| Objective Using animal experiments to investigate expression of glucose transporter4(GLUT-4) and p38mitogen-activated protein kinase(P38MAPK) in myocardial cells of impaired glucose tolerance(IGT)’s rats fed by high-sugar and high-fat,and to explore the role of GLP-1receptor agonist on GLUT-4expression in myocardial cells of IGT’s rats.Methods Fifty-four male Wistar rats in4-5weeks (150g-170g) of clean grade were purchased in the animal breeding center of Shanxi Medical University. After one week adaptive feeding (five/cage), they were divided into A group (n=18) and B group (n=36) randomly. The A group rats were fed by normal diet (13.4kJ/g, which accounted for10.2%of calories, fat and protein accounted for23.3%respectively, carbohydrate accounted for66.5%); The B group rats were given high-sugar and high-fat feed (21.8kJ/g, which accounted for56.0%of calories, fat and protein accounted for7.0%respectively, carbohydrates accounted for37.0%) and free access to water, at room temperature controlled at18-22℃, relative humidity30%-70%. Two groups of rats twice a day morning and evening feeding, daily food in take for each rat to vote for3%of body weight. When12weeks, do oral glucose tolerance test (OGTT):after fasting8h, cut the tail blood and rapid blood glucose meters measure fasting blood glucose (FBG),intragastric administration with50%glucose injection2g/kg body weight, after2h cut the tail blood again and measure2h postprandial blood glucose (2hPG). Building a suceessful model was7.8mmol/L<2hPG<11.1mmol/L and continued for more than a week. The A group, blood glucose to normal, and being setted to normoal glucose tolerance control group (NGT group, n=18). Thirty-two rats in B group were into models, it has the making model success rate of over88%, and randomly divided the B group into two groups, the impaired glucose tolerance group (IGT group, n=16), Exendin-4interventionin group (Ex group, n=16). Select randomly nine rats in NGT group, eight rats in IGT group and Ex group respectively, weighing, and then do oral glucose tolerance test measure FBG and2hPG. The next day,after fasting12-14h. anesthetized rats with5%chloral hydrate by intraperitoneal injection0.6ml/100g body weight, taken abdominal primary venous blood, rapid centrifugation of blood samples of serum specimens. 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) and P38MAPK by Western blot. Put the remaining ventricular part rapidly in liquid nitrogen, after thoroughly frozen, stored in-70C 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 interventing4weeks, weighing, and then measure2hPG. The next day, anesthetized rats, quickly remove the heart, and measured the expression of GLUT-4mRNA by RT-PCR and P38MAPK by Western blot. All results were measured by (x±s), using SPSS17.0software package, multiple groups means were compared with single factor analysis of variance, LSD test. P<0.05was considered statistically significant. Then Pearson correlations were used to determine the relationship between P38MAPK and GLUT-4.Results1. The changes of clinical characteristics and biochemical indices between rats in each groups Before intervention, compared with the NGT group, the body weigh of rats in the IGT group and the Ex group were higher (514.13±13.41vs.448.67±12.90)(513.12±11.86vs.448.67±12.90) and the differences were also significant (both P<0.05). the2hPG of rats were higher (9.69±0.33vs.5.96±0.77)(9.28±0.38vs.5.96±0.77) the differences were also significant (both P<0.05). Compared with the IGT group, the body weigh and the2hPG of rats in the Ex group were decreased (513.12±11.86vs.514.13±13.41)(9.28±0.38vs.9.69±0.33) but the difference was not significant (both P>0.05). After intervented with Exendin-44weeks, compared with the IGT group, the body weigh and the2hPG of rats in the Ex group were decreased (445.88±20.27vs.520.75±18.42)(7.19±0.34vs.10.28±0.37) the differences were significant (both.P<0.05). Compared with the Ex group before intervented, the levels were decreased (445.88±20.2vs.513.12±11.86)(7.19±0.34vs.9.28±0.38) the differences were significant (both P<0.05). Compared with the NGT group, the body weigh levels were lower (445.88±20.2vs.459±11.20) but the difference was not significant (P>0.05) and the2hPG levels were higher (7.19±0.34vs.6.26±0.53) but the difference was not significant (P>0.05).2. Expression of CLUT-4mRNA in myocardium with each groups Before intervention,:ompared with the NGT group, the expression of GLUT-4with rats in the IGT group and the Ex group were decreased (0.08±0.034vs.1.20±0.367)(0.08±0.040vs.1.20±0.367) and the lifferences were significant (both P<0.05). The expressions of GLUT-4with rats in the Ex group and the IGT group were same (0.08±0.040vs.0.08±0.034), the difference was not significant (P>0.05). After intervented with Exendin-44weeks, compared with the IGT and Ex group, the expression of GLUT-4in the Ex group was increased (1.16±0.400vs.0.07±0.025)(1.16±0.400 vs.0.08±0.040) the differences was significant (both P<0.05). Compared with the NGT group the level was decreased (1.16±0.400vs.1.21±0.426) but the difference was not significant (P>0.05).3. The expression of P38MAPK in myocardium with eath groups Before intervention, compared with the NGT group, the expression of P38MAPK with rats in the IGT group and the Ex group were incresed (1.044±0.010vs.0.592±0.084)(1.043±0.012vs.0.592±0.084) and the differences were significant (both P<0.05). Compared with the IGT group, the expression of P38MAPK with rats in the Ex group was decreased (1.043±0.012vs.1.044±0.010) but the difference was not significant (P>0.05). After intervented with Exendin-44weeks, compared with the IGT and Ex group, the expression of P38MAPK in the Ex group was decreased (0.567±0.102vs.1.041±0.012)(0.567±0.102vs.1.043±0.012) the differences was significant (both P<0.05). Compared with the NGT group the level was decreased (0.567±0.102vs.0.587±0.083) but the difference was not significant (P>0.05).4. The expression of GLUT-4and the expression of P38MAPK in myocardium was significantly correlated in rats with impaired glucose tolorence (r=-0.884, P<0.01).Conclusions1. Impaired glucose tolerance stage already exists the myocardial expressions of GLUT-4declined, that meanwhile exists myocardial tissue glucose uptake obstacled.2. P38MAPK expression involved in the regulation of myocardial GLUT-4expression in rats with impaired glucose tolorence.3. GLP-1receptor agonist Exendin-4could reduce blood sugar, meanwhile increase the myocardial expression of GLUT-4in rats with impaired glucose tolerance by inhibit the expression of P38MAPK, improving the energy metabolism of myocardial cells of rats with impaired glucose tolerance. |
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