Neuroprotective effects of Alda-1 mitigate spinal cord injury in mice:involvement of Alda-1-induced ALDH2 activation-mediated suppression of reactive aldehyde mechanisms

Spinal cord injury(SCI)is associated with high production and excessive accumulation of pathological 4-hydroxy-trans-2-nonenal(4-HNE),a reactive aldehyde,formed by SCI-induced metabolic dysregulation of membrane lipids.Reactive aldehyde load causes redox alteration,neuroinflammation,neurodegeneration,pain-like behaviors,and locomotion deficits.Pharmacological scavenging of reactive aldehydes results in limited improved motor and sensory functions.In this study,we targeted the activity of mitochondrial enzyme aldehyde dehydrogenase 2(ALDH2)to detoxify 4-HNE for accelerated functional recovery and improved pain-like behavior in a male mouse model of contusion SCI.N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide(Alda-1),a selective activator of ALDH2,was used as a therapeutic tool to suppress the 4-HNE load.SCI was induced by an impactor at the T9–10 vertebral level.Injured animals were initially treated with Alda-1 at 2 hours after injury,followed by once-daily treatment with Alda-1 for 30 consecutive days.Locomotor function was evaluated by the Basso Mouse Scale,and pain-like behaviors were assessed by mechanical allodynia and thermal algesia.ALDH2 activity was measured by enzymatic assay.4-HNE protein adducts and enzyme/protein expression levels were determined by western blot analysis and histology/immunohistochemistry.SCI resulted in a sustained and prolonged overload of 4-HNE,which parallels with the decreased activity of ALDH2 and low functional recovery.Alda-1 treatment of SCI decreased 4-HNE load and enhanced the activity of ALDH2 in both the acute and the chronic phases of SCI.Furthermore,the treatment with Alda-1 reduced neuroinflammation,oxidative stress,and neuronal loss and increased adenosine 5′-triphosphate levels stimulated the neurorepair process and improved locomotor and sensory functions.Conclusively,the results provide evidence that enhancing the ALDH2 activity by Alda-1 treatment of SCI mice suppresses the 4-HNE load that attenuates neuroinflammation and neurodegeneration,promotes the neurorepair process,and improves functional outcomes.Consequently,we suggest that Alda-1 may have therapeutic potential for the treatment of human SCI.Animal procedures were approved by the Institutional Animal Care and Use Committee(IACUC)of MUSC(IACUC-2019-00864)on December 21,2019.