[3H]L-NG-nitroarginine binding after transient focal ischemia and NMDA-induced excitotoxicity in type I and type III nitric oxide synthase null mice.
We investigated the density and distribution of nitric oxide synthase (NOS) binding by quantitative autoradiography using [3H]L-NG-nitroarginine ([3H]L-NNA) after transient focal ischemia or intrastriatal injection of N-methyl-D-aspartate (NMDA) in wild-type (SV-129 and C57black/6) and type I (neuronal) and type III (endothelial) NOS-deficient mice. The middle cerebral artery (MCA) was occluded by an intraluminal filament for 3 h followed by 10 min to 7 days of reperfusion. Specific [3H]L-NNA binding, observed in the wild-type and type III mutant mouse at baseline, increased by 50-250% in the MCA territory during ischemia and the first 3 h of reperfusion. The density of binding sites (Bmax), but not the dissociation constant (Kd), increased significantly during the ischemic period as did type I NOS mRNA as detected by quantitative reverse transcription polymerase chain reaction. [3H]L-NNA binding after intrastriatal NMDA injection also increased by 20-230%. In the type I NOS-deficient mouse, [3H]L-NNA binding was low and only a very small increase was observed after ischemia or excitotoxicity. Under conditions of this study, [3H]L-NNA did not bind to type II NOS as there was no difference in the distribution or density of [3H]L-NNA binding in the rat spleen obtained after lipopolysaccharide treatment despite induction of NOS type II catalytic activity. Our data suggest that an ischemic/excitotoxic insult up-regulates type I NOS gene expression and [3H]L-NNA binding and that this up-regulation may play a pivotal role in the pathogenesis of ischemic/excitotoxic diseases.
Hara
H
H
Department of Neurosurgery and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown 02129, USA.
Ayata
C
C
Huang
P L
PL
Waeber
C
C
Ayata
G
G
Fujii
M
M
Moskowitz
M A
MA
D000818:Animals; D001345:Autoradiography; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000493:pharmacokinetics*; D018690:Excitatory Amino Acid Agonists / Q000008:administration & dosage / Q000633:toxicity*; D005260:Female; D002546:Ischemic Attack, Transient / Q000201:enzymology*; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D016202:N-Methylaspartate / Q000008:administration & dosage / Q000633:toxicity*; D019001:Nitric Oxide Synthase / Q000032:analysis / Q000172:deficiency* / Q000235:genetics; D019335:Nitroarginine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D011869:Radioligand Assay; D051381:Rats; D014018:Tissue Distribution; D014316:Tritium
D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D014316:Tritium; D019335:Nitroarginine; D016202:N-Methylaspartate; D019001:Nitric Oxide Synthase