The effects of perphenazine and bromocriptine on follicular dynamics and endocrine profiles in anestrous pony mares.

摘要

19 anoestrous pony mares were given daily intramuscular injections of perphenazine (a dopamine antagonist; 0.375 mg/kg body weight), 2-bromo-ergocriptine (a dopamine agonist; 0.08 mg/kg metabolic weight) or saline (controls). Treatment began on January 20, 1994 and continued until ovulation occurred. Mares were teased 3 times weekly with an intact stallion. The ovaries were palpated and imaged weekly using an ultrasonic B-mode unit until they had a follicle >=20 mm. At this time, the ovaries were palpated and imaged 4 times per week. Blood samples were obtained immediately prior to ultrasonic imaging for measurement of prolactin, FSH and oestradiol-17beta. Compared with control, perphenazine advanced the spring transitional period and subsequent ovulation by approximately 30 days; onset of oestrus behaviour also occurred earlier (27.5 vs. 42.1 days; P<0.01). The animals developed large follicles (>30 mm) earlier than bromocriptine-treated mares (47.0±8.8 vs. 88.1±8.2 days; P<0.01) or controls (67.3±8.8 days). Bromocriptine, but not perphenazine, decreased (P<0.05) plasma prolactin levels throughout the study. However, perphenazine increased (P<0.05) mean plasma prolactin concentration from day 31 to 60 of treatment. There was no difference in mean plasma FSH or oestradiol-17beta concentration between treatment groups.