The central melanocortin system is essential for the regulation of food intake and body weight in humans and rodents. Agouti-related protein (AgRP) is the sole orexigenic component of the central melanocortin system and is conserved across mammalian species. AgRP is currently known to express exclusively in the mediobasal hypothalamus, and hypothalamic AgRP-expressing neurons are essential for feeding regulation. Here we describe a previously unknown population of AgRP cells in the area postrema (AP) and the adjacent commissural nucleus of the solitary tract (cNTS) of the causal brainstem. AgRP was expressed in the embryonic AP, and hindbrain AgRP expression in adult mice was low under ad libitum fed condition but increased with food deprivation. AgRP cells in the AP and cNTS consisted of locally projecting neurons as well as tanycyte-like cells. In mice that lack hypothalamic AgRP neurons, diphtheria-toxin mediated ablation of AgRP cells led to anorexia and weight loss, whereas chemogenetic activation of AgRP neurons resulted in hyperphagia and weight gain. Moreover, focal transcranial photo-stimulation of AgRP cells in the AP and cNTS with a step-function opsin with ultra-high light sensitivity (SOUL) stimulated feeding in mice with or without hypothalamic AgRP neurons, suggesting that the hyperphagic effects of hindbrain AgRP neurons are independent of hypothalamic AgRP neurons. Collectively, our study indicates that the hindbrain has a balanced melanocortin system, complete with both orexigenic and anorexigenic components, and that AgRP neurons in the hindbrain drive feeding in adult animals.


T.P.Bachor: None. K.Attal: None. E.Vagena: None. F.Mifsud: None. V.Pham: None. M.Valdearcos-contreras: None. C.Vaisse: None. A.Xu: Advisory Panel; Pennington Biomedical Research Center, Research Support; Eli Lilly and Company.


National Institute of Diabetes and Digestive and Kidney Diseases (1P30DK098722-01A1, P30DK63720-06A1)

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