Melatonin relieved early brain injury by NLRP3 pathway in the mouse model of subarachnoid hemorrhage

MAO Chongdan; ZHEN Endi; LIU Yangyang; ZHANG Haifeng; HAO Guangzhi; DONG Yushu

Abstract：Objective The protective effects of melatonin against early brain injury (EBI) induced by subarachnoid hemorrhage (SAH) was explored and the potential mechanisms via regulating nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome was elucidated.Methods Mice subjected to SAH model were divided into four groups:Sham group,Sham + vehicle group,SAH +vehicle group and SAH + melatonin group.SAH grade and neurological function scores were assayed.The degree of cerebral edema was evaluated by the water content of brain tissue.The permeability of blood brain barrier was determined by Evas-blue staining method.Malondialdehyde and glutathione were measured.The ratio of surviving and apoptotic neurons were detected by neuronal nuclear antigen (NeuN) and TdT-mediated dUTP nick end labeling (TUNEL) assay.The protein expression of apoptosis-associated speck-like protein containing apoptosis-associated specklike protein (ASC),interleukin-lβ (IL-1β),NLRP3,B-cell lymphoma-2 (Bcl2),pro-apoptotic Bc1-2 proteins (Bim) and active caspase-1 was detected by Western Blot.Cytokines IL-1β and interleukin-6 (IL-6) was measured by enzyme linked immunosorbent assay (ELISA).Results Melatonin increased survival rate,as well as elevated neurological score,greater survival of neurons,preserved brain glutathione levels and reduced brain edema,malondialdehyde concentrations,apoptotic ratio,and blood brain barrier (BBB) disruption.Melatonin also attenuated the expressions of NLRP3,ASC,cleaved caspase-1,IL-1β,and IL-6;these changes were also associated with an increase in the anti-apoptotic factor (Bcl2) and reduction in the pro-apoptotic factor (Bim).Conclusion Melatonin treatment attenuates the EBI following SAH by inhibiting NLRP3 inflammasome-associated apoptosis.