| Objective: Diabetes is one of the top three hazardous diseases to humanhealth presently, which with an increasing incidence rate, and its chroniccomplications can spread throughout most of the vital organs of the body.Diabetic encephalopathy is a cognitive dysfunction induced by Diabetes,which is characterized by learning and memory impairment, but itspathogenesis is not clear yet. In recent studies, it has been shown thatoxidative stress plays an important role in the development of diabeticencephalopathy. The role of oxidative damage in the pathogenesis of Diabeticencephalopathy has been investigated extensively. Heme oxygenase-1(HO-1)is the most important antioxidant protease in the nuclear factor E2-relatedfactor2(Nrf2) pathway. Superoxide dismutase (SOD) reflects the body’sability to scavenge oxygen free radicals, which means the oxidative stresslevels in the body. And malondialdehyde (MDA) reflects the concentrations offree radicals and lipid peroxidation，which represents the levels of oxidativestress in the body. As it has been shown that, α-Lipoic Acid is a well knownantioxidant, and in recent studies, troxerutin has also been confirmed to haveanti-oxidant and anti-inflammatory effects. In this study, we set up thecognitive dysfunctional Diabetes Type1rats as our animal models, and makethe powerful antioxidant α-Lipoic Acid as our matched control, to observe theeffects of troxerutinthe on the cognitive function, HO-1, SOD, and MDA inSTZ diabetic rats.Methods:1. The method of setting up animal models:Healthy male Sprague-Dawley (SD) rats were treated with intraperitonealinjection of streptozotocin (STZ)(60mg/kg),3days later, the ones with bloodglucose of the caudal vein above16.7mmol/Ｌwere considered as the successful models,then feeding for12weeks to set up the cognitive dysfunction.2.Grouping:70healthy male SD rats(150～170g) were randomly divided into the normalcontrolling group (NC group, n=10) and the diabetes group (DM group, n=60).Then the diabetes group was randomly divided into4groups: the diabeticnormal controlling group (DC, n=15), the diabetic group treated withintraperitoneal saline injection,0.7ml/kg (DN, n=15), the diabetic group treatedwith intraperitoneal α-lipoic acid injection,60mg/kg (DL, n=15), and thediabetic group treated with intraperitoneal troxerutin injection,60mg/kg (DTgroup, n=15). The treatment of intervention was lasted for6weeks.3. Observation:Mental status and general conditions such as eating,drinking and urinevolume of the rats were observed and recorded. The blood glucose and weight ofthe rats were detected and recorded.4. Ethological test:Morris water maze test was executed respectively in the1st,12thand18thweek. Escape latencies (s) were recorded to analyze the changs of learning andmemory.5. Specimen handling and index observation:The intervention was lasted for6weeks, then cut the hippocampus of thecerebrum, detected the following indexes: the expression of HO-1mRNA bymethods of Real-Time RCR, the level of HO-1protein by methods of Westernblot, the level of SOD by methods of xanthine oxidase, and the concentration ofMDA by methods of thiobarbituric acid.6. Statistics methods:All analyses were performed using the statistical software SPSS13.0. Andmeasurement data were expressed as mean±standard deviation(X±S). Thewater maze data were compared with repeated measurement and multivariateanalysis of variance, the results of Real-Time PCR、Western blot、SOD and MDAwere analyzed by one-way analysis of variance (ANOVA), and the pairwisecomparisons among the means were analyzed using the Student-Newman-Keuls test. P<0.05was considered statistically significant.Results:1.General conditions,blood glucose and body weight:The NC group rats were in good spirit, and had sheeny fur, sensitiveresponsive, their food and water intake, as well as the urine output were normal,the body weight were significantly increased. But the spirit of the DM rats werein poor condition, had dirty and dull fur, polyuria, polydipsia, polyphagia, andgrowed slowly, the body weight lossed significantly. Comparing with NC group,DM group had significantly weight loss (P<0.01), and blood glucose increasedsignificantly (P<0.01).2. The Morris water maze escape latency:①The1stafter modeling: There was no significant difference between DMgroup and NC group (P>0.05).②The12thweek after modeling (before intervention): The escape latency ofDM group was significantly prolonged than NC group (P<0.01).③The18thweek after modeling (after intervention): Compared with NCgroup, the escape latency of DL, DT, DC and DN group were significantlyprolonged (P<0.01)；Compared with DC group and DN group, the escape latencyof DL group and DT group were significantly shorter (P<0.01), while there wasno significant difference between DL group and DT group(P>0.05)；Also therewas no significant difference between DC group and DN group (P>0.05). Therewas no interaction between the days and the groups (P>0.05).3. The Real-Time PCR results (the expression of HO-1mRNA):Compared with NC group（1±0）, the expression of hippocampus HO-1mRNA in DC group（0.6705±0.1557）and DN group（0.6617±0.1122）weresignificantly decreased (P<0.05)；There was no significant difference betweenDC group and DN group(P>0.05).Compared with DC group and DN group, the HO-1mRNA expression inhippocampus of DL group（0.9933±0.1276）and DT group（0.9328±0.1823）were significantly increased (P<0.05), up to the level of NC group (P>0.05); Andthere was no significant difference between DL group and DT group (P>0.05). 4. Western blot results (the Hippocampus HO-1protein levels):Compared with NC group （1±0）, the HO-1protein levels inhippocampus of DC group（0.8967±0.0257）and DN group（0.8544±0.0296）were significantly lower (P<0.05); There was no significant differencebetween DC group and DN group (P>0.05).Compared with DC group and DN group, the HO-1protein levels inhippocampus of DL group（1.0539±0.0300）and DT group（1.0390±0.0300）were significantly increased (P<0.05), up to the level of NC group (P>0.05);There was no significant difference between DL group and DT group(P>0.05).5. The levels of SOD and MDA in hippocampus:①The vitality of SOD:Compared with NC group（115.98±7.57）, thevitality of SOD in hippocampus of DC group（61.81±3.94）and DN group（68.24±7.62） were significantly lower (P<0.05); There was no significantdifference between DC group and DN group (P>0.05).Compared with DC group and DN group, the vitality of SOD inhippocampus of DL group（200.32±6.17）and DT group（191.99±11.41）were significantly increased (P <0.05), and they were higher than NC group(P<0.05); There was no significant difference between DL group and DTgroup (P>0.05).②The level of MDA: Compared with NC group（2.74±0.21）, the levelof MDA in hippocampus of the DC group（3.83±0.11）and DN group（3.71±0.20）was significantly increased (P<0.05);There was no significantdifference between DC group and DN group (P>0.05).Compared with DC group and DN group, the level of MDA inhippocampus of DL group（2.02±0.23）and DT group（2.54±0.20）weredecreased significantly (P<0.05);There was no significant difference betweenDT group and NC group (P>0.05), the DL group had the minimal level ofMDA in hippocampus, it was significantly lower than DT group and NCgroup (P<0.05). Conclusions:1.Diabetes can cause the function of learning and memory decline in rats,and there has been significant cognitive impairment in the12thweek STZdiabetic rats;2.In the hippocampus of the STZ induced diabetic rats, both theexpression of HO-1mRNA and the HO-1protein concentration decreased,which indicates that, the rats with antioxidant disability can lead increasedoxidative stress damage;3.Troxerutin can improve the diabetic rats’ cognitive dysfunction, and itseffect is roughly the same with α-lipoic acid;4.Troxerutin can increase the expression of HO-1mRNA and HO-1protein level in the hippocampus of STZ diabetic rats, and up-regulate thelevel of SOD, down-regulate the concentration of MDA, its effect is less thanα-lipoic acid. |
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