Antidepressant-like effect of bright light is potentiated by L-serine administration in a mouse model of seasonal affective disorder.

Abstract

Bright light therapy is used as the primary treatment for seasonal affective disorder; however, the mechanisms underlying its antidepressant effect are not fully understood. Previously, we found that C57BL/6J mice exhibit increased depression-like behavior during a short-day condition (SD) and have lowered brain serotonin (5-HT) content. This study analyzed the effect of bright light on depression-like behaviors and the brain serotonergic system using the C57BL/6J mice. In the mice maintained under SD, bright light treatment (1000 lx, daily 1 h exposure) for 1 week reduced immobility time in the forced swimming test and increased intake of saccharin solution in a saccharin intake test. However, the light treatment did not modify 5-HT content and selective 5-HT uptake in the amygdala, or temporal patterns of core body temperature and wheel-running activity throughout a day. In the next experiment, we attempted to enhance the effect of bright light by using L-serine, a precursor of D-serine that acts as an N-methyl-D-aspartic acid receptor coagonist. Daily subcutaneous injection of L-serine for 2 weeks prior to the bright light strongly reduced the immobility time in the forced swimming test, suggesting a synergistic effect of light and L-serine. Furthermore, bright light increased the total number of 5-HT-immunoreactive cells and cells that had colocalized 5-HT and c-Fos immunosignals in several subregions of the raphe nuclei. These effects were potentiated by prior injection of L-serine. These data suggest that the bright light may elicit an antidepressant-like effect via enhanced 5-HT signals in the brain and L-serine can enhance these effects.

• Authors: Misato Kawai, Ryosei Goda, Tsuyoshi Otsuka, Ayaka Iwamoto, Nobuo Uotsu, Mitsuhiro Furuse, Shinobu Yasuo
• Journal: Brain research bulletin (Brain Res Bull) Vol. 118 Pg. 25-33 (Sep 2015) ISSN: 1873-2747 [Electronic] United States
• PMID: 26340905 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015 Elsevier Inc. All rights reserved.

Chemical References

• Antidepressive Agents
• Serotonin Uptake Inhibitors
• Fluoxetine
• Serotonin
• Serine

Topics

• Animals
• Antidepressive Agents (pharmacology)
• Behavior, Animal (drug effects)
• Brain (drug effects)
• Disease Models, Animal
• Fluoxetine (pharmacology)
• Light
• Male
• Mice
• Mice, Inbred C57BL
• Phototherapy (methods)
• Random Allocation
• Seasonal Affective Disorder (drug therapy, metabolism, therapy)
• Serine (pharmacology)
• Serotonin (metabolism)
• Selective Serotonin Reuptake Inhibitors (pharmacology)