Department of Forensic Medicine, Medical School of Soochow University, Suzhou 215123, China.
Department of Forensic Medicine, Wenzhou Medical University, Wenzhou 325035, China.
Neurobiol Learn Mem. 2019 May;161:12-25. doi: 10.1016/j.nlm.2019.03.002. Epub 2019 Mar 6.
Traumatic brain injury (TBI) is a complex injury that can cause severe disabilities and even death. TBI can induce secondary injury cascades, including but not limited to endoplasmic reticulum (ER) stress, apoptosis and autophagy. Although the investigators has previously shown that salubrinal, the selective phosphatase inhibitor of p-eIF2α, ameliorated neurologic deficits in murine TBI model, the neuroprotective mechanisms of salubrinal need further research to warrant the preclinical value. This study was undertaken to characterize the effects of salubrinal on cell death and neurological outcomes following TBI in mice and the potential mechanisms. In the current study, ER stress-related proteins including p-eIF2α, GRP78 and CHOP showed peak expressions both in the cortex and hippocampus from day 2 to day 3 after TBI, indicating ER stress was activated in our TBI model. Immunofluorescence staining showed that CHOP co-located NeuN-positive neuron, GFAP-positive astrocyte, Iba-1-positive microglia, CD31-positive vascular endothelial cell and PDGFR-β-positive pericyte in the cortex on day 2 after TBI, and these cells mentioned above constitute the neurovascular unit (NVU). We also found TBI-induced plasmalemma permeability, motor dysfunction, spatial learning and memory deficits and brain lesion volume were alleviated by continuous intraperitoneal administration of salubrinal post TBI. To investigate the underlying mechanisms further, we determined that salubrinal suppressed the expression of ER stress, autophagy and apoptosis related proteins on day 2 after TBI. In addition, salubrinal administration decreased the number of CHOP+/TUNEL+ and CHOP+/LC3+ cells on day 2 after TBI, detected by immunofluorescence. In conclusion, these data imply that salubrinal treatment improves morphological and functional outcomes caused by TBI in mice and these neuroprotective effects may be associated with inhibiting apoptosis, at least in part by suppressing ER stress-autophagy pathway.
创伤性脑损伤 (TBI) 是一种复杂的损伤，可导致严重残疾甚至死亡。TBI 可诱导继发性损伤级联反应，包括但不限于内质网 (ER) 应激、细胞凋亡和自噬。尽管研究人员之前已经表明，选择性磷酸酶抑制剂 p-eIF2α 的 salubrinal 可改善小鼠 TBI 模型中的神经功能缺损，但 salubrinal 的神经保护机制需要进一步研究，以保证其临床前价值。本研究旨在描述 salubrinal 对小鼠 TBI 后细胞死亡和神经功能结果的影响及其潜在机制。在本研究中，我们发现 ER 应激相关蛋白 p-eIF2α、GRP78 和 CHOP 在 TBI 后第 2 天至第 3 天在皮质和海马体中表达达到峰值，表明 ER 应激在我们的 TBI 模型中被激活。免疫荧光染色显示，CHOP 在 TBI 后第 2 天与皮质中 NeuN 阳性神经元、GFAP 阳性星形胶质细胞、Iba-1 阳性小胶质细胞、CD31 阳性血管内皮细胞和 PDGFR-β 阳性周细胞共定位，这些细胞构成了神经血管单元 (NVU)。我们还发现，连续腹腔内给予 salubrinal 可减轻 TBI 后的血脑屏障通透性、运动功能障碍、空间学习和记忆缺陷以及脑损伤体积。为了进一步探讨潜在机制，我们发现 salubrinal 抑制了 TBI 后第 2 天 ER 应激、自噬和细胞凋亡相关蛋白的表达。此外，salubrinal 给药可减少 TBI 后第 2 天 CHOP+/TUNEL+和 CHOP+/LC3+细胞的数量，这通过免疫荧光检测到。总之，这些数据表明，salubrinal 治疗可改善小鼠 TBI 引起的形态和功能结果，这些神经保护作用可能与抑制细胞凋亡有关，至少部分是通过抑制 ER 应激-自噬途径。
