EN
Aging is a major risk factor for ischemia. Old experimental animals demonstrate bigger infarct progression and more extensive neuronal degeneration after stroke compared to young animals. Activation and expression of metalloproteinases (MMPs), MMP- 2 and MMP-9 particularly, is strongly up-regulated after stroke and it was proved to have a detrimental role. The present study was designed to compare MMPs activity in old and young brains after ischemia. Cortical photothrombotic stroke was induced in young (3–4 months) and aged (12–13 months) C57/BL mice. MMPs activity on the infarcted area and surrounding tissue was examined at 1, 7 and 14 days after stroke. Although in situ zymography revealed that the time-course of gelatinolytic activity and the pattern of distribution of digested products were similar in both groups, old mice exhibited stronger fl uorescein signals of MMPs activity in the ischemic and peri-infarct areas, as compared to young animals. Analysis of brain homogenates by SDS-Page zymography showed the upregulation of MMP-9 activity after stroke in old brains, while in young brains activity of this metalloproteinase was detected at low level. MMP-2 activity remained at stable and comparable level in both groups at all investigated time-points. These results suggest that old brains exhibit stronger proteolytic reaction after stroke, which may contribute to a more severe course of the disease. Supported by Polish-German Grant P-N/026/2006 and Statutory Funds.