The transduction of neurobehavioral effects by serotonin (5-hydroxy tryptamine; 5-HT) is mediated via at least 6 major 5-HT receptor subtypes. Non-selective 5-HT receptor agonists, such as mCPP, induce many behavioral responses in rats, including increased anxiety, hypophagia, and hypoactivity. BW 723C86 is in fact anxiolytic, and its only other prominent behavioral effect is hyperphagia. This effect is likely due to the 10-fold selectivity of BW 723C86 for the HT2B receptor. Direct infusion of 1-3 μg of BW 723C86 into the cerebral ventricles of rats evokes maximal behavioral responses; the response was attenuated at both higher and lower doses.