Nitric oxide synthase inhibitors protect cholinergic neurons against quinolinic acid toxicity in the rat brain

The aim of this study was to examine the effects of intrastriatally injected nitric oxide synthase (NOS) inhibitors, Nω-nitro-l-arginine methyl ester (L-NAME) and 7-nitroindazole (7-NI), on quinolinic acid (QA)-induced toxicity in selective vulnerable brain regions of adult Wistar rats. QA was administered into the striatum unilaterally, in a single dose of 150 nM/L with a stereotaxic instrument. The other two experimental groups were pretreated with L-NAME and 7-NI, respectively. The control group of animals was treated with 0.154 mM/L saline solution. The animals were decapitated seven days after the treatment. Samples of both striatum and forebrain cortex were prepared for measurement of acetylcholinesterase (AChE) activity. QA injection revealed a significant increase in AChE activity in both the ipsi- and contralateral striatum and forebrain cortex compared to the control animals. Treatment with NOS inhibitors, followed by QA, very clearly demonstrated lower levels of AChE bilaterally in these brain structures, compared to the QA-treated group