Melatonin ameliorates spinal cord injury by suppressing the activation of inflammasomes in rats

Background The activation of inflammasomes plays an important role in the pathogenesis of spinal cord injury (SCI). In addition, the administration of melatonin (MT) has been shown to suppress the activation of inflammasomes. In this study, we aimed to investigate the molecular mechanisms underlying the therapeutic effect of MT in the treatment of SCI. Methods Basso-Beattie-Bresnahan (BBB) locomotion scaling was conducted to evaluate the therapeutic effect of MT on post-SCI locomotion recovery. In addition, the measurement of spinal cord water content was performed together with Nissl staining to evaluate the protective effect of MT against SCI. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, immunohistochemistry (IHC) assay, Western blot analysis, and real-time polymerase chain reaction (PCR) were also conducted to clarify the molecular mechanisms underlying the therapeutic effect of MT in the treatment of SCI. Results BBB scores of SCI + MT rats were increased compared with the BBB scores of SCI rats, thus confirming the beneficial role of MT treatment in post-SCI functional recovery. Meanwhile, the administration of MT could alleviate SCI by reducing spinal cord water content and by exerting a neuroprotective effect on motor neurons. Furthermore, in the treatment of SCI, MT also attenuated cell apoptosis. Moreover, the relative expression of NLRP3, interleukin-1 beta (IL-1 beta), and caspase-1 were markedly elevated in the SCI group compared with that in the sham group, while the administration of MT reduced the expression of NLRP3 in SCI rats. Conclusions MT treatment accelerated the recovery of SCI by suppressing the activation of inflammasomes.