Increased hypothermic responses to ethanol in rats selectively bred for cholinergic supersensitivity.

The behavioral and hypothermic effects of ethanol were studied in the Flinders Sensitive Line (FSL) and Flinders Resistant Line (FRL) rats, selectively bred for differences in cholinergic sensitivity. The FSL hypercholinergic rats exhibited a significantly greater degree of hypothermia than the FRL rats, or a group of weight-matched randomly bred rats. Although there were some trends for the FSL rats to appear more depressed behaviorally after receiving ethanol, there were no significant differences between the FSL and FRL rats on quantitative behavioral measures. Blood ethanol concentrations were slightly lower in the FRL rats, but there were no differences between the FSL and control rats. These findings suggest an association between cholinergic mechanisms and ethanol sensitivity with regard to body temperature effect, but a direct causal relationship cannot be established because of similar differential sensitivities of FSL and FRL rats to a range of other neurotransmitter-altering drugs on this parameter.