Differential vulnerability of immature murine neurons to oxygen-glucose deprivation.
In vivo studies support selective neuronal vulnerability to hypoxia-ischemia (HI) in the developing brain. Since differences in intrinsic properties of neurons might be responsible, pure cultures containing immature neurons (6-8 days in vitro) isolated from mouse cortex and hippocampus, regions chosen for their marked vulnerability to oxidative stress, were studied under in vitro ischemic conditions-oxygen-glucose deprivation (OGD). Twenty-four hours of reoxygenation after 2.5 h of OGD induced significantly greater cell death in hippocampal than in cortical neurons (67.8% vs. 33.4%, P = 0.0068). The expression of neuronal nitric oxide synthase (nNOS) protein, production of nitric oxide (NO), and reactive oxygen species (ROS), as well as glutathione peroxidase (GPx) activity and intracellular levels of reduced glutathione (GSH), were measured as indicators of oxidative stress. Hippocampal neurons had markedly higher nNOS expression than cortical neurons by 24 h of reoxygenation, which coincided with an increase in NO production, and significantly greater ROS accumulation. GPx activity declined significantly in hippocampal but not in cortical neurons at 4 and 24 h after OGD. The decrease in GSH level in hippocampal neurons correlated with the decline of GPx activity. Our data suggest that developing hippocampal neurons are more sensitive to OGD than cortical neurons. This finding supports our in vivo studies showing that mouse hippocampus is more vulnerable than cortex after neonatal HI. An imbalance between excess prooxidant production (increased nNOS expression, and NO and ROS production) and insufficient antioxidant defenses created by reduced GPx activity and GSH levels may, in part, explain the higher susceptibility to OGD of immature hippocampal neurons.
Department of Neurology, University of California-San Francisco, 521 Parnassus Avenue, San Francisco, CA 94143-0663, USA.
Xiangning
X
Jiang
Dezhi
D
Mu
Catherine
C
Manabat
Anita A
AA
Koshy
Stephan
S
Christen
Martin G
MG
Täuber
Zinaida S
ZS
Vexler
Donna M
DM
Ferriero
D000818:Animals; D016923:Cell Death; D015687:Cell Hypoxia; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000196:embryology; D005947:Glucose / Q000172:deficiency / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000196:embryology; D020925:Hypoxia-Ischemia, Brain / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000096:biosynthesis; D052248:Nitric Oxide Synthase Type I; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000096:biosynthesis; D013997:Time Factors
D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D005979:Glutathione Peroxidase; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496321:Nos1 protein, mouse; D013482:Superoxide Dismutase; D005978:Glutathione; D005947:Glucose