Synthesis and Release of Prolactin in vitro from the Anterior Pituitary of Mouse During Estrous Cycle

The prolactin secretory activity of anterior pituitary during estrous cycle was determined from 14C-leucine incorporation in vitro into the hormone, using IVCS mice which showed regular 4-day-cycles. Prolactin in the anterior pituitary and in the incubation medium was fractionated by disc electrophoresis on polyacrylamide gel.The synthesis and release of prolactin were significantly lower at estrus than at proestrus and diestrus. The release rate was higher at estrus than at diestrus.It was demonstrated that the mouse did not show the similar patterns to the rat (Ieiri et al., 1971) in the changes of pituitary prolactin secretory activity during estrous cycle.