Obesity in insulin receptor substrate-2-deficient mice: disrupted control of arcuate nucleus neuropeptides.
OBJECTIVE
Disturbances in insulin signaling have been shown to induce obesity and/or hyperphagia in brain insulin receptor or insulin receptor substrate-2 (IRS-2) knockout (KO) mice. This study aimed to examine the central and peripheral mechanisms underlying the phenotype in IRS-2 KO mice.


METHODS
We measured the histological characterization of adipose tissues, mRNA levels of pro-opiomelanocortin, agouti-related protein, and neuropeptide Y in the hypothalamus and uncoupling proteins (UCPs) in peripheral tissues of IRS-2 KO mice.


RESULTS
Female IRS-2 KO mice showed increased daily food intake. Body weight and adiposity were increased in both sexes, although these differences were more pronounced in female than in male IRS-2 KO mice. Both male and female IRS-2 KO mice showed decreased UCP1 mRNA expression in brown adipose tissue with defective thermoregulation, and UCP2 mRNA expression was increased in the white adipose tissue of female knockout mice. Furthermore, arcuate nucleus mRNA expression of pro-opiomelanocortin, was decreased in both male and female IRS-2 KO mice, whereas expression of agouti-related protein and neuropeptide Y were increased in female IRS-2 KO mice.


CONCLUSIONS
In IRS-2 KO mice, disrupted control of hypothalamic neuropeptide levels and UCP mRNA expression may contribute to the development of obesity.
Masaki
Takayuki
T
Department of Internal medicine, School of Medicine, Oita Medical University, Hasama, Oita 879-5593, Japan. Masaki@oita-med.ac.jp
Chiba
Seiichi
S
Noguchi
Hitoshi
H
Yasuda
Tohru
T
Tobe
Kazuyuki
K
Suzuki
Ryo
R
Kadowaki
Takashi
T
Yoshimatsu
Hironobu
H
D000273:Adipose Tissue / Q000737:chemistry / Q000473:pathology; D054369:Agouti-Related Protein; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000378:metabolism*; D001786:Blood Glucose / Q000032:analysis; D001823:Body Composition; D004435:Eating; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D015870:Gene Expression; D005786:Gene Expression Regulation; D007031:Hypothalamus / Q000737:chemistry; D007328:Insulin / Q000097:blood; D055504:Insulin Receptor Substrate Proteins; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D007473:Ion Channels; D008099:Liver / Q000737:chemistry; D008297:Male; D026901:Membrane Transport Proteins / Q000032:analysis / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D024101:Mitochondrial Proteins / Q000032:analysis / Q000235:genetics; D018482:Muscle, Skeletal / Q000737:chemistry; D009478:Neuropeptide Y / Q000235:genetics; D009479:Neuropeptides / Q000235:genetics*; D009765:Obesity / Q000378:metabolism* / Q000473:pathology; D010750:Phosphoproteins / Q000172:deficiency* / Q000502:physiology; D011333:Pro-Opiomelanocortin / Q000235:genetics; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D012727:Sex Characteristics; D014280:Triglycerides / Q000032:analysis / Q000097:blood; D000071246:Uncoupling Protein 2; D015430:Weight Gain
D054369:Agouti-Related Protein; C515199:Agrp protein, mouse; D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D007473:Ion Channels; C526298:Irs2 protein, mouse; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D009478:Neuropeptide Y; D009479:Neuropeptides; D010750:Phosphoproteins; D011506:Proteins; D012333:RNA, Messenger; D014280:Triglycerides; C000604390:Ucp2 protein, mouse; D000071246:Uncoupling Protein 2; D011333:Pro-Opiomelanocortin