title: Deficiency of adrenomedullin induces insulin resistance by increasing oxidative stress.
abstract: Hypertension, insulin resistance, and obesity are common age-related metabolic disorders that are often associated with increased oxidative stress and the resultant vascular damage. Underlying mechanisms have been suggested, and age-related overproduction of oxidative stress is one possible candidate. Since we recently found a vasoactive peptide, adrenomedullin, to be an endogenous antioxidant that potently inhibits oxidative stress-induced vascular damage, in the current study we evaluated oxidative stress-induced changes in aged mice. Insulin sensitivities in young and aged adrenomedullin-deficient mice were measured by means of the hyperinsulinemic-euglycemic clamp method; insulin resistance was apparent in aged adrenomedullin-deficient mice with increased urinary excretion of 8-iso-prostaglandin F2alpha, a marker of oxidative stress, but not in young adrenomedullin-deficient mice. Concomitantly, only aged adrenomedullin-deficient mice not only showed increased production of muscular reactive oxygen species, as demonstrated by the electron spin resonance method, but also had significantly decreased insulin-stimulated glucose uptake into the soleus muscle associated with impairment of insulin signals such as insulin receptor substrate-1,2 and phosphatidylinositol-3 kinase activities. In turn, these abnormalities could be nearly reversed by either treatment with 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, a membrane-permeable superoxide dismutase mimetic, or adrenomedullin supplementation. Evidence presented in this report suggests that age-related accumulation of oxidative stress is involved in blood pressure regulation and insulin resistance in aged adrenomedullin-deficient mice, and adrenomedullin is thus an endogenous substance counteracting oxidative stress-induced insulin resistance associated with aging.
authors.affiliation: Department of Internal Medicine, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Shimosawa
authors.forename: Takehide
authors.initials: T
authors.lastname: Ogihara
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Matsui
authors.forename: Tomoichiro
authors.initials: T
authors.lastname: Asano
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Ando
authors.forename: Toshiro
authors.initials: T
authors.lastname: Fujita
mesh_terms: D053607:Adrenomedullin; D000375:Aging / Q000502:physiology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D003497:Cyclic N-Oxides / Q000494:pharmacology; D003847:Deoxyglucose / Q000493:pharmacokinetics; D005260:Female; D005838:Genotype; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D007333:Insulin Resistance / Q000502:physiology*; D028421:Isoprostanes / Q000652:urine; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D010455:Peptides / Q000172:deficiency* / Q000235:genetics / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D003497:Cyclic N-Oxides; D007328:Insulin; D028421:Isoprostanes; D010455:Peptides; D053607:Adrenomedullin; D003847:Deoxyglucose; C003959:TEMPO