Reduction in ethanol preference following injection of centrally and peripherally acting antimuscarinic agents

Selectively bred alcohol-preferring (P) and alcohol non-preferring (NP) lines of rats were administered saline subcutaneously, and doses of 0.5 and 2.0 mg/kg of two antimuscarinic agents scopolamine (centrally acting) and methscopolamine (peripherally acting), twice daily respectively for a period of one day. Compared to saline, both doses of scopolamine and methscopolamine induced a significant reduction in ethanol consumption in the P line of rats, and both antimuscarinic agents significantly increased water intake. Thus, ethanol preference was dramatically reduced in these rats. In contrast, scopolamine had relatively little effect on either ethanol or water intake in the NP line of rats, while methscopolamine tended to suppress both ethanol and water intake. These findings suggest that peripheral muscarinic mechanisms may be involved in ethanol preference in P rats.