Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China.
Zhejiang Provincial Key Laboratory of Orthopaedics, Wenzhou, China.
Br J Pharmacol. 2024 Mar;181(5):712-734. doi: 10.1111/bph.16255. Epub 2023 Oct 21.
Autophagy is a protective factor for controlling neuronal damage, while necroptosis promotes neuroinflammation after spinal cord injury (SCI). DADLE (D-Ala , D-Leu ]-enkephalin) is a selective agonist for delta (δ) opioid receptor and has been identified as a promising drug for neuroprotection. The aim of this study was to investigate the mechanism/s by which DADLE causes locomotor recovery following SCI.
Spinal cord contusion model was used and DADLE was given by i.p. (16 mg·kg ) in mice for following experiments. Motor function was assessed by footprint and Basso mouse scale (BMS) score analysis. Western blotting used to evaluate related protein expression. Immunofluorescence showed the protein expression in each cell and its distribution. Network pharmacology analysis was used to find the related signalling pathways.
DADLE promoted functional recovery after SCI. In SCI model of mice, DADLE significantly increased autophagic flux and inhibited necroptosis. Concurrently, DADLE restored autophagic flux by decreasing lysosomal membrane permeabilization (LMP). Additionally, chloroquine administration reversed the protective effect of DADLE to inhibit necroptosis. Further analysis showed that DADLE decreased phosphorylated cPLA , overexpression of cPLA partially reversed DADLE inhibitory effect on LMP and necroptosis, as well as the promotion autophagy. Finally, AMPK/SIRT1/p38 pathway regulating cPLA is involved in the action DADLE on SCI and naltrindole inhibited DADLE action on δ receptor and on AMPK signalling pathway.
DADLE causes its neuroprotective effects on SCI by promoting autophagic flux and inhibiting necroptosis by decreasing LMP via activating δ receptor/AMPK/SIRT1/p38/cPLA pathway.
自噬是控制神经元损伤的保护因素，而坏死性凋亡则促进脊髓损伤（SCI）后的神经炎症。DADLE（D-丙氨酸，D-亮氨酸]脑啡肽）是δ 阿片受体的选择性激动剂，已被确定为一种有前途的神经保护药物。本研究旨在探讨 DADLE 引起 SCI 后运动功能恢复的机制。
使用脊髓挫伤模型，通过腹腔注射（16mg·kg）给予 DADLE 进行后续实验。通过足迹和 Basso 小鼠量表（BMS）评分分析评估运动功能。Western blot 用于评估相关蛋白表达。免疫荧光显示各细胞的蛋白表达及其分布。网络药理学分析用于寻找相关信号通路。
DADLE 促进 SCI 后的功能恢复。在 SCI 模型小鼠中，DADLE 显著增加自噬流并抑制坏死性凋亡。同时，DADLE 通过降低溶酶体膜通透性（LMP）来恢复自噬流。此外，氯喹给药逆转了 DADLE 抑制坏死性凋亡的保护作用。进一步分析表明，DADLE 降低磷酸化 cPLA，cPLA 的过表达部分逆转了 DADLE 抑制 LMP 和坏死性凋亡以及促进自噬的作用。最后，调节 cPLA 的 AMPK/SIRT1/p38 通路参与了 DADLE 对 SCI 的作用，naltrindole 抑制了 DADLE 对 δ 受体和 AMPK 信号通路的作用。
DADLE 通过激活 δ 受体/AMPK/SIRT1/p38/cPLA 通路，通过降低 LMP 促进自噬流并抑制坏死性凋亡，从而对 SCI 产生神经保护作用。
