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.%目的 探讨褪黑素通过调节核苷酸结合寡聚化结构域样受体3炎症复合体(NLRP3)对蛛网膜下腔出血(SAH)后早期脑损伤(EBI)的保护作用和机制.方法 建立小鼠颈动脉线穿法SAH模型,分为假手术组、假手术+溶剂组、SAH+溶剂组和SAH+褪黑素组四组,进行SAH出血量评级和小鼠神经功能缺陷评分,脑组织水含量测定脑水肿,伊文思蓝法测定血脑屏障(BBB)通透性,检测脑丙二醛(MDA)和谷胱甘肽(GSH)水平,神经核抗原(NeuN)和末端脱氧核苷酸转移酶介导的dUTP缺口末端标记测定法(TUNEL)检测神经元存活和死亡率,Western Blot检测脑凋亡相关斑点样蛋白(ASC)、白细胞介素-1β(IL-1β)、核苷酸结合寡聚化结构域样受体3炎症复合体(NLRP3)、B淋巴细胞瘤-2基因(Bcl2)、前凋亡因子(Bim)和活化的caspase-1蛋白表达,酶联免疫吸附测定(ELISA)脑中细胞因子白介素-1β (IL-1β)和白介素-6(IL-6)水平.结果 槲皮素可以提高SAH小鼠生存率,降低神经功能缺陷评分,减少脑神经元凋亡,提高脑谷胱甘肽(GSH)水平,降低丙二醛(MDA)水平,减轻脑水肿和BBB通透性损害.槲皮素可以降低NLRP3以及细胞凋亡相关斑点样蛋白(ASC)的表达,抑制IL-1ββ、IL-6的分泌和活化的caspase-1的蛋白表达,并可以增高抗凋亡因子Bcl2的表达,降低凋亡前体因子Bim的表达.结论 槲皮素通过抑制NLRP3炎性相关的凋亡来减轻SAH后的EBI.
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