title: Nocturnal light exposure alters hepatic Pai-1 expression by stimulating the adrenal pathway in C3H mice.
abstract: Recent studies have suggested the possibility that nocturnal light exposure affects many biological processes in rodents, especially the circadian rhythm, an endogenous oscillation of approximately 24 h. However, there is still insufficient information about the physiological effects of nocturnal light exposure. In this study, we examined the changes in gene expression and serum levels of plasminogen activator inhibitor-1 (PAI-1), a major component of the fibrinolytic system that shows typical circadian rhythmicity, in C3H/He mice. Zeitgeber time (ZT) was assessed with reference to the onset of light period (ZT0). Exposure to fluorescent light (70 lux) for 1 h in the dark period (ZT14) caused a significant increase in hepatic Pai-1 gene expression at ZT16. Serum PAI-1 levels also tended to increase, albeit not significantly. Expression levels of the typical clock genes Bmal1, Clock, and Per1 were significantly increased at ZT21, ZT16, and ZT18, respectively. Exposure to nocturnal light significantly increased plasma adrenalin levels. The effects of nocturnal light exposure on Pai-1 expression disappeared in adrenalectomized mice, although the changes in clock genes were still apparent. In conclusion, our results suggest that nocturnal light exposure, even for 1 h, alters hepatic Pai-1 gene expression by stimulating the adrenal pathway. Adrenalin secreted from the adrenal gland may be an important signaling mediator of the change in Pai-1 expression in response to nocturnal light exposure.
authors: Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
authors: Yoshiki
authors: Y
authors: Aoshima
authors: Hiroyuki
authors: H
authors: Sakakibara
authors: Taka-aki
authors: TA
authors: Suzuki
authors: Shunsuke
authors: S
authors: Yamazaki
authors: Kayoko
authors: K
authors: Shimoi
mesh_terms: D000311:Adrenal Glands / Q000378:metabolism*; D000818:Animals; D001683:Biological Clocks / Q000235:genetics / Q000528:radiation effects; D002940:Circadian Rhythm / Q000502:physiology / Q000528:radiation effects*; D003624:Darkness; D004837:Epinephrine / Q000378:metabolism* / Q000502:physiology*; D015870:Gene Expression / Q000528:radiation effects*; D008027:Light; D008099:Liver / Q000378:metabolism*; D008297:Male; D008809:Mice, Inbred C3H; D058258:Serpin E2 / Q000097:blood / Q000378:metabolism*
chemical_list: D058258:Serpin E2; C511869:Serpine2 protein, mouse; D004837:Epinephrine