PrP^Sc causes loss of excitatory postsynaptic markers without affecting presynaptic markers.

Hippocampal neurons were treated for 24 hrs with purified PrPSc (F, G, P, Q) or with mock-purified material (A, B, K, L). Cultures were then fixed and stained with fluorescent phalloidin (green) (A, F, K, P) along with antibodies to either GluR1 (excitatory postsynaptic marker) (B,G) or synaptophysin (presynaptic marker) (L, Q) (both red). The boxed regions in each pair of horizontal panels (A and B; F and G; K and L; P and Q) are shown at higher magnification in the pair of smaller panels to the right (C and D; H and I; M and N; R and S, respectively). Panels E, J, O, and T show merged green and red images for each pair of smaller panels. Quantitation of spine number of synaptic marker staining is shown in panel U, normalized to the values in mock-treated cultures. Pooled measurements were collected from 15–20 cells from 3 independent experiments. ***p<0.001 by Student’s t-test; N.S., not significantly different. Scale bar in panel Q = 20 μm (also applicable to panels A, B, F, G, K, L, and P); scale bar in panel T = 20 μm (also applicable to panels C-E, H-J, M-O, and R-S).