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Background and Purpose: Autophagy is a protective factor for controlling neuronal damage, while necroptosis promotes neuroinflammation after spinal cord injury (SCI). DADLE (D‐Ala2, D‐Leu5]‐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. Experimental approach: Spinal cord contusion model was used and DADLE was given by i.p. (16 mg·kg−1) 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. Key Results: 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 cPLA2, overexpression of cPLA2 partially reversed DADLE inhibitory effect on LMP and necroptosis, as well as the promotion autophagy. Finally, AMPK/SIRT1/p38 pathway regulating cPLA2 is involved in the action DADLE on SCI and naltrindole inhibited DADLE action on δ receptor and on AMPK signalling pathway. Conclusion and Implication: DADLE causes its neuroprotective effects on SCI by promoting autophagic flux and inhibiting necroptosis by decreasing LMP via activating δ receptor/AMPK/SIRT1/p38/cPLA2 pathway. [ABSTRACT FROM AUTHOR]

Background and Purpose: Necrosis of random‐pattern skin flaps limits their clinical application. Helix B surface peptide (HBSP) protects tissues from ischaemia–reperfusion injury but its short plasma half‐life limits its applications. Here, we have synthesized cyclic helix B peptide (CHBP) and investigated its role in flap survival and the underlying mechanisms. Experimental Approach Flap viability was evaluated by survival area analysis, laser Doppler blood flow and histological analysis. RNA sequencing was used to identify mechanisms underlying the effects of CHBP. Levels of autophagy, oxidative stress, pyroptosis, necroptosis and molecules related to the AMP‐activated protein kinase (AMPK)–TRPML1–calcineurin signalling pathway were assayed with Western blotting, RT‐qPCR, immunohistochemistry and immunofluorescence. Key Results: The results indicated that CHBP promoted the survival of random‐pattern skin flaps. The results of RNA sequencing analysis indicated that autophagy, oxidative stress, pyroptosis and necroptosis were involved in the ability of CHBP to promote skin flap survival. Restoration of autophagy flux and enhanced resistance to oxidative stress contributed to inhibition of pyroptosis and necroptosis. Increased autophagy and inhibition of oxidative stress in the ischaemic flaps were regulated by transcription factor E3 (TFE3). A decrease in the levels of TFE3 caused a reduction in autophagy flux and accumulation of ROS and eliminated the protective effect of CHBP. Moreover, CHBP regulated the activity of TFE3 via the AMPK–TRPML1–calcineurin signalling pathway. Conclusion and Implications: CHBP promotes skin flap survival by up‐regulating autophagy and inhibiting oxidative stress in the ischaemic flap and may have potential clinical applications. [ABSTRACT FROM AUTHOR]

Background and Purpose: Autophagy is a protective factor for controlling neuronal damage, while necroptosis promotes neuroinflammation after spinal cord injury (SCI). DADLE (D-Ala 2 , D-Leu 5 ]-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., Experimental Approach: Spinal cord contusion model was used and DADLE was given by i.p. (16 mg·kg -1 ) 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., Key Results: 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 2 , overexpression of cPLA 2 partially reversed DADLE inhibitory effect on LMP and necroptosis, as well as the promotion autophagy. Finally, AMPK/SIRT1/p38 pathway regulating cPLA 2 is involved in the action DADLE on SCI and naltrindole inhibited DADLE action on δ receptor and on AMPK signalling pathway., Conclusion and Implication: 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 2 pathway., (© 2023 British Pharmacological Society.)