| Objective: The incidence of type 2 diabetes mellitus is proportion 85%-90% of all diabetes in external.While in internal it has been reported over 90%. So ,It may have momentous significance for investigations of diabetic pathogenesis and chronic complications to develop the rat model of type 2 diabetes mellitus.At present,In internal the research of diabetes mostly adopt that a greatly dosage STZ(60mg/kg) intraperitoneal injection once to induce a rat model of diabetes.But this model closely simulates the human type 1 diabetes mellitus.In external,the reseach of diabetes mostly adopt a heredity model. But in this model the hereditary factor is a leading role. This does not agree with clinic. In recently 20 years , along with deepgoing of pathogenesis research of type 2 diabetes we gradually recognize that the happen of type 2 diabetes is a result of insulin resistance firstly ,then the function of pancreas will decompemsate and lastly haperglycemia is produced. In guiding of this theory , We build the rat model of type 2 diabetes in recent years.This study was aimed at developing a rat model that closely simulates the metabolic abnormalities of the human type 2 diabetes mellitus.In different period,we measure the electrophysiologic change of sciatic nerve and observe the pathologic developing of peripheral nerve .At the same time ,we observe the affection of the drug to electrophysiology and pathology.Methods:Female Wistar rats were fed with the diets enriched with sucrose(20% w/w) and lard (15% w/w) to induce insulin resistance. Hyperglycemia was developed by intraperitoned injection in these rats with 30mg/kg streptozotocin(STZ) after 1 month on the diets. After 1 month of STZ injection, Glucose and plasma insulin were measured. The rats were accepted as diabetic in the light of their blood glucose exceeded 7.8mmol/L after 1 month of STZ injection and their insulin sensitiveness dropped. Then , the model rats were divided into two groups: diabetes mellitus group and treatment group (the rats were fed with mindiab 5mg/kg. d). The two groups continue to feed with the diets enriched sucrose and lard. After 1, 2, 4 month of STZ injection , respectively, we ramdomly sample some rats in every group to observe the electrophysioloyic changes, and two rats of every group were put to death to observe the pathology developing of sutal nerve and dorsal root ganglion meurons.Results: 1 Blood glucose levels increased in response to diets but did not reach diabetes. Insulin levels increased and insulin resistance was confirmed, with hyperlipidemia. 2 After STZ injection hyperglycemia was developed, and after 1 month of STZ injection the hyperglycemia was steady [(11.17±5.06)mmol/L VS (4.06±0.29)mmol/L in controls,p<0.01] and plasma insulin decreased but was higher than the control [(29.38±6.69)ulu/ml vs (19.47±1.44)ulu/ml in controls, p<0.05]. Insulin resistance and hyperlipidemia still existed. 3 The characteristics of nerve system: 3.1 In those diabetic rats, the motor latent velocity and conduction velocity of sciatic nerve were slower, and the waves of action potential were lower than the controls [(30.52±6.43)m/s vs (45.5±5.00)m/s, p<0.05. (39.66±8.21)m/s vs (61.13±9.46)m/s ,p0.05. (20.50±5.74)mv vs (32.67±7.55)mv ,p<0.05.]. 3.2 Pathomophological study and compute image analysis of sural nerve and dorsal root ganglion .The number and area of myelin sheath, myelin sheath area percentage were smaller than the control group and treatment group[110±25 vs 149±16,p<0.05; 29423.96±5302.57 vs 40704.85±2068.00 p<0.01; 1573.40±356.99 vs 2117.66±229.72 p<0.01]. 4 Blood glucose of treatment group decreased , the motor latent velocities , conduction velocities and wave of action potential were improving , the---- pathological change was lighter than diabetes group.Conclusion: 1 The novel rat model which is similar to human type 2 diabetes is induced by way of feeding w... |
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