The Expression Of Aβ In Brain Tissues Of Spleen-Yin Deficiency Diabetic Encephalopathy Model Rats And Possible Mechanisms Of Nourishing Spleen Yin Recipe

Objectives:Diabetic encephalopathy is one of the chronic comp- lications of diabetes mellitus. But the pathogenesis of diabetic encep- halopathy is still unclear. Numerous epidemiological studies suggest that the pathogenesis of Alzheimer's disease(AD) is associated with that of diabetes mellitus, diabetes mellitus is one of the risk factors for AD. AD is characterized by extracellular senile plaques(SP) composed primarily of amyloidβpeptide(Aβ) and intracellular neurofibrillary tangles. The aggregation and deposits of Aβcould result in inflammatory cascade response, neurofibrillary tangles, axonal injury, synapse loss, neuronal degeneration and neuron apoptosis, inducing cognitive dyfunction. Therefore, to detect Aβdeposits in brain tissue of diabetic encephalopathy could contribute to understanding the pathogenesis of diabetic encep- halopathy, and provide new direction and idea for prevention and therapy of diabetic encephalopathy.Nourishing spleen yin recipe(Zibu Piyin Recipe,ZBPYR), created by Professor Libin Zhan, could reinforce spleen and nourish spleen yin. It was established to treat spleen-yin deficiency syndrome. It had been showed that ZBPYR had notable effects on neuroprotection and anti-aging of brain, and ZBPYR could protect the spleen-yin deficiency Alzheimer's disease animal models and primary cultured rat hippocampal neurons against Aβ1-40 toxicity. Therefore, this study was to observe the protective effects and meachnisms of ZBPYR further on spleen-yin deficiency diabetic encephalopathy animal models. Methods:1. Healthy adult male Sprague Dawley(SD)rats were divided randomly into control group, spleen-yin deficiency group, diabetic encep- halopathy group, spleen-yin deficiency diabetic encephalopathy group, and spleen-yin deficiency diabetic encephalopathy+ZBPYR group, five groups totally.2. Firstly, type 2 diabetes mellitus models were established by 4 weeks of high-fat food feeding and low dose STZ(30mg/kg) intraperitoneal injection. Second, the classical compound method was used to construct spleen-yin deficiency rats model by improper diet, over exertion and yin fluids exhaustion. Then all the factors of making models were stopped, ZBPYR were administrated to spleen-yin deficiency diabetic encep- halopathy rats intragastrically. Then the changes of physical signs of the rats were observed.3. Step-down test and Morris water maze test were performed to evaluate the behavioral changes.4. Using immunohistochemistry to examine the Aβ? deposits in hippocampuses and using the wersten blotting method to detect protein expression levels of GSK-3αand phospho-GSK-3α(Ser21) in rat hippo- campuses.Results:1. The feeding of high-fat diet food for 4 weeks resulted in significant increase in body weight (P<0.05). After injection of STZ, diabetes mellitus model rats all presented polydipsia, polyphagia, polyuria, impaired oral glucose tolerance (P<0.01), and impaired insulin tolerance. Fasting insulin serum levels were similar between diabetes rats and non-diabetes rats (P>0.05).2. The spleen-yin deficiency group presented endogenous heat symptomes caused by yin-deficiency, such as the increment of water drinking(P<0.01), objective elevation of rectal temperature(P<0.05). The results of Morris water maze test and step-down test showed that learning and memory ability of the diabetic encephalopathy group and spleen-yin deficiency diabetic encephalopathy group were reduced significantly (P<0.05), and that of ZBPYR treatment group were increased significantly (P<0.05). 3. The expression level of Aβin the cytoplasm of hippocampus neurons of the diabetic encephalopathy group and spleen-yin deficiency diabetic encephalopathy group were significantly increased(P<0.01, P<0.05, respectivly), and after ZBPYR treatment, the expression level of Aβ? in the cytoplasm of hippocampus neurons of spleen-yin deficiency diabetic encephalopathy rats was significantly decreased(P<0.05).4. The protein expression of GSK-3αof all the groups was not changed. The phosphorylation level of GSK-3α(Ser21) in hippocampuses of the diabetic encephalopathy group and spleen-yin deficiency diabetic encephalopathy group was significantly increased(P<0.05, P<0.01, resp- ectivly), and that of ZBPYR treatment group wasn't signigicantly changed (P>0.05), compared to control group.Conclusions:1. The spleen-yin deficiency diabetic encephalopathy model rats could be induced by the classical method of the spleen-yin deficiency in combination of high-fat diet and low dose STZ injection, the models could simulate the behavior changes of diabetic encephalopathy patients, so it could be taken as an ideal diabetic encephalopathy animal model.2. The increased expression of brain Aβmay be the pathogenesis of diabetic encephalopathy.3. ZBPYR could improve learning and memory ability of the spleen- yin deficiency diabetic encephalopathy rats significantly.4. The protective effects of ZBPYR on the ability of learning and memory of spleen-yin deficiency diabetic encephalopathy rats may be associated with the decrease in expression of Aβin brain tissue, indepen- dently of the inhibition of GSK-3α?activity possibily.