Endocrine Abstracts

Prolactin is associated with seasonal transitions into and out of anestrus in the mare. The earliest anestrous transitional changes are declining progesterone secretion and a concomitant prolactin decline. Ovarian changes include slowed follicular development and prolonged luteal activity. Dopamine antagonist administration during the autumnal transition prevented a seasonal progesterone decline, suggesting a cause-and-effect between prolactin and progesterone production. The ...