title: Acute phencyclidine neurotoxicity in rat forebrain: induction of haem oxygenase-1 and attenuation by the antioxidant dimethylthiourea.
abstract: Phencyclidine and other N-methyl-D-aspartate receptor antagonists are toxic to pyramidal neurons in the posterior cingulate/retrosplenial cortex of rat brain. Previous studies have shown induction of heat shock protein 70 in affected neurons. In this study, expression of haem oxygenase-1, a heat shock protein induced by oxidative stress, was examined in rat forebrain after administration of a single intraperitoneal dose of phencyclidine (50 mg/kg). Northern and Western blot analyses of brain tissue extracts from phencyclidine-treated rats revealed a marked induction of haem oxygenase-1 mRNA and protein, respectively. Immunohistochemistry studies revealed that phencyclidine increased haem oxygenase-1 immunoreactivity primarily in posterior cingulate/retrosplenial, piriform and entorhinal cortices, striatum and hippocampus. Haem oxygenase-1 protein was induced in non-neuronal cells, mainly astrocytes. Some microglia expressing haem oxygenase-1 protein were also found in the posterior cingulate/retrosplenial cortex. Haem oxygenase-1 immunoreactive astrocytes and microglia were present in close proximity to the heat shock protein 70-positive neurons in the posterior cingulate/retrosplenial cortex following phencyclidine. Pretreatment of rats with 1,3-dimethylthiourea, an antioxidant, significantly reduced haem oxygenase-1 protein induction by phencyclidine. Thus, induction of haem oxygenase-1 in glia by phencyclidine appears to be mediated mostly by oxidative stress. Experiments with the amino cupric silver stain for neuronal degeneration revealed phencyclidine-induced neurotoxicity in the posterior cingulate/retrosplenial cortex. The number of affected neurons was significantly reduced after 1,3-dimethylthiourea pretreatment. This suggests that the neurotoxicity of N-methyl-D-aspartate antagonists is due in part to the oxidative stress and may be amenable to therapeutic interventions.
authors.affiliation: Department of Neurology, University of California, San Francisco 94143, USA. rajdev@itsa.ucsf.edu
authors.forename: S
authors.initials: S
authors.lastname: Rajdev
authors.forename: A S
authors.initials: AS
authors.lastname: Fix
authors.forename: F R
authors.initials: FR
authors.lastname: Sharp
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D018691:Excitatory Amino Acid Antagonists / Q000633:toxicity*; D005260:Female; D016166:Free Radical Scavengers / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism*; D051547:Heme Oxygenase-1; D009498:Neurotoxins / Q000494:pharmacology; D018384:Oxidative Stress / Q000502:physiology; D010622:Phencyclidine / Q000633:toxicity*; D016548:Prosencephalon / Q000187:drug effects / Q000201:enzymology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D018691:Excitatory Amino Acid Antagonists; D016166:Free Radical Scavengers; D009498:Neurotoxins; D012333:RNA, Messenger; C038983:1,3-dimethylthiourea; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D013890:Thiourea; D010622:Phencyclidine