| Objective Using animal experiments,to investigate expression of glucose transporter 4(GLUT-4) in myocardial cells of impaired glucose tolerance(IGT)'s rats fed by high-sugar and high-fat,and to explore the effects of GLP-1 receptor agonist on GLUT-4 expression in myocardial cells of IGT's rats.Methods Forty-eight male Wistar rats in 4-5 weeks (150g-180g) of clean grade were purchased in Institute of Chinese Medicine of Shanxi. After one week adaptive feeding (five/cage), they were divided into A group (n=16) and B group (n=32) randomly. The A group rats were fed by normal diet (13.4kJ/g, which accounted for 10.2% of calories, fat and protein accounted for 23.3% respectively, carbohydrate accounted for 66.5%); The B group rats were given high-sugar and high-fat feed (21.8kJ/g, which accounted for 56.0% of calories, fat and protein accounted for 7.0% respectively, carbohydrates accounted for 37.0%) and free access to water, at room temperature controlled at 18-22℃, relative humidity 30%-70%. Two groups of rats twice a day morning and evening feeding, daily food in take for each rat to vote for 3% of body weight. When 12 weeks, do oral glucose tolerance test (OGTT):after fasting 8h, cut the tail blood and rapid blood glucose meters measure fasting blood glucose (FBG), intragastric administration with 50% glucose injection 2g/kg body weight, after 2h cut the tail blood again and measure 2h postprandial blood glucose (2hPG). Building a suceessful model was 7.8mmol/L<2hPG< 11.lmmol/L and continued for more than a week[1]. The A group, blood glucose to normal, and being setted to normoal glucose tolerance control group (NGT group, n=16). Twenty-eight rats in B group were into models, it has the making model success rate of over 87.5%, and randomly divided the B group into two groups, the impaired glucose tolerance group (IGT group, n=14). Exendin-4 interventionin group (Ex group, n=14). Select randomly eight rats in NGT group, seven rats in IGT group and Ex group respectively, weighing, and then do oral glucose tolerance test measure FBG and 2hPG. The next day. after fasting 12-14h, anesthetized rats with 5% chloral hydrate by intraperitoneal injection 0.6ml/100g body weight, taken abdominal primary venous blood.rapid centrifugation of blood samples of serum specimens,detect fast plasma insulin by chemiluminescence methord and calculation insulin sensitive index.Then quickly remove the heart after taking the blood,with ice PBS wash clean and dry with filter paper water.Obtain the apical tissues and measured the expression of GLUT-4mRNA by real time quantitative polymerase chain reaction(RT-PCR).Put the remaining ventricular part rapidly in liquid nitrogen,after thoroughly frozen,stored in-70℃refrigerator.The remaining rats in NGT group continue to give normal diet, the IGT group and Ex group were to continue to give high-sugar high-fat feeding and freedom drinking water. Ex group received Exendin-4 (Eli Lilly and Company to provide) 5ug/kg subcutaneously, twice daily, in the NGT group and the IGT group were given equal volume of saline injection. When interventing 4 weeks, weighing, and then measure FBG and 2hPG. The next day, anesthetized rats with 5% chloral hydrate by intraperitoneal injection 0.6ml/100g body weight, taken abdominal primary venous blood,rapid centrifugation of blood samples of serum specimens,detect fast plasma insulin by chemiluminescence methord and calculation insulin sensitive index.Then quickly remove the heart after taking the blood,with ice PBS wash clean and dry with filter paper water.Obtain the apical tissues and measured the expression of GLUT-4mRNA by real time quantitative polymerase chain reaction(RT-PCR).Put the remaining ventricular part rapidly in liquid nitrogen,after thoroughly frozen,stored in-70℃refrigerator. All results were measured by (x±s), using SPSS 17.0 software package, multiple groups means were compared with single factor analysis of variance, LSD test. P≤0.05 was considered statistically significant.Results1.The changes of clinical characteristics and biochemical indices between rats