Ascorbic acid antagonizes ethanol-induced locomotor activity in the open-field.

It has been reported that ascorbic acid (AA) antagonizes the physiological and behavioral effects of dopamine (DA). AA reduces locomotor activity induced by dopaminergic agonist drugs. Also, AA amplifies the action of antidopaminergic drugs. Ethanol, like other drugs, produces a release of DA in the mesolimbic pathway, and at some doses, induces locomotor activity in mice. The ethanol-induced locomotor activity could be dopamine-dependent because it can be reduced by antidopaminergic drugs. In the present study, we investigated whether an acute administration of AA reduces ethanol-induced locomotor behavior. AA, at doses (0.0, 21.85, 87.5, 175, 350. and 1400 mg/kg) was injected i.p. into mice, 0, 30, 60, or 90 min before an i.p. injection of ethanol (0.0, 0.8, 1.6, 2.4, and 3.2 g/kg). Locomotor activity was evaluated in open-field chambers. Our results showed that AA (350 and 1400 mg/kg) reduced ethanol-induced locomotor activity when injected 30 min before ethanol treatment. This effect was lost when ethanol was administered 90 min after AA injection. AA also reduced locomotor activity produced by d-amphetamine and methanol. The results support a pro-dopaminergic action of ethanol, and suggest a common dopaminergic pathway for the drugs of abuse in locomotor activity.