title: Prolonged exposure to hyperbaric oxygen induces neuronal damage in primary rat cortical cultures.
abstract: While seizure attack is one of the serious complications during the hyperbaric oxygen (HBO) therapy, there is still no direct evidence showing that HBO can induce neuronal damage in the brain. The objective of this study was first to investigate whether HBO would lead to neurotoxicity in the primary rat cortical culture. Second, since alterations in neurotransmitters have been suggested in the pathophysiology of central nervous system (CNS) oxygen toxicity, the protective effects of the N-methyl-D-aspartate (NMDA) receptor antagonism and nitric oxide (NO) synthase inhibition on the HBO-induced neuronal damage were examined. The results showed that HBO exposure to 6 atmosphere absolute pressure (ATA) for 30, 60, and 90 min increased the lactate dehydrogenase (LDH) activity in the culture medium in a time-dependent manner. Accordingly, the cell survival, measured by the 3,(4,5-dimethyl-2-thiazolyl)2, 5-diphenyl-tetrazolium bromide (MTT) assay, was decreased after HBO exposure. Pretreatment with the NMDA antagonist MK-801 protected the cells against the HBO-induced damage. The protective effect was also noted in the cells pretreated with L-N(G)-nitro-arginine methyl ester, an NO synthase inhibitor. Thus, our results suggest that activation of NMDA receptors and production of NO play a role in the neurotoxicity produced by hyperbaric oxygen exposure.
authors.affiliation: Institute of Undersea and Hyperbaric Medicine, National Defense Medical Center, ROC, Taipei, Taiwan.
authors.forename: K L
authors.initials: KL
authors.lastname: Huang
authors.forename: J N
authors.initials: JN
authors.lastname: Wu
authors.forename: H C
authors.initials: HC
authors.lastname: Lin
authors.forename: S P
authors.initials: SP
authors.lastname: Mao
authors.forename: B
authors.initials: B
authors.lastname: Kang
authors.forename: F J
authors.initials: FJ
authors.lastname: Wan
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D017077:Culture Media, Conditioned / Q000378:metabolism; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006931:Hyperbaric Oxygenation / Q000009:adverse effects*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D018696:Neuroprotective Agents / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052248:Nitric Oxide Synthase Type I; D010100:Oxygen / Q000633:toxicity*; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D018696:Neuroprotective Agents; D016194:Receptors, N-Methyl-D-Aspartate; D013778:Tetrazolium Salts; D013844:Thiazoles; D016291:Dizocilpine Maleate; D007770:L-Lactate Dehydrogenase; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; C022616:thiazolyl blue; D010100:Oxygen; D019331:NG-Nitroarginine Methyl Ester