Effect of dietary fatty acids on insulin resistance in OLETF rats

Objective To investigate the effect of dietary fatty acids composition on insulin resistance in OLETF rats. Methods Forty 14-week-old male Otsuka Long-Evans Tokushima Fatty(OLETF) rats were ran-domizedly divided into 4 groups(n = 10, each). They were fed with standard diet(A) , high fat diet(C) , high n-6 polyunsaturated fatty acid(PUFA) diet(D) and high n-3 PUFA diet(E), respectively for 10 weeks. Ten male LE-TO rats served as control were fed with standard diet. Oral glucose tolerance tests, C peptide and immunoreactive insulin(IRI) were measured. Hyperinsulinemia clamp was used to evaluate the insulin resistance of the rats. Results At the age of 24-weeks, all OLETF rats except group E had higher levels of fasting plasma glucose, 120' postloading plasma glucose and IRI than those of the control group(P 0.05). However, the levels of fasting and 120' postloading C peptide were similar in all groups. In addition, LETO and group E rats had higher level of glucose infusion rate than group C and D rats(P 0.05). Conclusion The OLETF rats had higher levels of plasma glucose and lower insulin sensitivity than the LETO rats, suggesting that diet with high n-3 PUFA may improve glucose metabolism and insulin resistance in OLETF rats.