Nitric oxide

What is nitric oxide?

Nitric oxide (NO) is a gas that acts as a signalling molecule in the CNS. It mediates cellular communication via cyclic GMP second messenger systems, activating guanylate cyclase, and its actions influence neurotransmitter release, learning and memory systems, and it also plays a key role in neurodevelopment. NO is produced endogenously by the conversion of L-arginine into L-citruline by nitric oxide synthase (NOS) enzyme. There are three NOS isoforms, inducible NOS (iNOS), which is released in response to pathogens, as well as endothelial (eNOS) and neuronal (nNOS), which are expressed constitutively. NO is a highly reactive free radical, and is rapidly converted into other forms. NO reacts with molecular oxygen and accumulates in the plasma as nitrate NO3- and nitrite NO2-, which can contribute to oxidative stress. Disturbances in NO formation or release could interfere with the known functions of NO activity, including neural maturation and synapse formation, which could have relevance for possible neurodevelopmental aetiology of schizophrenia.

What is the evidence on nitric oxide?

Moderate quality evidence finds increased blood NO levels in medicated people with schizophrenia, with no differences in drug-free patients. Longer duration of illness was related to increased NO levels.

October 2020

Last updated at: 3:34 am, 27th October 2020
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NeuRA Libraries

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