Chunk #55 — 6. ALCOHOL-ASSOCIATED CHANGES IN GENE/PROTEIN EXPRESSION OF P RATS — 6.3 Expression Differences for Glutamate Transporters, Enzymes, and Postsynaptic Density (Table 3)
In the adult AcbSh, P rats had lower gene expression of Homer1 than NP rats.211 However, operant self-administration of ethanol by adult P rats upregulated Homer1 by 3.5-fold in the AcbSh.214 These data are interesting as studies of rodents with free-access to ethanol83–85,89,180 or rodents injected repeatedly with alcohol86,88 have consistently detected increases in Homer2 protein expression within Acb and amygdala structures, without detecting significant changes in Homer1 protein expression. This raises the possibility that ethanol-induced changes in Homer1 mRNA/protein expression may depend upon nonpharmacologic factors associated with the act of ethanol taking, which has recently been demonstrated to be the case with respect to intravenous cocaine taking.216 Again in the AcbSh, P rats had higher expression levels of Shank1, whereas NP rats had higher expression levels of Shank2 and Shank3.211 Our data suggest a dissociation between the effects of home-cage ethanol drinking which decreased expression of Shank1 by ~15%204 as opposed to operant ethanol self-administration which increased expression levels of Shank1 by ~20%214 in the AcbSh. Some support for this dissociation can be deduced from the fact that operant ethanol self-administration also increased Shank2 expression levels by ~ 20% in the AcbSh.214
