Inducible nitric oxide synthase is an endogenous neuroprotectant after traumatic brain injury in rats and mice
Elizabeth H. Sinz, … , Donald W. Marion, Timothy R. Billiar
Elizabeth H. Sinz, … , Donald W. Marion, Timothy R. Billiar
Published September 1, 1999
Citation Information: J Clin Invest. 1999;104(5):647-656. https://doi.org/10.1172/JCI6670.
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Inducible nitric oxide synthase is an endogenous neuroprotectant after traumatic brain injury in rats and mice

Abstract

Nitric oxide (NO) derived from the inducible isoform of NO synthase (iNOS) is an inflammatory product implicated both in secondary damage and in recovery from brain injury. To address the role of iNOS in experimental traumatic brain injury (TBI), we used 2 paradigms in 2 species. In a model of controlled cortical impact (CCI) with secondary hypoxemia, rats were treated with vehicle or with 1 of 2 iNOS inhibitors (aminoguanidine and L-N-iminoethyl-lysine), administered by Alzet pump for 5 days and 1.5 days after injury, respectively. In a model of CCI, knockout mice lacking the iNOS gene (iNOS–/–) were compared with wild-type (iNOS+/+) mice. Functional outcome (motor and cognitive) during the first 20 days after injury, and histopathology at 21 days, were assessed in both studies. Treatment of rats with either of the iNOS inhibitors after TBI significantly exacerbated deficits in cognitive performance, as assessed by Morris water maze (MWM) and increased neuron loss in vulnerable regions (CA3 and CA1) of hippocampus. Uninjured iNOS+/+ and iNOS–/– mice performed equally well in both motor and cognitive tasks. However, after TBI, iNOS–/– mice showed markedly worse performance in the MWM task than iNOS+/+ mice. A beneficial role for iNOS in TBI is supported.

Authors

Elizabeth H. Sinz, Patrick M. Kochanek, C. Edward Dixon, Robert S.B. Clark, Joseph A. Carcillo, Joanne K. Schiding, Minzhi Chen, Stephen R. Wisniewski, Timothy M. Carlos, Debra Williams, Steven T. DeKosky, Simon C. Watkins, Donald W. Marion, Timothy R. Billiar

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Figure 7

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Assessment of motor function in mice using wire-grip scores (mean ± SEM)...
Assessment of motor function in mice using wire-grip scores (mean ± SEM). Uninjured iNOS+/+ (open squares) and iNOS–/– (filled squares) mice performed equally well in this task, as assessed for 5 days. In 2 separate groups of mice, both iNOS+/+ (open circles) and iNOS–/– (filled circles) exhibited reduced scores (deficits) in this task after injury (day 1 shows preinjury score; day 2 of testing represents the first postinjury day). *P < 0.05 vs. preinjury scores. There were no differences between iNOS+/+ and iNOS–/– groups after injury.