The action of LH-releasing hormone and five analogues on oestradiol, oxytocin and vasopressin secretion by bovine granulosa cells in culture.

The release of oxytocin, arginine-8-vasopressin and oestradiol-17 beta by bovine granulosa cells in culture was analysed either with or without LH-releasing hormone (LHRH), its agonists (cyclo [Pro1DPhe6] LHRH and des 1-3, 10[DAla6] LHRH) or antagonists ([DPhe2DPhe6] LHRH, [DPhe2DPhe(NH2)6] LHRH or cyclo [Pro1DPhe2DPhe6] LHRH). All preparations used stimulated granulosa oxytocin and oestradiol secretion. Vasopressin release was significantly increased after all treatments with LHRH antagonists, but not after LHRH or its agonists. Our observations demonstrated a direct influence of LHRH and its analogues on the secretion of oestrogen and nonapeptide hormones by bovine granulosa cells. A comparison of the effects of LHRH, its agonists and antagonists suggests that the action of these peptides at the hypophysial and ovarian level is relatively independent.