Chronic treatment with antipsychotics in rats as a model for antipsychotic-induced weight gain in human

Several clinical reports have demonstrated that most antipsychotics of the new generation, but not the typical antipsychotic haloperidol, induce weight gain in schizophrenic patients. Since weight gain induces serious health complications in humans, it is crucial to test upcoming antipsychotic compounds in an animal model of weight gain. With the aim of evaluating whether the rat can be used as a model for antipsychotic-induced weight gain, we have investigated the effect of chronic treatment (3 weeks) with one antipsychotic drug inducing weight gain in clinic (olanzapine) and one antipsychotic not inducing weight gain in clinic (haloperidol), on food and water intake and body weight gain in rats. We included both female and male rats in this study. To reduce spontaneous high food intake in rats, and to be able to evaluate the treatment effect on a potential increase of food intake or metabolic changes, we allowed animal to receive only low-palatability chow. In male rats, none of the two compounds induced weight gain, but in female rats, both compounds induced weight gain. Consequently, the effect observed in rats does not match the clinical situation, and Wistar rats in this set-up cannot be considered a relevant model for antipsychotic-induced weight gain in humans.