The Effects Of Jin Zhida Capsule On Endoplasmic Reticulum Stress In Hippocampus Of Diabetic Encephalopathy Rats

Objective:With the population aging, the living standards improving and the lifestyle changing, the morbidity of Diabetes mellitus increases every year. Diabetes mellitus(DM) is a common and frequently-occuring disease. It is divided into four types:Type 1 Diabetes Mellitus (T1DM), Type 2 Diabetes Mellitus (T2DM), Gestational Diabetes Mellitus(GDM) and the other type DM in new WHO Classification. T2DM is associated with insulin resistance (IR). With the disease developing, DM can cause multi-system and multi-organ damages. Diabetic encephalopathy (DE) is a complication of central nervous system. DE is associated with chronic cognitive dysfunction, but the mechanism isn't clear so far. The endoplasmic reticulum stress (ERS) is a protective mechanism of cells to maintain its internal environment stable and protect cell surviving during stress. It is proved that ERS may participate in insulin resistance. IR presences not only in peripheral, but also in the brain, and causes insulin effect obstructed and inadequate to cause or promote diabetic encephalopathy. Therefore, we would study the relationship of ERS and diabetic encephalopathy, and find new strong evidences for diabetic encephalopathy mechanism.Jin zhida Capsule was investigated as Multi-component Chinese Medi-cine, and was created by Professor Libin Zhan's disscusion group according to the experimental and clinical experience. They choosed the ingredients improving the ability of learning and memory. The ingredients of this recipe are concise. This recipe can calm the nerves, make people smarter and have great meaning in research and development. Therefore, this study is to research the effects of Jin zhida Capsule on ERS in the hippocampus of diabetic encephalopathy rats and its mechanism.Methods:1. After 3 days feeding adaptation, healthy adult male Sprague Dawley (SD) rats were randomly divided into control group,diabetic encephalopathy group, low, middle and high-dose Jin zhida Capsule group, five groups totally.2. We fed the rats with high fat diet and injected them with low dose STZ to establish Type 2 diabetes mellitus models. The rats who were fed with the high fat diet were injected with low dose STZ, and the others were injected with the citric acid buffer. After 72h, the rat whose radom blood glucoses was more than 16.7mmol/L was identified as type 2 diabetes mellitus models.We detected the level of fasting serum insulin(FSI), oral glucose tolerance test(OGTT)and insulin tolerance test(ITT)to prove whether the model rats appeared impaired glucose tolerance and insulin resistance. Then the changes of physical signs of the rats were observed. The radom blood glucoses were detected every 10 days.3. During the treatment, we treated the diabetic encephalopathy rats respectively with low, middle and high-dose Jin zhida Capsule Ig, twice a day and intervals for 12 hours. The control and diabetic encephalopathy groups were treated with NS for 5 weeks. After the treatment the rat brains were obtained, then reserved in fridge.4. Step-down test and Morris water maze test were used to evaluate the behavioral changes.5.Detected the protein expression of GRP78, PERK, phospho-PERK, eIF2α, phospho-eIF2αin rat hippocampus by Western blotting.Results:1. The rats who were fed with high-fat diet significantly increased in weight(P<0.05). After injection of STZ, the radom blood glucose and fasting insulin serum levels significantly increased(P<0.05). Diabetes mellitus model rats all presented polydipsia, polyphagia, polyuria, impaired oral glucose tolerance (P<0.01), and impaired insulin tolerance. The weight decreased later. 2. After the treatment, the other groups rats' weight decreased signifi-cantly(P<0.05), polydipsia and polyphagia(P<0.01) except the control group. The rectal temperature and blood glucose didn't change after the treatment.3. The results of step down test and Morris water maze test showed that the ability of learning and memory of the diabetic encephalopathy group reduced significantly (P<0.05). That of the high-dose Jin zhida Capsule group increased significantly (P<0.05), but the low and middle-dose group didn't.4. Western Blotting results indicated the levels of GRP78, phospho-PERK, phospho-eIF2αin hippocampus of the diabetic encephalopathy group,low and middle-dose group were significantly increased(P<0.05), and that of the high-dose group was signigicantly decreased(P<0.05).But the total protein levels of PERK and eIF2αwere not changed.Conclusions:1. The impaired ability of learning and memory occurred on the Type 2 diabetes mellitus model rats being induced by the method of combination of high-fat diet feeding and low dose STZ injection,so it could be taken as an ideal diabetic encephalopathy animal model.2. The impaired ability of learning and memory of diabetic encephal-opathy rats may relate to the PERK signaling pathway of ERS being initiated.3. Jin zhida Capsule improved the ability of learning and memory of diabetic encephalopathy rats,particularly the high-dose group.4. The protective effects of the high-dose Jin zhida Capsule on the ability of learning and memory of the diabetic encephalopathy rats may affect the PERK signaling pathway of ERS. This may be related to inhibit the expressions of GRP78,phospho-PERK and phospho-eIF2α.