Substitution of the selective serotonin reuptake inhibitors fluoxetine and paroxetine for the discriminative stimulus effects of ethanol in rats

 Rats trained to discriminate ethanol (EtOH, 1 g/kg IP) from saline in a two-lever procedure completely generalized to the selective serotonin reuptake inhibitors (SSRIs) fluoxetine and paroxetine. Substitution of fluoxetine was completely blocked by the selective 5-HT_2A receptor antagonist MDL 100,907 and not affected by the selective 5-HT_1A receptor antagonist WAY-100635. It is suggested that the previously reported effectiveness of SSRIs in reducing EtOH consumption could be based on similarities in discriminative stimulus effects of SSRIs and EtOH. Stimulation of 5-HT_2A receptors may underlie these stimulus similarities and contribute to the EtOH intake-reducing effects of SSRIs. Received: 22 November 1996 / Final version: 30 January 1997