Department of Neurology, Chengdu Second People's Hospital, No. 2, Huatai Road, Chenghua District, Chengdu, Sichuan 610017, People's Republic of China.
Department of Neurology, The First Affiliated Hospital of Chengdu Medical College, No, 278, Middle Baoguang Avenue, Xindu District, Chengdu, Sichuan 610050, People's Republic of China.
Neuroscience. 2023 Oct 1;529:23-36. doi: 10.1016/j.neuroscience.2023.08.009. Epub 2023 Aug 10.
Intranasal insulin reduces lesion size and enhances memory capacity in traumatic brain injury (TBI) models, but the molecular mechanisms behind this neuroprotective action not yet understood. Here we used Feeney's free-falling method to construct TBI mouse models and administrated intranasal insulin, rapamycin, insulin and rapamycin, or normal saline to assess their effects on neurological functions, cerebral edema, and the expression of Iba1 in microglia through immunofluorescence assay. We also measured concentrations of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the brain using enzyme immunosorbent assay, investigated apoptosis with TUNEL staining and Western blotting, and evaluated autophagy, endoplasmic reticulum (ER) stress, and PI3K/Akt/mTOR signaling pathway with Western blotting. The autophagosome was assessed through transmission electron microscopy. Our findings demonstrated that intranasal insulin promoted neurological recovery, decreased brain swelling, and reduced injury lesions on days 1, 3, and 7 post TBI. Moreover, intranasal insulin reduced microglia activation and the concentration of IL-1β or TNF-α on the same days. Through Western blotting and transmission electron microscopy, we observed that intranasal insulin suppressed autophagy while activating the PI3K/AKT/mTOR signaling pathway on days 1 and 3 post TBI. TUNEL assay and Western blotting also indicated that intranasal insulin inhibited ER stress-mediated apoptosis. Interestingly, the mTOR inhibitor rapamycin partially blocked the pro-autophagy and anti-apoptosis effects of intranasal insulin both on days 1 and 3 post TBI. Our results suggest that intranasal insulin can ameliorate TBI by regulating autophagy and ER stress-mediated apoptosis through the PI3K/AKT/mTOR signaling pathway, providing a promising therapeutic strategy for TBI.
鼻内胰岛素可减少创伤性脑损伤（TBI）模型中的损伤大小并增强记忆能力，但这种神经保护作用的分子机制尚不清楚。在这里，我们使用 Feeney 的自由落体法构建 TBI 小鼠模型，并给予鼻内胰岛素、雷帕霉素、胰岛素和雷帕霉素或生理盐水，通过免疫荧光法评估它们对神经功能、脑水肿和小胶质细胞中 Iba1 表达的影响。我们还使用酶联免疫吸附试验测量大脑中白细胞介素-1β（IL-1β）和肿瘤坏死因子-α（TNF-α）的浓度，通过 TUNEL 染色和 Western blot 检测细胞凋亡，通过 Western blot 评估自噬、内质网（ER）应激和 PI3K/Akt/mTOR 信号通路。通过透射电子显微镜评估自噬体。我们的研究结果表明，鼻内胰岛素可促进神经恢复，减轻脑水肿，并减少 TBI 后第 1、3 和 7 天的损伤病变。此外，鼻内胰岛素还可减少小胶质细胞活化和 IL-1β或 TNF-α的浓度。通过 Western blot 和透射电子显微镜，我们观察到 TBI 后第 1 和 3 天，鼻内胰岛素抑制自噬，同时激活 PI3K/AKT/mTOR 信号通路。TUNEL 检测和 Western blot 还表明，鼻内胰岛素抑制 ER 应激介导的细胞凋亡。有趣的是，mTOR 抑制剂雷帕霉素部分阻断了 TBI 后第 1 和 3 天鼻内胰岛素的自噬和抗细胞凋亡作用。我们的研究结果表明，鼻内胰岛素通过调节自噬和 ER 应激介导的细胞凋亡，通过 PI3K/AKT/mTOR 信号通路改善 TBI，为 TBI 提供了一种有前途的治疗策略。
