Figure 3.

TrkB blockade suppresses increases of PSD-95 synaptic puncta after eye opening. A, PSD-95-GFP-expressing neurons in layer 2/3 of VC were treated in vivo with 1NM-PP1 (TrkB block) or Bph-PP1 (control) over the eye-opening interval. Dashed rectangles are magnified in C. B, Using a Sholl analysis, numbers of PSD-95 puncta on apical dendrites were significantly reduced at many distances from the soma TrkB-blocked neurons after eye opening. The same analysis for basal dendrites showed the same trend, but only 2 Sholl intervals of 13 showed significance at p < 0.05. C, PSD-95-GFP puncta intensity in secondary branches of apical dendrites was reduced in TrkB-blocked neurons. Three-dimensional graphs show intensities of puncta after thresholding that eliminate GFP signal in dendritic shafts and allow visualization of the PSD-95 distribution and intensity along the dendritic segment. D, E, Before EO, treatment with Bph-PP1 or 1NM-PP1 from P9 to P12 revealed that PSD-95-GFP puncta intensities in secondary branches of apical dendrites were unchanged between neurons treated for the same duration but not over the eye-opening interval. Dashed rectangles are magnified in E. *p < 0.05; **p < 0.01; ***p < 0.001. Error bars represent SEM. Scale bars: 10 μm.