Study On The Role Of Estrogen Improves The Contractile Function Of Mesenteric Lymphatics Following Hemorrhagic Shock In Rats

The function of lymphatic is closely related to the development of hemorrhagic shock,the favourable lymphatic contractile function contributes to improvement of hemorrhagic shock.Studies have demonstrated that estrogen can inhibit inflammatory responses by binding to receptors on organs such as heart,lung,and liver,in turn to improve heart,lung,liver function,and relieve tissue injury,thereby improving the prognosis of hemorrhagic shock.However,it is still unclearly whether estrogen can improve the dysfunction of mesenteric lymph microcirculation.The endoplasmic reticulum is an important organelle,not only critical in the modification,folding,and maturation of proteins,but also plays an important role in maintaining calcium homeostasis.Apoptosis caused by excessive endoplasmic reticulum stress?ERS?aggravates tissue injury after hemorrhagic shock.Studies have reported that estrogen can reduce the tissue injury caused by ERS.However,the role of ERS on the dysfunction of mesenteric lymphatic contraction following hemorrhagic shock has not been reported.So we have a hypothesis that whether estrogen can increase the contractile functions of mesenteric lymphatic after hemorrhagic shock? What is the effect of inhibiting ERS on mesenteric lymphatic contractile function after hemorrhagic shock? Whether estrogen can increase the function of mesenteric lymphatics through inhibiting ERS caused by hemorrhagic shock,and in turn improving the dysfunction of lymph microcirculation? These questions need to be further investigated.So in this experiment we duplicated the hemorrhagic shock model in rats and used mesenteric lymphatic contractility in vivo,isolate mesenteric lymphatic contractility in vitro,and its relationship with Ca²⁺ concentration as indicators evaluating mesenteric lymphatic contactile function to investigate:?1?Effects of estrogen and its receptor agonists PPT,DPN,and G1 on contractile function of mesenteric lymphatic following hemorrhagic shock in rats;?2?Effects of Estrogen Receptor?ER?Inhibitors ICI and G15 on estrogen improving mesentery lymphatic contraction following hemorrhagic shock in rats;?3?Effect of ERS inhibitor 4-PBA on mesenteric lymphatic contraction after hemorrhagic shock in rats;?4?Effect of ERS agonist XCT-790 on the mesenteric lymphatic contraction after treatment with estrogen and its receptor agonists PPT,DPN,and G1 following hemorrhagic shock in rats.Through the above experiments,the role of ERS on estrogen and its receptors improving the contractility of mesenteric lymphatics after hemorrhagic shock,and determine the mechanism of estrogen improving mesenteric lymphatic function following hemorrhagic shock,providing a new experiment data for the prevention and treatment of hemorrhagic shock.144 healthy and male wistar rats weighing 280±20g were randomly divided into sham group,shock group,sham/shock+E2 group,sham/shock+PPT group,and sham /shock+DPN group,sham/shock+G-1 group,sham/shock+E²⁺G15 group,sham/shock+E²⁺ICI group,sham/shock+XCT-790+E2 group,sham/shock+XCT-790+PPT group,sham/shock+XCT-790+DPN group,sham/shock+XCT-790+G-1 group,sham/shock+4-PBA group,24 groups.Both sham group and the sham administrated with tool agents group were subjected to bilateral femoral and abdominal surgeries only executing blood pressure monitoring without bloodletting.Both shock group and shock administrated with agents groups executed bilateral thigh and abdominal surgery to establish hemorrhagic shock model.?Mean arterial blood pressure maintaining at 40±2 mm Hg,resuscitating after 1.5 h?.Interventions were performed subcutaneously at the time of fluid resuscitation or at the corresponding time.All mesenteric lymphatic contraction of rats were observed at 3 hours or corresponding time points after fluid resuscitation.The maximum systolic diameter,diastolic diameter,static diameter,and contraction frequency?CF?of lymphatic vessels were recorded to calculate the indices: Index I,Index II and LD-Index for evaluating mesenteric lymphatic contractile function.Results showed that the systolic function of mesenteric lymphatic vessels in shock group was significantly lower than that in the sham group in vivo;Estrogen and its receptor agonist,ERS inhibitor 4-PBA improved the mesenteric lymphatic systolic function in sham group and shock group,respectively;ERS agonist XCT-790 inhibited the effects of estrogen and its receptor agonists on the systolic function of mesenteric lymphatic in sham and shock rats in vivo.Then mesenteric lymphatics were obtained from each group to prepare isolated mesenteric lymphatic rings.According to the routine method of our department,fluorescence Fura-2 was administrated and then recorded lymphatic calcium transient base value,calcium transient peak,end-systolic diameter?ESD?,end-diastolic diameter?EDD?,contraction frequency?CF?,passive diameter?PD?using Ionoptix system and sequently administrated with different concentrations of substance P?1×10-8 mol/L,3×10-8 mol/L,1×10-7 mol/L,and 3×10-7 mol/L?,after recording ESD,EDD and CF at different concentration points,we calculated the change of calcium transient,tension index?TI?,contraction amplitude?CA?and pump flow fraction?FPF?,combined with CF as indexs to evaluate lymphatic contractile function;calculated the maximum difference between TI,CA,CF,FPF and basal state at different SP concentrations as indexs for evaluating lymphatic vessel reactivity.The results showed that the difference in contractility,reactivity,and calcium transients of isolated mesenteric lymphatics in shock group were significantly lower than that in sham group;Estrogen and its receptor agonists 4-PBA improved the contractility and reactivity of isolated mesenteric lymphatics in sham group and shock group and increased calcium transients.And these improved effects were all reversed by XCT-790.The studies above showed that estrogen and its receptors can improve mesenteric lymphatic contractile function following hemorrhagic shock significantly,which were inhibited by ER inhibitors ICI and G15;inhibition of ERS can improve mesenteric lymphatic contractile function following hemorrhagic shock in rats;Enhanced ERS can inhibite the effects of E2,PPT,DPN,and G1 on mesenteric lymphatic contractile function in hemorrhagic shock rats.These data suggest that estrogen improves the mesenteric lymphatic contractile function following hemorrhagic shock through estrogen receptors,and its mechanism is related to the inhibition of ERS.