EFFECTS OF CHRONIC ETHANOL TREATMENT AND ETHANOL WITHDRAWAL ON [H-3] SCH23390 BINDING TO RAT STRIATAL MEMBRANES

The effects of chronic ethanol administration and ethanol withdrawal o n the kinetic and pharmacological properties of [H-3]SCH23390 binding sites and the labelling of central dopamine D-1 receptors were studied in the striatum of the rat. Chronic 40 day ethanol treatment produced a statistically significant decrease (p < 0.05) in maximum binding (B -max) on striatal dopamine D-1 receptors of the rat, K-D remaining una ltered. The withdrawal of ethanol did not affect the kinetic binding p arameters. The rank order of potency in displacing the specific [H-3]S CH23390 binding of several dopamine antagonists, agonists and serotoni n-related drugs was consistent with the pharmacological profile of dop amine D-1 receptors. Chronic ethanol treatment led to a statistically significant increase in receptor affinity (lower K-i than controls) fo r (+)-butaclamol (p < 0.05). Ethanol withdrawal for 24 hr increased th e affinity of [H-3]SCH233390-labeled binding sites for norepinephrine. The addition of 0.03-0.68 M ethanol in vitro had no significant effec ts on [H-3]SCH23390 binding in striatal preparations taken from both c ontrol and ethanol-treated rats. The results show that rat striatal [H -3]SCH23390-labelled binding sites are affected by different condition s of ethanol exposure, possibly suggesting the mediation of striatal d opamine pathways in the responses to ethanol intoxication. (C) 1997 El sevier Science Ltd.