Melatonin Alleviates Early Brain Injury(EBI) After Subarachnoid Hemorrhage(SAH) In Mice

Recent studies have shown that melatonin plays an important protective role in the ischemia and reperfusion injury of various organs such as the heart and kidney.Subarachnoid hemorrhage(subarachnoid,SAH)is a general term for the disease that causes blood to flow into the subarachnoid cavity.While the role and mechanism of melatonin in SAH is not quite clear.In this study,an animal model of SAH was established and treated with melatonin(MT)to investigate the potential role of SIRT3-oxygen radicals in post-SAH EBI.The mice were randomly divided into three groups,sham group sham group,SAH group,SAH and injection of melatonin group,and the SAH model was constructed with internal carotid artery puncture.TUNEL assay was carried out to detect effect of MT on apoptosis of neuronal cells,real-time PCR,western-blot analysis and immunohistochemistry were performed to investigate influence of MT on SIRT3 Bcl-2,SOD2,Bax and cleaved caspase-3.And luciferase assays were carried out to clarify the role of how MT increased SIRT3 expression and SIRT3-oxygen radicals in post-SAH brain injuries.A significant decrease in the neurological score and a significant increase in brain water content were observed in the SAH group.However,MT treatment increased neurological deficits and reduced brain swelling following SAH.A higher rate of apoptosis was also observed in the SAH group,whereas the administration of MT inhibited the apoptosis of neuronal cells.Meanwhile,a higher level of SOD2,Bax and cleaved caspase-3 was observed in the SAH group,accompanied by a lower level of SIRT3 and Bcl-2.In contrast,the treatment with MT down-regulated the expression of SOD2,Bax and cleaved caspase-3,but enhanced the expression of SIRT3 and Bcl-2 following SAH.In addition,the protein level 38 of SIRT3 in the SHA+MT group was much lower than that in the SHA+MT and the SAH groups.Meanwhile,the ratio of GSH/GSSG was significantly decreased in the SAH group,40 whereas the treatment with MT somewhat increased the ratio of GSH/GSSG.Furthermore,the level of MDA was much higher in the SAH group,but was evidently reduced after the MT treatment.Finally,MT up-regulated SIRT3 expression by increasing the transcription efficiency of SIRT3 promoter in U87 and U251 cells.This study indicated that melatonin-mediated generation of reactive oxygen 45 species could provide a certain protection against post-SAH brain injury by regulating the expression of SIRT3.