Doxycycline blocks gastric ulcer by regulating matrix metalloproteinase-2 activity and oxidative stress

Figure 3 Effect of doxycycline on secreted and synthesized matrix metalloproteinase-2 and -9 activities during protection of ethanol-treated gastric ulcer. Low (0.4 mL/rat) and high (0.8 mL/rat) doses of 70% ethanol were administered intragastrically to induce moderate and maximum gastric ulcers, and doxycycline was administered 30 min prior to ethanol. Gelatin zymography was performed using phosphate buffered saline (PBS) (A) and Triton X-100 (TX) (C) extracts of gastric tissues from different group of rats. Histographic representation of arbitrary activity of pro-matrix metalloproteinase (MMP)-9 (B) and proMMP-2 and MMP-2 (D) in PBS and TX extracts of gastric tissues as measured by Lab Image software using the above zymogram and two other representative zymograms from independent experiments. PBS extracts were subjected to Western blotting (E) and probed with polyclonal anti-MMP-2 and β-tubulin antibody. Fold changes of MMP-2 (F) are represented in a histogram as measured by Lab Image software using the above western blot and two other representative blots from independent experiments. Data expressed as mean ± SE. ^aP < 0.05, ^bP < 0.01, ^dP < 0.001, vs control; ^eP < 0.05, ^fP < 0.001 vs high-dose ethanol; ^gP < 0.05, ^hP < 0.01 vs low-dose ethanol of respective PBS and TX extracts. L.EtOH: Low dose ethanol; H.EtOH: High dose ethanol.