Sex differences and the effects of tail pinch on ethanol drinking in Maudsley rats

Voluntary consumption of 10% ethanol (EtOH) vs. water was compared in EtOH-naive, male and female Maudsley Reactive (MR) inbred rats that were exposed to either daily episodes of tail pinch (TP), or no-stress controls for 35 consecutive days. Females drank significantly more EtOH than males as measured by preference for 10% EtOH vs. water, and for intake of pure EtOH. Females exposed to TP had a higher preference for EtOH relative to controls after 21 days, but there was no difference over the entire 35 days. Males exposed to TP tended to drink more EtOH during the last week of testing relative to controls. Experiment 2 compared MR females with Maudsley Nonreactive (MNRA) females for 3 weeks in the conditions described above; TP exposure increased EtOH preference in MR, but not in MNRA, females. MR females also consumed significantly more EtOH than MNRA females. In both experiments female rats drank amounts of EtOH following a 6-week period of EtOH abstinence comparable to their preabstinence levels. The large degree of variability found in inbred MR rats has implications for developing a model for the investigation of environmental influences on the development of EtOH abuse in genetically susceptible individuals.