Effect of Hyperthyroidism On Haemopoietic Stem Cell Kinetics In Mice

Abstract

Changes in the pool of hemopoietic colony-forming units (CFU) of bone marrow and spleen were studied in experiments with mice fed dried thyroid gland (TH) for 21 days, and during the 13 days that followed feeding. After TH treatment, the number of CFU in DNA synthesis was estimated. As early as the 2nd day of TH treatment, the pool of CFU was gradually increased, leading to an increase in the total number of splenic and bone marrow CFU persisting after TH treatment for the period examined. Simultaneously, the number of nucleated cells in the bone marrow and spleen increased. During TH feeding and following its termination, the total number of erythrocytes and the hematocrit values did not change significantly, whereas an increased number of leukocytes was observed in the peripheral blood after TH treatment. Elevation of the proliferative activity of CFU occurred early in the period of TH treatment, with the maximum attained by the end of the 1st wk of TH feeding. This suggests a rapid response of the hemopoietic stem cell compartment to the administration of TH hormones. The participation of humoral factors controlling CFU compartments in the mechanism of the stimulatory effect of TH hormones on hemopoietic stem cells is discussed.