Rats meet all the criteria for animal models of alcoholism, including: the ability to orally self-administer ethanol; elevation of blood ethanol concentration after alcohol consumption; willingness to work for ethanol access; development of functional tolerance; and, after a deprivation period, relapse-like behavior [64]. A study on recombinant inbred rat strains identified several genomic regions on chromosomes 1, 6 and 12 that harbor candidate genes for alcohol consumption, including the genes encoding actin filament associated protein, cholecystokinin 2 receptor, melanocortin 4 receptor; protein tyrosine phosphatase receptor type E and tubulin B6 [65]. Furthermore, several microarray studies have identified differential expression of genes between alcohol-preferring and alcohol-non-preferring rat strains, including the genes encoding alpha-adducin (Add1), retinal dehydrogenase 1 (Aldh1a1), adenylate cyclase type 3 (Adcy3), alpha-crystallin B chain (Cryab), glutamate decarboxylase 1 (Gad1) and NPY (Npy) [66,67]. However, most studies on the genetic underpinnings of alcohol-related phenotypes have focused on mice, because, in contrast to rats, they can be more easily genetically manipulated. Mice are amenable to complete elimination of the gene of interest, gene silencing by RNA interference (RNAi), overexpression and mutagenic
