Neuroprotection by melatonin against ischemic neuronal injury associated with modulation of DNA damage and repair in the rat following a transient cerebral ischemia.
In the present study, double fluorescence staining combined with confocal laser scanning microscopy analysis were used to examine the effects of melatonin on ischemia-induced neuronal DNA strand breaks and its possible mechanisms in a transient middle cerebral artery (MCA) occlusion model. Results showed that melatonin dose-dependently reduced infarct areas and decreased both DNA double and single strand breaks (DSB and SSB) and enhanced cell viability in the peri-ischemic brain regions. Furthermore, Bcl-2 induction in the ischemic brain was further enhanced by melatonin treatment. Double staining analysis indicated that the cells costained for Bcl-2 and TdT-mediated-deoxyuridine triphosphate (dUTP) nick-end labeling (TUNEL), a DSB marker, displayed a relative regular morphology compared with the cells only stained with TUNEL. Transient ischemia induced an expression of excision repair cross-complementing factor 6 (ERCC6) mRNA, a gene essential for the preferential repair of nuclear excision repair, in the injured neurons. Double labeling showed that ERCC6 only co-localized with proliferating cell nuclear antigen (PCNA), a member of the nuclear excision repair complex, but not with TUNEL. Melatonin further and statistical significantly up-regulated ERCC6 mRNA expression in the peri-ischemic region of rat brains. The results suggest that neuroprotection by melatonin against ischemic injury may be related to modulation of apoptosis and DNA repair capacity.
Sun
Feng-Yan
FY
National Key Laboratory of Medical Neurobiology, Medical Center of Fudan University, Shanghai, China. fysun@shmu.edu.cn
Lin
Xiang
X
Mao
Li-Zhen
LZ
Ge
Wei-Hong
WH
Zhang
Ling-Mei
LM
Huang
Ya-Lin
YL
Gu
Jin
J
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002545:Brain Ischemia / Q000473:pathology / Q000517:prevention & control*; D002536:Cerebral Arteries; D004247:DNA / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects*; D004265:DNA Helicases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects*; D004277:DNA, Single-Stranded / Q000187:drug effects; D004195:Disease Models, Animal; D020287:In Situ Nick-End Labeling; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D018613:Microscopy, Confocal; D009474:Neurons / Q000187:drug effects / Q000473:pathology*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D004277:DNA, Single-Stranded; D018696:Neuroprotective Agents; D019253:Proto-Oncogene Proteins c-bcl-2; D004247:DNA; D004265:DNA Helicases; D008550:Melatonin