Nitric oxide amplifies the excitatory to inhibitory neurotransmitter imbalance accelerating oxygen seizures.

Journal Article (Journal Article)

CNS O2 toxicity is manifested most profoundly by generalized motor convulsions. The hypothesis was tested that HBO2 triggers seizures by an excitatory to inhibitory neurotransmitter imbalance produced by neuronal nitric oxide (NO) activity. Anesthetized rats were exposed to 5 ATA HBO2 for 75 min with or without prior inhibition of nNOS. Interstitial NO and amino acids: aspartate (Asp), glutamate (Glu) and gamma-aminobutyric acid (GABA) were determined in the striatum by microdialysis coupled with HPLC. Blood flow and EEG in the same striatal region were measured simultaneously. Rats treated with 7-NI showed no EEG spikes of O2 toxicity, while seizure latency for untreated rats was 63 +/- 7 min. Significant increases in NO metabolites and blood flow were observed in control rats before seizures. HBO2 did not change Glu significantly and increased Asp slightly whereas GABA decreased progressively by 37 +/- 7%. Pretreatment with 7-NI led to a significantly smaller decline in GABA. Overall, the simplified excitotoxicity index Glu/GABA increased significantly after 60 min of HBO2 in control but fell in rats treated with 7-NI. We conclude that HBO2-stimulated neuronal NO production promotes an imbalance between glutamatergic and GABAergic synaptic function implicated in the genesis of oxygen-induced seizures.

Full Text

Duke Authors

Cited Authors

  • Demchenko, IT; Piantadosi, CA

Published Date

  • 2006

Published In

Volume / Issue

  • 33 / 3

Start / End Page

  • 169 - 174

PubMed ID

  • 16869530

International Standard Serial Number (ISSN)

  • 1066-2936


  • eng

Conference Location

  • United States