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J Exp Biol. 2015 May 15;218(Pt 10):1521-6. doi: 10.1242/jeb.111864. Epub 2015 Mar 24.

Transcranial light affects plasma monoamine levels and expression of brain encephalopsin in the mouse.

Author information

1
University of Oulu, Department of Biology, P.O. Box 3000, Oulu FIN-90014, Finland antti.flyktman@oulu.fi.
2
Finnish Institute of Occupational Health, Aapistie 1, Oulu FI-90220, Finland.
3
University of Oulu, Department of Biology, P.O. Box 3000, Oulu FIN-90014, Finland University of Oulu, Institute of Health Sciences, P.O. Box 5000, Oulu FIN-90014, Finland.
4
University of Oulu, Institute of Health Sciences, P.O. Box 5000, Oulu FIN-90014, Finland.
5
University of Oulu, Department of Biology, P.O. Box 3000, Oulu FIN-90014, Finland.

Abstract

Encephalopsin (OPN3) belongs to the light-sensitive transmembrane receptor family mainly expressed in the brain and retina. It is believed that light affects mammalian circadian rhythmicity only through the retinohypothalamic tract, which transmits light information to the suprachiasmatic nucleus in the hypothalamus. However, it has been shown that light penetrates the skull. Here, we present the effect of transcranial light treatment on OPN3 expression and monoamine concentrations in mouse brain and other tissues. Mice were randomly assigned to control group, morning-light group and evening-light group, and animals were illuminated transcranially five times a week for 8 min for a total of 4 weeks. The concentrations of OPN3 and monoamines were analysed using western blotting and HPLC, respectively. We report that transcranial light treatment affects OPN3 expression in different brain areas and plasma/adrenal gland monoamine concentrations. In addition, when light was administered at a different time of the day, the response varied in different tissues. These results provide new information on the effects of light on transmitters mediating mammalian rhythmicity.

KEYWORDS:

Cerebellum; Circadian rhythm; Hypothalamus; OPN3; Signal transmitter

PMID:
25805701
DOI:
10.1242/jeb.111864
[Indexed for MEDLINE]
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