FIGURE 6.

Metalloproteinase inhibition impairs psychosine-induced globoid cell formation and phagocytic activity of microglia. (A–C) Following a 7-day treatment with psychosine (10 μM), the presence of Iba-1+ globoid cells (green; nuclei-blue) were significantly increased (A) compared with control (B), while this effect was reversed with the addition of a pan-MMP inhibitor (MMPi; GM6001, 12.5 μM) (C, J). Panel B demonstrates the large amoeboid shape of Iba-1+ cells treated with psychosine, which was reversed with the MMPi. (D–F) Primary mixed glial cultures (Iba-1+ cells-red; FITC+ beads-green; nuclei-blue) incubated for last 48 hr of 7 days psychosine treatment with latex FITC-labeled beads (white arrows) demonstrates that psychosine treatment significantly increased the phagocytic activity Iba-1+ cells, which was also significantly decreased by addition of the MMPi (K). Primary mixed glial culture from wild-type mouse (G) was treated with psychosine (10 μM) alone (H), or psychosine and NNGH (0.1 μM) concomitantly (I) for 7 days. Immunocytochemistry study revealed that psychosine induced Iba-1+ (green) globoid cells containing multiple nuclei (DAPI, blue) (H), but failed to induce globoid cells when NNGH was added together (I). Number of globoid cells was quantified (L). Data represent mean ± SEM. ***P < 0.001, *P < 0.05. Scale bar top = 30 μm; middle = 20 μm; bottom = 18 μm. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]