TESTOSTERONE ACTION ON ERYTHROPOIETIC BURST FORMING UNITS AND ERYTHROID COLONY FORMING UNITS CORRELATION BETWEEN ENHANCEMENT OF PROLIFERATIVE RATE AND AMPLIFICATION OF POOL SIZE

As previously reported, a single administration of testosterone propionate (TP) in ex-hypoxic polycythemic mice induced an 18-24 h amplification of the erythroid burst-forming unit (BFU-E) pool and a 60-h expansion of the erythroid colony-forming unit (CFU-E) compartment. In this study both phenomena were temporally associated with an increase of the in vitro 3H-TdR sensitivity of these compartments, thus indicating an elevation of their proliferative rate. No significant modification of the DNA synthesis index and the pool size of BFU-E and CFU-E were observed at, respectively, 60 or 18 h. At either time interval, 3H-TdR sensitivity and compartment size were not modified at the level of the myeloid-macrophage colony-forming unit (CFU-C). The early and late expansion of, respectively, BFU-E and CFU-E number after TP injection is apparently at least partially mediated by enhancement of the proliferative rate within the respective compartments. Mechanisms underlying TP action on BFU-E and CFU-E pools were discussed in the light of present and previous observations.