The neurotransmitter serotonin/5-hydroxytryptamine (5-HT) regulates a wide variety of neurological functions. A family of 13 receptors (12 GPCRs and one ion channel) mediate the effects of serotonin. The serotonin receptor 5-HT6 is a Gs coupled receptor expressed solely in the CNS, primarily in the limbic and cortical regions. 5-HT6 appears to play a role in memory and learning, obesity, psychosis, anxiety and epilepsy. In particular, a 5-HT6-selective agonist caused significant weight loss in a rat model of diet-induced obesity.