Role Of Endoplasmic Reticulum Stress On Estrogen Relieve Intestinal Injury Following Hemorrhagic Shock In Rats

Gut is one of the first affected organs by ischemia insult after hemorrhagic shock,more sensitive to the damage of ischemia-hypoxia.As intestinal bacteria/endotoxin translocation and inflammatory mediators escape into systemic circulation through the impaired intestine barrier,as a “two-hit”,can cause distant organs injury.Therefore,the preservation of intestine function plays a key role in the treatment of hemorrhagic shock.It has been reported that estrogen alleviates intestinal injury induced by hemorrhagic shock.However,the specific estrogen receptors by which estrogen exerts its function in these circumstances remains to be further studied.Endoplasmic reticulum stress(ERS)plays a key role in the apoptosis induced by ischemia/reperfusion injury.What does it do in intestinal injury after hemorrhagic shock? Whether are the effects of 17β-estradiol(E2)and its receptor agonist antagonizing hemorrhagic shock associated with its inhabiting for ERS? These problems remain to be further answered.Therefore,based on a rat hemorrhagic shock model,this study is to observe the role of estrogen reducing intestinal injury and the relationship with endoplasmic reticulum stress to reveal the mechanism of estrogen attenuating intestinal injury after hemorrhagic shock and provide experimental evidence for the treatment of hemorrhagic shock.Firstly,hemorrhagic shock model was established by routine method in rats.Briefly,the rat was induced anesthesia by 3% VOL isoflurane.After intramuscular injection of 1% pentobarbital sodium solution(50 mg/kg),the rat was placed in a small animal operating table.According to routine methods in our lab to replicated hemorrhagic shock model(40 mm Hg for 1.5 h by reinfusing or withdrawing blood as needed).In the first experiment,16 healthy male rats were used to test the effect of E2 treatment on survival time and survival rate following hemorrhagic shock.The results showed that E2 treatment prolonged the survival time and improved the survival rate of rats following hemorrhagic shock.In the next experiment,according to different intervention factors: E2,ER agonists(PPT,DPN,G1)and inhibitors(ICI,G15),ERS inhibitors(4-PBA)and agonists(XCT790),144 rats were randomly divided into 24 groups(n=6): sham,sham+E2,sham+PPT,sham+DPN,sham +G1,sham+E2+ICI,sham+E2+G15,sham+E2+XCT790,sham+PPT+XCT790,sham+DPN+XCT790,sham+G1+XCT790,sham+4-PBA,Shock,Shock+E2,Shock+PPT,Shock+DPN,Shock+G1,Shock+E2+ICI,Shock+E2+G15,Shock+E2+XCT790,Shock+PPT+XCT790,Shock+ DPN+XCT790,Shock+G1+XCT790,and Shock+4-PBA groups.At 3 hours after the end of fluid resuscitation or at corresponding time points,animal arterial blood samples were collected to detect D-lactic acid(D-LA)and intestinal fatty acid-binding protein(I-FABP)for detecting intestinal injury.The intestinal tissue was harvested for histopathological assay,wet/dry ratio(W/D)measurement and permeability determination in vivo.The results showed that hemorrhagic shock induced intestinal injury and hyper-permeability,which were manifested by increased W/D,and elevated I-FABP and D-LA levels in plasma.The treatment of E2 or estrogen receptor agonist PPT,PDN and G1 significantly suppressed the intestinal injury,decreased the W/D and I-FABP and D-LA levels in plasma in rats following hemorrhagic shock.The antagonist of E2 receptor of ICI abrogated the antagonistic effects of E2 to hemorrhagic shock.The ERS antagonist 4-PBA reduced W/D,decreased the I-FABP and D-LA levels in plasma in rats following hemorrhagic shock.The treatment with ERS enhancer XCT790 blunted the effects of E2 and its receptor agonist antagonizing hemorrhagic shock.The above results show that E2 can effectively improve the survival state of rats with hemorrhagic shock,and E2 through the ER to play a role in reducing intestinal damage in rats subjected to hemorrhagic shock,and its mechanism is related to inhibition of ERS.