Behavior Genetics, Vol. 14, No. 1, 1984 A Biometrical Genetic Analysis of Ethanol Response in Selectively Bred Long-Sleep and Short-Sleep Mice Bruce C. Dudek 1 and Michael E. Abbott l Received 11 Mar. 1983--Final 4 Aug. 1983 A classical Mendelian cross was derived from Long-Sleep (LS) and Short- Sleep (SS) mice, lines selectively bred for differences in response to hyp- notic doses of ethanol (ETOH). Biometrical genetic procedures applied to the selection phenotype, namely, duration of the ETOH-induced loss of the righting reflex, suggest that a simple additive genetic system con- trols this depressant response. Sex differences were present in the Men- delian cross generations that had the longest duration responses. An es- timate of the number of loci differentiated by the selection was nine. Blood ethanol levels at the time of regaining the righting reflex in the seven genotypes of the Mendelian cross showed that the selection operated solely by changing tissue sensitivity to ethanol. KEY WORDS: Mice; alcohol; selective breeding; pharmacogenetics; biometrical genetics. INTRODUCTION The selective breeding program of McClearn and Kakihana (1973, t981) produced two lines of mice which differ markedly in their response to a hypnotic dose of ethanol (ETOH). The Long-Sleep (LS) mice and the Short-Sleep (SS) mice show nonoverlapping distributions of the selection phenotype, duration of the loss of the righting reflex (LRR) following ETOH administration. McClearn and others (McClearn and Anderson, 1979; Deitrich and Collins, 1977) have persuasively argued for the utility of these mice in research into behavioral and physiological effects of al- cohol. These research questions may be broad in nature and touch issues This work was supported by a grant from the SUNY Research Foundation. Department of Psychology and the Neurobiology Research Center, State University of New York at Albany, Albany, New York 12222. 1 0001-8244/84/0100-0001503.50 9 1984 Plenum Publishing Corporation