Age-related differences and circadian and seasonal variations of myelopoietic progenitor cell (CFU-GM) numbers in mice.
The effect of aging on the myelopoietic progenitor cell (CFU-GM) numbers in mice was studied with special emphasis on biological rhythms in hemopoiesis. Female C3H mice, 16-, 21- and 26-month-old, were investigated versus 3-month-old controls every 3 hours during the 24-h period at three different times of the year. Strong circadian rhythms were observed in both CFU-GM concentration and content in the femur of all age-groups. The amplitudes and the 24-h mean values were declining in mice aged 21 and 26 months. From 16 months of age, a significant advance of circadian peak phases was observed. The overlapping was variable during the 24-h period. The present results may explain previous inconsistencies regarding myelopoietic progenitor cell numbers in aging mice. Some seasonal differences in rhythmicity patterns were also observed. Fitting of original data to single sinus functions was highly significant, although important details sometimes were obscured.
Sletvold
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Gade Institute, Department of Pathology, University of Bergen, Haukeland Hospital, Norway.
Laerum
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Riise
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D000375:Aging / Q000502:physiology*; D000818:Animals; D001853:Bone Marrow / Q000502:physiology*; D002452:Cell Count; D002455:Cell Division; D002940:Circadian Rhythm; D005260:Female; D051379:Mice; D008809:Mice, Inbred C3H; D012621:Seasons; D013234:Stem Cells / Q000502:physiology*