Neuronal nitric oxide synthase inhibitor has a neuroprotective effect in a rat model of brain injury.

Purpose: The aim of the present study was to assess the effects of neuronal nitric oxide synthase (NOS I) inhibitors and a combination of NOS I and NOS II inhibitors on lesion volume after experimental brain injury.

Methods: Cold lesion of the brain was induced by application of a precooled (.... 78 °C) copper cylinder to the intact dura of the rat for 6 s. Brains were removed 24 h after the injury and lesion volume determined using the triphenyltetrazolium-chloride method.

Results: The specific NOS I inhibitor 3-bromo-7-nitroindazole (Br-7-NI) reduced lesion volume significantly by 21 % compared with the vehicle control. In contrast, 7-nitroindazole had no effect on lesion volume. When aminoguanidine, a specific NOS II inhibitor, was adminis-tered after Br-7-NI, lesion volume was significantly reduced but not significantly more than with either compound alone.

Conclusion: Brain injury after cold lesion is partly mediated by NOS I activity and can be attenuated successfully with Br-7-NI, while coin-hibition of NOS II does not improve the outcome significantly.