Figure 3.

Memory potentiation induced by VO-OHpic injection correlates with a long-term increment of immature dendritic spines in the auditory cortex. A, Representative micrographs of Te2 cryosections showing the effect of PTEN inhibition on p-rpS6 (Ser240/244) immunoreactivity 30 min after VO-OHpic injection. Scale bar, 100 µm. B, Bar graphs represent rpS6²⁴⁰⁺ cell density 30 min after VO-OHpic injection. C, Representative images in Te2 of L2/3 pyramidal neuron dendrites from vehicle- or VO-OHpic-injected mice stained with DiOlistic. Scale bar, 5 µm. Arrows indicate immature spines. Arrowheads indicate mature spines. D-F, Total spine density remained unchanged in both vehicle and VO-OHpic conditions. No significant difference was detected in mature spine density (E), while immature spines increased after VO-OHpic injection (F). G, Cumulative analysis of spines distribution based on neck/head ratio. Dotted line indicates immature/mature spine cutoff point. H, Representative images of Te2 pyramidal neurons dendrites in naive and conditioned mice. Scale bar, 5 µm. I, K, Total dendritic spine density was increased 72 h after training in both vehicle- and VO-OHpic- injected mice compared with naive animals. Mature spine density remained unchanged after VO-OHpic injection (J), while immature spines were significantly increased (K). L, Cumulative analysis of spine neck/head ratio. Dotted line indicates immature/mature spine cutoff point. *p < 0.05; **p < 0.01; ***p < 0.001; Student's t test, two-way ANOVA, and Fisher's LSD post hoc test and KS fitting test. Data are mean ± SEM.