Effect of nonsuckling interval in the ether-induced release of immunoprecipitable prolactin in the plasma of the lactating rat.

The concentration of prolactin in the plasma of lactating rats increased from 24 to 74 ng/ml following acute ether stress as the length of the preceding period of nonsuckling diminished from 12 to 8 hr. In a second experiment the prolactin concentration increased from 24 to 79 to 104 ng/ml as the frequency of 10-min sucklings during a 12-hr period was altered from once at the end of the twelfth hr to once every 6 hr to once every 4 hr and the mothers then exposed to ether 12 hr after the last suckling. These results indicate that more frequent activation of the prolactin-releasing mechanism facilitates the subsequent release of prolactin in response to ether stress.