Transplantation or removal of intra-abdominal adipose tissue prevents age-induced glucose insensitivity.
Increases in intra-abdominal fat, a common feature associated with aging, is an established risk factor for insulin resistance, diabetes and the metabolic syndrome. To examine the direct contribution of intra-abdominal fat in the pathophysiology of insulin resistance we altered fat volume via removal or transplantation in a naturally occurring age-induced moderate model of obesity and insulin resistance. This was accomplished by bilateral removal of epididymal white adipose tissue (Lipx) or transplantation of donor fat into the intra-abdominal side of the peritoneal cavity of 28-week old rats. Control animals received sham surgery. Glucose tolerance was evaluated at baseline and 4 and 8weeks post-surgery in all groups, and fasting insulin and leptin were additionally measured in 28-week old rats. In addition, fasted and fed triglyceride, cholesterol and fatty acid concentrations were measured. Before surgery 28-week old rats weighed more and were glucose intolerant compared with 8-week old controls. Both Lipx and transplantation significantly prevented age-induced decreases in glucose tolerance, with Lipx causing improvement at 4weeks which declined by 8weeks; and with a significant transplantation improvement at 8weeks only. Lipx significantly increased insulin secretion 15min after a bolus injection of 0.75mg/kg dextrose at 4 and 8weeks compared with controls, while transplantation caused a significant ( approximately 220%) increase in fasted leptin level at 4weeks only. Taken together, these data suggest that surgical removal or addition of intra-abdominal fat prevents age-induced insulin resistance by different mechanisms and is a suitable model to investigate naturally occurring obesity.
Foster
Michelle T
MT
Obesity Research Center, Department of Psychiatry, University of Cincinnati, 2170 E. Galbraith Road, Cincinnati, OH 45237, United States. Michelle.Foster@uc.edu
Shi
Haifei
H
Seeley
Randy J
RJ
Woods
Stephen C
SC
D000367:Age Factors; D000375:Aging; D000704:Analysis of Variance; D000818:Animals; D015992:Body Mass Index; D005947:Glucose / Q000494:pharmacology; D005951:Glucose Tolerance Test / Q000379:methods; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D050152:Intra-Abdominal Fat / Q000378:metabolism* / Q000473:pathology / Q000637:transplantation; D020738:Leptin / Q000097:blood; D050356:Lipid Metabolism / Q000187:drug effects; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans; D013997:Time Factors; D016378:Tissue Transplantation / Q000502:physiology*
D007328:Insulin; D020738:Leptin; D005947:Glucose