Serotonergic receptors modify the voluntary intake of alcohol and morphine but not of cocaine and nicotine by rats.

Effects of fluvoxamine, a relatively selective 5-HT uptake inhibitor, and ipsapirone, a relatively selective 5-HT1A agonist, were studied on the initiation and/or maintenance of the voluntary intake of alcohol, morphine, cocaine, and/or nicotine in rats using the two-bottle free-choice method. Fluvoxamine (30 mg/kg/day in the drinking fluid) when given during existing morphine consumption increased the intake of this drug (1 +/- 1 vs. 3 +/- 1 mg/kg/day) but had no effect on alcohol (2 +/- 2 vs.