目的 采用臂丛神经根性撕脱伤（brachial plexus root avulsion，BPA）再植大鼠模型和过氧化氢（hydrogen peroxide，H₂O₂）诱导的小鼠运动神经元细胞系NSC-34神经元损伤模型，探讨丹参酮II_A对BPA的治疗作用及其作用机制。方法 将60只SD大鼠随机分为假手术组、模型组和丹参酮II_A低、高剂量（10、30 mg/kg）组，每组15只。造模后连续给药8周，每周通过Terzis梳洗试验（Terzis grooming test，TGT）评估运动功能恢复情况；取肱二头肌称定质量，并进行苏木素-伊红（hematoxylin-eosin，HE）染色观察肌肉组织形态；采用中性红染色检测脊髓前角运动神经元存活情况；采用荧光金逆行标记及肌皮神经胆碱乙酰转移酶（choline acetyltransferase，ChAT）与神经丝蛋白200（neurofilament 200，NF200）免疫荧光染色评估轴突再生；免疫荧光法检测脊髓前角离子钙结合衔接分子1（ionized calcium-binding adapter molecule 1，Iba1）、胶质纤维酸性蛋白（glial fibrillary acidic protein，GFAP）及神经元型一氧化氮合酶（neuronal nitric oxide synthase，nNOS）的表达；检测损伤侧脊髓中丙二醛（malondialdehyde，MDA）水平及超氧化物歧化酶（superoxide dismutase，SOD）活性；Western blotting检测损伤侧脊髓中Ras相关的C3肉毒素底物1（Ras-related C3 botulinum toxin substrate l，Racl）、细胞分裂周期蛋白42（cell division control protein 42，Cdc42）、c-Jun氨基末端激酶（c-Jun N-terminal kinase，JNK）及c-Jun蛋白表达。体外实验设置对照组、模型组、丹参酮II_A组和Rac1抑制剂组，以400 μmol/L H₂O₂诱导NSC-34细胞氧化损伤，给予丹参酮II_A组或NSC 23766干预后，采用CCK-8法检测细胞活力，测定MDA、活性氧（reactive oxygen species，ROS）及SOD活性，Western blotting检测Rac1/JNK通路相关蛋白表达。结果 术后1周模型组大鼠TGT评分均为0，提示模型建立成功。与模型组比较，丹参酮II_A组可显著提高TGT评分（P＜0.05、0.01），促进轴突再生水平（P＜0.01），提升运动神经元存活数量（P＜0.01），改善肌肉萎缩（P＜0.05、0.01），并降低Iba1及GFAP表达（P＜0.05、0.01）。同时，丹参酮II_A组能减轻氧化应激损伤，表现为nNOS阳性运动神经元数量显著减少（P＜0.05、0.01），MDA水平明显下降（P＜0.001），SOD活性明显升高（P＜0.01），并显著上调Rac1、Cdc42、JNK及c-Jun蛋白表达（P＜0.01、0.001）。细胞实验中，丹参酮II_A可显著提高H₂O₂损伤的细胞活力（P＜0.01），增加SOD活性（P＜0.01），降低MDA和ROS水平（P＜0.01），并上调Rac1、Cdc42、JNK及c-Jun蛋白表达（P＜0.05、0.01、0.001）；而联合使用Rac1抑制剂NSC 23766则可部分逆转丹参酮II_A的保护效应（P＜0.01、0.001）。结论 丹参酮II_A可能通过激活Rac1/JNK信号通路，抑制氧化应激及神经炎症反应，促进运动神经元存活与轴突再生，从而改善BPA大鼠运动功能恢复。

Objective To investigate the therapeutic effect and mechanism of tanshinone II_A on motor function recovery after brachial plexus root avulsion (BPA) using a rat brachial plexus root avulsion (BPA)-replantation model and an hydrogen peroxide (H₂O₂)-induced oxidative damage model in NSC-34 cells. Methods A total of 60 SD rats were randomly divided into sham group, model group, tanshinone II_A low- and high-dose (10, 30 mg/kg) groups, with 15 rats in each group. After modeling, continuous administration was performed for eight weeks. Motor function recovery was evaluated using Terzis grooming test (TGT). The biceps brachii muscle was weighed and processed for hematoxylin-eosin (HE) staining to assess morphological changes. Motor neuron survival in the spinal cord was determined by neutral red staining. Axonal regeneration was assessed by Fluoro-Gold retrograde labeling and immunofluorescence staining for choline acetyltransferase (ChAT) and neurofilament 200 (NF200) in the musculocutaneous nerve. Immunofluorescence was performed to detect ionized calcium-binding adapter molecule 1 (Iba1), glial fibrillary acidic protein (GFAP) and neuronal nitric oxide synthase (nNOS) expressions. Level of malondialdehyde (MDA) and activity of superoxide dismutase in the injured spinal cord were measured. The protein expressions of Ras-related C3 botulinum toxin substrate l (Rac1), cell division control protein 42 (Cdc42), c-Jun N-terminal kinase (JNK) and c-Jun in the injured spinal cord were detected by Western blotting. In vitro, control group, model group, tanshinone II_A group and Rac1 inhibitor group were established. NSC-34 cells were induced with 400 μmol/L H₂O₂ to cause oxidative damage. After intervention with tanshinone II_A or NSC 23766, cell viability was assessed using CCK-8 assay. Levels of MDA, reactive oxygen species (ROS) and activity of SOD were measured, and the expressions of Rac1/JNK pathway-related proteins was analyzed by Western blotting. Results The BPA model was successfully established as evidenced by consistently 0 TGT scores in model group at 1 week post-surgery. Compared with model group, tanshinone II_A significantly improved the TGT scores (P < 0.05, 0.01), enhanced axonal regeneration (P < 0.01), increased motor neuron count (P < 0.01), mitigated muscle atrophy (P < 0.05, 0.01), and reduced the expressions of Iba1 and GFAP (P < 0.05, 0.01). Meanwhile, tanshinone II_A improved oxidative stress damage, including decreased nNOS positive motor neurons (P < 0.05, 0.01), reduced MDA level (P < 0.001), elevated SOD activity (P < 0.01), while up-regulating Rac1, Cdc42, JNK and c-Jun expressions in spinal cord tissue (P < 0.01, 0.001). In vitro, tanshinone II_A significantly increased viability of H₂O₂-injured NSC-34 cells (P < 0.01), elevated SOD activity (P < 0.01), decreased MDA and ROS levels (P < 0.01), up-regulated Rac1, Cdc42, JNK and c-Jun protein expressions (P < 0.05, 0.01, 0.001). Notably, these protective effects of tanshinone II_A were partially attenuated by co-administration of Rac1 inhibitor NSC 23766 (P < 0.05, 0.01). Conclusion Tanshinone II_A promotes motor function recovery following brachial plexus root avulsion by activating Rac1/JNK signaling pathway, which attenuates oxidative stress and neuroinflammation, thereby enhancing motor neuron survival and axonal regeneration.

R285.5

广东省中医药局科研项目（20241084）；广东省基础与应用基础研究基金项目（2021A1515110800）