Neuronal circuits involving neuropeptide Y in hypothalamic arcuate nucleus-mediated feeding regulation.

Neuropeptide Y (NPY) is a 36-amino-acid neuropeptide that was first discovered in porcine brain extracts and later in the porcine intestine. It is widely distributed in both the central and peripheral nervous systems and exerts a powerful orexigenic effect. NPY-producing neuronal cell bodies are abundantly localized in the medial arcuate nucleus of the hypothalamus, this being a brain center that integrates signals for energy homeostasis. Accumulated evidence shows that hypothalamic neuropeptides such as ghrelin, orexin, melanin-concentrating hormone (MCH), galanin-like peptide (GALP) and proopiomelanocortin (POMC) are involved in the regulation of feeding behavior and energy homeostasis via neuronal circuits in the hypothalamus. NPY also forms part of the feeding-regulating neuronal circuitry in conjunction with other feeding-regulating peptide-containing neurons within the hypothalamus. We summarize here current knowledge of the neuronal interactions between NPY and the different types of feeding-regulating peptide-containing neurons in the hypothalamus based on evidence at the immunohistochemicl level and with calcium imaging techniques.