Melatonin Attenuates Cerebral Ischemia/Reperfusion Injury Through Inducing Autophagy

Introduction: The aim of this study was to investigate how melatonin administration for 3 days or 7 days following cerebral ischemia injury (CI/R) would affect autophagy, and therefore, survival in neurons of the penumbra region. Moreover, it was also aimed to determine how this melatonin treatment would affect the neurological deficit score and rotarod and adhesive removal test durations.Methods: Focal CI (90 min) was achieved in a total of 105 rats utilizing a middle cerebral artery occlusion model. After the start of reperfusion, the groups were treated with melatonin (10 mg/kg/day) for 3-days or 7-days. On all groups, neurological deficit scoring, rotarod and adhesive removal test were executed during reperfusion. Infarct areas were determined by TTC (2,3,5-triphenyltetrazolium chloride) staining at the end of the 3rd and 7th days of reperfusion. Beclin-1, LC3, p62 and caspase-3 protein levels were assessed using Western blot and immunofluorescence methods in the brain tissues. Moreover, penumbra areas were evaluated by transmission electron microscopy (TEM).Results: Following CI, it was observed that melatonin treatment improved the rotarod and adhesive removal test durations from day 5 and reduced the infarct area after CI. It also induced autophagic proteins Beclin-1, LC3 and p62 and suppressed the apoptotic protein cleaved caspase-3. According to TEM findings, melatonin treatment partially reduced the damage in neurons after CI.Conclusion: Melatonin treatment following CI reduced the infarct area and induced the autophagic proteins Beclin-1, LC3 and p62 via inhibiting the apoptotic caspase-3 protein. The functional reflection of melatonin treatment on neurological tests scores was became significant from the 5th day onward.