Different stages in the temporal course of estrogen treatment produce opposite effects on voluntary alcohol consumption in male rats

The purpose of this study was to examine alcohol consumption in different stages of the estrogen treatment. Three groups of castrated male Wistar rats were used. One group was treated with 5 ?g of estradiol benzoate (E) per day per rat for 6 days and oil from days 7 to 12 (EO group). The second group was treated with oil for 6 days and E from days 7 to 12 (OE) and the third with E for 12 consecutive days (EE). The three groups were exposed to a choice of both water and ethanol (10%) before treatment (PreT), from days 7 to 12 of the oil or the E treatment (T2), and during 6 additional days in the post-treatment period (PosT). Alcohol was not available from days 1 to 6 of the oil or the E treatment (T1). Alcohol consumption in the EO group during T2 was higher than in PreT and PosT periods and all periods in the other two groups. In contrast, alcohol consumption during T2 was significantly lower than during the PreT of the OE group and T2 of the EE group. At the same time in the EE group, alcohol intake in the T2 was higher than in the PreT and the PosT periods. These results reveal the opposite effects of estrogen treatment on alcohol consumption, which apparently depended on the physiological conditions produced by the temporal course of hormone treatment. � 2005 Elsevier Inc. All rights reserved