Figure 2.

Microglia activation resulting from microinjection of aggregates of HypF-N and PI₃SH3 into the NBM of rat brains. Activation was detected by MHC class II immunoreactivity imaged by light microscopy, using the monoclonal antibody OX-6, followed by staining with DAB, as described in Materials and Methods. A, Micrographs (10× magnification) of representative regions of tissue slices 7 d after injection of PBS, 5000 ng of fibrillar aggregates, or 0.0002 or 5000 ng of HypF-N prefibrillar aggregates (top left to bottom right, respectively). B, Similar micrographs taken 7 d after injection of 5000 ng of fibrillar and 5000 ng of prefibrillar aggregates of PI₃SH3. C, Quantification of microglia activation 7 d after the injections (5 sections per animal). Rats were injected with PBS, 5000 ng of native HypF-N, 5000 ng of fibrillar HypF-N, or with 5000, 500, and 0.0002 ng of prefibrillar HypF-N (n = 6 for each type of injection). Data are reported as total OX-6-positive area in pixels of microglia activation after injection. Statistical analysis of the mean was performed using one-way ANOVA, followed by the Newman–Keuls multiple comparison test (F = 16.13; p < 0.05). D, The same as in C but after the injection of PBS or 5000 ng of native, prefibrillar, or fibrillar PI₃SH3. Statistical analysis of the mean was performed as in C. ∗p < 0.05, ∗∗p < 0.01, and ∗∗∗p < 0.001 versus PBS. For details, see Materials and Methods. Scale bar, 60 μm