iNOS is linked with neurodegeneration in colchicine injected (i.c.v.) rats (ICIR). Treatment with aminoguanidine resulted in fewer plaques in hippocampus of ICIR. Inhibition of iNOS reduces the nitrite level in hippocampus. Aminoguanidine has neuroimmunomodulatory role on colchicine induced neurodegeneration. First report on the role of iNOS on neurotoxicity and memory impairment in ICIR