Effects Of 17β-estradiol On Lactate Metabolism In Hypoxic Pulmonary Hypertension

Objective: The pathogenesis of pulmonary hypertension is complex and involves many pathways.Estrogen has protective effect on pulmonary hypertension,but the relationship between estrogen and lactic acid metabolism in the pathogenesis of pulmonary hypertension is not clear.This study mainly studies the protective mechanism of estrogen on hypoxic pulmonary hypertension,and to explore the action pathway of estrogen on pyruvate kinase M2(PKM2)in this process,and then affect the content of lactic acid in glycolytic metabolite,so as to provide a new idea for the targeted therapy of pulmonary hypertension.Methods:The 42 female SD rats were divided into 7 groups according to random number table: sham operation + normoxic group,sham operation+ hypoxic group,castration + normoxic group,castration + hypoxia group,castration + normoxic + 17β-estradiol(E2)group,castration +hypoxic + E2 group,castration + hypoxia + PKM2 specific agonist(TEPP-46)group.The ovariectomized group was surgically removed from the ovary;the non-castrated group(sham operation group)opened the abdominal cavity to find the ovary and did not treat it,and directly sutured it.The hypoxic group was kept in a hypoxic chamber,normal oxygen group is given normal air.The castration + normoxic + E2 group and castration + hypoxic + E2 group were given subcutaneous injection of E2 [20ug/(kg·d)].The other groups were subcutaneously injected with normal saline.The castration + hypoxia + PKM2 specific agonist(TEPP-46)group were given TEPP-46[5mg/(kg·2d)] intraperitoneal injection.The other groups were intraperitoneal injected with normal saline.A model of hypoxic pulmonary hypertension was established for 8weeks.The mean pulmonary artery pressure(m PAP)of each group of animals was measured by right heart catheterization and the left and right ventricles and ventricular septum were weighed to calculate the right ventricular hypertrophy index(RVHI).The morphology of pulmonary arterioles was observed by HE staining and WA% and WT% were measured.The amount of lactic acid and the level of pyruvate were measured by kit method,the expression of reactive oxygen species(ROS)was measured by immunofluorescence method.The distribution and intensity of PKM2 were shown by the same method.PKM2 protein levels in lung tissue and nucleus were measured by immunohistochemistry.Results:1.Successfully established a model of hypoxic pulmonary hypertension ratsCompared with the normoxic group,the rats in hypoxic group were slow in response,dark in color,faster in respiratory rate,less in intake and activity,and no dead specimens were found.The castration + hypoxia+ E2 group increased faster than the castration + hypoxia group,and the activity was good.The growth rate of castration + hypoxia + PKM2 specific agonist(TEPP-46)group and castration + hypoxia + E2 group were not significantly different,but they were slower than those of normoxia group.2.mPAP and RVHI for each group of samplesMPAP and RVHI in hypoxic group were higher than those in normoxic group(P<0.05),and accord with the pressure level of pulmonary hypertension.Compared with castration + hypoxia group,m PAP and RVHI of castration + hypoxia +E2 group and castration +hypoxia + PKM2 specific agonist(TEPP-46)group were decreased(all P<0.05),reminder that estrogen and TEPP-46 can improve hypoxic pulmonary hypertension.3.Morphological changes of lung tissue in groupsThe pulmonary artery wall was thickened and the artery lumen was narrowed obviously in the sham + hypoxic group and the castrated +hypoxic group,while the castration + hypoxia + E2 group and castration+ hypoxia + PKM2 specific agonist(TEPP-46)groups showed varying degrees of reversal of the pulmonary artery lumen.WA% and WT% were also lower than those in castration + hypoxia group.4.Research indicatorsCompared with normoxic groups,lactate production,pyruvate level,ROS level,PKM2 protein level in lung tissue and PKM2 protein level in nucleus were significantly increased under hypoxic condition,with statistical differences(P<0.05).PKM2 immunofluorescence results showed that the immunofluorescence intensity of hypoxia group was significantly stronger than that of normal oxygen group,and the immunofluorescence intensity of castrated + hypoxia + E2 group and castrated + hypoxia + TEPP-46 group was slightly weaker than that of castrated + hypoxia group,however,the PKM2 level in the lung tissues of rats was significantly decreased,and the difference was statistically significant(P<0.05),suggesting reduced PKM2 nuclear translocation.Conclusion:Long-term chronic hypoxia can induce the occurrence of hypoxic pulmonary hypertension,and the Warburg effect increases the content of lactic acid.E2 can enhance the PKM2 activity by reducing ROS,inhibit its nuclear translocation,reduce the Warburg effect and reduce the level of lactic acid,thus improving pulmonary hypertension.