Fig. 5. Early effects of propofol anesthesia on dendritic spine morphology. Frequency distribution histograms of apical dendritic spine head diameters in control (red columns ), single-bolus propofol (blue columns ) and 6-h-long propofol exposure (green columns ) groups showing the early effects of these treatment paradigms on dendritic spine morphology at postnatal days 10 (A ), 15 (B ), and 60 (C ). Results are expressed as mean ± SD. *=P < 0.05; **=P < 0.01; one-way ANOVA with Bonferroni correction posttests within each group of diameter for control versus propofol one shot or 6 h treatment. n = 4 animals per experimental group for each developmental stage (8–12 injected cells were averaged for each animal, at total 710 spines were analyzed in A , 792 in B , and 499 in C ). PND = postnatal day.