Doxycycline inhibits matrix metalloproteinase-9 and laminin degradation after transient global cerebral ischemia

Doxycycline, a tetracycline antibiotic inhibits matrix metalloproteinase (MMP) and reduces neuronal damage in focal brain ischemia. This study was undertaken to assess if doxycycline reduces delayed neuronal damage following transient global cerebral ischemia through MMP inhibition. C57BL/6 mice were subjected to 20 min global cerebral ischemia. Doxycycline was administered to mice 30 min before and 2 h after ischemia. In TUNEL assay, damaged neurons were also apparent in the CA1 and CA2 areas and doxycycline reduced TUNEL-positive neurons. Gelatin gel and in situ zymography showed upregulation of gelatinase activity after ischemia. Doxycycline significantly inhibited MMP-9 activity in gel zymography and also suppressed in situ gelatinase activity. Laminin degradation was remarkable in CA1 and CA2 areas after ischemia and doxycycline reduced the laminin degradation and neuronal loss. Our data suggest that doxycycline may provide a neuroprotection against global cerebral ischemia since it reduces perineuronal laminin degradation by inhibiting MMP-9 activity.