AFT (Gallaher et al. 1996). Subsequent tests show quantitative trait loci (QTL) for ethanol tolerance on chromosomes 9 and 11. While these studies did not identify a role for GABAA receptors in tolerance, it is possible that subunits from the GABAA receptor subunit gene cluster on chromosome 11 may be involved. Other studies show that mice selectively bred for ethanol withdrawal severity do not differ in tolerance to ethanol’s hypothermic or sedative-hypnotic effects (Crabbe and Kosobud 1986), although these mice exhibit differences in GABAA receptor mRNA subunit expression (Keir and Morrow 1994) as well as differential changes in subunit expression after chronic ethanol (Buck et al. 1991a). Together, these results support the notion that various genes contribute to ethanol-related responses and that tolerance to specific ethanol-related behaviors may be independent of withdrawal.
