| Objective:The purpose of this study is to explore the effects of green tea on cerebrum cognitive function and histological structure in diabetes mellitus rats by the examination of expression of MLCK,ERK,P-ERK and observed the changes of hippocampal neurons and cognitive function in rats.Methods:1.Determine the content of 11 components in green tea infusion is used to HPLC.2.The replicative diabetic rat model was induced by streptozotocin,and the diabetic rats were randomly divided into eight groups:model group,insulin group,green tea infusion low,medium,high dose group,EGCG low,medium,high dose group,the normal matched rats were taken as control group,12 for each group.From the 4th week to the 12 th week,the diabetic rats in group green tea infusion low(EGCG2mg/kg·d),medium(EGCG5mg /kg·d),high(EGCG8mg/kg·d)dose group,EGCG low(EGCG2mg/kg·d),medium(EGC G5mg/kg·d),high(EGCG8mg/kg·d)dose group,insulin separately(8U/kg,2times/day),fasting blood glucose and body weight weekly.3.Cognitive function of all rats was detected by Morris water maze test.4.The tissue morphology of hippocampus was observed by HE stain.5.The ultrastructure of hippocampus was observed by transmission electron microscope.6.The expressions of MLCK,ERK,P-ERK in hippocampus were detected by western blot.Results: 1.The relative retention time and RSD of Relative peak area of the 5 batches of green tea tea soup HPLC common peak were all less than 5% with good repeatability.2.The weight of the rats in the control group increased,and the weight of the rats in the model group decreased.After the model was added to the green tea infusion,EGCG,and insulin injection,the body weight of the rats decreased slowly.After the green tea infusion,EGCG,and insulin injection,the rats gained weight.And in a dose-dependent manner,the weight gain trend of the green tea infusion group was greater than the EGCG group in same dose.3.Compared with the control group,the blood glucose of the model group was significantly increased(P<0.01).Compared with the model group,the blood glucose of the insulin group was significantly decreased(P<0.01),and the blood glucose of the green tea infusion and EGCG was significantly decreased after 8 weeks.(P <0.01),and dose-dependent,the hypoglycemic effect of the green tea infusion group was better than the EGCG group in same dose.4.Compared with the control group,the escape latency of the model group was significantly prolonged,and the crossing platform times was significantly reduced(P<0.01),compared with the model group,the escape latency of the insulin group was significantly shortened,and the crossing platform times was significantly increased(P<0.01);After intervention of green tea and EGCG,the escape latency of each group was shortened(P<0.01),the crossing platform times increased(P<0.01),and it was dose-dependent.The effect of the green tea infusion group was better than the EGCG group in same dose.5.The results of HE staining showed that compared with the control group,the hippocampal neurons in the model group were irregular in shape,evacuated,the boundary was not clear,and the nuclei were lightly stained,compared with the model group,the hippocampal neurons in the insulin group were more complete and arranged,it is more tidy and the boundary is clear,after the intervention of green tea and EGCG,the morphology of hippocampal neurons is improved to different extents in each group,the morphology of neurons is intact and the structure is not clear,compared with the same dose group,the green tea group has better effect than the EGCG group.6.The results of electron microscopy showed that,compared with the control group,the nucleus morphology of hippocampal neurons was irregular in the model group,the distribution of chromatin in the nucleus was uneven,the mitochondria in the cytoplasm showed swelling and vacuolation,and the rough endoplasmic reticulum showed vesiculation and expansion,compared with the model group,the nucleus morphology of hippocampal neurons was more complete in the insulin group,the nucleoli were more obvious,the chromatin distributio was more uniformn in the nucleus,the cytoplasmic organelles were more abundant,the endoplasmic reticulum had no vesiculation and expansion,and the mitochondria had no swelling,after the intervention of green tea and EGCG,the morphology of hippocampal neurons was changed to varying degrees in each group,the nucleus morphology of hippocampal neurons was more regular,and the cytoplasmic organelles were more numerous and the structure was more regular,compared with the dose group,the effect of the green tea infusion group was better than that of the EGCG group.7.Compared with the control group,the expressions of MLCK and p-ERK in the hippocampus of the model group were increased,but there was no significant change in the expression of ERK.Compared with the model group,the expressions of MLCK and p-ERK in both the green tea infusion and EGCG intervention groups were decreased in a dose-dependent manner,and the effect of the green tea infusion group was better than the EGCG in same dose.Conclusion: 1.Green tea and its main component EGCG can improve the cognitive ability of diabetic rats.2.The effect of hypoglycemia and improving cognitive ability of green tea is better than that of the same dose of EGCG group,indicating that green tea improves the cognitive ability of diabetic rats as a result of a combination of various active ingredients.3.The level of MLCK and P-ERK in the hippocampal tissue of rats with diabetic cognitive dysfunction was increased,and the expression of MLCK and P-ERK could be regulated by the ERK pathway after the administration of green tea and EGCG,thus exerting neuroprotective effects on diabetic cognitive dysfunction rats. |
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