Melatonin attenuates the cerebral ischemic injury via the MEK/ERK/p90RSK/bad signaling cascade.
Melatonin prevents neuronal cell death in ischemic brain injury. This study investigated whether melatonin inhibits the apoptotic signal through the activation of Raf-MEK-ERK and its downstream targets, including 90 ribosomal S6 kinase (p90RSK) and Bad. Adult male rats were treated with melatonin (5 mg/kg) or vehicle prior to middle cerebral artery occlusion (MCAO). Brains were collected 24 hr after MCAO. We confirmed that melatonin significantly decreases the number of TUNEL positive cells in the cerebral cortex. Western blot analysis showed that levels of Raf-1, MEK1/2, and ERK1/2 phosphorylation decrease in vehicle-treated animals. Melatonin prevents the injury-induced decrease of Raf-1, MEK1/2, and ERK1/2 phosphorylation. Also, it inhibits the injury-induced decrease of p90RSK and Bad phosphorylation. Recently, we reported that melatonin prevents the injury-induced reduction of interaction between pBad and 14-3-3 and inhibits the activation of caspase-3. Subsequently, melatonin prevents the injury-induced an increase of cleaved PARP levels. Taken together, these results suggest that melatonin prevents cell death resulting from ischemic brain injury, and that its neuroprotective effects are mediated by the activation of Raf/MEK/ERK/p90RSK cascade.
Koh
Phil-Ok
PO
Department of Anatomy, Research Institute of Life Science, Gyeongsang National University, Jinju, South Korea. pokoh@gsnu.ac.kr
D000818:Animals; D001930:Brain Injuries / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D002545:Brain Ischemia / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D016923:Cell Death / Q000187:drug effects; D002544:Cerebral Infarction / Q000517:prevention & control; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007839:Functional Laterality; D020287:In Situ Nick-End Labeling; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D008297:Male; D008550:Melatonin / Q000627:therapeutic use*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism; D051025:bcl-Associated Death Protein / Q000378:metabolism
D051025:bcl-Associated Death Protein; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D048049:Extracellular Signal-Regulated MAP Kinases; D048369:MAP Kinase Kinase 1; D008550:Melatonin