目的：研究中药五味子（Schisandra Chinensis，SC）提取物对辐射所致小鼠外周血淋巴细胞减少的预防效果及其机制。方法：将48只BALB/c小鼠随机分为4组，分别为SC预防组（SC+ray）、NS对照组（NS+ray）、SC对照组（SC）和正常对照组（NS）。一次性6 Gy γ射线照射，照射后进行小鼠外周血白细胞和淋巴细胞计数，细胞免疫荧光检测外周血Ｔ淋巴细胞亚群，Gimsa染色观察小鼠胸腺细胞形态，流式细胞术检测胸腺细胞凋亡率，RTPCR法检测胸腺组织中Bcl2和Fas 基因mRNA的表达。结果：NS对照组小鼠照射后外周血白细胞总数和淋巴细胞数量及亚群均明显下降(P<0.0)，SC预防组较NS对照组白细胞总数和淋巴细胞数量均明显升高(P<0.01)；SC预防组小鼠外周血中CD3+、CD4+和CD8+T细胞百分率较NS对照组小鼠明显升高（P<0.01）。NS对照组小鼠照射后胸腺细胞数目减少，并可见多处片状细胞凋亡和坏死；SC预防治疗组较NS对照组胸腺细胞凋亡率明显降低\[(21.32±2.56)% vs (2.87±1.03)%，P<0.01\]；RTPCR结果表明,照射后小鼠胸腺细胞Bcl2表达明显降低，Fas表达明显升高(均P<0.01)，而SC预防组较NS对照组Bcl2表达明显升高，Fas表达明显降低(均P<0.05)。结论：SC通过升高Bcl2表达、降低Fas表达调控胸腺细胞凋亡，从而有效预防辐射所致小鼠外周血淋巴细胞的减少。

Objective:To study the efficacy of Schisandra Chinensis (SC) extract in prevention of lymphocyte reduction caused by radiation and to explore the related mechanism. Methods: A total of 48 BALB/c mice were divided into 4 groups: SC treated group (SC+ray), NS control group (NS+ray), SC control group (SC), and normal control group (NS). After BALB/c mice were radiated with 6 Gy, the WBC and lymphocyte numbers were counted; T lymphocyte subsets in peripheral blood were detected by immunofluorescence cell staining; morphology of thymocytes was observed by Gimsa staining; lymphocyte subsets and apoptosis rate of thymocytes were examined by flow cytometry; Bcl2 and Fas mRNA expressions in thymus tissues were measured by RTPCR. Results: In NS+ray group, the quantities of WBC, lymphocytes, and lymphocyte subsets were significantly decreased after radiation (P<0.01), but in SC+ray group, the numbers of WBC and lymphocytes were significantly increased compared with those in NS+ray group (P<0.01). The percentages of CD3+, CD4+, and CD8+ T cells in peripheral blood were significantly increased in SC+ray group compared with those in NS+ray group (P<0.01). The quantity of thymocytes was decreased and apoptosis of thymocytes was increased in NS+ray group; cell apoptosis rate in SC+ray group was significantly increased than that in NS+ray group (\[2.87±103\]% vs \[21.32±2.56\]%, P<0.01). The expression of Bcl2 mRNA was significantly downregulated and Fas mRNA was upregulated in NS+ray group (P<0.01); Bcl2 mRNA was upregulated and Fas mRNA was significantly downregulated in SC+ray group compared with those in NS+ray group (P<0.01). Conclusion: SC can prevent radiationinduced lymphocyte reduction through regulating apoptosis of thymocytes, which is mediated by upregulation of Bcl2 and downregulation of Fas.

国家自然科学基金资助项目（No. 30772752）