Protective Effect Of Melatonin On Cerebral Ischemia-Reperfusion Injury In Rats After MCAO

Objective:To investigate the protective effect of melatonin on cerebral ischemia-reperfusion injury in rats after MCAO,and to explore the potential mechanism.Methods:36 rats were randomly divided into 3 groups:sham group,MCAO+vehicle group,MCAO+melatonin group.After 2 hours MCA occlusion and 24 hours reperfusion,rats in MCAO+vehicle group and MCAO+melatonin group got intraperitoneal injection of 10%Dimethyl sulfoxide(1mL/kg)and melatonin(1mL/kg)30min before and after MCA occlusion respectively.After 24 hours reperfusion,brain tissue and serum samples were collected to analyze the degree of ischemia-reperfusion injury,oxidation and inflammation.Results:The neurological behavior scores of group A(sham operation group),group B(MCAO+Vehicle group)and group C(MCAO+melatonin group)were 0±0 vs.2.00 ±0.28 vs.1.33 ± 0.14,respectively.Compared with group B,the neurological behavior score was significantly lower in group C(p<0.05).TTC staining was used to calculate the percentage of cerebral infarct volume of three groups(0 ± 0 vs.66.05 ± 8.89%vs.39.96±7.37%,resp.).Compared with group B,the percentage of cerebral infarct volume was significantly decreased in group C(p<0.05).The mean OD of NF-κB immunohistochemical staining of brain tissue in group B and group C were significantly higher than that in group A(p<0.01);while mean OD in group C was significantly lower than that in group B(p<0.05).The mean OD of IL-1β immunohistochemical staining of brain tissue in group B and group C were significantly higher than that in group A;while mean OD in group C was significantly lower than group B(p<0.05).Serum total SOD activity in group B and group C were significantly lower than that in group A(p<0.01);and compared with group B,it was significantly higher in group C(p<0.01),Serum MDA in group B was significantly higher than that in group A(p<0.01);and there was no significant difference(p = 0.1052)between group C and group A(p<0.05).Compared with group B,serum MDA was significantly decreased in group C(p<0.01).The results of oxidation and inflammation-related factor in protein level showed that compared with group B,the expression of IL-γ,NF-κB,iNOS and S100β in group C were significantly decreased and the expression of Nrf-2 was significantly increased(p<0.05).And the results of RT-PCR also showed that gene expression of IL-1β,NF-κB,iNOS in groupwere significantly decreased and gene expression of Nrf-2 was significantly increased(p<0.05).Further study of inflammasomes-related pathways in protein level revealed that compared with group B,the expression of NLRC4,ASC and CASP-1 in group C were significantly lower(p<0.05)and there was no significant difference in expression of AIM2(p =0.4901).We also discovered that gene expression of NLRC4,ASC and CASP-1 in group C were significantly lower(p<0.05)and there was no significant difference in expression of AIM2(p =0.9884).Conclusion:MCAO can cause cerebral ischemia-reperfusion injury in rats.Melatonin may have the protective effect for cerebral ischemia-reperfusion injury through the function of anti-oxidation and anti-inflammation.The NLRC4 inflammasomes related pathway may contribute to inflammatory regulation of melatonin in cerebral ischemia-reperfusion injury.