title: ATP-Sensitive Potassium Channel-Deficient Mice Show Hyperphagia but Are Resistant to Obesity.
abstract: BACKGROUND
  The hypothalamus, the center for body weight regulation, can sense changes in blood glucose level based on ATP-sensitive potassium (K(ATP)) channels in the hypothalamic neurons. We hypothesized that a lack of glucose sensing in the hypothalamus affects the regulations of appetite and body weight.
  
  
  METHODS
  To evaluate this hypothesis, the responses to glucose loading and high fat feeding for eight weeks were compared in Kir6.2 knock-out (KO) mice and control C57BL/6 mice, because Kir6.2 is a key component of the K(ATP) channel.
  
  
  RESULTS
  The hypothalamic neuropeptide Y (NPY) analyzed one hour after glucose injection was suppressed in C57BL/6 mice, but not in Kir6.2 KO mice, suggesting a blunted hypothalamic response to glucose in Kir6.2 KO mice. The hypothalamic NPY expression at a fed state was elevated in Kir6.2 KO mice and was accompanied with hyperphagia. However, the retroperitoneal fat mass was markedly decreased in Kir6.2 KO mice compared to that in C57BL/6 mice. Moreover, the body weight and visceral fat following eight weeks of high fat feeding in Kir6.2 KO mice were not significantly different from those in control diet-fed Kir6.2 KO mice, while body weight and visceral fat mass were elevated due to high fat feeding in C57BL/6 mice.
  
  
  CONCLUSIONS
  These results suggested that Kir6.2 KO mice showed a blunted hypothalamic response to glucose loading and elevated hypothalamic NPY expression accompanied with hyperphagia, while visceral fat mass was decreased, suggesting resistance to diet-induced obesity. Further study is needed to explain this phenomenon.
authors.affiliation: Department of Neurosurgery, Yeungnam University College of Medicine, Daegu, Korea.
authors.forename: Yeul Bum
authors.initials: YB
authors.lastname: Park
authors.forename: Yun Jung
authors.initials: YJ
authors.lastname: Choi
authors.forename: So Young
authors.initials: SY
authors.lastname: Park
authors.forename: Jong Yeon
authors.initials: JY
authors.lastname: Kim
authors.forename: Seong Ho
authors.initials: SH
authors.lastname: Kim
authors.forename: Dae Kyu
authors.initials: DK
authors.lastname: Song
authors.forename: Kyu Chang
authors.initials: KC
authors.lastname: Won
authors.forename: Yong Woon
authors.initials: YW
authors.lastname: Kim