Female Sex Hormones Protect Red Blood Cells from Damage after Trauma-Hemorrhagic Shock

Sex hormones affect bone marrow dysfunction after trauma and hemorrhagic shock

OBJECTIVE

Bone marrow (BM) dysfunction after trauma and hemorrhagic shock (T/HS) results in a decrease in clonogenic growth of BM progenitors through a plasma-mediated process. Although sex hormones have been shown to modulate some end-organ injury after shock, post-T/HS BM dysfunction has only been studied in male animals. Therefore, the present study examines the effects of sex hormones on post-T/HS BM dysfunction by measuring clonogenic growth of BM progenitors in castrated male rats and in ovariectomized and proestrus female rats.

DESIGN

Laboratory experiment.

SETTING

University surgical research laboratory.

SUBJECT

Castrated and noncastrated male and ovariectomized and proestrus female Sprague-Dawley rats.

INTERVENTION

All rats were subjected to either T/HS or sham shock with laparotomy (n = 3-5 per group). At 3 hrs after resuscitation, the rats were killed and plasma and BM mononuclear cells from bilateral femurs were harvested.

MEASUREMENTS AND MAIN RESULTS

BM mononuclear cells were cultured for erythroid burst-forming unit and granulocyte-macrophage colony-forming unit colonies to assess the extent of progenitor BM dysfunction. BM from noncastrated male rats subjected to T/HS demonstrated a significant decrease in granulocyte-macrophage colony-forming unit and erythroid burst-forming unit colony formation compared with BM of all the sham shock groups and with the castrated male and both female rat groups subjected to T/HS. In addition, plasma from noncastrated shocked male rats incubated in vitro with BM cells from unmanipulated male rats caused a significant suppression of BM granulocyte-macrophage colony-forming unit and erythroid burst-forming unit colonies compared with plasma from castrated rats subjected to either sham shock with laparotomy or T/HS.

CONCLUSION

The profound BM dysfunction observed in noncastrated male rats after T/HS is not observed in proestrus female rats and castrated male rats. In addition, the in vitro plasma-mediated BM suppression present in male rats after T/HS is also lost in castrated male rats. Sex hormones seem to play a significant role in BM dysfunction after T/HS.