Figure 6. Deletion of PSD-95 attenuates 5-HT_2C receptor-mediated induction of c-fos.

(A) 5-HT_2C and c-fos double-label immunochemistry in the hippocampus of PSD- 95^wildtype and PSD-95^null mice after MK-212 treatment (N=3 littermate pairs). Representative images of CA1 and CA2 are shown. There are fewer c-fos-positive cells in the PSD-95^null mice treated with MK-212 in both CA1 and CA2. (B) Higher magnification image of CA1 in order to examine co-localization of 5- HT_2C receptors and c-fos. 5-HT_2C receptor co-localizes with c-fos, suggesting that 5-HT_2C is inducing this IEG directly, rather than indirectly in surrounding neurons. (C) Analysis of c-fos induction was performed by counting the number of c-fos-positive cells in CA1, CA2, CA3, and dentate gyrus (DG). Data are presented as the mean number of c-fos-positive cells +/− the SEM. There is a significant reduction in c-fos-positive cells in the absence of PSD-95 in all four regions that were measured. c-fos counts were performed separately in the hippocampus of each hemisphere (2 values for each section analyzed). Every 7^th section was analyzed, for a total of 6 sections per animal. ^*p < .05, ^**p < .01, ^***p < .001; one-tailed unpaired t-test.