Microglia activation and its mediated production of proinflammatory mediators play important roles in different neurodegenerative diseases; hence, modulation of microglia activation has been considered a potential therapeutic strategy to ameliorate neurodegeneration. This study was aimed to determine whether Gastrodin, a common herbal agent known to possess neuroprotective property, can attenuate production of proinflammatory mediators in activated microglia through the renin-angiotensin system (RAS) and Sirtuin3 (SIRT3). Expression of various members of the RAS including ACE, AT₁, AT_2, and SIRT3 in activated microglia was assessed by immunofluorescence and Western blot in hypoxic-ischemia brain damage (HIBD) in postnatal rats, and in BV-2 microglia in vitro challenged with lipopolysaccharide (LPS) with or without Gastrodin treatment. Expression of NOX-2, a subunit of NADPH oxidase, and proinflammatory mediators including iNOS and TNF-α, was also evaluated. The present results showed that expression of ACE, AT₁, NOX-2, iNOS and TNF-α was markedly increased in activated microglia in the corpus callosum of HIBD rats, and in LPS stimulated BV-2 microglia. Remarkably, the expression was markedly attenuated following Gastrodin treatment. Conversely, Gastrodin enhanced AT₂ and SIRT3 protein expression. In BV-2 microglia treated with Azilsartan, a specific inhibitor of AT₁ (AT₁I group), NOX-2 expression was decreased whereas that of SIRT3 in LPS + AT₁I and LPS + Gastrodin group was increased when compared with the controls. In LPS + AT₁I + Gastrodin group, SIRT3 expression was further augmented. More importantly, Gastrodin effectively reduced caspase 3 protein expression level in the HIBD rats coupled with a significant decrease in caspase 3 positive cells. We conclude that Gastrodin can exert its protective effects against the hypoxic-ischemia brain damage in the present experimental HIBD model. It is suggested that this is mainly through suppression of expression of RAS (except for AT₂ and SIRT3) and proinflammatory mediators e.g. TNF-α in activated microglia.

小胶质细胞的激活及其介导的促炎性介质的产生在不同的神经退行性疾病中起重要作用。因此，小胶质细胞活化的调节已被认为是缓解神经变性的潜在治疗策略。这项研究旨在确定天麻素，一种已知具有神经保护特性的常见草药，是否可以通过肾素-血管紧张素系统（RAS）和Sirtuin3（SIRT3）减弱活化的小胶质细胞中促炎介质的产生。通过免疫荧光和Western印迹评估出生后大鼠缺氧缺血性脑损伤（HIBD）和体外BV-2小胶质细胞中RAS各种成员（包括ACE，AT ₁，AT ₂和SIRT3）在活化小胶质细胞中的表达。接受或未接受天麻素处理的脂多糖（LPS）攻击。还评估了NOX-2（NADPH氧化酶的亚基）和促炎介质（包括iNOS和TNF-α）的表达。目前的结果表明，在HIBD大鼠的call体活化的小胶质细胞和LPS刺激的BV-2小胶质细胞中，ACE，AT ₁，NOX-2，iNOS和TNF-α的表达显着增加。值得注意的是，天麻素处理后该表达显着减弱。相反，天麻素增强AT ₂和SIRT3蛋白表达。在AT ₁的特异性抑制剂Azilsartan治疗的BV-2小胶质细胞中（AT ₁ I组），LPS + AT _1中NOX-2的表达降低，而SIRT3的表达降低。与对照组相比，I和LPS +天麻素组增加。在LPS + AT ₁ I + Gastrodin组中，SIRT3表达进一步增强。更重要的是，天麻素能有效降低HIBD大鼠的caspase 3蛋白表达水平，同时使caspase 3阳性细胞显着减少。我们得出结论，天麻素可以在当前的实验性HIBD模型中发挥其对缺氧缺血性脑损伤的保护作用。提示这主要是通过抑制激活小胶质细胞中RAS（AT ₂和SIRT3除外）和促炎性介质（如TNF-α）的表达。