title: Apoptotic characteristics of cell death and the neuroprotective effect of homocarnosine on pheochromocytoma PC12 cells exposed to ischemia.
abstract: We recently improved an in vitro ischemic model, using PC12 neuronal cultures exposed to oxygen-glucose deprivation (OGD) for 3 hr in a special device, followed by 18 hr of reoxygenation. The cell death induced in this ischemic model was evaluated by a series of markers: lactate dehydrogenase (LDH) release, caspase-3 activation, presence of cyclin D1, cytochrome c leakage from the mitochondria, BAX cellular redistribution, cleavage of poly (ADP-ribose) polymerase (PARP) to an 85-kDa apoptotic fragment, and DNA fragmentation. The OGD insult, in the absence of reoxygenation, caused a strong activation of the mitogen-activated protein kinase (MAPK) isoforms extracellular regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and stress-activated protein kinase (SAPK), also known as p-38. The detection of apoptotic markers and activation of MAPKs during the ischemic insult strongly suggest that apoptosis plays an important role in the PC12 cell death. Homocarnosine, a neuroprotective histidine dipeptide, present in high concentrations in the brain, was found to provide neuroprotection, as expressed by a 40% reduction in LDH release and caspase-3 activity at 1 mM. Homocarnosine reduced OGD activation of ERK 1, ERK 2, JNK 1, and JNK 2 by 40%, 46%, 55%, and 30%, respectively. These results suggest that apoptosis is an important characteristic of OGD-induced neuronal death and that antioxidants, such as homocarnosine, may prevent OGD-induced neuronal death by inhibiting the apoptotic process and/or in relation to the differential attenuation of activity of MAPKs.
authors.affiliation: Department of Pharmacology and Experimental Therapeutics, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel.
authors.forename: Rinat
authors.initials: R
authors.lastname: Tabakman
authors.forename: Hao
authors.initials: H
authors.lastname: Jiang
authors.forename: Robert A
authors.initials: RA
authors.lastname: Levine
authors.forename: Ron
authors.initials: R
authors.lastname: Kohen
authors.forename: Philip
authors.initials: P
authors.lastname: Lazarovici
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002336:Carnosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D016716:PC12 Cells; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats
chemical_list: D018696:Neuroprotective Agents; C005038:homocarnosine; D002336:Carnosine