Influence of gender differences on gene expression of TLR4 and MD-2 in myocardium in septic rats

Objective: To investigate the influence of gender differences on gene expression of Toll-like receptor 4 （TLR4）, myeloid differential protein-2 （MD-2） and tumor necrosis factor-alpha （TNF-α） in myocardium in septic rats. Methods: Sepsis was replicated by injected LPS （5mg/kg） into abdominal cavity. Male and female rats were sacrificed at 2 hours after injected LPS, the gene expression of TLR4, MD-2 and TNF-α in myocardium were measured by semi-quantitative reverse transcription polymerase chain reaction （RT-PCR）. The level of plasma estrogen were measured also. Results: The gene of TLR4, MD-2 and TNF-α were expressed in very low values in normal male and female rats. After stimulated by LPS 2 hours later, the gene expression was markedly up-regulated, and the gene expression in female group lower than that in male group （P＜0.01）. The gene expression of TLR4 and TNF-α in myocardium of female or male septic rats have significantly negative correlation with the level of plasma estrogen （P＜0.05）. Conclusion: There are significantly gender differences in activation of TLR4 signal transduction in myocardium when stimulated by LPS. The reaction to LPS is lower in female septic rats than that in male septic rats.