Changes in glucocorticoid receptor expression and activity in lung tissue of acute lung injury induced by lipopolysaccharide in rats / 解放军医学杂志

ABSTRACT

Objective To investigate changes in glucocorticoid receptor (GR) expression and activity in lung tissue of acute lung injury induced by lipopolysaccharide (LPS) within 24h in rat. Methods A total of 70 Wistar rats were divided randomly into LPS treatment group and LPS+ Dexamethasone (Dex) treatment group. The GR mRNA and GR protein expressions in the lung tissue of LPS challenged rats were assessed by RT-PCR and Western blot at different time points. Electrophoretic mobility shift assays (EMSA) were used to determine the GR activity in the lung tissue. Results The expression level of GR mRNA was depressed, but it returned to normal level at 24h after LPS challenge. The expression level of GR was also lowered, reaching the lowest level at 8h. GR activity was decreased, reaching the lowest level at 1h, and remaining lower than that of normal control at 24h. Dex treatment showed no obvious effect on GR activity during the late period of treatment. Conclusion The GR protein expression decreases in lung tissue of acute lung injury in rats, and it maybe associated with the decreased expression of mRNA and accelerated degradation of GR protein. The activity of GR is inhibited sharply, resulting in glucocorticoid resistance.