印楝素A对粉纹夜蛾Hi-5细胞的毒性机理

利用粉纹夜蛾Trichoplusia ni Hübner卵细胞系（Hi-5细胞系）在细胞水平研究了印楝素(azadirachtin) A杀卵活性的毒性机理。以MTT法研究了印楝素A对粉纹夜蛾Hi-5细胞的生长抑制率，结果表明最初两天印楝素 A对Hi-5细胞无较明显活性，但随后几天抑制率显著增加。用Giemsa染色法对细胞进行染色，观察细胞形态发生的变化，发现：1.25 μg/mL印楝素 A处理Hi-5细胞1 d后，细胞已无法贴壁，形状变圆，接着细胞形态变得极不规则，有凋亡小体出现。用Ho33342染料对Hi-5细胞核DNA染色，通过荧光显微镜观察发现：经印楝素A处理后第1天，部分细胞核染色体发生异常凝聚，此后异常细胞核比例增多，核膜严重破损。以异硫氰酸荧光素(FITC)荧光染料研究了Hi-5细胞的蛋白质含量变化，发现1.25 μg/mL印楝素A 处理Hi-5细胞1 d后，细胞蛋白质指数(DI)为1.070±0.018，至第3 d DI值上升到1.912±0.019。分析了印楝素A处理后Hi-5的还原性谷胱甘肽(GSH)的相对含量变化，发现1.25 μg/mL处理浓度下，各天处理组GSH抑制率有显著差异。结果显示印楝素A能够抑制Hi-5细胞增殖，影响细胞骨架正常功能，降低细胞活力。

Mechanism of cell toxicity of azadirachtin A to Trichoplusia ni Hübner Hi-5 cells

Trichoplusia ni Hübner cells were used to study the toxicity mechanism of azadirachtin A (Aza A) at the cellular level. Growth inhibition effect of Aza A on Hi-5 cells was tested. No obvious growth inhibition effect of Aza A on Hi-5 cells was found in the first two days post treatment. However, the inhibition effect went higher in the following days. By using the Giemsa dying method, we observed the change in shape of Hi-5 cells treated with 1.25 μg/mL Aza A. Most cells could not attach to the bottom wall of tissue culture flasks. The cells changed into rotundity. Apoptotic bodies appeared in the treated cells. The fluorescence microscope was used to observe the cell nucleus after stained with Ho33342. The results showed that some of Hi-5 cell chromosomes were abnormally condensed after treatment for 1 d. The ratios of condensed nuclei increased later, and the nuclear membrane was damaged obviously. To study the effect of Aza A on protein content, the FITC staining was performed. The DI value was 1.070±0.018 on the 1st day post treatment with 1.25 μg/mL Aza A, and increased to 1.912±0.019