TY - JOUR
T1 - Antidepressant-like effect of bright light is potentiated by l-serine administration in a mouse model of seasonal affective disorder
AU - Kawai, Misato
AU - Goda, Ryosei
AU - Otsuka, Tsuyoshi
AU - Iwamoto, Ayaka
AU - Uotsu, Nobuo
AU - Furuse, Mitsuhiro
AU - Yasuo, Shinobu
N1 - Funding Information:
We thank Dr. Ryuichi Tatsumi and Dr. Wataru Mizunoya for the use of fluorescent microscopy system. This work was supported by Grants-in-Aid for Young Scientists (B) (No. 24780286 ) to S.Y., Challenging Exploratory Research (No. 24650490 ) and Scientific Research (A) (No. 23248046 ) to M.F. from the Japanese Society for the Promotion of Science .
Publisher Copyright:
© 2015 Elsevier Inc.
PY - 2015/9/1
Y1 - 2015/9/1
N2 - 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.
AB - 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.
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U2 - 10.1016/j.brainresbull.2015.08.010
DO - 10.1016/j.brainresbull.2015.08.010
M3 - Article
C2 - 26340905
AN - SCOPUS:84941071641
SN - 0361-9230
VL - 118
SP - 25
EP - 33
JO - Brain Research Bulletin
JF - Brain Research Bulletin
ER -