Figure 4.

RU486 pretreatment antagonized the effects of MPA on MMP-9 activity. (A) Representative zymogram showing MMP-9 activity of MPA-treated conditioned media (CM). DMSO at 0.1% was used as the vehicle control and constitutively showed MMP-9 gelatinolytic activity (lane 1). C6 cells were pretreated with mifepristone, RU486 (2 μM), for 30 min, followed by MPA treatment for another 48-h. Treatment with RU486, alone, did not alter MMP-9 enzymatic activity (lane 2). Upon MPA treatment, MMP-9 gelatinolytic activity was significantly decreased (100 nM, lane 3; 10 μM, lane 5). Pretreatment with RU486 (2 μM) antagonized MPA’s effect on enzymatic activity (100 nM, lane 4; 10 μM, lane 6). (B) Densitometric analysis of conditioned media from astroglia determined by gelatin zymography. Results are expressed as percentage of activity of treated to untreated cells (mean ± SEM). MMP-9 gelatinolytic activity of untreated cells is expressed as 100%. RU486 treatment is represented by the white bar, 100 nM MPA treatments are represented by the light gray bars (solid and striped), 10 μM MPA treatments are represented by the dark gray bars (solid and striped). Results are representative of three independent experiments. **p < 0.01.