| Objective: Insulin resistance (IR) is related withoccurrence of various diseases in vivo. There is an importantrelation of dietary composition with IR occurrence. The relationwith IR is also different with Different type of carbohydrate andfat in the diets. In this research we offer male Wistar rat withhigh sucrose, high-saturated fatty acid and high-unsaturatedfatty acid diets to observe the effect of the different foodcomposition upon IR in rats so as to find a reasonable basic foodformulation for mankind.Method: 72 male Wistar rats (5 months, weight: 250-300 g)were randomly assigned into four groups: normal control group(group NC, n=18) fed with normal diets; experimental groupswere high sucrose group (group HS, n=18), high saturated fattyacid group (group HSF, n=18) and high unsaturated fatty acidgroup (group HUF, n=18) fed with different diets. Calorieprovided by Carbohydrate, fat and protein was 65.5%, 10.3%and 24.2% respectively in the normal regulation animal diets.The high sucrose diets were made by adding 20% sucrose in thenormal regulations animal diets and calorie provided bycarbohydrate, fat and protein was 76.5% , 7.0% and 16.5%respectively; The high saturated fatty acid diets were made byadding 20% butter in the normal regulations animal diets andcalorie percentage provided by carbohydrate, fat and proteinwas 43.0%, 41.0% and 16.0%. The high-unsaturated fatty aciddiets were made by adding 20% soybean oil in the normalregulations animal diets and calorie percentage was the same asin high-saturated fatty acid feed. The proportion of unsaturatedfatty acid and saturated fatty acids content was 84% and 16% inthe soybean oil and which was 69.1% and 30.9% in the butter,pure degree of sucrose was 99%. All diets were provided byexperimental animal center of Hebei medical college. Weoffered all rats with normal regulation diets for 2 weeks to adaptto the environment, and then offered rats with different diets tocorrespond group. We measured the body weight (BW), systolicpressure (SBP) every 4 weeks, and took the blood sample fromheart to measure the fasting plasma glucose (FBG), the totalcholesterol (TC), the serum triglyceride (TG), the fasting seruminsulin (FINS). We measured the serum free fatty acids( FFA)and took 6 rats from each group for high insulin euglycemicclamp technique at 0,12 and 24 week.Result: 1. Change of weight Weight of rats increasedsignificantly(p <0.05-p <0.01)in HSF and HUF groups and itwas not obviously in HS group. BW increased by 24%, 31%,39%, 36% in NC group, HS group, HUF group and HSF groupat 24 week. 2. Chang of blood fat TC and TG was highersignificantly(p<0.01)in HSF group than that in NC group from4 week to the end of the test. TC was higher obviously in HUFgroup than that in NC group from 12 week to the end of the test,but significant increasing of TG didn't appear until 24 week. TCand TG increased significantly in HS group at 20,16 week andthis status kept on till the end. 3. Chang of FBG FBGincreased Significantly in all experimental groups at 8 week.This status kept on till the end of the test and there was nodifference of BG among experimental groups. 4. Chang of FINSFINS in all experimental groups increased obviously from 8week and there was no difference among experiment groups.This status kept on till the end of the test. 5.Chang of FFALevel of FFA of rats in each experimental group all had anobvious increasing than that in NC group (p <0.01) after 16weeks. It was much higher in HSF group than that in HS andHUF group (p<0.01). Level of FFA in each experimental grouphad an obvious increasing than that in NC group (p <0.01) at 24week but there was no difference among experimental groups. 6.Chang of blood pressure and appearance of stroke SBP ofrats in all experimental groups was obviously higher than that inNC group(p<0.01)at 4 week and increased following time. SBPof rats in HSF, HUF and HS group was high enough to diagnosehypertension at 12, 16, 20 week respectively. One rat developedinto stroke in HSF group at 20 week and the symptom lasted tothe end of test. Two rats developed into stroke in HS group at 21and 22 week respectively and the symptom of one disappearedafter a week. 7. Chang of insulin sensitivity (ISI) and glucoseinfusion rate (GIR) Insulin sensitivity index(ISI)decreasedsignificantly from 8 week to 24 week in the experimental groups(p <0.01) . GIR were obviously difference among experimentalgroups at 12 week and 24 week(p <0.01). GIR in HSF groupwas lower than that in HS group and in HUF group. GIRdecreased by 50%, 54%, 34%, 26% in high saturated fatty acid(HSF) group, high unsaturated fatty acid (HUF) group, highsucrose (HS) group and NC group respectively from 0 week to24 weeks.We merged all rats'GIR and did a relative analysisbetween GIR and other indexes. The result showed that TG, FFA,GLU,INS,SBP were obviously negatively related with GIR (rvalue was -0.6076, -0.3562, -0.4790, -0.5419, -0.6441, -0.6291and p value was 0.0010, 0.0459, 0.0115, 0.0035, 0.0003,0.0004 respectively ).TC was negatively related with GIR, but itwas not significant(p>0.05). Multiple stepwise regressionsshowed that TG and FFA were the major risk factors affectingGIR.Conclusion: We successfully assessed the insulinsensitivity by ISI and high insulin euglycemic clamp techniquein rats feeding by different diets. IR will be caused by long-termhigh-unsaturated fatty acids, high-saturated fatty acids and highsucrose diets. Disorder of lipid metabolism and high level ofFFA are caused by different diets that could cause IR. Dietscomposition is more important to IR in rats although there is adecreasing trend of GIR following age. Hypertension even...
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