EFFECTS OF A RANGE OF DOPAMINE-RECEPTOR AGONISTS AND ANTAGONISTS ON ETHANOL INTAKE IN THE RAT

The aim of this study was to assess the effects of a range of dopamine rgic agents on consumption of an ethanol solution (10% ethanol, 3% glu cose) in rats. A two-bottle, free-choice paradigm was used following i nduction of ethanol consumption and preference in standard laboratory rats. The model used provides a robust and reliable level of ethanol o ral administration in normal laboratory rats. Both ethanol intake and preference were reduced by a dopamine D-1 receptor partial agonist, SF K 38393 nyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrochlori de), in a dose-dependent manner. The dopamine D-2/D-3 receptor agonist 7-OH-DPAT (+/-)-7-hydroxy-N,N-(di-n-propyl-2-aminotetralin)) at the l owest dose of 0.01 mg/kg increased both ethanol intake and preference. At higher doses (0.03-0.1 mg/kg) no significant effects were found. T he dopamine D-1 receptor antagonist SCH 23390 etrahydro-3-methyl-1-phe nyl-1H-3-benzazepine-8-ol) dopamine D-2/D-3 receptor antagonist raclop ride and 5-HT2/D-2 receptor antagonist risperidone did not affect etha nol consumption, although all at high doses induced a significant decr ease in water intake, indicating a non-specific decrease in consummato ry behavior with these compounds. These results suggest the involvemen t of the dopaminergic system in ethanol intake and ethanol reinforceme nt with dopamine D-1 and D-2/D-3 receptors playing opposing roles. Blo ckade of dopamine D-2 receptors had no selective effect on ethanol con sumption and ethanol preference.