Alcohol dehydrogenases in the brain of mice

Alcohol dehydrogenase (ADH) phenotypes were investigated in the brain of 15 different inbred mice by isoelectric focusing followed by staining of enzyme activities. The Class III ADH activity was detected in all the strains studied, whereas the Class II ADH activity was found only in few strains (including the alcohol-preferring strain--C57BL/6J) having the "a" allele (ADH-C2(2)) for this isozyme in stomach. The inbred strains having the "b" allele (ADH-C2(1)) for the Class II ADH in stomach (including the alcohol avoiding strains--BALB/c, CBA/H, C3H/He, DBA/2J, and SJL/J) demonstrated null variant for this phenotype in their brain. The Class I ADH activity was very low or absent in the brain extracts of all the strains studied. The ADH activities were confined to the cytosolic fractions of brain and were higher in the extracts of cerebral hemispheres than in cerebellum. The genetic linkage studies showed that the locus for the brain Class II ADH is closely linked to the "Adh gene complex" on chromosome 3 of mice.