The influence of Liuwei Dihuang Wan on the behavior and TLR4/NF-κB signaling pathway of Alzheimer's disease model mice / 中华行为医学与脑科学杂志

ABSTRACT

Objective:To explore the effects of Liuwei Dihuang Wan on the behaviors and Toll-like receptor 4/nuclear factor kappa-B(TLR4/NF-κB) signal transduction pathway of amyloid β-precursor protein/presenilin-1(APP/PS1) double transgenic mice.Methods:Forty 3-month-old female APP/PS1 mice were randomly divided into model group, low-dose group(0.59 g/kg), medium-dose group(1.18 g/kg), high-dose group(2.36 g/kg)of Liuwei Dihuang Wan(gavaged according to grouped doses), and ibuprofen group(0.04 g/kg, gavage) using a random number table method, with 8 mice in each group.Eight 3-month-old wild-type female C57BL/6 mice with matched body weight were used as the control group.The mice in control group and model group were given an equal volume of 0.9% sodium chloride solution by gavage.The gavage administration was twice a day for a continuous period of 3 months.Morris water maze test was used to detect the learning and memory abilities of mice. ELISA was used to detect the serum levels of tumor necrosis factor-α (TNF-α), interleukin-1β(IL-1β) and immunohistochemistry was used to detect the levels of amyloid β-protein (Aβ), glial fibrillary acidic protein(GFAP) and NF-κB in hippocampal tissue.Western blot was used to detect the expression levels of TLR4, myeloid differentiation primary response gene 88(MyD88), and phosphorylated NF-κB(p-NF-κB) proteins in hippocampal tissue.The SPSS 20.0 software was used for data analysis. Multiple group comparisons were conducted by repeated measure ANOVA or one-way ANOVA.Results:The results of repeated measure ANOVA showed that as for the escape latency of the 6 groups of mice, the interaction effect between time and group was significant ( Finteraction=117.219, P<0.001). The escape latencies of mice in the 6 groups on the 5th day were all lower than those on the 1st day (all P<0.05). The escape latencies of mice in the ibuprofen group and the medium-dose and high-dose groups of Liuwei Dihuang Wan were lower than that in the model group from 1st day to 5th day(all P<0.05). On the 3rd to 5th day, the escape latencies of mice in the medium-dose and high-dose groups of Liuwei Dihuang Wan were lower than those in the low-dose group of Liuwei Dihuang Wan (all P<0.05). There were statistically significant differences in the percentage of residence time in the platform quadrant and the numbers of crossing platform among the 6 groups of mice ( F=5.451, 4.824, both P<0.05). The percentage of residence time in the platform quadrant (50.77±5.49)%, (54.39±5.71)%, (51.98±6.12)%), and the numbers of crossing platform((5.9±1.1) times, (6.0±1.3) times, (5.1±0.8) times) in the high-dose and medium-dose groups of Liuwei Dihuang Wan and the ibuprofen group were all higher than those in the model group ((27.32±3.22)%, (2.2±1.0) times )(all P<0.05). The immunohistochemical results showed that there were statistically significant differences in the integrated optical density values of Aβ, GFAP and NF-κB in the hippocampal tissues of 6 groups of mice ( F=57.52, 45.37, 79.10, all P<0.05). The integrated optical density values of Aβ, GFAP and NF-κB in the high-dose and medium-dose groups of Liuwei Dihuang Wan and the ibuprofen group were all lower than those in the model group (all P<0.05). And the integrated optical density values of Aβ, GFAP, and NF-κB in the high-dose and medium-dose groups of Liuwei Dihuang Wan were all lower than those in the low-dose group of Liuwei Dihuang Wan (all P<0.05). There were statistically significant differences in the levels of serum TNF-α and IL-1β detected by ELISA ( F=3.996, 6.395, both P<0.05) and the proteins levels of TLR4, MyD88, and p-NF-κB in hippocampal tissue detected by Western blot among the 6 groups( F=15.710, 3.522, 4.119, all P<0.05). The serum TNF-α and IL-1β levels in the high-dose and medium-dose groups of Liuwei Dihuang Wan and ibuprofen group were all lower than those in the model group (all P<0.05). The serum TNF-α ((18.90±2.33) ng/L, (21.56±2.49) ng/L) and IL-1β ((5.88±0.80) ng/L, (6.75±0.83) ng/L) levels in the high-dose and medium-dose groups of Liuwei Dihuang Wan were lower than those in the low-dose group ((30.77±2.89) ng/L, (9.11±1.27) ng/L) (all P<0.05). The protein expression levels of TLR4, MyD88, and p-NF-κB in the hippocampus of the high-dose and medium-dose groups of Liuwei Dihuang Wan and ibuprofen group were lower than those of the model group (all P<0.05). The protein expression levels of TLR4 ((0.254±0.091), (0.318±0.122)), MyD88 ((0.229±0.077), (0.386±0.119)), and p-NF-κB ((0.412±0.188), (0.358±0.119)) in the hippocampus of the high-dose and medium-dose groups of Liuwei Dihuang Wan were lower than those of the low-dose group ((0.617±0.172), (0.672±0.166), (0.799±0.227)) (all P<0.05). Conclusion:Liuwei Dihuang Wan can significantly alleviate learning and memory impairment in Alzheimer's disease model mice, possibly by inhibiting TLR4/NF-κB signal pathway, reducing TNF-α and IL-1β expression, thereby alleviate central immune inflammatory response and exert anti Alzheimer's disease effects.