5-HT\(_{\text{2C}}\)Rs Expressed by Pro-Opiomelanocortin Neurons Regulate Energy Homeostasis

Abstract

Drugs activating 5-hydroxytryptamine 2C receptors (5-HT({\text{2C}})Rs) potently suppress appetite, but the underlying mechanisms for these effects are not fully understood. To tackle this issue, we generated mice with global 5-HT({\text{2C}})Rs deficiency (2C null) and mice with 5-HT({\text{2C}})Rs re-expression only in pro-opiomelanocortin (POMC) neurons (2C/POMC mice). We show that 2C null mice predictably developed hyperphagia, hyperactivity, and obesity and showed attenuated responses to anorexigenic 5-HT drugs. Remarkably, all these deficiencies were normalized in 2C/POMC mice. These results demonstrate that 5-HT({\text{2C}})R expression solely in POMC neurons is sufficient to mediate effects of serotoninergic compounds on food intake. The findings also highlight the physiological relevance of the 5-HT(_{\text{2C}})R-melanocortin circuitry in the long-term regulation of energy balance.