X射线胸部照射对小鼠精子发生的影响

Effects of thoracic X-ray irradiation on the spermatogenesis of adult male mice

目的探讨X射线胸部照射对雄性成年小鼠精子发生的影响。方法将24只健康雄性成年C57BL/6小鼠(6~8周龄)按照随机数表法分为X射线照射组(Radiation)和假照射组(Sham),每组12只。胸部照射面积为1.5 cm×2 cm,剂量率3.04 Gy/min,8 Gy/d,连续照射3 d,总剂量24 Gy,于照射后第7天和第21天取材。剥离双侧睾丸,计算睾丸系数;HE染色法观察睾丸组织形态,并测量生精小管直径和生精上皮厚度;游离附睾尾中的精子用于统计精子数量;TUNEL和Western blot分别检测睾丸组织凋亡及凋亡相关蛋白水平变化,ELISA检测睾丸内干细胞因子(SCF)和胶质源性神经营养因子(GDNF)的水平。结果与假照射组相比,照射组小鼠的睾丸和附睾组织形态结构严重破坏,生精小管直径在照射后第21天,生精小管直径减小,差异有统计学意义(t=8.93,P<0.05),生精上皮厚度在照射后第7天和第21天均明显减小,差异有统计学意义(t=4.24、12.77,P<0.05),精子数量减少,差异有统计学意义(t=4.30、2.98,P<0.05);生精小管内TUNEL阳性细胞数在照射后第7天和第21天显著上调(t=-2.73、-3.74,P<0.05);睾丸内Cleaved Caspase-3蛋白水平在照射后第7天和第21天也显著上调,差异有统计学意义(t=-2.96、-2.46,P<0.05);睾丸内SCF和GDNF水平在照射后第7天无明显改变,在照射后第21天均显著上调(t=-10.46、-5.42,P<0.05)。结论本研究条件下X射线胸部照射可损伤雄性成年小鼠精子发生障碍,其机制可能与生精细胞凋亡增加和支持细胞分泌功能紊乱有关。

Objective To investigate the effect of thoracic X-ray irradiation on the spermatogenesis of adult male mice.Methods A total of 24 healthy adult male C57BL/6 mice(6-8 weeks old)were randomly divided into radiation group(Radiation)and sham-radiation group(Sham),12 mice in each group.The area of thoracic irradiation was 1.5 cm×2 cm,and the dose rate was 3.04 Gy/min,8 Gy/d for 3 consecutive days,24 Gy in total.At 7 d and 21 d after thoracic irradiation,the bilateral testes and epididymal tails were stripped and the testicular index was calculated.The morphology of testis was examined by haematoxylin-eosin(HE)staining,then the diameter of seminiferous tubules and the thickness of seminiferous epithelium were measured.The sperms were collected from the bilateral epididymal tails for sperm counting.The level of apoptosis in testis and levels of apoptosis-related proteins were detected by TUNEL and Western blot,respectively.Results Compared with Sham group,the morphology of testis and epididymis was seriously damaged,the diameter of seminiferous tubules significantly decreased at 21 d after irradiation(t=8.93,P<0.05),and the seminiferous epithelium ignificantly decreased at 7 d and 21 d after irradiation(t=4.24,12.77,P<0.05).In addition,the number of sperms significantly decreased(t=4.30,2.98,P<0.05).The number of TUNEL positive cells in the seminiferous epithelium significantly increased at 7 d and 21 d after irradiation(t=-2.73,-3.74,P<0.05).Meanwhile,the level of cleaved Caspase-3 protein significantly increased at 7 d and 21 d after irradiation(t=-2.96,-2.46,P<0.05).The concentrations of SCF and GDNF did not change at 7 d after irradiation,but were significantly increased at 21 d after irradiation(t=-10.46,-5.42,P<0.05).Conclusions The thoracic X-ray irradiation could lead to spermatogenesis disorder in male adult mice,and the induction of spermatogenic cell apoptosis and the secretory dysfunction of sertoli cells may be involved.