Effects of biperiden (cholinergic muscarinic m1/m4 receptor antagonist) on ethanol conditioned place preference in mice.

BACKGROUND

Previous studies suggest that muscarinic cholinergic receptors might act upon the dopamine release in the mesolimbic system and alter drug-reinforcing values related to drug craving.

AIMS

We examined the effects of systemic biperiden administration, a muscarinic cholinergic (M1/M4) receptor antagonist, on ethanol (dose of 2 g/Kg) conditioned place preference (CPP), neuronal activation, dopamine and its metabolites levels in the nucleus accumbens.

METHODS

Thirty minutes before the ethanol-induced CPP test, mice received saline or biperiden at doses of 1.0, 5.0, or 10.0 mg/kg. The time spent in each compartment was recorded for 15 min. After the CPP protocol, animals were euthanized, and we investigated the activation of the nucleus accumbens by immunohistochemistry for Fos. We also quantified dopamine, homovanillic acid (HVA), and dihydroxyphenylacetic acid (DOPAC) levels in the nucleus accumbens by high-performance liquid chromatography (HPLC). Additionally, the rotarod was employed to evaluate the effects of biperiden on motor coordination.

RESULTS

Biperiden at different doses (1.0, 5.0, and 10.0 mg/kg) blocked the expression of ethanol-induced CPP. These biperiden doses increased the number of Fos-positive cells and the dopamine turnover in the nucleus accumbens. None of the doses affected the motor coordination evaluated by the rotarod.

CONCLUSIONS

Our results show that biperiden can modulate the effect of alcohol reward, and its mechanism of action may involve a change in dopamine and cholinergic mesolimbic neurotransmission.