Nitric oxide (NO) is highly reactive signal molecule that is widely distributed in the body, and in the mammalian brain in particular. The agent is a gaseous chemical messenger that acts as a universal modulator of a diversity of physiological functions, such as interneuronal communications, synaptic plasticity, memory formation, receptor functions, intracellular signal transmission, mediator release. NO is assumed to be a key pathological agent due to its neurotoxic effect in developing neurological disorders, such as ischemia, cerebral stroke, epileptiform seizures. The agent is shown to be significantly increased in the brain of rats with abnormalities.