Baicalin ameliorates neuroinflammation-induced depressive-like behavior through inhibition of toll-like receptor 4 expression via the PI3K/AKT/FoxO1 pathway
Baicalin ameliorates neuroinflammation-induced depressive-like behavior through inhibition of toll-like receptor 4 expression via the PI3K/AKT/FoxO1 pathway
复制标题
黄芩苷通过 PI3K/AKT/FoxO1 通路抑制 Toll 样受体 4 表达，改善神经炎症诱发的抑郁样行为
DOI：
10.1186/s12974-019-1474-8
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发表时间：
2019-05-08
影响因子：
9.3
通讯作者：
Ma, Shi-Ping
中科院分区：
文献类型：
--
作者：
Guo, Li-Ting;Wang, Si-Qi;Ma, Shi-Ping
研究背景黄芩苷（Baicalin）是从中药黄芩中分离得到的一种具有抗炎等多种生物活性的化合物。近年来研究表明，黄芩苷的抗炎作用与Toll样受体4（TLR 4）有关，TLR 4参与抑郁症等中枢神经系统疾病的病理变化。在这项研究中，我们探讨黄芩苷是否可以产生抗抑郁作用，通过调节TLR 4信号在小鼠中，并试图阐明其潜在的mechanism.MethodsA慢性不可预知的轻度应激（MERS）小鼠模型，以探讨黄芩苷是否可以产生抗抑郁作用，通过抑制神经炎症。为阐明TLR 4在黄芩苷抗神经炎作用中的作用，采用脂多糖（LPS）特异性激活小鼠TLR 4，并测定其行为学变化。此外，我们使用LY 294002检测黄芩苷在体内和体外调节TLR 4表达的分子机制，使用western blot，ELISA试剂盒和免疫染色。在体外实验中，BV 2小胶质细胞系和原代培养的小胶质细胞用黄芩苷和LY 292002预处理1h，然后用LPS刺激24 h。将叉头转录因子叉头盒蛋白O 1（FoxO 1）特异性siRNA转染原代小胶质细胞5 h，然后用黄芩苷和LPS共刺激，观察FoxO 1是否参与黄芩苷对TLR 4表达的影响。（尤其是60 mg/kg）显著改善CNS诱导的抑郁样症状;显著降低海马中白细胞介素-1 β（IL-1）、白细胞介素-6（IL-6）和肿瘤坏死因子α（TNF-α）的水平;并显著降低TLR 4的表达。LPS激活TLR 4可引起小鼠神经炎症反应和抑郁样行为，黄芩苷（60 mg/kg）可减轻炎症反应和抑郁样行为。此外，黄芩苷的应用显着增加磷脂酰肌醇3-激酶（PI 3 K），蛋白激酶B（AKT）和FoxO 1的磷酸化。黄芩苷的应用还促进FoxO 1核排斥，并有助于抑制FoxO 1的反式激活潜力，从而导致TLR 4在LPS处理的BV 2细胞和原代小胶质细胞中的表达下调。然而，预防性治疗LY 294002取消了黄芩苷的上述作用。此外，我们发现，FoxO 1发挥了至关重要的作用，黄芩苷通过调节TLR 4和TLR 4介导的神经炎症引发的LPS通过敲低FoxO 1的表达在原代小glia.ConclusionCollectively，这些结果表明，黄芩苷改善神经炎症诱导的抑郁样行为，通过抑制TLR 4的表达通过PI 3 K/AKT/FoxO 1通路。
BackgroundBaicalin, which is isolated from Radix Scutellariae, possesses strong biological activities including an anti-inflammation property. Recent studies have shown that the anti-inflammatory effect of baicalin is linked to toll-like receptor 4 (TLR4), which participates in pathological changes of central nervous system diseases such as depression. In this study, we explored whether baicalin could produce antidepressant effects via regulation of TLR4 signaling in mice and attempted to elucidate the underlying mechanisms.MethodsA chronic unpredictable mild stress (CUMS) mice model was performed to explore whether baicalin could produce antidepressant effects via the inhibition of neuroinflammation. To clarify the role of TLR4 in the anti-neuroinflammatory efficacy of baicalin, a lipopolysaccharide (LPS) was employed in mice to specially activate TLR4 and the behavioral changes were determined. Furthermore, we used LY294002 to examine the molecular mechanisms of baicalin in regulating the expression of TLR4 in vivo and in vitro using western blot, ELISA kits, and immunostaining. In the in vitro tests, the BV2 microglia cell lines and primary microglia cultures were pretreated with baicalin and LY292002 for 1h and then stimulated 24h with LPS. The primary microglial cells were transfected with the forkhead transcription factor forkhead box protein O 1 (FoxO1)-specific siRNA for 5h and then co-stimulated with baicalin and LPS to investigate whether FoxO1 participated in the effect of baicalin on TLR4 expression.ResultsThe administration of baicalin (especially 60mg/kg) dramatically ameliorated CUMS-induced depressive-like symptoms; substantially decreased the levels of interleukin-1 beta (IL-1), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-) in the hippocampus; and significantly decreased the expression of TLR4. The activation of TLR4 by the LPS triggered neuroinflammation and evoked depressive-like behaviors in mice, which were also alleviated by the treatment with baicalin (60mg/kg). Furthermore, the application of baicalin significantly increased the phosphorylation of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and FoxO1. The application of baicalin also promoted FoxO1 nuclear exclusion and contributed to the inhibition of the FoxO1 transactivation potential, which led to the downregulation of the expression of TLR4 in CUMS mice or LPS-treated BV2 cells and primary microglia cells. However, prophylactic treatment of LY294002 abolished the above effects of baicalin. In addition, we found that FoxO1 played a vital role in baicalin by regulating the TLR4 and TLR4-mediating neuroinflammation triggered by the LPS via knocking down the expression of FoxO1 in the primary microglia.ConclusionCollectively, these results demonstrate that baicalin ameliorated neuroinflammation-induced depressive-like behaviors through the inhibition of TLR4 expression via the PI3K/AKT/FoxO1 pathway.