It is important to note that previous experiments using gabra2 KO mice have shown a decrease in sensitivity to the acute effects of ethanol as shown by a reduced loss of righting reflex [24], the direct opposite response to the one reported here. The discrepancy between this experiment and the current data are not attributable to differences in generation of the knockout, as in both cases the mice were derived from the same original line [19], [24]. Furthermore, the two knockout colonies have both been maintained on the same background strain (50% C57BL/6J, 50% 126SvEv) which minimises the possibility of differences in epistatic interactions with genes from the background strain influencing the behaviour. At present, we can only suggest that differences may reflect consequences of genetic drift within two independently-maintained colonies.
