Abstract：
Busulfan, a chemotherapeutic agent for cancer, has detrimental effects on germ cells and fertility, yet the specific mechanisms remain largely uncertain. The blood-testis barrier (BTB) maintains a suitable microenvironment for germ cells self-renewal and spermatogenesis by blocking the interference and damage of deleterious substances. Therefore, we hypothesized that BTB abnormalities might be involved in busulfan-induced oligospermia. To verify the hypothesis, thirty male Balb/c mice were randomly administered with busulfan (at a total dose of 40 mg/kg body weight) by intraperitoneal injection for 4 weeks to establish the model of oligospermia. The results displayed that busulfan caused testicular histopathological lesions and spermatogenesis disorder. Meanwhile, busulfan disrupted BTB integrity and lessened the expressions of BTB junction proteins, including Occludin, Claudin-11 and Connexin-43. Furthermore, busulfan activated the endoplasmic reticulum (ER) stress and PERK-eIF2α signaling pathway, reflected by the increased protein expressions of GRP78, p-PERK, p-eIF2α, ATF4 and CHOP. Finally, to evaluate whether the ER stress is involved in busulfan-induced BTB destruction, the ER stress inhibitor 4-Phenylbutyric acid (4-PBA, 1 mM) was used to intervene in busulfan-exposed TM4 cells. The results displayed that inhibition of ER stress alleviated the reduction of BTB junction protein expressions induced by busulfan in TM4 cells. These data collectively indicated that busulfan-induced BTB impairment was mediated by triggering ER stress and activation of the PERK-eIF2α signaling pathway, thereby damaging the spermatogenesis, providing a new therapeutic target for male infertility induced by busulfan.
摘要：
白消安,癌症的化疗药物，对生殖细胞和生育能力有有害影响，然而具体机制在很大程度上仍不确定。血睾丸屏障（BTB）通过阻断有害物质的干扰和损伤，为生殖细胞的自我更新和精子发生维持合适的微环境。因此,我们假设BTB异常可能与白消安诱导的少精子症有关.为了验证假设，30只雄性Balb/c小鼠随机腹腔注射白消安（总剂量为40mg/kg体重）4周，建立少精子症模型。结果表明白消安引起睾丸组织病理学病变和精子发生障碍。同时,白消安破坏了BTB的完整性，降低了BTB连接蛋白的表达，包括Occludin,Claudin-11和Connexin-43。此外，白消安激活内质网应激和PERK-eIF2α信号通路,反映在GRP78、p-PERK、p-eIF2α，ATF4和CHOP。最后,为了评估ER应激是否参与白消安诱导的BTB破坏，内质网应激抑制剂4-苯丁酸(4-PBA，1mM）用于干预暴露于白消安的TM4细胞。结果表明，抑制内质网应激减轻了白消安诱导的TM4细胞BTB连接蛋白表达的减少。这些数据共同表明白消安诱导的BTB损伤是通过触发ER应激和激活PERK-eIF2α信号通路介导的，从而损害精子发生，为白消安致男性不育提供了新的治疗靶点。
