Sensitivity to ethanol in inbred mice: genotypic correlations among several behavioral responses.

The sensitivity of several inbred strains of mice was assessed for ethanol's effects on activity, body temperature, ataxia, balance, and the righting reflex. Genotypic correlations among the mean responses for the strains were estimated as indexes of pleiotropic influences of genes on drug responses. Three major groups of genetic influence were detected: (a) hypothermic sensitivity to ethanol, (b) activity change (increase after ethanol), and (c) high basal activity. In the first group of variables, strains that had large reductions in body temperature after being given ethanol had high baseline temperatures, pronounced ataxic response to ethanol, and a long-lasting loss of righting reflex. Home cage baseline activity was negatively correlated with body temperature variables. The second group of variables was composed largely of ethanol-induced increases and decreases in activity, which were negatively intercorrelated. Strains with larger increases in activity showed more rapid loss of balance after ethanol. The third group of variables indicated that high levels of basal activity in an open field and in the home cage were determined by the action of common genes. Strains with higher basal activity levels had reduced sensitivity to ambulatory ataxia following ethanol. Thus, there were substantial pleiotropic effects of common genes on several behavioral responses to ethanol in inbred mice. Conversely, the three major groups were not systematically correlated with one another to a major extent. This suggests the influence of three reasonably distinct sets of genes on these responses to ethanol.