Department of Environmental Health, College of Public Health, Zhengzhou University, Henan, P.R. China.
Tohoku J Exp Med. 2011 Jul;224(3):235-42. doi: 10.1620/tjem.224.235.
Toxic cyanobacterial blooms in freshwater have been considered as threats to human health. Microcystins are a family of cyclic polypeptides produced by cyanobacteria and are toxic to plants and animals. Microcystin-LR (MC-LR) is the most toxic variant among the microcystin family and could cause oxidative stress in various organs, including the reproduction system. The aim of this study was to investigate the effect of MC-LR on apoptosis of Sertoli cells that play an essential role in the development and maturation of sperm cells. Sertoli cells were isolated from healthy immature rats and cultured with MC-LR. The viability of Sertoli cells was decreased after treatment with MC-LR at 10 µg/ml for 24 h (P < 0.05). Moreover, the MC-LR-treated cells exhibited condensed chromatin and fragmented nuclei, features of apoptosis, as judged by Hoechst 33258 staining. We also analyzed the mRNA and protein levels of three apoptosis-related genes, p53, bax and bcl-2, using reverse transcription-polymerase chain reaction and Western blot analyses, respectively. Both p53 and bax function as promoters of apoptosis, while bcl-2 is an apoptotic suppressor. The mRNA and protein expression levels of p53 and bax were increased in Sertoli cells treated with MC-LR at 10 µg/ml compared with the control group (P < 0.05), while the bcl-2 protein levels were decreased in cells treated with MC-LR at 10 µg/ml (P < 0.05). Moreover, caspase-3 activity that is involved in the induction of apoptosis was significantly increased in Sertoli cells treated with MC-LR. These results indicate that MC-LR induces apoptosis of Sertoli cells.
淡水有毒蓝藻水华已被认为是对人类健康的威胁。微囊藻毒素是由蓝藻产生的一类环状多肽，对植物和动物都有毒性。微囊藻毒素-LR（MC-LR）是微囊藻毒素家族中毒性最强的变体，可导致包括生殖系统在内的各种器官的氧化应激。本研究旨在探讨 MC-LR 对支持精子细胞发育和成熟的 Sertoli 细胞凋亡的影响。Sertoli 细胞从健康的未成熟大鼠中分离出来并与 MC-LR 一起培养。用 10μg/ml 的 MC-LR 处理 24 小时后，Sertoli 细胞的活力下降（P<0.05）。此外，用 Hoechst 33258 染色判断，MC-LR 处理的细胞表现出染色质浓缩和核碎片，这是凋亡的特征。我们还使用逆转录-聚合酶链反应和 Western blot 分析分别分析了三个与凋亡相关的基因（p53、bax 和 bcl-2）的 mRNA 和蛋白水平。p53 和 bax 均作为凋亡的促进剂，而 bcl-2 是凋亡的抑制剂。与对照组相比，用 10μg/ml 的 MC-LR 处理的 Sertoli 细胞中 p53 和 bax 的 mRNA 和蛋白表达水平均增加（P<0.05），而用 10μg/ml 的 MC-LR 处理的细胞中 bcl-2 蛋白水平降低（P<0.05）。此外，MC-LR 处理的 Sertoli 细胞中参与诱导凋亡的 caspase-3 活性显著增加。这些结果表明 MC-LR 诱导 Sertoli 细胞凋亡。
