Effect of Pregnancy on the LH Response to Synthetic Gonadotropin-Releasing Hormonein the Ewe

Synthetic gonadotropin-releasing hormone (Gn-RH) was administered by intracarotid infusion (1.5 µg⁄hr for 5 hr) into groups of ewes at 6, 13 and 18 weeks gestation, at about the time of parturition and at 3 and 6 weeks postpa. rtum. There was a progressive decrease in the LH response to Gn-RH during gestation with no detectable LH release by 18 weeks. Little or no responsewas obtained at term or 3 weeks postpartum, and recovery was only partial as late as 6 weeks after delivery. (Endocrinology 94: 291, 1974)