Chronic ethanol intake modifies estrous cyclicity and alters prolactin and LH levels.

The effect on the estrous cycle, as well as prolactin, luteinizing hormone (LH) and alcohol levels, were studied in female rats during chronic alcohol intake. Rats were fed the following diets for 5 weeks: a liquid ethanol diet (5% ethanol, w/v), an isocaloric liquid diet (pair-fed) or laboratory rat-chow and water ad lib. Ethanol-fed rats showed an irregular estrous cycle with a significant decrease in the frequency of the estrus + proestrus phases, and an increase in the duration of the diestrus + metaestrus phases, when compared with both the pair-fed and rat-chow groups. In these alcoholic rats, the estrous cycle phase was correlated with blood alcohol levels, which were found to be lower in the estrus + proestrus than in the other phases of the cycle. At the same time plasma prolactin levels were higher and plasma LH levels lower in the alcoholic rats than in either control group. These data indicate that chronic ethanol consumption prolongs the diestrus phase together with altered plasma prolactin and LH levels in female rats.