ELEVATED ENDOGENOUS NITRIC-OXIDE SYNTHASE INHIBITOR IN SCHIZOPHRENIC PLASMA MAY REFLECT ABNORMALITIES IN BRAIN NITRIC-OXIDE PRODUCTION

Cellular origins of methylarginines are not precisely known but the pr esence of free methyl and dimethylarginines in the brain were reported . We have investigated the circulating concentrations of asymmetrical dimethylarginine N-G,N-G-dimethylarginine (ADMA), N-G,N-G-dimethylargi nine (SDMA), nitrate and nitrite levels in drug naive first episode sc hizophrenic patients and matched control subjects. Three of those pati ents were treated with neuroleptics for 3 months. Plasma ADMA levels i ncreased significantly but nitrate levels were significantly low compa red to control subjects. Drug treatment apparently lowered ADMA levels and increased nitrate levels in plasma. Methylation of arginine to me thylarginines may have an important role in regulating signal transduc tion through the nitric oxide system in the brain, and suggest novel t herapeutic targets.