title: Signal transducer and activator of transcription-3 is required in hypothalamic agouti-related protein/neuropeptide Y neurons for normal energy homeostasis.
abstract: Signal transducer and activator of transcription (Stat)-3 signals mediate many of the metabolic effects of the fat cell-derived hormone, leptin. In mice, brain-specific depletion of either the long form of the leptin receptor (Lepr) or Stat3 results in comparable obese phenotypes as does replacement of Lepr with an altered leptin receptor locus that codes for a Lepr unable to interact with Stat3. Among the multiple brain regions containing leptin-sensitive Stat3 sites, cells expressing feeding-related neuropeptides in the arcuate nucleus of the hypothalamus have received much of the focus. To determine the contribution to energy homeostasis of Stat3 expressed in agouti-related protein (Agrp)/neuropeptide Y (Npy) arcuate neurons, Stat3 was deleted specifically from these cells, and several metabolic indices were measured. It was found that deletion of Stat3 from Agrp/Npy neurons resulted in modest weight gain that was accounted for by increased adiposity. Agrp/Stat3-deficient mice also showed hyperleptinemia, and high-fat diet-induced hyperinsulinemia. Stat3 deletion in Agrp/Npy neurons also resulted in altered hypothalamic gene expression indicated by increased Npy mRNA and decreased induction of suppressor of cytokine signaling-3 in response to leptin. Agrp mRNA levels in the fed or fasted state were unaffected. Behaviorally, mice without Stat3 in Agrp/Npy neurons were mildly hyperphagic and hyporesponsive to leptin. We conclude that Stat3 in Agrp/Npy neurons is required for normal energy homeostasis, but Stat3 signaling in other brain areas also contributes to the regulation of energy homeostasis.
authors.affiliation: Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, 550 East Canfield, Detroit, MI 48201, USA.
authors.forename: Lijie
authors.initials: L
authors.lastname: Gong
authors.forename: Fayi
authors.initials: F
authors.lastname: Yao
authors.forename: Kristin
authors.initials: K
authors.lastname: Hockman
authors.forename: Henry H
authors.initials: HH
authors.lastname: Heng
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Morton
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Takeda
authors.forename: Shizuo
authors.initials: S
authors.lastname: Akira
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Low
authors.forename: Marcelo
authors.initials: M
authors.lastname: Rubinstein
authors.forename: Robert G
authors.initials: RG
authors.lastname: MacKenzie
mesh_terms: D050154:Adiposity / Q000187:drug effects / Q000235:genetics; D054369:Agouti-Related Protein / Q000378:metabolism*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004041:Dietary Fats / Q000494:pharmacology; D004734:Energy Metabolism / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D020738:Leptin / Q000378:metabolism; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009478:Neuropeptide Y / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000502:physiology*; D015430:Weight Gain / Q000187:drug effects
chemical_list: D054369:Agouti-Related Protein; D004041:Dietary Fats; D020738:Leptin; D009478:Neuropeptide Y; D050796:STAT3 Transcription Factor