School of Life Science and Biopharmaceutics, Shenyang Pharmaceutical University, No. 103, Wenhua Road, Shenyang, 110016, China; Beijing Key Laboratory of Drug Targets Identification and Drug Screening, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, NO.2 Nanwei Road, Beijing, 100050, China.
Beijing Key Laboratory of Drug Targets Identification and Drug Screening, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, NO.2 Nanwei Road, Beijing, 100050, China.
Biomed Pharmacother. 2019 Sep;117:109102. doi: 10.1016/j.biopha.2019.109102. Epub 2019 Jun 19.
Ischemic stroke is a cerebrovascular disease with high morbidity, high mortality, and high disability, representing a serious threat to human life and health. Clinically, the extensive injury caused by ischemic stroke results from ischemia-reperfusion (I/R) injury thrombolytic treatment. However, there are few reports on the use of medications in the subacute stage of cerebral I/R. Baicalein (5,6,7-trihydroxyflavone) is a biologically active ingredient extracted from the root of Scutellaria baicalensis Georgi. In the present study, we investigated the therapeutic effect of baicalein administered in the subacute phase of cerebral I/R injury in a rat model of ischemia induced by occlusion of the middle cerebral artery (MCA). Rats were treated daily with baicalein (200 mg/kg, i.g.) in the subacute phase (24 h after reperfusion) for 7 days. The results showed that baicalein significantly reduced neurobehavioral deficits and decreased brain infarct volume from 18.99% to 7.41%. Immunofluorescence analysis of the ischemic penumbra showed that baicalein significantly reduced expression of the M1 marker, cluster of differentiation (CD) 16 and CD86, and increased expression of the M2 marker, CD 163 and CD206, indicating that baicalein inhibited M1 transformation and promoted M2 transformation of microglia/macrophage to inhibit neuroinflammation. Moreover, baicalein suppressed NF-κB signaling by reducing IκBα phosphorylation and nuclear translocation of NF-κB/p65, which decreased the release of the pro-inflammatory factors IL-6, IL-18, and TNF-α. In addition, baicalein reduced phosphorylation of JNK, ERK and p38, which are involved modulation of microglia/macrophage M1/M2 polarization. Western blot analysis of apoptosis- and autophagy-related proteins showed that baicalein increased the Bcl-2/Bax ratio and reduced caspase-3 expression to decrease neuronal apoptosis and ameliorate neuronal loss. Baicalein also decreased the LC3-II/LC3-I ratio and promoted phosphorylation of the PI3K/Akt/mTOR signaling pathway which implied inhibition of autophagy. These observations suggest that baicalein exerts neuroprotective effects by reducing neuroinflammation, apoptosis and autophagy, and protects against cerebral I/R injury in the subacute phase in vivo.
缺血性脑卒中是一种具有高发病率、高死亡率和高致残率的脑血管疾病，严重威胁着人类的生命和健康。临床上，缺血性脑卒中引起的广泛损伤是由缺血再灌注（I/R）损伤溶栓治疗引起的。然而，关于在脑 I/R 的亚急性期使用药物的报道很少。黄芩素（5,6,7-三羟基黄酮）是从黄芩根中提取的一种具有生物活性的成分。在本研究中，我们在大脑中动脉阻塞（MCA）诱导的缺血大鼠模型中，研究了黄芩素在脑 I/R 损伤亚急性期给药的治疗效果。大鼠在亚急性期（再灌注后 24 小时）每天用黄芩素（200mg/kg，灌胃）治疗 7 天。结果表明，黄芩素显著降低神经行为缺陷，并将脑梗死体积从 18.99%降低到 7.41%。缺血半影区的免疫荧光分析表明，黄芩素显著降低了 M1 标志物 CD16 和 CD86 的表达，并增加了 M2 标志物 CD163 和 CD206 的表达，表明黄芩素抑制了小胶质细胞/巨噬细胞的 M1 转化，并促进了 M2 转化，从而抑制神经炎症。此外，黄芩素通过减少 IκBα磷酸化和 NF-κB/p65 的核转位来抑制 NF-κB 信号通路，从而减少促炎因子 IL-6、IL-18 和 TNF-α的释放。此外，黄芩素减少了 JNK、ERK 和 p38 的磷酸化，这些磷酸化参与了小胶质细胞/巨噬细胞 M1/M2 极化的调节。凋亡和自噬相关蛋白的 Western blot 分析表明，黄芩素增加了 Bcl-2/Bax 比值，减少了 caspase-3 的表达，从而减少了神经元凋亡和改善了神经元丢失。黄芩素还降低了 LC3-II/LC3-I 比值，并促进了 PI3K/Akt/mTOR 信号通路的磷酸化，这暗示了自噬的抑制。这些观察结果表明，黄芩素通过减少神经炎症、凋亡和自噬来发挥神经保护作用，并在体内保护大脑免受 I/R 损伤的亚急性期。
