3 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-Svasopressin ( 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 oestradioL17P 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. Keywords: Ovary; Oxytocin; Vasopressin;Vasotocin;Progesterone; Oestradiol 1. Introduction Oxytocin (OT) , arginine-8-vasopressin (AVP) and related peptide hormones can be synthesised within the gonads and play an important role as autocrine regulators of gonadal hormone production (Wathes, 1989; Wathes and Denning-Kendall, 1992). However, avail- able data about the steroidogenic effects of peptide hormones are limited mainly to an inhibitory influence of OT on progesterone production by isolated luteal cells (Mukhopa- * Corresponding author. 0378-4320/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDIO378-4320(95)01379-2