[Effects of cadmium chloride on testicular autophagy and blood-testis barrier integrity in prepubertal male rats].

Objective: To study the effects of cadmium chloride (CdCl(2)) exposure on testicular autophagy levels and blood-testis barrier integrity in prepubertal male SD rats and testicular sertoli (TM4) cells. Methods: In July 2021, 9 4-week-old male SD rats were randomly divided into 3 groups: control group (normal saline), low dose group (1 mg/kg·bw CdCl(2)) and high dose group (2 mg/kg·bw CdCl(2)), and were exposed with CdCl(2) by intrabitoneal injection. 24 h later, HE staining was used to observe the morphological changes of testis of rats, biological tracer was used to observe the integrity of blood-testis barrier, and the expression levels of microtubule-associated protein light chain 3 (LC3) -Ⅰ and LC3-Ⅱ in testicular tissue were detected. TM4 cells were treated with 0, 2.5, 5.0 and 10.0 μmol/L CdCl(2) for 24 h to detect the toxic effect of cadmium. The cells were divided into blank group (no exposure), exposure group (10.0 μmol/L CdCl(2)), experimental group[10.0 μmol/L CdCl(2)+60.0 μmol/L 3-methyladenine (3-MA) ] and inhibitor group (60.0 μmol/L 3-MA). After 24 h of treatment, Western blot analysis was used to detect the expression levels of LC3-Ⅱ, ubiquitin binding protein p62, tight junction protein ZO-1 and adhesion junction protein N-cadherin. Results: The morphology and structure of testicular tissue in the high dose group were obvious changed, including uneven distribution of seminiferous tubules, irregular shape, thinning of seminiferous epithelium, loose structure, disordered arrangement of cells, abnormal deep staining of nuclei and vacuoles of Sertoli cells. The results of biological tracer method showed that the integrity of blood-testis barrier was damaged in the low and high dose group. Western blot results showed that compared with control group, the expression levels of LC3-Ⅱ in testicular tissue of rats in low and high dose groups were increased, the differences were statistically significant (P<0.05). Compared with the 0 μmol/L, after exposure to 5.0, 10.0 μmol/L CdCl(2), the expression levels of ZO-1 and N-cadherin in TM4 cells were significantly decreased, and the expression level of p62 and LC3-Ⅱ/LC3-Ⅰ were significantly increased, the differences were statistically significant (P<0.05). Compared with the exposure group, the relative expression level of p62 and LC3-Ⅱ/LC3-Ⅰ in TM4 cells of the experimental group were significantly decreased, while the relative expression levels of ZO-1 and N-cadherin were significantly increased, the differences were statistically significant (P<0.05) . Conclusion: The mechanism of the toxic effect of cadmium on the reproductive system of male SD rats may be related to the effect of the autophagy level of testicular tissue and the destruction of the blood-testis barrier integrity.目的： 以氯化镉（CdCl(2)）染毒青春前期雄性SD大鼠和睾丸支持细胞（TM4细胞），研究镉暴露对睾丸自噬水平和血睾屏障完整性的影响。 方法： 于2021年7月，将9只4周龄雄性SD大鼠随机分为3组：对照组（生理盐水）、低剂量组（1 mg/kg体重CdCl(2)溶液）、高剂量组（2 mg/kg体重CdCl(2)溶液），采用腹腔注射的方式进行染毒。24 h后采用HE染色法观察大鼠睾丸组织形态学变化，生物示踪法观察血睾屏障的完整性，并检测睾丸组织中微管相关蛋白轻链3（LC3）-Ⅰ、LC3-Ⅱ的表达水平。0、2.5、5.0和10.0 μmol/L CdCl(2)溶液处理TM4细胞24 h检测镉的毒作用，将细胞分为空白组（未染毒）、染毒组（10 μmol/L CdCl(2)）、实验组[10 μmol/L CdCl(2)+60 μmol/L 3-甲基腺嘌呤（3-MA）]和抑制剂组（60 μmol/L 3-MA），处理24 h后，Western blot分析LC3-Ⅱ、泛素结合蛋白p62、紧密连接蛋白ZO-1和黏附连接蛋白N-cadherin的表达情况。 结果： 高剂量组大鼠睾丸组织形态结构发生明显变化，曲细精管分布不均匀，形态不规则，生精上皮变薄，结构疏松，细胞排列紊乱，细胞核异常深染，支持细胞出现空泡；生物示踪法结果显示低剂量组和高剂量组大鼠血睾屏障完整性受到破坏；Western blot结果发现与对照组比较，低、高剂量组大鼠睾丸组织中LC3-Ⅱ表达水平升高，差异有统计意义（P<0.05）。与0 μmol/L比较，5.0、10.0 μmol/L CdCl(2)染毒后，TM4细胞中ZO-1和N-cadherin表达水平明显下降，p62表达水平和LC3-Ⅱ/LC3-Ⅰ比值明显升高，差异均有统计学意义（P<0.05）。与染毒组比较，实验组TM4细胞p62表达水平、LC3-Ⅱ/LC3-Ⅰ比值明显下降，ZO-1和N-cadherin相对表达量明显升高，差异均有统计学意义（P<0.05）。 结论： 镉对雄性SD大鼠生殖系统的毒性作用机制可能与影响睾丸组织细胞自噬水平和破坏血睾屏障完整性有关。.