The Changes Of White Matter And Myelinated Nerve Fibers Were Found By The Stereological Analysis In Type 1 Diabetes Rats

Part ? The changes of total volume of white matter were found by the stereological analysis in type 1 diabetes ratsObjective: We investigated the effects of white matter injury on the diabetes cognitive dysfunction by using the stereological method to quantify the changes of total volume of white matter in type 1 diabetes mellitus rats.Methods: Forty healthy adult SD rats were used including STZ-injected group(20 rats)and control(20 rats).Each group has half male and half female.Each rat was weighed and labeled.We cut tails to get blood and then test blood glucose.A large dose of STZ(60mg/kg)was used into rats by intraperitoneal injection,and then the model of type 1 diabetes was established,while the control group was injected with the citric acid buffer solution.The body weight and fasting blood glucose were respectively measured at seventh day.After STZ injection for 3 months,the rats in the STZ-injected group which survived and reached the blood glucose standard of type 1 diabetic rats were set as type 1 diabetes group(12 rats).The Morris water maze was used to detect the spatial learning and memory ability.After perfusion and fixation,the brain was removed.The 1mm continuous isometric brain slices through the coronal plane were obtained.The total volume of white matter in each group was measured and calculated by Cavalieri's principle.Results: After STZ injection for 1 week,the fasting blood glucose in the STZ-injected group was obviously higher than that in the control group,and it was still in the hyperglycemic state after 3 months(P<0.05).Compared with the control group,the escape latency of the Morris Water Maze test in type 1 diabetes group was increased while the total volume of white matter was decreased(P<0.05).Conclusion: We successfully established type 1 diabetes rats with a large dose of intraperitoneal STZ injection.The spatial learning ability of diabetes rats was decreased,and atrophy and injury of white matter appeared in diabetes rats.Therefore,white matter injury maybe plays an important role in cognitive dysfunction in type 1 diabetes rats,which could help us to clarify the mechanism of cognitive dysfunction in diabetes.Part ? The changes of myelinated nerve fibers were found by the stereological analysis in type 1 diabetes rats.Objective: We explored the relation between cognitive dysfunction and injury of white matter by using the unbiased stereological method to quantify the changes of myelinated nerve fibers and myelin sheath in type 1 diabetes rats.Methods: The obtaining methods of model and brain slices were the same as the part I.Five rats were randomly chosen from the respective groups.The ultrathin sections of brain were gotten according to the principles of isotropic.The sections were observed with the transmission electron microscope after special staining.We took randomly photographs of 6,000 and 15,000 times respectively,then used the unbiased stereological method to measure the total volume,total length and mean diameter of myelinated nerve fibers,and the total volume and average thickness of its myelin sheath.Results: 1.The total volume of the myelinated nerve fibers was decreased by 46.1% in the diabetic model group,and the difference is significant(P<0.01).The total length of the myelin nerve fibers was remarkably reduced by 45.0%(P<0.05).No significant change appeared for the mean diameter of the myelinated nerve fibers.2.We analyzed the influence factor of the changes of the total length of myelinated nerve fibers,and the results from the reduction in the number of myelinated nerve fibers with the diameter between 0.5?m and 1.1?m(P<0.05).3.Compared with the control,the total volume of myelin nerve fibers was reduced by 47.0% in the diabetes group,and the difference is significant(P<0.01).The average thickness of the myelin sheath was increased,but the difference is not significant(P>0.05).4.By observing the length distribution of myelin sheath thickness in white matter,the decrease of myelinated nerve fibers of diabetes rats was mainly due to the reduction in the number of myelin sheath with the thickness of 0.15?m to 0.25?m(P<0.05).Conclusion: We found the decreases of the total volume of the myelinated nerve fiber and the myelin sheath in the white matter,so as the total length of myelinated nerve fiber,which was resulted from the reduction in the number of the myelinated nerve fiber with small diameter and thin myelin sheath thickness.The results indicated that cognitive dysfunction was closely associated with changes of white matter and its myelinated nerve fiber,which can provide some morphologic data for clarifying the mechanism of cognitive dysfunction in type 1 diabetes rats.