The Effect Of Sevoflurane On The Cognitive Function In Aged Diabetic Rats And The Role Of MTOR/Grb10 Pathway

Part One: Construction of Aged Rat Models with Diabetes-Associated Cognitive DeclineObjective: To establish aged rat models with Diabetes-Associated Cognitive Decline(DACD)and provide good animal models for follow-up studies.Methods: 80 male Sprague Dawley rats,weight 440-500 g and 18-20 months old,were randomly separated into two groups according to a random number table.Group A: normal control group,n=40;Group B: diabetic model group,n=40.Rats in group A were fed a normal diet.Rats in group B were fed a high-fat diet combined with 1% intraperitoneal injection of Streptozotocin(35mg/kg)to prepare animal models of type 2 diabetes.Rats with a Random Blood Glucose(RBG)level of 16.7 mmol/L at 72 hours after STZ injection can determine the success of the model.After 8weeks of feeding the two groups of rats,the Morris Water Maze was used to test the learning and memory ability.Results: 1.After 4 weeks of high-fat diet,the rats in group B became fat and body weight of rats was significant higher than that of group A(p(27)0.01).2.After 72 hours of intraperitoneal injection of STZ,the RBG of group B was significant higher than that of group A(p(27)0.01).3.After 8 weeks of intraperitoneal injection of STZ,compared with rats in group A,the escape latency was lengthened and the times of platform crossing were reduced in group B,they have statistical significance(p(27)0.05).Conclusion: Type 2 diabetes animal models were successfully established by high-fat diet combined with 1% intraperitoneal injection of low dose STZ.With the extension of the course of disease,the behavior of animals was changed.The learning and memory ability test could be used to determine the success of the aged DACD rat models.Part Two: The Effect of Sevoflurane on the Cognitive Function in Aged Rats with Diabetes-Associated Cognitive Decline and the Role of mTOR/Grb10 PathwayObjective: To investigate the effect of sevoflurane on the cognitive function in Aged Rats with DACD(Diabetes-Associated Cognitive Decline,DACD)and the mechanism of mTOR/Grb10 signaling pathway in hippocampus.Methods: According to a random number table,ninety-six aged DACD rats were randomly divided into four groups(n=24,respectively).During the experiment,aged DACD rats were placed in a self-made gas anesthesia box to inhale 3% sevoflurane or O2 for 3h,the rapamycin solution(20mg/kg)or an equal volume of solvent(DMSO)was intraperitoneally injected 2 days before the experiment,once a day,continued until 4 days after the experiment.1.Control group(CON group): intraperitoneal injection of equal volume of DMSO,inhalation of O2 for 3h.2.Rapamycin group(RAP group): intraperitoneal injection of rapamycin,inhalation of O2 for 3h.3.Sevoflurane group(SEV group): intraperitoneal injection of equal volume of DMSO,inhalation of 3% sevoflurane for 3h.4.Rapamycin + sevoflurane group(RAP + SEV group): intraperitoneal injection of rapamycin,inhalation 3% sevoflurane 3h.On the 1st and 7th days after the experiment,12 rats were randomly selected from each group for 5 consecutive days of cognitive function test.At the end of the test,they were taken to detect apoptosis of hippocampal neurons,expression of mTOR,p-mTOR,Grb10,p-Grb10 and expression of Grb10 m RNA.Results: 1.Escape latency: one day after the experiment,compared with CON group and RAP+SEV group,the escape latency of rats in SEV group was significantly prolonged(p<0.01);Compared with the CON group and RAP+SEV group,the escape latency of the rats in RAP group was significantly shorter(p<0.01).Times of platform crossing: compared with the CON group and the RAP+SEV group,the times of platform crossing in SEV group were significantly reduced(p<0.05);Compared with the CON group and RAP+SEV group,the times of platform crossing in RAP group were significantly increased(p<0.05).After 7 days of the experiment,there was no statistically significant difference in escape latency and the times of platform crossing(p(29)0.05).2.The phosphorylation levels of mTOR and Grb10 in hippocampus: on the5 th day after the experiment,compared with CON group and RAP+SEV group,the phosphorylation levels of mTOR and Grb10 in SEV group were significantly increased(p(27)0.01).Compared with the CON group and RAP+SEV group,the phosphorylation levels of mTOR and Grb10 were significantly declined in the RAP group(p(27)0.05).On the 11 th day,the phosphorylation levels of mTOR and Grb10 were no significantly difference in each group(p(29)0.05).3.Apoptosis of hippocampal neurons: compared with CON group and RAP+SEV group,the proportion of TUNEL positive cells in the total cells in SEV group was significantly increased on the 5th day after the experiment,the difference was statistically significant(p(27)0.01).Compared with CON group and RAP+SEV group,the proportion of TUNEL positive cells in the total cells in RAP group was significantly reduced,the difference was statistically significant(p(27)0.05).On the 11 th day,no significant difference was found in the proportion of TUNEL positive cells in the total cells in each group(p(29)0.05).4.The expression of Grb10 m RNA in hippocampus: there was no significant difference in the expression of Grb10 m RNA in each group(p(29)0.05).Conclusions:1.The cognitive impairment of aged DACD rats was aggravated in the short term after sevoflurane anesthesia,rapamycin can reduce the degree of cognitive impairment.2.Sevoflurane aggravated cognitive dysfunction in aged DACD rats,it may be related to the up-regulation activity of mTOR/Grb10 pathway in the hippocampus.