Changes Of Glucagon In Hypoglycemia Of Two Experimental Diabetic Rats

Objective:To investigate the difference of serum glucagon response to insulin-induced hypoglycemia (once and twice) in two kinds of diabetic rats.Methods:Administrating different feeding approaches and different doses of Streptozotocin intraperitoneal injection to induce type1and type2diabetes mellitus in rats. Normal rats, T1DM rats and T2DM rats were divided randomly into control group (NC, TIC, T2C), hypoglycemia group (NL1, T1L1, T2L1) and recurrent hypoglycemia group (NL2, T1L2, T2L2) respectively. The occurrence of hypoglycemia of the rats was induced by injecting insulin. Blood samples were obtained from heart at the time before peritoneal injection (insulin or0.9%sodium chloride solution) and1.5h,4.5h after injection. After blood glucose being detected by glucometer, the blood serum was extracted by centrifugation and kept for the subsequent glucagon determination with ELISA kit. Immunohistochemical method was used to observe a cells and β cells in pancreatic islet of the rats.Results:1). Glucagon (GC):There were no statistical differences in baseline levels of glucagon among normal and two kinds of diabetic rats (P>0.05). While the peak levels of glucagon of hypoglycemia groups were at1.5h in NL1group, at4.5h in T1L1group, at Oh in T2L1group respectively; the peak concentrations of glucagon of recurrent hypoglycemia groups were at1.5h in NL2group, at4.5h in T1L2group, at4.5h in T2L2group respectively.2).Ratio of glucagon and blood glucose (GC/BG):This value could better reflect the relative level of glucagon on their respective glycaemic conditions. The baseline of relative level of GC was significantly elevated comparing to both kinds of diabetic rats (P<0.05, P<0.01respectively). In T1DM rats, the relative level of GC at1.5h was obviously higher than normal rats in first and recurrent hypoglycemia (all P<0.05); the relative level of GC at4.5h was distinctly increased compared with1.5h in the same group(all,P<0.05), but no differences compared with normal rats(P>0.05). In T2DM rats, the relative level of GC at1.5h and4.5h were significantly lower compared with normal rats and T1DM rats(all P<0.01).Conclusion:The defects of glucagon counterregulatory response to hypoglycemia do exist in both kinds of diabetic rats, especially in the early stage. Between two kinds of diabetic rats, the defects are different, which indicates that T2DM rats more seriously.