in each groups Before intervention, compared with the NGT group, the body weight of rats in the IGT group and the Ex group were higher (542.9136.23 vs.614.32±40.43) (542.91±36.23vs. 620.50±43.34) and the differences were also significant (both P<0.05).The FBG of rats were higher(5.43±0.53vs6.07±0.43) (5.43±0.53vs.6.06±0.32)the differences were also significant (both P<0.05), the 2hPG of rats were higher (6.22±0.91vs.9.81±0.90) (6.22±0.91 vs.9.62±1.02) the differences were also significant (both P<0.05). Compared with the IGT group, the body weigh of rats in the Ex group was higher (614.32±40.43vs.620.50±43.34) but the difference was not significant (P>0.05),the FBG and the 2hPG were lower (6.07±0.43 vs. 6.06±0.32)(9.81±0.90 vs.9.62±1.02)but the difference was not significant (both P> 0.05). After intervented with Exendin-44 weeks, compared with the IGT group, the body weigh,the FBG and the 2hPG of rats in the Ex group were decreased (636.21±37.59vs.555.95±52.00) (6.95±0.67 vs.5.39±0.42)(10.06±0.85 vs.6.76±1.61) the differences were significant (both P<0.05). Compared with the Ex group before intervented. the levels were decreased (620.50±43.34 vs.555.95±52.00) (6.06±0.32 vs.5.39±0.42)(9.62±1.02vs.6.76±1.61)the differences were significant (both P<0.05).Compared with the NGT group the levels were higher (533.89±44.08 vs.555.95±52.00) (5.25±0.34 vs.5.39±0.42) (6.45±1.47vs.6.76±1.61) but the difference was not significant (P>0.05).2.The changes of fast plasma insulin and insulin sensitive index in each groups Before intervention, compared with the NGT group, the FIN of rats in the IGT group and the Ex group were higher(8.65±1.48vs.16.95±2.12)(8.65±1.48 vs.16.10±1.98) and the differences were also significant (both P<0.05). The ISI of rats were lower(-3.83±0.19 vs.-4.62±0.14)(-3.83±0.19vs.±4.58±0.45)the differences were also significant (both P<0.05). Compared with the IGT group, the FIN of rats in the Ex group was lower (16.95±2.12vs.16.10±1.98),the ISI was higher(—4.62±0.14 vs.—4.58±0.45) but the differences were not significant (both P> 0.05). After intervented with Exendin-44 weeks, compared with the IGT group, the FIN of rats in the Ex group was lower(20.24±1.88vs.10.91±1.41) the differences were significant (P<0.05),the ISI of rats was higher(—4.94±0.07vs.—4.06±0.15) the differences were significant (P<0.05).Compared with the Ex group before intervented, the levels of FIN was lower(16.10±1.98 vs.10.91±1.41) the differences were significant (bothP<0.05),the ISI was higher(—4.58±0.45 vs.—4.06±0.15) the differences were significant (bothP<0.05).Compared with the NGT group,the FIN was higher (7.65±0.76vs.10.91±1.41),the ISI was lower (—3.69±0.12vs.—4.06±0.15) the differences were significant (bothP<0.05).3.Expression of GLUT-4mRNA in myocardium with each groups Before intervention, compared with the NGT group, the expression of GLUT-4 with rats in the IGT group and the Ex group were decreased (1.13±0.18vs.0.64±0.08)(1.13±0.18 vs.0.65±0.21)and the differences were significant (both P<0.05). Compared with the IGT group, the expression of GLUT-4 with rats in the Ex group was higher (0.64±0.08 vs.0.65±0.21) but the difference was not significant (P> 0.05). After intervented with Exendin-44 weeks, compared with the IGT and Ex group, the expression of GLUT-4 in the Ex group was increased (0.58±0.32 vs.0.99±0.17) (0.65±0.21 vs.0.99±0.17) the differences was significant (both P<0.05). Compared with the NGT group the level was incresed (1.01±0.05 vs.0.99±0.17) but the difference was not significant (P>0.05).Conclusions1 Impaired glucose tolerance stage already exists insulin sensitivity to decline, meanwhile exists that the myocardial expression of GLUT-4 declined and myocardial tissue glucose uptake obstacled.2 When the GLUT-4 expression of myocardial tissue drops, the body has insulin resistance.3 GLP-1 receptor agonist could reduce blood sugar, meanwhile increase the myocardial expression of GLUT-4 in rats with impaired glucose tolerance, improving the insulin sensitivity of rats with impaired glucose tolerance.
|
PDF Full Text Request