Figure 12.

The effect of DHPG treatment on BRAG2a, PSD-95, and GluA1/2 levels in the PSD and extrasynaptic region using acute hippocampal slice cultures. A, B, The effect of the DHPG treatment on the expression of GluA1/2 and Arc/Arg3.1, and the phosphorylation of p38 MAPK in acute hippocampal slice cultures. A, Representative immunoblots of acute hippocampal slices treated with or without DHPG with anti-GluA1/2, anti-Arc/Arg3.1, anti-phospho-p38 MAPK, anti-p38 MAPK, and anti-α-tubulin antibodies. B, Quantification of immunoreactive intensities of GluA1/2, Arc/Arg3.1, and phospho/total p38 MAPKs. Each immunoreactive intensity was normalized by the respective intensity for α-tubulin and expressed as the ratio with the control value. Note that the DHPG treatment induced the significant upregulation of Arc/Arg3.1 and the phosphorylation of p38 MAPK in hippocampal slices. Data for each group were obtained from three culture plates (n = 3). These results were confirmed by three independent experiments. C–T, Representative postembedding immunoelectron microscopic images (C–F, I–L, O–R) and histograms (G, H, M, N, S, T) of the lateral distribution of immunogold particles for BRAG2a (C–H), PSD-95 (I–N), and GluA1/2 (O–T) in axospinous asymmetric synapses in the CA1 stratum radiatum of acute mouse hippocampal slices following 50 μm DHPG treatment. The edge of the postsynaptic density (arrowheads) is defined as 0. The bin size of the histogram is 25 nm. U, V, Quantification of immunogold particles for BRAG2a, PSD-95, and GluA1/2 in the PSD (U) and extrasynaptic (V) region along the postsynaptic membrane. Values in U and V are expressed as the average immunogold particle numbers in the PSD of axospinous synapses and the percentage of immunogold particles in the extrasynaptic region in total immunoreactive particles along the postsynaptic membrane, respectively. Note that the DHPG treatment decreased the immunogold particles for GluA1/2 but not BRAG2a or PSD-95 without any changes in the proportion of BRAG2a, PSD-95, or GluA1/2 in the extrasynaptic region. *p < 0.05 (t test). Data for each group were obtained from three slices (n = 3). These results were confirmed by three independent experiments from different mice. Scale bars, 100 nm.