ATP-sensitive K+ channels in the hypothalamus are essential for the maintenance of glucose homeostasis

Glucose-responsive (GR) neurons in the hypothalamus are thought to be criti cal in glucose homeostasis, but it is not known how they function in this c ontext. Kir6.2 is the pore-forming subunit of K-ATP channels in many cell t ypes, including pancreatic beta -cells and heart. Here we show the complete absence of both functional ATP-sensitive K+ (K-ATP) channels and glucose r esponsiveness in the neurons of the ventromedial hypothalamus (VMH) in Kir6 .2(-/-) mice. Although pancreatic alpha -cells were functional in Kir6.2(-/ -), the mice exhibited a severe defect in glucagon secretion in response to systemic hypoglycemia. In addition, they showed a complete loss of glucago n secretion, together with reduced food intake in response to neuroglycopen ia. Thus, our results demonstrate that K-ATP channels are important in gluc ose sensing in VMH GR neurons, and are essential for the maintenance of glu cose homeostasis.