Lmo3 is 1 of 4 Lmo genes in the mouse. We have studied another member of this family, Lmo4, in behavioral responses to cocaine and ethanol. We found that mice with a 50% reduction in Lmo4 levels exhibit enhanced locomotor sensitization to cocaine (Lasek et al., 2010). However, these mice did not show any differences in several behavioral assays related to alcohol, including locomotor stimulation, LORR, and 2-bottle choice ethanol consumption (David Kapfhamer, personal communication). Interestingly, however, Drosophila dLmo, which is the only Lmo gene in flies, regulates behavioral responses to both cocaine and ethanol. These findings suggest that inmammals, the role of the Lmo genes in regulating responses to abused drugs has diverged such that different homologs function in pathways that are drug-specific.
