In the present paper we show the inhibitory effect of melatonin on rat cerebellar nitric oxide synthase (NOS) activity. NO production was monitored by the stoichiometric conversion of L-arginine to L-citrulline. The inhibitory effect of melatonin was dose-dependent, with an IC50 value of about 0.1 mM. However, a significant inhibition of enzyme activity (> 22%) was observed at 1 nM melatonin which is in the range of the physiological serum concentration of the hormone at night. The inhibitory effect of melatonin was observed exclusively in the presence of Ca++. Results suggest a new and important role of the pineal hormone melatonin on central nervous system processes, i.e., by modulating NO production.
- nitric oxide
- pineal gland
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)