Evidence for a refractory period in the neuroendocrine mechanism for the release of prolactin.

In the lactating rat, a period of time must elapse following a release of prolactin by acute suckling before suckling can again effect release of the hormone. The time delay also is evident though prolactin release at the initial suckling is blocked by injecting prolactin releaseinhibiting factor. The temporary lack of responsiveness thus does not appear to be related to a lack of releasable prolactin in the pituitary, but rather to the failure of some central component in the releasing mechanism to respond to stimulation. (Endocrinology 88: 355, 1971)