Estrogen Exhibits Its Anti-inflamatory Effects Through IκBα In Myocardial Cells

Our previous study have proved that hypoxia / reoxygenation (H / R) could promote the nuclear translocation of nuclear transcriptional factor-κB (NF-κB) subunit p65 and increase the expression of ICAM-1, VCAM-1 in the primary cultured cardiac cells, which could induce inflammatory response. However, estrogen (E2) can inhibit this increasing by partly blocking the nuclear translocation of p65. IκBαis the key member of NF-κB inhibitory protein family (IκBs), and plays a critical role in the regulation of NF-κB activation in the classical pathway. So we designed this experiment to examine the influence of estrogen on IκBα. [Aim] Examine the effect of estrogen on IκBαphosphorylation, expression and nuclear translocation during the hypoxia / reoxygenation injury in primary cultured cardiac cells. Verify whether estrogen exhibites its anti-inflammatory effects by regulating IκBαprotain. [Method] Primary cultured cardiac cells and a successful hypoxia / reoxygenation model were used to simulate myocardial ischemia / reperfusion injury. Establish the time depence of estrogen (5μM) incubation (2h, 4h, 6h, 8h). Detect IκBαmRNA expression level by RT-PCR the IκBαprotein level, IκBαphosphorylation (p-IκBα) level, and the distribution of IκBαprotein in cytoplasm and nucleus by western blot. [Results] The results show that hypoxia / reoxygenation can increase the phosphorylation level of IκBα, reduce the levels of IκBαmRNA and protein and the nucleus IκBαprotein level. Compared with the H/R group, estrogen pretreatment can increase the IκBαmRNA and protein levels, and the nucleus IκBαprotein level, while reduce the IκBαphosphorylation level during the H/R injury. [Conclusion] These results suggest that estrogen maintain a relatively stable and high level of IκBαprotein in cardiac cells through inhibiting hypoxia/reoxygenation induced IκBαphosphorylation, promoting the mRNA and protain expression of IκBαat the same time while estrogen can also promote IκBαtranslate to nuclear, inactivate NF-κB by binding to it, thereby promoting NF-κB export from the nucleus, which can terminate the transcription of inflammatory factor, protect cardiac cells from inflammatory injury. In this way estory show its cardiovascular protection function.