Mianserin enhancement of ethanol-induced conditioned place preference

This experiment examined the influence of mianserin, a 5-HT(2) receptor antagonist, on the rewarding effect of ethanol in a place conditioning paradigm. Swiss-Webster mice received four pairings of a tactile stimulus with drug treatment consisting of two i.p. injections separated by a 30min interval. Drug treatment groups were as follows: saline (10mg/kg) followed by ethanol (2mg/kg); mianserin (10mg/kg) followed by ethanol; mianserin followed by saline. A different stimulus was paired with two saline injections. During conditioning, ethanol produced increases in locomotor activity that were reduced by mianserin. Mianserin alone reduced activity levels. As expected, group saline-ethanol showed a nonsignificant trend towards conditioned place preference. However, mianserin enhanced the acquisition of ethanol preference, whereas mianserin alone did not produce either place preference or aversion. The results are consistent with the notion that serotonergic systems are important in the response to ethanol, and further suggest that 5-HT(2) receptor blockade increases the rewarding effects of ethanol.