Impaired glucose tolerance is a hallmark of aging even in the absence of attendant pathology, and is associated with increased mortality due to enhanced risk for development of diabetes and cardiovascular disease. Intolerance of aging is typically attributed to the development of insulin resistance, resulting from changes in adiposity, diet, and/or sedentary lifestyle, and studies to understand the pathogenesis of intolerance have focused on the relative contributions of insulin resistance and pancreatic islet dysfunction. We have demonstrated that insulin-independent mechanisms of glucose regulation are equally important in determining glucose tolerance. These processes, termed """"""""glucose effectiveness"""""""", are defined as the actions of glucose to regulate its own utilization (Rd) and hepatic production (HGO) independent of elevated insulin. The purpose of this proposal is to examine the role of glucose effectiveness in the glucose intolerance of normal, non-diseased aging in the rat. We will test the hypothesis that in insulin-resistant states such as aging, efficient disposition of a carbohydrate challenge becomes increasingly dependent on metabolic factors which are independent of insulin action, i.e. glucose effectiveness. These studies will establish the role of glucose effectiveness in the glucose intolerance of normal, non-diseased aging. We will apply newly developed methods to quantify glucose effectiveness directly in young and old rats, and determine how aging alters the relative contributions of Rd vs HGO and the specific tissue sites and glucose transporters involved. We will examine the mechanisms by which glucose effectiveness may compensate in aging-associated insulin resistance. Finally, we propose to examine the ability of caloric restriction to improve tolerance through their actions on glucose effectiveness, and determine the tissue sites, mechanisms, and glucose transporters which may be involved.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
1R01AG015111-01A1
Application #
2766671
Study Section
Nutrition Study Section (NTN)
Program Officer
Finkelstein, David B
Project Start
1998-12-02
Project End
2002-11-30
Budget Start
1998-12-02
Budget End
1999-11-30
Support Year
1
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of Southern California
Department
Physiology
Type
Schools of Medicine
DUNS #
041544081
City
Los Angeles
State
CA
Country
United States
Zip Code
90089
Catalano, Karyn J; Bergman, Richard N; Ader, Marilyn (2005) Increased susceptibility to insulin resistance associated with abdominal obesity in aging rats. Obes Res 13:11-20
Bergman, Richard N; Ader, Marilyn; Huecking, Katrin et al. (2002) Accurate assessment of beta-cell function: the hyperbolic correction. Diabetes 51 Suppl 1:S212-20
Bergman, R N; Ader, M (2000) Free fatty acids and pathogenesis of type 2 diabetes mellitus. Trends Endocrinol Metab 11:351-6