Session: SUN 780-806-Determinants of Insulin Resistance & Associated Metabolic Disturbances
Poster Board SUN-803
Muscle, liver, thigh fat and blood were collected from 2 weeks, 4 weeks, 4 months and 1 year-old male SD rats or spontaneous dwarf rats (SDRs), which have GH deficiency. The 2 week-old rats were separated from their mother 1 hour before sacrifice, and the others were sacrificed after overnight fasting. The tissue lysates were immunoprecipitated using an anti-insulin receptor antibody. The protein samples were electrophoresed by SDS-page, and membranes were probed with anti-IGF-I receptor antibody, and the amount of HR was determined. The tissue lysate after immunoprecipitation, which had insulin receptor removed, was immunoprecipitated again with anti-IGF-I receptor antibody, and the protein samples were electrophoresed, and probed with anti-IGF-I receptor antibody to investigate IGF-I/IGF-I receptor. HR and insulin/insulin receptor were investigated using the opposite method as above. The serum concentration of glucose and insulin were measured and HOMA-R was calculated.
HR was 1.2 to 2.2-fold increased in each organ sample with aging. The insulin/insulin receptor and IGF-I/IGF-I receptor was decreased in each organ with aging. The insulin/insulin receptor in each organ from 1-year old SD rat was about 0.2-fold compared to 2 week-old SD rat. There was significant correlation between serum concentration of insulin or HOMA-R and amount of HR in liver and fat. There was no difference in amount of HR, insulin/insulin receptor and IGF-I/IGF-I receptor between SD rats and SDR.
Our study clearly describes that the expression of HR increased, whereas insulin/insulin receptor and IGF-I/IGF-I receptor decreased with aging. The expression of HR was not influenced by the GH-IGF-I system. It is shown that the fasting serum insulin levels are increased compensatory to decreased expression of insulin/insulin receptors and increased expression of HRs in the muscle, fat and liver of aging rats.
Nothing to Disclose: MI, TM, SM, GY
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