The influence of mating on estrogen receptor alpha protein level in spleen and uterine macrophages in female mice

SUMMARYMacrophages are antigen-presenting cells that have a key role in the regulation of immune phenomena and are responsible for the recognition of paternal antigens during pregnancy. The aim of this study was to investigate changes in the estrogen receptor alpha (ERα) protein level in splenic and uterine mature (F4/80+MHC II+) and immature (F4/80+MHC II−) macrophages in female mice during time corresponding to the preimplantation period. C57BL/6J females in estrus were mated with Balb/c male mice or were mechanically stimulated through the vagina to achieve pseudopregnancy. Uterine and spleen cells were isolated on days 0.5 and 3.5 after mating or after uterine cervix stimulation. ERα content in macrophages was measured by flow cytometry and expressed as mean fluorescence intensity (MFI). The ERα level in splenic macrophages on 0.5 day after mating was higher than that in splenic macrophages of pseudopregnant mice on 0.5 day after stimulation. The ERα level was also higher in mature than in immature macrophages present in both the spleen and uterus, especially in mated mice. In the spleen, a correlation was found between the percentage of mature macrophages and ERα level in these cells. In conclusion, the elevated ERα level observed shortly after mating in splenic but not in uterine macrophages indicates an early systemic response to male antigens.