title: Effects of bright light exposure during daytime on peripheral clock gene expression in humans.
abstract: Light is the strongest synchronizer controlling circadian rhythms. The intensity and duration of light change throughout the year, thereby influencing body weight, food preferences, and melatonin secretion in humans and animals. Although the expression of clock genes has been examined using human samples, it currently remains unknown whether bright light during the daytime affects the expression of these genes in humans. Therefore, we herein investigated the effects of bright light exposure during the daytime on clock gene expression in the hair follicular and root cells of the human scalp. Seven healthy men (20.4 ± 2.2 years old; 172.3 ± 5.8 cm; 64.3 ± 8.5 kg; BMI 21.7 ± 3.1 kg/m2, mean ± SD) participated in this study. Subjects completed 3-day experimental sessions twice in 1 month during which they were exposed to bright and dim light conditions. The mRNA expression of Per1-3, Cry1-2, Rev-erb-α (Nr1d1), Rev-erb-β (Nr1d2), and Dec1 was analyzed using branched DNA probes. No significant changes were observed in the expression of Per1, Per2, Per3, Cry1, Cry2, Rev-erb-α (Nr1d1), or Dec1 following exposure to bright light conditions. However, the expression of Rev-erb-β (Nr1d2) tended to be stronger under bright light than dim light conditions. These results suggest that the bright light stimulus did not influence the expression of clock genes in humans. Long-lasting bright light exposure during the daytime may be required to change the expression of clock genes in humans.
authors.affiliation: Department of Physiology, Aichi Medical University, Nagakute, Aichi, 480-1195, Japan. msato@aichi-med-u.ac.jp.
authors.forename: Maki
authors.initials: M
authors.lastname: Sato
authors.affiliation: Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Wakamura
authors.affiliation: Department of Environmental Science, Fukuoka Women's University, Fukuoka, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Morita
authors.affiliation: Research Institute for Time Studies, Yamaguchi University, Yamaguchi, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Okamoto
authors.affiliation: Research Institute for Time Studies, Yamaguchi University, Yamaguchi, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Akashi
authors.affiliation: Department of Physiology, Aichi Medical University, Nagakute, Aichi, 480-1195, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Matsui
authors.affiliation: Department of Physiology, Aichi Medical University, Nagakute, Aichi, 480-1195, Japan. motosato@aichi-med-u.ac.jp.
authors.forename: Motohiko
authors.initials: M
authors.lastname: Sato
mesh_terms: D000293:Adolescent; D000328:Adult; D056925:Circadian Rhythm Signaling Peptides and Proteins / Q000235:genetics*; D015870:Gene Expression / Q000528:radiation effects*; D018859:Hair Follicle / Q000166:cytology / Q000378:metabolism; D006801:Humans; D008027:Light; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D055815:Young Adult
chemical_list: D056925:Circadian Rhythm Signaling Peptides and Proteins; D012333:RNA, Messenger
keywords: Biological rhythm; Bright light; Clock genes; Hair follicular and root cells; Human