Abstract:

Objective To investigate the correlation of glucocorticoid receptor (GR) expression in mouse Leydig tumor cells (MLTC) and cell apoptosis induced by corticosterone (CORT) at stress level. Methods In the experiment with GR overexpression, blank control group 1, GR plasmid group and control plasmid group were established, gene cloning was used to achieve the over-expression of GR in MLTC in GR plasmid group, and identification was performed by Western blotting. In the experiment with knockdown of GR expression, blank control group 2, Lipofectamine control group, GR siRNA group and control siRNA group were set, RNA interference was adopted to achieve the knockdown of GR in MLTC, and identification was performed by Western blotting. MLTC in these two experiments were treated by CORT at stress level (200 nmol/L)(GR over-expression+CORT group, control plasmid+CORT group, blank control group 1, and knockdown of GR expression+CORT group, control siRNA+CORT group and blank control group 2), MLTC in blank control group 1 and 2 treated by CORT were served as single CORT treatment group 1 and 2, apoptotic rate of MLTC in each group was detected by flow cytometry, and correlation of GR expression and cell apoptotic rate was analysed. Results The cell apoptotic rates in GR over-expression+CORT group, control plasmid+CORT group, single CORT treatment group 1 and blank control group 1 were (36.6±0.6)%, (23.8±0.8)%,（24.3±0.6）% and （4.1±0.5）% respectively, and the cell apoptotic rate of GR over-expression+CORT group was significantly higher than the other groups （P<0.01）. The cell apoptotic rates in knockdown of GR expression+CORT group, control siRNA+CORT group, single CORT treatment group 2 and blank control group 2 were （12.2±0.6）%,（22.5±0.6）%,（22.3±0.9）% and (4.1±0.5）% respectively, and the cell apoptotic rate of knockdown of GR expression+CORT group was significantly lower than control siRNA+CORT group and single CORT treatment group 2 （P<0.01）. The expression of GR in MLTC was significantly positively related to cell apoptotic rate （r=0.947, P<0.05）. Conclusion The changes of GR expression in Leydig cells are significantly positively related to the changes of cell apoptotic rates induced by CORT at stress level, and the glucocorticoid has direct effect on Leydig cell apoptosis induced by stress.

Key words: glucocorticoid receptor, corticosterone, Leydig cell, apoptosis