EFFECTS OF CHRONIC ETHANOL-CONSUMPTION AND AGING ON DOPAMINE, SEROTONIN, AND METABOLITES

This study examined the hypothesis that chronic ethanol consumption re sults in significant abnormalities in both the dopaminergic and the se rotonergic system of aged rats. Levels of dopamine (DA), serotonin [5- hydroxytryptamine (5-HT)], 3,4-dihydroxyphenylacetic acid (DOPAC), and 5-hydroxyindole-3-acetic acid (5-HIAA) were determined in brain areas of both the nigrostriatal and mesocorticolimbic DA systems in 5-, 14- , and 24-month-old male Fischer 344 rats. Aging was associated with a reduced concentration of DA in the striatum (ST), ventral tegmental ar ea (VTA), and ventral pallidum (VP) and an increased concentration of 5-HIAA in the ST, globus pallidus, nucleus accumbens, frontal cortex, and VP. In addition, there was an increase in the 5-HIAA/5-HT ratio in all brain areas analyzed. Six weeks of ethanol consumption was accomp anied by significant changes in mesocorticolimbic brain areas. In the VTA of 5-month-old ethanol-fed rats DA content was decreased to the le vels found in aged rats, e.g., 24 months of age. Ethanol also signific antly lowered 5-HT and 5-HIAA contents in the VTA and reduced DOPAC an d 5-HIAA levels in the VP. In addition, ethanol blunted the normal age -related increase in 5-HIAA/5-HT ratio in the VTA, VP, and substantia nigra. It is interesting that although the age-related changes were fo und in both nigrostriatal and mesocorticolimbic brain areas, the ethan ol-associated effects were found only in brain areas of the mesocortic olimbic system. The changes in DA and 5-HT function that accompany agi ng and ethanol consumption may contribute to the problems in motor fun ction and ethanol abuse found in the aged.