title: Preconditioning triggered by carbon monoxide (CO) provides neuronal protection following perinatal hypoxia-ischemia.
abstract: Perinatal hypoxia-ischemia is a major cause of acute mortality in newborns and cognitive and motor impairments in children. Cerebral hypoxia-ischemia leads to excitotoxicity and necrotic and apoptotic cell death, in which mitochondria play a major role. Increased resistance against major damage can be achieved by preconditioning triggered by subtle insults. CO, a toxic molecule that is also generated endogenously, may have a role in preconditioning as low doses can protect against inflammation and apoptosis. In this study, the role of CO-induced preconditioning on neurons was addressed in vitro and in vivo. The effect of 1 h of CO treatment on neuronal death (plasmatic membrane permeabilization and chromatin condensation) and bcl-2 expression was studied in cerebellar granule cells undergoing to glutamate-induced apoptosis. CO's role was studied in vivo in the Rice-Vannucci model of neonatal hypoxia-ischemia (common carotid artery ligature +75 min at 8% oxygen). Apoptotic cells, assessed by Nissl staining were counted with a stereological approach and cleaved caspase 3-positive profiles in the hippocampus were assessed. Apoptotic hallmarks were analyzed in hippocampal extracts by Western Blot. CO inhibited excitotoxicity-induced cell death and increased Bcl-2 mRNA in primary cultures of neurons. In vivo, CO prevented hypoxia-ischemia induced apoptosis in the hippocampus, limited cytochrome c released from mitochondria and reduced activation of caspase-3. Still, Bcl-2 protein levels were higher in hippocampus of CO pre-treated rat pups. Our results show that CO preconditioning elicits a molecular cascade that limits neuronal apoptosis. This could represent an innovative therapeutic strategy for high-risk cerebral hypoxia-ischemia patients, in particular neonates.
authors.affiliation: Chronic Diseases Research Center (CEDOC), Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal.
authors.forename: Cláudia S F
authors.initials: CS
authors.lastname: Queiroga
authors.forename: Simone
authors.initials: S
authors.lastname: Tomasi
authors.forename: Marius
authors.initials: M
authors.lastname: Widerøe
authors.forename: Paula M
authors.initials: PM
authors.lastname: Alves
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vercelli
authors.forename: Helena L A
authors.initials: HL
authors.lastname: Vieira
mesh_terms: D000818:Animals; D017209:Apoptosis; D002248:Carbon Monoxide / Q000737:chemistry*; D017536:Carotid Artery, Common / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology; D020925:Hypoxia-Ischemia, Brain; D007249:Inflammation; D009336:Necrosis / Q000473:pathology; D009474:Neurons / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D002248:Carbon Monoxide; D053148:Caspase 3