Changes in the prolactin levels after administration of ethanol in diestrus 2

: The effect of ethanol administered at 18.00 h. of diestrus 2 on prolactin secretion has been studied in rats. Serum levels and pituitary content of prolactin were measured at 30, 60, 90 and 120 min. after administration of different doses of ethanol (0.5, 2 and 4 g/kg). Moreover, the variation of the prolactin release was determined at different hours of the rat estrous cycle, after administration of a single dose of ethanol (2 g/kg) at 18.00 h of diestrus. 2. Serum prolactin levels were significantly elevated after the preovulatory administration of ethanol with all the doses tested. The hyperprolactinemia appeared 60 min after ethanol treatment and the high prolactin levels were maintained during all the estrous cycles, especially in the proestrus day. The normal levels were re-established the 5th day after treatment. The ethanol produced a byphasic effect on pituitary prolactin content. During the first post-treatment hours, the pituitary prolactin concentration decreased with respect to the control group, but 24 hours after treatment, these values were increased and the normal concentration was restored 36 hours after treatment.