Lack of effect of dopamine receptor blockade on expression of ethanol-induced conditioned place preference in mice

Rationale: Self-administration studies have suggested that dopamine (DA) is important for the reinforcing effects of ethanol. However, ethanol place conditioning studies have less consistently demonstrated a role for DA in conditioned place preference. Objectives: The purpose of the present study was to determine whether blockade of D₁, D₂ or D₃ DA receptors would impact the expression of the conditioned place preference induced by ethanol in DBA/2J mice. Methods: Mice underwent an unbiased place conditioning procedure with 2 g/kg ethanol. Prior to the preference test, mice were injected i.p. with SCH23390 (0, 0.015 or 0.03 mg/kg), raclopride (0, 0.3 or 0.6 mg/kg) or U99194A (0, 10 or 20 mg/kg). Results: Ethanol produced a significant conditioned place preference that was not affected by any of the dopamine antagonists tested. Each of the antagonists decreased locomotor activity, though U99194A was minimally effective. Conclusions: These findings suggest that the conditioned reinforcing effects of ethanol in DBA/2J mice as assessed by place conditioning are mediated by non-dopaminergic mechanisms.