The present study examined the hypothesis that chronic
alcoholism augments the age-related loss of
dopamine D1 receptors. This hypothesis was investigated because previous studies reported that both aging and chronic
alcoholism produce significant changes in dopaminergic systems, and because chronic
alcoholism potentiates some age-related CNS losses. In addition, this study investigated the effects of aging on D1 receptors in animals 1 and 7 days after withdrawal from chronic
ethanol. Quantitative autoradiography was used to measure [3H]
SCH 23390 binding to D1 receptors in brain areas associated with both the nigrostriatal and mesocorticolimbic
dopamine systems. Receptors were assessed in 5-, 14-, and 24-month-old male Fischer 344 rats that were pair-fed a control or 6.6% (v/v)
ethanol-containing liquid diet for 6 weeks. The results of these studies demonstrated that aging is associated with a significant decline in D1 receptors in the rostral and caudal striatum, and substantia nigra of both control and
ethanol-fed rats. These receptor changes in the nigrostriatal system may be associated with motor abnormalities. In addition, there was an age-related decline in D1 receptors in two brain areas of the mesocorticolimbic system: the nucleus accumbens and frontal cortex. The latter findings may be important because of the involvement of this system with the rewarding properties of
ethanol and other drugs of abuse. There were no age-related differences in the response of D1 receptors to
ethanol withdrawal in the caudal and rostral striatum, substantia nigra, and nucleus accumbens.(ABSTRACT TRUNCATED AT 250 WORDS)