Integration of metabolic stimuli in the hypothalamic arcuate nucleus.

Integration of peripheral and central anabolic and catabolic inputs within the hypothalamic arcuate nucleus (ARC) is believed to be central to the maintenance of energy balance. In order to perform this complex task, neurons in the ARC express receptors for all major humoral and central transmitters involved in the maintenance of energy homeostasis. The integration of these inputs occurs at the cellular and circuit level and the resulting electrical output forms the origins for the activation of feeding and energy balance-related networks. Here, we discuss the role that active intrinsic membrane conductances, K(ATP) channels and intracellular second messenger systems play in the integration of metabolic stimuli at the cellular level in the ARC. We conclude that the research into the integration of hunger and satiety signals in the ARC has made substantial progress in the last decade, but we are far from unraveling the complex neuronal networks involved in the maintenance of energy homeostasis. The diverse range of inputs, neuronal integrative properties, targets, output signals and how these signals relate to the physiological output provides us with a colossal challenge for years to come. However, to battle the current obesity epidemic, target-specific drugs need to be developed for which the knowledge of neuronal pathways involved in the maintenance of energy homeostasis will be crucial.