Genotypic differences in ethanol sensitivity in two tests of motor incoordination

1 Portland Alcohol Research Center, Department of Behavioral Neuroscience, Oregon Health & Science University, and Veterans Affairs Medical Center, Portland, Oregon 97239; and 2 Department of Psychology and Centre for Neuroscience, University of Alberta, Edmonton, Alberta, Canada T6G 2E9 Submitted 7 February 2003 ; accepted in final form 16 April 2003 ABSTRACT Motor incoordination is frequently used as a behavioral index of intoxication by drugs that depress the central nervous system. Two tasks that have been used to assay incoordination in mice, the balance beam and the grid test, were evaluated to optimize aspects of apparatus and testing procedures for studying genetic differences. Mice of eight inbred strains were given one of several doses of ethanol or saline and tested for intoxication. Strains differed in sensitivity to ethanol in both tests, indicating a significant influence of genotype on ethanol sensitivity. For the balance beam, the width of the beam affected the strain sensitivity pattern, and only the widest beam worked well at all doses. For the grid test, both ethanol dose and the time after drug injection affected strains differentially. Although the behavioral sign of intoxication recorded for both tests was a foot-slip error, the correlations of strain means for ethanol sensitivity across the two tasks were generally not significant. This suggests that the genes influencing ethanol sensitivity in the two tasks are mostly different. These results make clear that a single set of task parameters is insufficient to characterize genetic influences on behavior. Several other issues affect the interpretation of data using these tests. inbred mouse strains; pharmacogenetics; ataxia; grid test; balance beam Address for reprint requests and other correspondence: J. C. Crabbe, VA Medical Center (R&D 12), 3710 SW US Veterans Hospital Rd., Portland, OR 97239 (E-mail: crabbe{at}ohsu.edu ).