Effect of 7-nitro indazole on quinolinic acid-induced striatal toxicity in the rat.

Nitric oxide (NO) is implicated as a mediator of cell death in models of neurodegenerative disease. However, the precise role of NO in neuronal degeneration remains controversial. In the present study we employed 7-nitro indazole (7-NI), reportedly a selective inhibitor of neuronal nitric oxide synthase (nNOS) in vivo, to investigate the possible involvement of NO in quinolinic acid (QA)-induced striatal toxicity in the rat. Intrastriatal injection of QA (30 nmol) caused loss of NADPH diaphorase (48%), NOS (48%) and acetylcholinesterase (AChE; 22%) positive neurones and a loss of NOS activity (78%) in striatal homogenates. 7-NI (30 mg kg-1, i.p. every 4 h for 20 h) did not affect the loss of NADPH diaphorase (52%), NOS (52%) and AChE (16%) positive neurones or the loss of NOS activity (66%) in striatal homogenates. The present study does not support a role for NO in QA-induced striatal toxicity.