title: Neuropeptide Y loses its orexigenic effect in rats with lesions of the hypothalamic paraventricular nucleus.
abstract: BACKGROUND
  Both neuropeptide Y (NPY) and ghrelin can enhance the feeding behavior. The purpose of this study was to determine whether NPY and ghrelin are involved in hyperphagia and obesity induced by lesions of the hypothalamic paraventricular nucleus (PVN).
  
  
  METHODS
  Sham-operated control rats and rats subjected to bilateral electrolytic lesions of the PVN were administered NPY (5 μg/rat) by intracerebroventricular infusion or ghrelin (20 μg/kg) by intraperitoneal (i.p.) injection. Control rats were administered the appropriate vehicle by the same route as the drug. We measured the cumulative food intake (FI) for 2 h after infusion of NPY and for 4 h after ghrelin injection.
  
  
  RESULTS
  NPY significantly increased the cumulative FI in sham-operated rats. In PVN-lesioned rats, however, the cumulative FI at each time point (15 min, 30 min, 1 h, and 2 h) after NPY infusion was not significantly different from vehicle infusion, showing that NPY lost its orexigenic effect in PVN-lesioned rats. Following ghrelin injection, the cumulative FI was greater in PVN-lesioned rats than sham-operated rats, indicating that PVN lesions enhanced the orexigenic effects of ghrelin.
  
  
  CONCLUSIONS
  These results suggest that the hyperphagia and obesity induced by PVN lesions may be related to an increased orexigenic action of ghrelin, but not NPY.
authors.affiliation: Department of Clinical Medicine, School of Medicine and Life Sciences, Zhejiang University City College, Hangzhou, PR China.
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: Z
authors.initials: Z
authors.lastname: Yuan
authors.forename: J
authors.initials: J
authors.lastname: Dong
authors.forename: D
authors.initials: D
authors.lastname: Zhang
authors.forename: T
authors.initials: T
authors.lastname: Usami
authors.forename: T
authors.initials: T
authors.lastname: Murata
authors.forename: K
authors.initials: K
authors.lastname: Narita
authors.forename: T
authors.initials: T
authors.lastname: Higuchi
mesh_terms: D000818:Animals; D004435:Eating / Q000187:drug effects*; D005247:Feeding Behavior / Q000187:drug effects; D054439:Ghrelin / Q000494:pharmacology; D008297:Male; D009478:Neuropeptide Y / Q000494:pharmacology*; D010286:Paraventricular Hypothalamic Nucleus / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D054439:Ghrelin; D009478:Neuropeptide Y