SummaryStudies have indicated that psychological stress impairs human fertility and that various stressors can induce apoptosis of testicular cells. However, the mechanisms by which psychological stress on males reduces semen quality and stressors induce apoptosis in testicular cells are largely unclear. Using a psychological (restraint) stress mouse model, we tested whether male psychological stress triggers apoptosis of spermatozoa and spermatogenic cells through activating tumour necrosis factor (TNF)-α signalling. Wild-type or TNF-α−/− male mice were restrained for 48 h before examination for apoptosis and expression of TNF-α and TNF receptor 1 (TNFR1) in spermatozoa, epididymis, seminiferous tubules and spermatogenic cells. The results showed that male restraint significantly decreased fertilization rate and mitochondrial membrane potential, while increasing levels of malondialdehyde, active caspase-3, TNF-α and TNFR1 in spermatozoa. Male restraint also increased apoptosis and expression of TNF-α and TNFR1 in caudae epididymides, seminiferous tubules and spermatogenic cells. Sperm quality was also significantly impaired when spermatozoa were recovered 35 days after male restraint. The restraint-induced damage to spermatozoa, epididymis and seminiferous tubules was significantly ameliorated in TNF-α−/− mice. Furthermore, incubation with soluble TNF-α significantly reduced sperm motility and fertilizing potential. Taken together, the results demonstrated that male psychological stress induces apoptosis in spermatozoa and spermatogenic cells through activating the TNF-α system and that the stress-induced apoptosis in spermatogenic cells can be translated into impaired quality in future spermatozoa.

中文翻译：

---

雄性小鼠束缚应激通过激活TNF-α系统引发精子和生精细胞凋亡


摘要研究表明，心理压力会损害人类的生育能力，并且各种压力源可诱导睾丸细胞凋亡。然而，男性心理压力降低精液质量和压力源诱导睾丸细胞凋亡的机制尚不清楚。使用心理（束缚）应激小鼠模型，我们测试了雄性心理应激是否通过激活肿瘤坏死因子（TNF）-α信号传导触发精子和生精细胞的凋亡。野生型或 TNF-α −/−将雄性小鼠束缚48小时，然后检查精子、附睾、生精小管和生精细胞的凋亡和TNF-α和TNF受体1（TNFR1）的表达。结果表明，雄性束缚显着降低了受精率和线粒体膜电位，同时增加了精子中丙二醛、活性caspase-3、TNF-α和TNFR1的水平。男性束缚还增加了附睾尾部、生精小管和生精细胞的凋亡以及 TNF-α 和 TNFR1 的表达。当男性束缚后 35 天回收精子时，精子质量也显着受损。 TNF-α 显着改善了约束引起的精子、附睾和曲细精管损伤−/−老鼠。此外，与可溶性 TNF-α 一起孵育显着降低了精子活力和受精潜力。综上所述，研究结果表明，男性心理压力通过激活TNF-α系统诱导精子和生精细胞凋亡，并且压力诱导的生精细胞凋亡可转化为未来精子质量受损。