Effects of Long-Term Exposure to Free Nε-(Carboxymethyl)lysine on Rats Fed a High-Fat Diet

Recently correlation studies between dietary advanced glycation end products (AGEs) and the progression of chronic diseases have attracted much attention. To explore the impact of dietary AGEs on the health risk of people consuming a high-fat diet (HFD), male Sprague Dawley rats were used as the research subject. Under HFD, free N-epsilon-(carboxymethyl)lysine (CML, a major AGE, 60 mg/kg body weight/day) was administered by gavage for 12 consecutive weeks. The results indicated that protein-bound CML accumulation in the kidney, heart, lung, pancreas, and muscle significantly increased to 178 +/- 36, 161 +/- 2, 106 +/- 11, 39 +/- 8, and 141 +/- 20 mu g/g dry matter, respectively, compared to HFD control levels of 86 +/- 9, 127 +/- 10, 89 +/- 6, 23 +/- 2, and 95 +/- 3 mu g/g dry matter, whereas no statistical increase was found in the liver and spleen. An increase of the proteinbound CML might be due to free CML binding to proteins in tissues by covalent bonds. Moreover, the rats' serum low-density lipoprotein cholesterol concentration, fasting blood glucose levels, and energy expenditure also increased obviously. These findings indicated that long-term intake of high-dose free CML might be a health risk factor for rats with HFD. This could provide valuable information for further study on the possible effects of long-term consumption of CML-rich fatty foods on human health, involving the progression of chronic disease.