HISS-dependent insulin resistance (HDIR) in aged rats is associated with adiposity, progresses to syndrome X, and is attenuated by a unique antioxidant cocktail.
The hypotheses were: HISS-dependent insulin resistance (HDIR) accounts for insulin resistance that occurs with aging; HDIR is the initiating metabolic defect that leads progressively to type 2 diabetes and the metabolic syndrome; a synergistic antioxidant cocktail in chow confers protection against HDIR, subsequent symptoms of diabetes, and the metabolic syndrome. Male Sprague Dawley rats were tested at 9, 26, and 52 weeks to determine their dynamic response to insulin, the HISS (hepatic insulin sensitizing substance)-dependent component of insulin action, and the HISS-independent (direct) insulin action using a dynamic insulin sensitivity test. In young rats, the HISS component accounted for 52.3+/-2.1% of the response to a bolus of insulin (50mU/kg) which decreased to 29.8+/-3.4% at 6 months and 17.0+/-2.7% at 12 months. HISS action correlated negatively with whole body adiposity and all regional fat depots (r(2) = 0.67-0.87). The antioxidants (vitamin C, vitamin E, and S-adenosylmethionine) conferred protection of HISS action, fat mass at all sites, blood pressure, postprandial insulin and glucose. Data are consistent with the hypotheses. Early detection and therapy directed towards treatment of HDIR offers a novel therapeutic target.
Department of Pharmacology & Therapeutics, Faculty of Medicine, University of Manitoba, Winnipeg, Man., Canada R3E 0T6. wlautt@cc.umanitoba.ca
W Wayne
WW
Lautt
Zhi
Z
Ming
M Paula
MP
Macedo
Dallas J
DJ
Legare
D000273:Adipose Tissue / Q000473:pathology; D050154:Adiposity / Q000187:drug effects / Q000502:physiology*; D000375:Aging / Q000473:pathology / Q000502:physiology; D000818:Animals; D000975:Antioxidants / Q000627:therapeutic use*; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology; D018450:Disease Progression; D017097:Electric Impedance; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D024821:Metabolic Syndrome / Q000473:pathology / Q000503:physiopathology* / Q000517:prevention & control; D009765:Obesity / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley
D000975:Antioxidants; D001786:Blood Glucose; D007328:Insulin