17β-estradiol administration following trauma-hemorrhage prevents the increase in Kupffer cell cytokine production and MAPK activation predominately via estrogen receptor-α

Background. 17 beta-estradiol (E2) administration following trauma-hemorrhage (T-H) attenuates the elevation in plasma cytokines and Kupffer cell (KC) cytokine production; however, it remains unknown whether the salutary effects are mediated via estrogen receptor (ER)-alpha or ER-beta. We hypothesized, that E2 mediates its salulary effects via ER-alpha and normalization of MAPK under those conditions. Methods. Male rats underwent T-H (mean blood pressure [BP] 40 mmHg for 90 min) and fluid resuscitation. ER-alpha agonist propyl pyrazole triol (PPT; 5 mu g/kg), ER-beta agonist diarylpropionitrile (DPN; 5 mu g/kg), E2 (50 mu g/kg), or vehicle (10% DMSO) was injected subcutaneously during resuscitation. Twenty four hours thereafter, KCs were isolated and their cytokine production (IL-6, TNF-alpha, IL-10) and MAPK activation were measured. Results. Cytokine production increased after T-H however, PPT or E2 administration after T-H normalized KC cytokine production. Although DPN attenuated increased production of these cylokines, KC capacity to produce the cytokines remained significantly higher than sham. PPT or E2 also prevented T-H-mediated activation of MAPK in KC. However, DPN did not prevent MAPK activation. Conclusions. Since PPT administration after T-H was more effective in decreasing KC cytokine production and MAPK activation than DPN, the salutary effects of E2 on KC functions are mediated predominantly via ER-alpha and normalization of MAPK following T-H.