Zuogui Jiangtang Jieyu Formula ameliorating hippocampal neuronal apoptosis in diabetic rats with depression by inhibiting JNK signaling pathway

Objective To investigate the effect of Zuogui Jiangtang Jieyu Formula(左归降糖解郁方,ZJJF)on hippocampal neuron apoptosis in diabetic rats with depression and to ascertain whether its mechanism involves the regulation of JNK signaling pathway.Methods(i)A total of 72 specific pathogen-free(SPF)grade male Sprague Dawley(SD)rats were randomly divided into six groups,with 12 rats in each group:control,model,metformin(Met,0.18 g/kg)+fluoxetine(Flu,1.8 mg/kg),and the high-,medium-,and low-ZJJF dosages(ZJJF-H,20.52 g/kg;ZJJF-M,10.26 g/kg;ZJJF-L,5.13 g/kg)groups.All groups except control group were injected once via the tail vein with streptozotocin(STZ,38 mg/kg)combined with 28 d of chronic unpredictable mild stress(CUMS)to establish diabetic rat models with depression.During the CUMS modeling period,treatments were administered via gavage,with control and model groups receiving an equivalent volume of distilled water for 28 d.The efficacy of ZJJF in reducing blood sugar and alleviating depression was evaluated by measuring fasting blood glucose,insulin,and glycated hemoglobin levels,along with behavioral assessments,including the open field test(OFT),forced swim test(FST),and sucrose preference test(SPT).Hippocampal tissue damage and neuronal apoptosis were evaluated using hematoxylin-eosin(HE)staining and terminal deoxynucleotidyl transferase-mediated dUTP nickend labeling(TUNEL)staining.Apoptosis-related proteins Bax,Bcl-2,caspase-3,and the expression levels of JNK/Elk-1/c-fos signaling pathway were detected using Western blot and real-time quantitative polymerase chain reaction(RT-qPCR).(ii)To further elucidate the role of JNK signaling pathway in hippocampal neuronal apoptosis and the pharmacological effects of ZJJF,an additional 50 SPF grade male SD rats were randomly divided into five groups,with 10 rats in each group:control,model,SP600125(SP6,a JNK antagonist,10 mg/kg),ZJJF(20.52 g/kg),and ZJJF(20.52 g/kg)+Anisomycin(Aniso,a JNK agonist,15 mg/kg)groups.Except for control group,all groups were established as diabetic rat models with depression,and treatments were administered via gavage for ZJJF and intraperitoneal injection for SP6 and Aniso for 28 d during the CUMS modeling period.Behavioral changes in rats were evaluated through the OFT,FST,and SPT,and hippocampal neuron damage and apoptosis were observed using HE staining,Nissl staining,TUNEL staining,and transmission electron microscopy(TEM).Changes in apoptosis-related proteins and JNK signaling pathway in the hippocampal tissues of rats were also analyzed.

Protective effects of Zuogui Jiangtang Jieyu Formula on hippocampal neurons in rats of diabetes complicated with depression via the TRP/KYN metabolic pathway

Objective To explore the protective effects and mechanism of Zuogui Jiangtang Jieyu Formula(左归降糖解郁方,ZGJTJYF)on hippocampal neurons in rats of diabetes complicated with depression(DD)via the TRP/KYN metabolic pathway.Methods(i)In vivo experiments:60 specified pathogen free(SPF)grade male Sprague-Dawley(SD)rats were randomly divided into six groups with 10 rats in each groups:control,DD model,positive(1.8 mg/kg fluoxetine+0.18 g/kg metformin),high-dose ZGJTJYF(ZGJTJYFH,40.500 g/kg ZGJTJYF),middle-dose ZGJTJYF(ZGJTJYF-M,20.250 g/kg ZGJTJYF),and lowdose ZGJTJYF(ZGJTJYF-L,10.125 g/kg ZGJTJYF)groups.Except for the control group,other groups were established DD model by high-fat emulsion intake with single tail vein streptozotocin(STZ)and four weeks of chronic unpredictable mild stress(CUMS).All drug administration groups were treated by gavage during CUMS modeling,and the control and model groups were given equal amount of distilled water.After four weeks,the serum levels of blood glucose and glycosylated hemoglobin were measured to determine the hypoglycemic effect of ZGJTJYF.Moreover,the open field test and Morris water maze test were performed to evaluate the antidepressant effect of ZGJTJYF.Changes in 5-hydroxytryptamine(5-HT)level were detected via high-performance liquid chromatography with electrochemical detection(HPLC-ECD);the levels of tryptophan(TRP),kynurenine(KYN),and indoleamine 2,3-dioxygenase(IDO)in the hippocampus were detected using enzyme-linked immunosorbent assay(ELISA);the protein expression levels of synaptophysin(SYN)and postsynaptic density material-95(PSD-95)were detected via immunohistochemistry(IHC);and the protein expression levels of N-methyl-D-aspartate receptor(NR)2 A and NR2 B were detected using Western blot.(ii)In vitro experiments:five SPF grade SD pregnant rats(E16–18)were used to obtain primary hippocampal neurons(Ne),six SD new-born rats were used to collected primary astrocytes(As)and microglia(MG),and to establish a Ne-As-MG co-culture system.All co-culture systems were divided into six groups:control(PBS),model[150 mmol/L glucose+200μmol/L corticosterone(G&P)+PBS],blank(G&P+blank serum),positive(G&P+positive drug-containing serum),ZGJTJYF(G&P+ZGJTJYF serum),and 1-methyl-D-tryptophan(1-MT,IDO inhibitor)(G&P+1-MT)groups.After 18 h of intervention by corresponding treatment,immunofluorescence was used to analyze the protein expression levels of SYN,PSD-95,NR2 A,and NR2 B;ELISA was performed to measure the levels of interleukin(IL)-1β,IL-6,tumor necrosis factor(TNF)-α,and TRP/KYN metabolic pathway-related factors[TRP,KYN,kynurenine acid(KYNA),quinolinic acid(QUIN)].Results(i)In vivo experimental results showed that ZGJTJYF-M and ZGJTJYF-L significantly improved the elevated blood glucose state of DD rats(P<0.01 and P<0.05,respectively);ZGJTJYF-H,ZGJTJYF-M,and ZGJTJYF-L increased their autonomous activity,learning,and memory ability(P<0.01,P<0.01,and P<0.05,respectively).Moreover,the levels of 5-HT and TRP were significantly increased(P<0.01),and the levels of KYN and IDO were significantly decreased in the hippocampus(P<0.01)of rats after ZGJTJYF-M treatment.The protein expression levels of SYN and PSD-95 were significantly upregulated in hippocampal neurons(P<0.01),while the abnormal activation of NR2A and NR2B was markedly inhibited in hippocampus(P<0.05)of rats after ZGJTJYF-M treatment.(ii)In vitro experimental results showed that ZGJTJYF-containing serum significantly increased the protein expression levels of SYN and PSD-95 in hippocampal neurons(P<0.01),decreased the levels of IL-1β(P<0.01),IL-6(P<0.05),TNF-α(P<0.01),IDO(P<0.05),KYN(P<0.05),and QUIN(P<0.01),and increased the levels of TRP and KYNA(P<0.01)in the simulated DD state.ZGJTJYF also had an significantly inhibitory effect on the abnormal activation of NR2A and NR2B in neurons(P<0.05)in a stimulated DD state.Conclusion ZGJTJYF can effectively improve 5-HT deficiency in the hippocampus of rats by inhibiting IDO expression and regulating the TRP/KYN metabolic pathway,and it has a favorable protective effect on hippocampal neuron injury caused by DD.Therefore,ZGJTJYF is an effective potential therapeutic drug for the prevention and treatment of DD.

