Reduced neuronal injury after treatment with NG-nitro-L-arginine methyl ester (L-NAME) or 2-sulfo-phenyl-N-tert-butyl nitrone (S-PBN) following experimental brain contusion.
OBJECTIVE
Nitric oxide (NO) and oxygen free radicals are implicated in the pathophysiology of traumatic brain injury (TBI). Peroxynitrite formation from NO and superoxide contributes to secondary neuronal injury but the neuroprotective effects of nitric oxide synthase (NOS)-inhibitors have been contradictory. This study was undertaken to examine whether PTtic administration of the (NOS)-inhibitor N-nitro-l-arginine methyl ester (L-NAME), and a combination of L-NAME and the nitrone radical scavenger 2-sulfo-phenyl-N-tert-butyl nitrone (S-PBN) favorable affects neuronal injury in a model of TBI.


METHODS
A weight-drop model of TBI was used. The animals received L-NAME, S-PBN or a combination of the drugs 15 minutes prothrombin time (PT) and sacrificed after 24 hours or six days. NOS activity was measured by the conversion of L-[U-C]arginine to L-[U-C]citrulline. Peroxynitrite formation, cellular apoptosis, neuronal degeneration and survival were assessed by nitrotyrosine-, TUNEL-, Fluoro-Jade- and NeuN-stainings.


RESULTS
eNOS and nNOS activity was significantly reduced in animals that received L-NAME alone or the combination with S-PBN. iNOS activity or iNOS immunoreactivity was not affected. All treatments significantly reduced neuronal degeneration and nitrotyrosine immunoreactivity at 24 hours and increased neuronal survival at six days PT. No differences were detected between L-NAME and L-NAME + S-PBN groups.


CONCLUSIONS
NO from NOS contributes to secondary neuronal injury in this TBI-model. PTtic treatment does not inhibit early beneficial NO-related effects. L-NAME and S-PBN limit peroxynitrite formation, promoting neuronal survival. The combination of L-NAME and S-PBN was neuroprotective; surprisingly no additive effects were found on nitrotyrosine formation, apoptosis or neuronal survival.
Gahm
Caroline
C
Department of Clinical Neuroscience, Section of Clinical CNS Research, Karolinska Institute, Stockholm, Sweden. Caroline.Gahm@karolinska.se
Danilov
Alexandre
A
Holmin
Staffan
S
Wiklund
Peter N
PN
Brundin
Lou
L
Mathiesen
Tiit
T
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001557:Benzenesulfonates / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology*; D001930:Brain Injuries / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology*; D002470:Cell Survival; D004338:Drug Combinations; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009410:Nerve Degeneration / Q000473:pathology; D009474:Neurons / Q000473:pathology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D009930:Organic Chemicals; D051381:Rats; D017207:Rats, Sprague-Dawley; D014443:Tyrosine / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors
D001557:Benzenesulfonates; D004338:Drug Combinations; D004791:Enzyme Inhibitors; D005452:Fluoresceins; D005456:Fluorescent Dyes; D009930:Organic Chemicals; C435731:fluoro jade; C094272:N-tert-butyl-(2-sulfophenyl)nitrone; C002744:3-nitrotyrosine; D014443:Tyrosine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D019331:NG-Nitroarginine Methyl Ester