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

Katsutaka Oishi, Kentaro Shibusawa, Hitosa Kakazu, Takao Kuriyama, Naoki Ohkura, Kazuhiko Machida

Research output: Contribution to journalArticle

11 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)29-35
Number of pages7
JournalBiological Rhythm Research
Issue number1
Publication statusPublished - 2006 Feb 1



  • Circadian rhythm
  • Corticosterone
  • Light
  • Natural killer cells
  • Stress

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Physiology

Cite this