左归降糖解郁方对糖尿病并发抑郁症模型大鼠海马齿状回神经元树突及Wnt5a/RhoA信号通路的影响

目的探讨左归降糖解郁方治疗糖尿病并发抑郁症的可能作用机制。方法60只大鼠随机分为正常组、模型组、无翅型MMTV整合位点家族成员5a(Wnt5a)激动剂组、左归降糖解郁方组、左归降糖解郁方+Wnt5a抑制剂组,每组12只。除正常组外,其余各组大鼠采用高脂饲料饲养、链脲佐菌素注射和慢性温和不可预知应激联用法建立糖尿病并发抑郁症大鼠模型。造模成功后Wnt5a激动剂组大鼠给予双侧海马立体定位注射Wnt5a激动剂Foxy-5各5μl,连续7天;左归降糖解郁方组给予左归降糖解郁方20.52 g/(kg·d)灌胃;左归降糖解郁方+Wnt5a抑制剂组进行灌胃给药和双侧海马立体定位注射Wnt5a抑制剂Box5,给药剂量和注射方法同上。正常组和模型组给予10 ml/(kg·d)生理盐水灌胃。各组灌胃均连续4周。干预结束后采用强迫游泳实验(不动时间)和旷场实验(活动次数)评价大鼠的抑郁样行为;检测大鼠的血糖和胰岛素含量,并计算胰岛素抵抗指数;采用高尔基染色观察大鼠海马齿状回神经元的树突形态;采用5-溴脱氧尿嘧啶核苷(Brdu)注射及免疫荧光检测齿状回神经元增殖水平;采用RT-qPCR和Western blot法检测齿状回Wnt5a、Ras同源物基因组成员A(RhoA)和Rho同源物相关卷曲螺旋蛋白激酶1(ROCK1)mRNA和蛋白表达。结果与正常组比较,模型组大鼠血糖、胰岛素及胰岛素抵抗指数均显著升高,不动时间显著延长,活动次数显著减少,海马齿状回中Brdu积分光密度值和Wnt5a、RhoA、ROCK1蛋白及mRNA表达均显著降低(P<0.05或P<0.01);大鼠海马齿状回神经元可见树突分支明显减少或断裂,长度缩短。与模型组比较,左归降糖解郁方组和左归降糖解郁方+Wnt5a抑制剂组大鼠血糖、胰岛素及胰岛素抵抗指数显著降低(P<0.05或P<0.01);Wnt5a激动剂组和左归降糖解郁方组大鼠不动时间显著缩短、活动次数显著增加、Brdu积分光密度值显著升高,Wnt5a、RhoA、ROCK1蛋白及mRNA表达均升高(P<0.05或P<0.01),海马齿状回神经元的树突分支数量显著增加、长度延长,树突的复杂性增加。与Wnt5a激动剂组比较,左归降糖解郁方组大鼠血糖、胰岛素及胰岛素抵抗指数显著降低,不动时间显著延长,活动次数显著减少,Brdu积分光密度值显著降低;除左归降糖解郁方组Wnt5a mRNA外,左归降糖解郁方组和左归降糖解郁方+Wnt5a抑制剂组Wnt5a、RhoA、ROCK1蛋白及mRNA表达均降低(P<0.05或P<0.01)。与左归降糖解郁方组比较,左归降糖解郁方+Wnt5a抑制剂组Wnt5a、RhoA、ROCK1蛋白及mRNA表达均降低(P<0.05或P<0.01)。结论左归降糖解郁方可改善糖尿病并发抑郁症模型大鼠的高血糖和抑郁样行为,其抗抑郁作用可能与激活海马Wnt5a/RhoA信号,促进齿状回神经元树突生长有关。