Although 17-estradiol administration following trauma-hemorrhage prevents the suppression in splenic macrophage cytokine production, it remains unknown whether the salutary effects are mediated via estrogen receptor (ER)- or ER- and which signaling pathways are involved in such 17-estradiol effects. Utilizing ER- or ER- specific agonist, this study examined the role of ER- and ER- in E2-mediated restoration of macrophage cytokine production following trauma-hemorrhage. In addition, since MAPK and NF-B are known to regulate macrophage cytokine production, we also examined the activation of those signaling molecules. Male rats underwent trauma-hemorrhage (mean arterial pressure 40 mmHg for 90 min) and fluid resuscitation. ER- agonist propyl pyrazole triol (PPT; 5 µg/kg), ER- agonist diarylpropionitrile (DPN; 5 µg/kg), 17-estradiol (50 µg/kg) or vehicle (10% DMSO) was injected subcutaneously during resuscitation. Twenty four hrs thereafter, splenic macrophages were isolated, and their IL-6 and TNF- production and activation of MAPK and NF-B was measured. Macrophages IL-6 and TNF- production and MAPK activation was decreased while NF-B activity was increased following trauma-hemorrhage. PPT or 17-estradiol administration after trauma-hemorrhage normalized those parameters. DPN administration, on the other hand, did not normalize the above parameters. Since PPT, but not DPN administration following trauma-hemorrhage was as effective as 17-estradiol in preventing the suppression in macrophage cytokine production, it appears that ER- plays a predominant role in mediating the salutary effects of 17-estradiol on macrophage cytokine production following trauma-hemorrhage and that such effects are likely mediated via normalization of MAPK, but not NF-B signaling pathways.