茶多酚通过调节海马小胶质细胞极化改善衰老2型糖尿病大鼠抑郁样行为

Tea polyphenols improves depression-like behavior in aged type 2 diabetes rats by regulating microglia polarization

目的探讨茶多酚通过调节海马小胶质细胞极化改善衰老2型糖尿病大鼠抑郁样行为的机制。方法40只8周龄雄性SD大鼠按照体重随机分为对照组(n=10)和造模组(n=30)。造模组饲喂高糖高脂饲料并每日腹腔注射50 mg/kg D-半乳糖至实验结束,对照组饲喂普通饲料并每日腹腔注射等量生理盐水。高糖高脂饲料饲喂4周后,造模组一次性腹腔注射25 mg/kg链脲佐菌素,对照组腹腔注射等量的柠檬酸缓冲液。注射链脲佐菌素2周后,大鼠空腹血糖≥16.7 mmol/L判定为2型糖尿病造模成功。造模成功后,根据空腹血糖随机分为模型组、150和300 mg/kg茶多酚干预组,每组10只。茶多酚灌胃干预8周后,检测大鼠空腹血糖,旷场实验及强迫游泳实验评估大鼠抑郁样行为,免疫荧光法检测海马CA1区小胶质细胞密度,Western Blot检测海马P53、Iba1、iNOS、Arg-1以及脑源性神经营养因子的表达。结果与对照组比较,模型组大鼠空腹血糖明显升高(P<0.01);旷场实验中直立次数、修饰次数显著减少,强迫游泳实验中不动时间显著增加(P<0.01);海马CA1区Iba1^(+)小胶质细胞密度显著增加(P<0.01);海马P53、Iba1及iNOS的表达水平显著上调,Arg-1及脑源性神经营养因子表达水平显著下调(P<0.01)。茶多酚干预8周后,与模型组比较,150、300 mg/kg茶多酚组大鼠旷场实验中直立次数、修饰次数增加(P<0.01);海马CA1区Iba1+小胶质细胞密度明显降低(P<0.01);海马组织P53、Iba1及iNOS的表达水平显著下调(P<0.01),脑源性神经营养因子表达水平显著上调(P<0.05)。此外,与模型组比较,300 mg/kg茶多酚组大鼠空腹血糖明显降低(P<0.01);强迫游泳实验中不动时间显著减少(P<0.01);海马组织Arg-1表达水平显著上调(P<0.01)。结论茶多酚可改善衰老2型糖尿病大鼠抑郁样行为,其机制可能与茶多酚调节海马小胶质细胞M1/M2型极化,上调脑源性神经营养因子蛋白表达水平有关。

OBJECTIVE To investigate the effect of tea polyphenols(TP)on improving depression-like behavior in aged type 2 diabetes(T2DM)model rats.METHODSS A total of 408-week-old SD male rats were randomly divided into the control group(n=10)and the modeling group(n=30)according to the body weight.The rats in the modeling group were fed with high-glucose and high-fat diet and treated with 50 mg/kg D-galactose by intraperitoneal injection daily until the end of the experiment,while the rats in the control group were fed with the standard diet and treated with an equal volume of saline by intraperitoneal injection.After 4 weeks,the rats in the modeling group were injected with 25 mg/kg STZ,meanwhile the rats in the control group were injected with an equal volume of citric acid buffer.The level of fasting blood glucose(FBG)was measured on the 14"day.When FBG≥16.7 mmol/L,the rats were identified as successful model of the T2DM rats.Then,the model rats were randomly divided into the model group,150,300 mg/kg TP groups(n=10,respectively),and the rats were given intragastric intervention for 8 weeks.The levels of the FBG were detected,and the depression-like behavior of rats was assessed by the open field test(OFT)and forced swimming test(FST).The density of microglia in hippocampus CA1 region was assessed by immunofluorescence staining,and protein expressions of P53,Ibal,iNOS,Arg-1 and BDNF were determined by western blot.RESULTS Compared with the control group,the levels of FBG in the rats of the model group were obviously increased(P<O.01).In the OFT,the frequencies of rearing and grooming in the rats of model group markedly was decreased,while in the FST,the immobility time extensively was increased(P<0.01).The density of microglia in hippocampus CA1 region was increased(P<0.01).The expressions of P53,Ibal and iNOS were increased,and the expressions of Arg-1 and BDNF were decreased(P<0.01).Additionally,compared with the model group,in the OFT,the frequencies of rearing and grooming were increased in the rats in 150 and 300 mg/kg TP group(P<0.01).The density of microglia in hippocampus CA1 region was decreased(P<0.01).The expressions of P53,Ibal and iNOS were downregulated,and the expression of BDNF was up-regulated(P<0.O1).Additionally,compared with the model group,the levels of FBG was decreased in the rats in the 300 mg/kg TP group(P<0.01).The immobility time was decreased in the FST(P<0.01).The expression of Arg-1 was down-regulated(P<0.01).CONCLUSION TP can improve depression-like behavior in aged T2DM model rats,and its mechanism may be related to regulate microglia M1/M2 polarization and up-regulate expression of BDNF in hippocampus.