Extended light exposure suppresses nocturnal increases in cytotoxic activity of splenic natural killer cells in rats

Authors: Oishi, Katsutaka¹; Shibusawa, Kentaro²; Kakazu, Hitosa²; Kuriyama, Takao³; Ohkura, Naoki⁴; Machida, Kazuhiko²

Source: Biological Rhythm Research, Volume 37, Number 1, February 2006 , pp. 21-35(15)

Publisher: Taylor and Francis Ltd

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Abstract:

To understand light-induced immune modulation in vivo , we evaluated the effect of nocturnal light exposure on splenic natural killer (NK) cell activity in rats. Nocturnal increases in the number and cytotoxic activity of NK cells were significantly suppressed under extended light exposure. Nocturnal increases in serum corticosterone levels were also suppressed by light exposure, suggesting that the light exposure-induced decrease in NK cell functions was not due to stress-induced glucocorticoid secretion in rats. These results suggest that nocturnal light exposure could profoundly affect NK cell functions perhaps through eye-brain hormonal modulation.

Keywords: Light; natural killer cells; stress; circadian rhythm; corticosterone

Document Type: Research article

DOI: http://dx.doi.org/10.1080/09291010500386774

Affiliations: 1: Clock Cell Biology Research Group, National Institute of Advanced Industrial Science and Technology, Central 6, 1-1-1, Higashi, Tsukuba, Ibaraki, 305-8566, Japan 2: Department of Hygiene and Public Health, School of Human Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama, 359-1192, Japan 3: Department of Public Health Sciences, Dokkyo University School of Medicine, 880 Kitakobayashi, Mibu, Tochigi, 321-0293, Japan 4: Clinical Molecular Biology, Faculty of Pharmaceutical Sciences, Teikyo University, 1091-1 Suarashi, Sagamiko, Tsukui, Kanagawa, 199-0195, Japan

Publication date: 2006-02-01