Department of Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, China.
Int J Biol Sci. 2018 Jun 13;14(9):1109-1121. doi: 10.7150/ijbs.22805. eCollection 2018.
We used chronic restraint-induced stress (CRIS) and iron ionizing radiation (IR) to mimic human exposure to psychological stress (PS) and IR in a mouse model, and to investigate the relationship among endoplasmic reticulum stress (ERS), apoptosis and autophagy in testicular toxicity. Male C57BL/6N mice were restrained for 6 h/day for 28 consecutive days, and total body irradiation with 0.1 or 2 Gy iron ion beam was performed on the day 8. Histopathological observation showed severely damaged spermatogenic cells, increased apoptotic cells, caspase-3 activation and cytochrome c release, indicating that IR and CRIS+IR induced testicular cell apoptosis. Upregulation of GRP78 (78-kDa glucose-regulated protein) suggested that IR and CRIS+IR induced ERS in the testes, and further analysis showed that apoptosis was enhanced by ERS through activation of the PERK/eIF2α/ATF4/CHOP pathway. Decreased expression of LC3II, Atg5 (autophagy related 5) and Beclin 1, and increased expression of p62, combined with ultrastructural changes seen under transmission electron microscopy, suggest that IR and CRIS+IR inhibit autophagosome formation. This process was related to inhibition of autophagy via activation of the PI3K/AKT/mTOR pathway under ERS. We showed that apoptosis was strengthened and autophagy was inhibited by ERS in mouse testes induced by IR and CRIPS+IR. These results showed that CRIS+IR had no difference in apoptosis induction and autophagy inhibition compared with IR alone. CIRS alone could induce apoptosis only in Leydig cells and its induction of pathological and molecular changes in testicular tissues was only a small extent as compared to those induced by IR. Of note, we showed that 28 consecutive days of CRIS did not exacerbate IR effects (no additive effect with IR). These findings also suggest that studies on the concurrent exposure to PS and IR should be done using different endpoints in both short and long-term CRIS models.
我们使用慢性束缚应激（CRIS）和铁离子辐射（IR）来模拟人类在老鼠模型中暴露于心理应激（PS）和 IR，研究内质网应激（ERS）、凋亡和自噬在睾丸毒性中的关系。雄性 C57BL/6N 小鼠每天束缚 6 小时，连续 28 天，第 8 天进行全身 0.1 或 2 Gy 铁离子束照射。组织病理学观察显示严重受损的生精细胞、增加的凋亡细胞、caspase-3 激活和细胞色素 c 释放，表明 IR 和 CRIS+IR 诱导睾丸细胞凋亡。GRP78（78 kDa 葡萄糖调节蛋白）的上调表明 IR 和 CRIS+IR 诱导睾丸中的 ERS，进一步分析表明 ERS 通过激活 PERK/eIF2α/ATF4/CHOP 通路增强凋亡。LC3II、Atg5（自噬相关 5）和 Beclin 1 的表达减少，p62 的表达增加，结合透射电子显微镜下看到的超微结构变化，表明 IR 和 CRIS+IR 抑制自噬体的形成。这一过程与 ERS 下通过激活 PI3K/AKT/mTOR 通路抑制自噬有关。我们表明，IR 和 CRIS+IR 诱导的小鼠睾丸中 ERS 增强凋亡并抑制自噬。这些结果表明，CRIS+IR 在诱导凋亡和抑制自噬方面与单独的 IR 没有差异。单独的 CIRS 只能诱导 Leydig 细胞凋亡，其对睾丸组织病理和分子变化的诱导程度与 IR 诱导的相比仅为一小部分。值得注意的是，我们表明，28 天的 CRIS 并没有加重 IR 的影响（与 IR 没有相加效应）。这些发现还表明，在短期和长期 CRIS 模型中，应该使用不同的终点来研究同时暴露于 PS 和 IR 的情况。
