Research of Heixiaoyao powder improve the Alzheimer's disease rats through the MKP-1/JNK pathway
Objective To investigate the effect and mechanism of Heixiaoyao powder in regulating mitogen-activated protein kinase phosphatase-1(MKP-1)/c-Jun N-terminal kinase(JNK)signaling pathway on the level of Tau protein and neuroinflammation in the hippocampus of Alzheimer's disease(AD)rats.Methods Male Wistar rats with SPF grade were randomly divided into blank,sham-operation,model,control and experimental-L,-M,-H groups with 10 rats per group.In addition to the blank and sham-operation groups,the other 5 groups of rats were injected with β-amyloid 1-42(Aβ1-42)solution in bilateral hippocampus to replicate AD rat model,and the sham-operation group was injected with the same amount of 0.9％NaCl in the same way.Animals successfully replicated in the model were randomly divided into model group,control group(0.5 mg·kg-1 donepezil hydrochloride)and experimental-L,-M,-H groups(3.82,7.65,15.30 g·kg-1 Heixiaoyao powder decoction).The blank,sham-operation and model groups were given equal volume of 0.9％NaCl by gavage.The drug was given by gavage once a day for 42 days.Morris water maze was used to detect the learning and memory ability of rats.The levels of tumor necrosis factor-α(TNF-α)and interleukin-6(IL-6)in hippocampus were detected by enzyme-linked immunosorbent assay.Western blot was used to detect the expression of MKP-1,phospho JNK(p-JNK)and phospho Tau(p-Tau)proteins.Results The escape latency on day 5 of the experimental-M,-H groups,control group,model group,sham-operation group and blank group were(8.28±7.67),(7.89±4.18),(7.86±2.68),(16.55±4.16),(6.46±3.30)and(3.60±1.53)s;the levels of TNF-α in the above groups were(406.56±28.44),(404.17±22.84),(402.28±28.36),(665.89±61.15),(226.44±34.84)and(218.50±30.16)pg·mL-1;IL-6 levels were(136.54±7.04),(121.67±5.19),(119.15±5.87),(166.27±8.91),(88.75±5.28)and(79.58±7.53)ng·L-1;the relative expression levels of MKP-1 protein were 2.31±0.34,2.59±0.38,2.58±0.37,1.23±0.25,2.64±0.19 and 2.84±0.18;the relative expression levels of p-JNK protein were 3.46±0.35,3.45±0.31,3.20±0.23,4.48±0.30,2.87±0.51 and 2.30±0.26;the relative expression levels of p-Tau protein were 3.46±0.33,3.24±0.48,3.09±0.31,4.85±1.06,2.69±0.34 and 2.40±0.55,respectively.Compared with the model group and the normal group,compared with the experimental group and the model group,the differences of above indexes were statistically significant(P＜0.05,P＜0.01).Conclusion Heixiaoyao powder can improve the learning and memory ability of AD rats,and its mechanism may be related to the regulation of MKP-1 and JNK proteins,thus inhibiting the phosphorylation level of Tau protein and alleviating neuroinflammation.
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