Effects of chronic alcohol ingestion on the mesostriatal dopamine system in the rat

The effects of chronic alcohol use on the mesostriatal dopamine (DA) system remain relatively unknown. The aim of the present study was to assess multiple measures of the status of the mesostriatal DA system in rats chronically fed an alcohol diet for approximately 1 year. Tissue levels of DA and its metabolite, 3,4-dihydroxyphenylacetic acid, were significantly decreased in both the dorsal striatum (34 and 33%, respectively) and ventral striatum (33 and 36%, respectively) in alcohol-fed rats compared to pair-fed matched controls. Western blotting revealed a mean 20% decrease in tyrosine hydroxylase protein levels in the dorsal and ventral striatum of alcohol-fed animals while dopamine transporter protein levels from the same animals were significantly increased compared to controls (mean 60% increase for the dorsal and ventral striatum). The present results demonstrate significant alterations in the mesostriatal DA system after 1 year of chronic alcohol use. It is possible that the observed changes in DA synthesis and re-uptake measures result in altered intracellular and extracellular DA levels, perhaps contributing to the addictive properties of alcohol.