Pathological Department of the Affiliated Hospital, Guiyang Medical University, Guiyang 550004, PR China.
Toxicol Lett. 2011 Jul 28;204(2-3):183-9. doi: 10.1016/j.toxlet.2011.04.030. Epub 2011 Apr 30.
In order to reveal the mechanism of the brain injury induced by chronic fluorosis, the levels of apoptosis and c-Jun N-terminal kinases (JNK) in brains of rats and SH-SY5Y cells exposed to different concentrations of sodium fluoride (NaF) were detected. The dental fluorosis and fluoride contents in blood, urine and bones of rats were measured to evaluate the exhibition of fluorosis. The apoptotic death rate was measured by flow cytometry and the expression of JNK at protein level by Western blotting. The results showed that as compared with controls, the apoptotic death rate was obviously increased in brains of the rats exposed to high-fluoride (50ppm) for 6 months with a concentration dependent manner, but no significant change for 3 months. In SH-SY5Y cells treated with high concentration (50ppm) of fluoride, the increased apoptotic death rate was obviously observed as compared to controls. In addition, the expressions of phospho-JNK at protein level were raised by 20.5% and 107.6%, respectively, in brains of the rats exposed to low-fluoride (5ppm) and high-fluoride for 6 months; while no significant changes were found between the rats exposed to fluoride and the controls for 3 months. The protein level of phospho-JNK was also increased in SH-SY5Y cells exposed to high-fluoride. There were no changes of total-JNK both in the rats and in the SH-SY5Y cells exposed to excessive fluoride as compared to controls. When SH-SY5Y cells were singly treated with SP600125, an inhibitor of phospho-JNK, the decreased expression of phospho-JNK, but no apoptosis, was detected. Interestingly, after JNK phosphorylation in the cultured cells was inhibited by SP600125, the treatment with high-fluoride did not induce the increase of apoptosis. In addition, there was a positive correlation between the expression of phospho-JNK and the apoptotic death rate in rat brains or SH-SY5Y cells treated with high-fluoride. The results indicated that exposure to excessive fluoride resulted in the increase of apoptosis in rat brains and SH-SY5Y cells, in which one of the mechanisms might be activating JNK phosphorylation.
为了揭示慢性氟中毒引起的脑损伤机制，检测了不同浓度氟化钠（NaF）暴露的大鼠脑和 SH-SY5Y 细胞中细胞凋亡和 c-Jun N-末端激酶（JNK）的水平。测量了大鼠的氟斑牙和血、尿、骨中的氟含量，以评估氟中毒的表现。通过流式细胞术测量细胞凋亡死亡率，通过 Western 印迹测量 JNK 蛋白水平的表达。结果表明，与对照组相比，暴露于高氟（50ppm）6 个月的大鼠脑细胞凋亡死亡率明显升高，且呈浓度依赖性，但 3 个月时无明显变化。与对照组相比，高浓度（50ppm）氟化物处理的 SH-SY5Y 细胞中，明显观察到细胞凋亡死亡率增加。此外，暴露于低氟（5ppm）和高氟（6 个月）的大鼠脑中，磷酸化 JNK 蛋白水平分别升高了 20.5%和 107.6%；而暴露于氟化物的大鼠与对照组相比，3 个月时无明显变化。暴露于高氟的 SH-SY5Y 细胞中磷酸化 JNK 蛋白水平也增加。与对照组相比，暴露于过量氟化物的大鼠和 SH-SY5Y 细胞中总 JNK 无变化。当 SH-SY5Y 细胞单独用 SP600125（磷酸化 JNK 的抑制剂）处理时，检测到磷酸化 JNK 表达减少，但没有凋亡。有趣的是，在用 SP600125 抑制培养细胞中 JNK 磷酸化后，用高氟处理不会诱导凋亡增加。此外，在高氟处理的大鼠脑或 SH-SY5Y 细胞中，磷酸化 JNK 的表达与细胞凋亡死亡率呈正相关。结果表明，暴露于过量氟化物会导致大鼠脑和 SH-SY5Y 细胞凋亡增加，其中机制之一可能是激活 JNK 磷酸化。
