Dopaminergic regulation of gonadotrophin secretion in seasonally anoestrous mares

摘要: We have previously demonstrated that daily administration of the dopamine D2 antagonist, sulpiride, during seasonal anoestrus, effectively advances mean time onset breeding season in mares. The purpose this study was to examine effect sulpiride on pulsatile FSH and LH secretion seasonally anoestrous mares, follicular development, first ovulation fertility at ovulation. Fourteen mares were selected based progesterone concentrations < 1 ng ml \m=-\1for 3 weeks largest follicle diameter 20 mm. Starting 30 January, eight treated with until year, six untreated control maintained under same environmental conditions. Ovarian activity monitored plasma samples collected every other day. On days 1, 11 21 treatment, 15 min for h Mares bred oestrus. Mean significantly advanced sulpiride-treated compared Pregnancy rate 18 after similar between groups. pulse frequency day treatment higher No significant difference observed groups parameters secretion. results suggest inhibits