| Objectives:In recent years, the adipose tissue has been verified to not only be the repository of lipid, but also an active endocrine organ, who can secret diversified adipocytokines in order to facilitate or ameliorate the pathological process of obesity-related illnesses. The maladjustment of adipocytokines plays an important role in the pathophysiologic process of insulin resistance (IR) and cardiovascular disease, which has been considered as a possible intermediate links between insulin resistance and cardiovascular disease. As one of the main protective adipocytokines, adiponectin(APN) has come into the spotlight of current research due to its negative correlation with obesity, insulin resistance, coronary heart disease and dyslipidemia[3,4]. The adiponectin, as an insulin sensitizer, may be a main manipulating factor of insulin and can lower the blood sugar level. Many researches have verified that[7,8] the adiponectin-gene knocked-out rats usually has insulin resistance, and the complement of adiponectin can totally reverse their insulin resistance situation. Rats, who are feeding on food high in glucose and fats, got a negative correlation between their serum concentration of adiponectin and insulin resistance as well as fasting insulin levels. The complement of adiponectin can lower their weight, serum concentration of glucose and free fatty acid (FFA). Therefore, the supplement of adiponectin may become a prospect cure solution of insulin resistance and type 2 diabetes mellitus.The patients suffering from type 2 diabetes often has the insulin resistance. Then, what role the hyperglycemia and hyperproinsulinemia play in adiponectin expression under insulin resistance? Some researchers found from cellular level[11,12,13] that as the concentration of glucose or insulin increases, the expression of adiponectin in adipocytes decreased. But others believe that[16] short-term stimulation of insulin can improve the adipocytes to produce and secrete adiponectin. Currently, most researches focus on the expression and secretion of adiponectin in adipocytes. Recently, some people found that adiponectin can also be expressed by hepatocytes and skeletal muscle cells. Then, whether the cardiac myocytes could express adiponectin? There has not any relative report about the role of the hyperglycemia and hyperproinsulinemia play in adiponectin expression of cardiomyocytes under insulin resistance. In this study, we observe that the influence of different concentration of glucose or insulin on the expression of adiponectin-mRNA of cardiomyocytes in vitro, in order to probe into the role of hyperglycemia and hyperproinsulinemia in adiponectin expression in cardiomyocytes under type 2 diabetes associated with insulin resistance.Methods: Primary cultures the cardiomyocytes from the hearts of 2-3 days'neonatal Sprague-Dawley(SD) rats, regardless of sex. After 48 hours'culture with serum and 24 hours'culture without serum, cells in good conditions are selected and put into 12 groups randomly. They are 6 groups in glucose part.①lower concentration of glucose control group (5.5mmol/L),②20mmol/L glucose group,③25mmol/L glucose group,④30mmol/L glucose group,⑤50mmol/L glucose group,⑥hypertonic control group. They are 6 groups in insulin part.①10-6mol/L group,②10-7mol/L group,③10-8mol/L group,④10-9mol/L group,⑤10-10mol/L group,⑥0 mol/L group. Culture these cardiomyocytes with different concentration of glucose or insulin for 48 hours, useβ-actin as the internal control, then detect the expression of adiponectin-mRNA with RT-PCR.Results: (1)The cardiomyocytes can express adiponectin. (2)When treating with the concentrations of glucose lower than 30mmol/L, the expression of adiponectin decreased with the elevation of glucose concentration. The adiponectin expression of the 30mmol/L group is the lowest. When treating with the concentration of glucose higher than 30mmol/L, the expression of adiponectin didn't change significantly comparable with the 30mmol/L group. (3)The influence of high glucose on the adiponectin expression in cardiomyocytes is due to the concentration of glucose, not the osmotic pressure. (4)When treating with the concentration of insulin lower than 10-7 mol/L, the expression of adiponectin decreased with the elevation of insulin concentration. The adiponectin expression of the 10-7 mol/L group is the lowest. When treating with the concentration of insulin higher than 10-7 mol/L, the expression of adiponectin didn't change significantly comparable with the 10-7 mol/L group.Conclusion: The cardiomyocytes can express adiponectin. The great concentration of glucose or insulin can change the expression of adiponectin in cardiomyocytes. When treating with the concentration of glucose lower than 30mmol/L, the expression of adiponectin decreased with the elevation of glucose concentration. The influence of high glucose on the adiponectin expression in cardiomyocytes is due to the concentration of glucose, not the osmotic pressure. When treating with the concentration of insulin lower than 10-7 mol/L, the expression of adiponectin decreased with the elevation of insulin concentration.
|
PDF Full Text Request