Background

Rhodiola crenulate (R. crenulate), a famous Tibetan medicine, has been demonstrated to possess superiorly protective effects in high-altitude hypoxic brain injury (HHBI). However, its mechanisms on HHBI are still largely unknown.

Methods

Herein, the protective effects and underlying mechanisms of R. crenulate on HHBI of BABL/c mice were explored through in vivo experiments. The mice model of HHBI was established using an animal hypobaric and hypoxic chamber. R. crenulate extract (RCE) (0.5, 1.0 and 2.0 g/kg) was given by gavage for 7 days. Pathological changes and neuronal viability of mice hippocampus and cortex were evaluated using H&E and Nissl staining, respectively. The brain water content (BWC) in mice was determined by calculating the ratio of dry to wet weight of brain tissue. And serum of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH-Px) and lactate dehydrogenase (LDH) were detected via commercial biochemical kits. Synchronously, the contents of total antioxidant capacity (T-AOC), lactic acid (LA), adenosine triphosphate (ATP), succinate dehydrogenase (SDH), pyruvate kinase (PK), Ca²⁺-Mg²⁺-ATPcase, Na⁺-K⁺-ATPcase, TNF-α, IL-1β and IL-6 in brain tissue were quantitative analysis by corresponding ELISA assay. Subsequently, NLRP3, ZO-1, claudin-5, occluding, p-p65, p65, ASC, cleaved-caspase-1, caspase-1 and IL-18 were determined by immunofluorescent and western blot analyses.

Results

The results demonstrated that RCE remarkably alleviated pathological damage, BWC, as well enhanced neuronal viability. Furthermore, the oxidative stress injuries were reversely abrogated after RCE treatment, evidenced by the increases of SOD, GSH-Px and T-AOC, while the decreases of MDA and LDH contents. Marvelously, the administration of RCE rectified and balanced the abnormal energy metabolism via elevating the levels of ATP, SDH, PK, Ca²⁺-Mg²⁺-ATPcase and Na⁺-K⁺-ATPcase, and lowering LA. Simultaneously, the expression of tight junction proteins (ZO-1, claudin-5 and occludin) was enhanced, illustrating RCE treatment might maintain the integrity of blood-brain barrier (BBB). Additionally, RCE treatment confined the contents of IL-6, IL-1β and TNF-α, and attenuated fluorescent signal of NLRP3 protein. Concurrently, the results of western blot indicated that RCE treatment dramatically restrained p-p65/p65, ASC, NLRP3, cleaved-caspase-1/caspase-1 and IL-18 protein expressions in brain tissues of mice.

Conclusion

RCE may afford a protectively intervention in HHBI of mice through suppressing the oxidative stress, improving energy metabolism and the integrity of BBB, and subsiding inflammatory responses via the NF-κB/NLRP3 signaling pathway. As a promising agent for the treatment of mice HHBI, the deep-crossing molecular mechanisms of R. crenulate still needs to be further elucidated to identify novel core hub targets.

中文翻译：

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红景天通过调节 NF-κB/NLRP3 介导的炎症减轻低压缺氧诱导的脑损伤

背景

红景天（R. crenulate）是一种著名的藏药，已被证明对高原缺氧性脑损伤（HHBI）具有优越的保护作用。然而，其对 HHBI 的机制仍然很大程度上未知。

方法

在此，通过体内实验探讨了R. crenulate对 BABL/c 小鼠 HHBI的保护作用和潜在机制。采用动物低压缺氧室建立HHBI小鼠模型。R. crenulate通过管饲法给予提取物 (RCE) (0.5、1.0 和 2.0 g/kg) 7 天。分别使用 H&E 和 Nissl 染色评估小鼠海马和皮质的病理变化和神经元活力。通过计算脑组织的干重与湿重的比率来确定小鼠的脑含水量（BWC）。并通过商业生化试剂盒检测血清丙二醛（MDA）、超氧化物歧化酶（SOD）、谷胱甘肽（GSH-Px）和乳酸脱氢酶（LDH）。同时，总抗氧化能力（T-AOC）、乳酸（LA）、三磷酸腺苷（ATP）、琥珀酸脱氢酶（SDH）、丙酮酸激酶（PK）、Ca ²⁺ -Mg ²⁺ -ATPcase、Na ⁺ -K ⁺-通过相应的ELISA法定量分析脑组织中的ATPcase、TNF-α、IL-1β和IL-6。随后，通过免疫荧光和蛋白质印迹分析确定 NLRP3、ZO-1、claudin-5、occluding、p-p65、p65、ASC、cleaved-caspase-1、caspase-1 和 IL-18。

结果

结果表明，RCE 显着减轻了病理损伤、BWC，并增强了神经元的活力。此外，RCE处理后氧化应激损伤被逆转消除，表现为SOD、GSH-Px和T-AOC增加，而MDA和LDH含量降低。神奇的是，RCE的给药通过提高ATP、SDH、PK、Ca ²⁺ -Mg ²⁺ -ATPcase和Na ⁺ -K ^{+的水平来纠正和平衡异常的能量代谢。}-ATPcase，并降低 LA。同时，紧密连接蛋白（ZO-1、claudin-5 和 occludin）的表达增强，说明 RCE 治疗可能维持血脑屏障（BBB）的完整性。此外，RCE 处理限制了 IL-6、IL-1 β和 TNF-α 的含量，并减弱了 NLRP3 蛋白的荧光信号。同时，蛋白质印迹结果表明，RCE 处理显着抑制了小鼠脑组织中 p-p65/p65、ASC、NLRP3、cleaved-caspase-1/caspase-1 和 IL-18 蛋白的表达。

结论

RCE 可能通过抑制氧化应激、改善能量代谢和 BBB 的完整性以及通过 NF-κB/NLRP3 信号通路抑制炎症反应，对小鼠 HHBI 提供保护性干预。作为治疗小鼠 HHBI 的有前途的药物，R. crenulate的深层交叉分子机制仍需要进一步阐明，以确定新的核心枢纽靶点。