The Effect Of Blood Glucose Fluctuation On Oxidative Stress And Cognitive Function In Type 2 Diabetic Rats

Objective To explore the effect of blood glucose fluctuation on oxidative stress and cognitive function in diabetic rats.Methods Forty male Wistar rats were randomly divided into normal control group（group N,n=13）and diabetic model group（group M,n=27）.The diabetic rat model was established by injection of a small dose of streptozotoein(STZ,30 mg·kg^-1)after feeding the model group wistar rats with high glucose and high fat diet after 6 weeks,then the diabetes model group（M）were randomly divided into two groups:high glucose sustain diabetes model group（MS n=13）;glucose fluctuate diabetes model group（MF n=14）.In which the latter group was given dietary intervention,resulting in a blood glucose fluctuation model with nocturnal hypoglycemia-postprandial hyperglycemia.After eight and twelve weeks of blood glucose fluctuation,Morris Water maze was used to perform training trial and probe trial in order to detect spatial learning and memory abilities.The regulation ability of the blood glucose of rats in each group were detected by the glucose tolerance test.Blood was collected after fasting for 12 hours,fasting blood glucose（FBG）,glycosylated hemoglobin（HbA1c）,superoxide dismutase（SOD）,glutathione peroxidase（GSH-PX）,catalase（CAT）and the content of malondialdehyde（MDA）,calculated blood glucose level standard deviation（SDBG）,the maximum amplitude of glycemic excursions（LAGE）,the mean blood glucose level（MBG）..Results 1)the MS、MF group compared with the N group:the water intake and urine volume increased significantly（P<0.05）,body weight was significantly reduced（P<0.05）;2)Compared to the N,the MS、MFgroup significant increase of FBG、SDBG、LAGE、MBG、HbA1c increased significantly（P<0.05）,the activity of SOD、GSH-Px、CAT were decreased significantly（P<0.05）,but the increase of MDA（P<0.05）.Compared with the MS group,LAGE and SDBG were significantly higher in group MF（P<0.05）,while FBG and MBG were significantly lower（P<0.05）;3)Morris water maze test:The escape latency of MS.MF was all significantly higher than that of N,compared to the N,latency distance was significantly prolonged（P<0.05）.and spatial probe test results show 120s through platform region number decreased significantly.Compared to MS,MF the escape latency was was further increased（P<0.05）,the latency diatance was significantly prolonged（P<0.05）.and the number of rats passing hidden platform in the quadrant of hidden platform in 120s were further significantly decreased（P<0.05）;4)with blood glucose fluctuation time prolonged,the learning and memory ability of rats in each group was decreased significantly,escape latency and latency distance increases（P<0.05）,space exploration experiment 120s across the platform region number decreased significantly（P<0.05）.Results The blood glucose fluctuation can aggravate oxidative stress reaction in diabetic rats,reduce the learning and memory ability,blood sugar fluctuation and oxidative stress play an important role in the pathogenesis of diabetic cognitive dysfunction.