EFFECTS OF A HIGH-FAT, SUCROSE DIET ON SERUM-INSULIN AND RELATED ATHEROSCLEROTIC RISK-FACTORS IN RATS

Hyperinsulinemia, hypertension, hypertriglyceridemia and obesity are a ll risk factors for atherosclerosis. The clustering of these risk fact ors in the same individual greatly increases the risk for atherosclero sis and has been termed 'Syndrome X' or 'The Deadly Quartet' The purpo se of the present study was to investigate the effects of diet on thes e risk factors in inbred, female Fischer 344 rats. Animals were raised on ad lib diets consisting of high-fat, sucrose (HFS) or low-fat, com plex-carbohydrate (LFCC). After 2 years, the HFS rats were obese (38% +/- 1% vs. 15% +/- 1% body fat), hypertensive (140 +/- 3 vs. 123 +/- 3 mmHg), hyperinsulinemic (439 +/- 118 vs. 98 +/- 10 pmol/l), and hyper triglyceridemic (1.1 +/- 0.2 vs. 0.4 +/- 0.07 mmol/l). The HFS rats al so exhibited enhanced clotting and impaired fibrinolytic response to s treptokinase. All these differences between the two groups were statis tically significant (P < 0.05). Insulin was significantly correlated w ith body weight (r = 0.71), triglycerides (r = 0.48), and systolic blo od pressure (r = 0.70). Total cholesterol was slightly, but not signif icantly higher, in the HFS group (2.8 +/- 0.3 vs 2.2 +/- 0.1 mmol/l) w hile HDL-cholesterol was unchanged. These results show that many risk factors for atherosclerosis can be induced in inbred rats by feeding a HFS diet. Aggregation of risk factors was found in the HFS group but not in the LFCC group. In fact, most of the rats on the LFCC diet deve loped no risk factors after 2 years, indicating that the development o f risk factors is not an aging phenomenon.