Effect of 5-HT3 antagonists and a 5-HT(1A) agonist on fluoxetine-induced conditioned gaping reactions in rats.

Rationale: The effect of manipulation of the serotonin (5-HT) system on conditioned gaping (presumably reflective of nausea in rats) was evaluated.

Objective: The potential of the selective serotonin reuptake inhibitor (SSRI), fluoxetine (which produces nausea in the clinic), to produce conditioned gaping in rats and of the 5-HT(3) antagonists (ondansetron and palonosetron) and the 5-HT(1A) autoreceptor agonist (8-OH-DPAT) to reverse this effect were evaluated.

Materials And Methods: In each of four experiments, rats received three pairings of intraorally delivered 17% sucrose solution and fluoxetine (0, 2, 10 or 20 mg/kg) and 72 h later were given a drug-free test trial.

Exposure to a context previously associated with nausea elicits conditioned gaping in rats: a model of anticipatory nausea.

Following one or more chemotherapy treatments, many patients report that they experience anticipatory nausea. This phase of nausea has been interpreted as a classically conditioned response where a conditional association develops between the contextual clinic cues and the nausea and/or vomiting that developed following treatment. Although rats do not vomit, they display a distinctive gaping reaction when exposed a flavored solution previously paired with a toxin.