Fig. 8.  Propofol anesthesia at postnatal day (PND) 15 induces persistent increase in dendritic spine density. (A ) Representative confocal images (three-dimensional volume rendering) showing the effects of propofol anesthesia, performed at PND 15, on dendritic spines at PND 20 and 90. (B  and C ) Quantitative analysis of spine density (left panels) and spine head diameters (right panels) at PND 10 (B ) and at PND 90 (C ) reveals a significant difference between control animals (red columns ) and those who received a single bolus (blue columns ) or a 6-h-long propofol anesthesia (green columns ) at PND 15. Results are expressed as mean ± SD. *=P < 0.05; **=P < 0.01; ***=P < 0.001, one-way ANOVA with Bonferroni correction posttests. At PND 10 and 90, control animals are identical to those shown originally in Figs. 2 and 4. Left Panels: both one-shot and 6-h propofol treatment groups are compared with the control group. Right panels: same comparisons but inside each diameter range classes. ⁺⁺⁺=P < 0.001, one-way ANOVA with Bonferroni correction posttests comparing single-bolus propofol versus  6-h propofol group's spine density in within the same head diameter range class. n = 5 animals per age group for each condition (8–10 neurons per animal), representing a total of 4,429 spines in B , left, 4,143 spines in C,  left, 870 spine heads in B , right, and 10,006 heads in C , right. PND = postnatal day;scale bar =5 μm.