title: Galanin-like peptide stimulates food intake via activation of neuropeptide Y neurons in the hypothalamic dorsomedial nucleus of the rat.
abstract: Galanin-like peptide (GALP), a 29-amino-acid neuropeptide, is located in the hypothalamic arcuate nucleus (ARC), binds to galanin receptor subtype 2, and induces food intake upon intracerebroventricular (icv) injection in rats. However, neural mechanisms underlying its orexigenic action remain unclear. We aimed to identify the nuclei and neuron species that mediate the food intake in response to icv GALP injection. Intracerebroventricular injection of GALP, as powerfully as that of neuropeptide Y (NYP), increased food intake for the initial 2 h. GALP injected focally into the dorsomedial nucleus (DMN), but not the ARC, lateral hypothalamus, or paraventricular nucleus (PVN), stimulated food intake for 2 h after injection. In contrast, galanin injected into the DMN had no effect. DMN-lesion rats that received icv GALP injection showed attenuated feeding compared with control rats. Intracerebroventricular GALP injection increased c-Fos expression in NPY-containing neurons in the DMN, but not the ARC. GALP increased the cytosolic calcium concentration ([Ca(2+)](i)) in NPY-immunoreactive neurons isolated from the DMN, but not the ARC. Furthermore, both anti-NPY IgG and NPY antagonists, when preinjected, counteracted the feeding induced by GALP injection. These data show that icv GALP injection induces a potent short-term stimulation of food intake mainly via activation of NPY-containing neurons in the DMN.
authors.affiliation: Department of Physiology, Division of Integrative Physiology, Jichi Medical School, Minamikawachi, Kawachi, Tochigi, Japan.
authors.forename: Motoki
authors.initials: M
authors.lastname: Kuramochi
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Onaka
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kohno
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kato
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Yada
mesh_terms: D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D004302:Dorsomedial Hypothalamic Nucleus / Q000502:physiology*; D004435:Eating / Q000187:drug effects*; D044089:Galanin-Like Peptide / Q000494:pharmacology*; D008297:Male; D009478:Neuropeptide Y / Q000032:analysis / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors; D018013:Receptors, Neuropeptide / Q000037:antagonists & inhibitors
chemical_list: D044089:Galanin-Like Peptide; D009478:Neuropeptide Y; C066211:Npy1r protein, rat; D016760:Proto-Oncogene Proteins c-fos; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D002118:Calcium