Present address: Institute of Life Sciences, Ajinomoto Co., Inc., Kanagawa 210-8681, Japan.
Oral administration of glycine increases extracellular serotonin but not dopamine in the prefrontal cortex of rats
Version of Record online: 17 MAR 2011
© 2011 The Authors. Psychiatry and Clinical Neurosciences © 2011 Japanese Society of Psychiatry and Neurology
Psychiatry and Clinical Neurosciences
Volume 65, Issue 2, pages 142–149, March 2011
How to Cite
Bannai, M., Kawai, N., Nagao, K., Nakano, S., Matsuzawa, D. and Shimizu, E. (2011), Oral administration of glycine increases extracellular serotonin but not dopamine in the prefrontal cortex of rats. Psychiatry and Clinical Neurosciences, 65: 142–149. doi: 10.1111/j.1440-1819.2010.02181.x
- Issue online: 17 MAR 2011
- Version of Record online: 17 MAR 2011
- Received 7 September 2008; revised 25 October 2010; accepted 28 November 2010.
Aim: Glycine, one of the non-essential amino acids, has been reported to be effective in reducing negative symptoms of schizophrenia. Recently, we found that glycine improves subjective sleep quality in humans. The aim of this study was to investigate the effects of oral glycine administration on endogenous 5-hydroxytryptamine (5-HT) and dopamine in the prefrontal cortex (PFC) of living rats.
Methods: Microdialysis probes were inserted stereotaxically into the rat prefrontal cortex. Cortical levels of 5-HT and dopamine were measured following oral administration of 1 or 2 g/kg glycine, 2 g/kg d-serine, or 2 g/kg L-serine.
Results: Both glycine and d-serine significantly increased extracellular 5-HT levels for 10 min, whereas dopamine levels remained unchanged. L-serine, in contrast, had no significant effects on 5-HT levels.
Conclusions: It is possible that the increase in 5-HT in response to glycine and d-serine was mediated by N-methyl-D-aspartate receptors. The transient increase in 5-HT in the PFC might be associated with the alleviation of negative symptoms in patients with schizophrenia and the amelioration of sleep quality in patients with insomnia.