[HTML][HTML] Clock mutation affects circadian regulation of circulating blood cells

K Oishi, N Ohkura, K Kadota, M Kasamatsu… - Journal of circadian …, 2006 - Springer
K Oishi, N Ohkura, K Kadota, M Kasamatsu, K Shibusawa, J Matsuda, K Machida, S Horie…
Journal of circadian rhythms, 2006Springer
Background Although the number of circulating immune cells is subject to high-amplitude
circadian rhythms, the underlying mechanisms are not fully understood. Methods To
determine whether intact CLOCK protein is required for the circadian changes in peripheral
blood cells, we examined circulating white (WBC) and red (RBC) blood cells in homozygous
Clock mutant mice. Results Daytime increases in total WBC and lymphocytes were
suppressed and slightly phase-delayed along with plasma corticosterone levels in Clock …
Background
Although the number of circulating immune cells is subject to high-amplitude circadian rhythms, the underlying mechanisms are not fully understood.
Methods
To determine whether intact CLOCK protein is required for the circadian changes in peripheral blood cells, we examined circulating white (WBC) and red (RBC) blood cells in homozygous Clock mutant mice.
Results
Daytime increases in total WBC and lymphocytes were suppressed and slightly phase-delayed along with plasma corticosterone levels in Clock mutant mice. The peak RBC rhythm was significantly reduced and phase-advanced in the Clock mutants. Anatomical examination revealed hemoglobin-rich, swollen red spleens in Clock mutant mice, suggesting RBC accumulation.
Conclusion
Our results suggest that endogenous clock-regulated circadian corticosterone secretion from the adrenal gland is involved in the effect of a Clock mutation on daily profiles of circulating WBC. However, intact CLOCK seems unnecessary for generating the rhythm of corticosterone secretion in mice. Our results also suggest that CLOCK is involved in discharge of RBC from the spleen.
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