Figure 5. DOI-induced dendritic spine enlargement is dependent on TGase activity.

A. F-actin in dendritic spines is labeled with phalloidin in primary cortical cultures treated with vehicle (Veh) and Veh, Veh and DOI, cystamine (Cys) and Veh, or Cys and DOI. Scale bar represents 5μm.

B. DOI causes an increase in dendritic spine area after 30min treatment. Bars represent absolute value of dendritic spine area. Each dendrite had 11–41 dendritic spines, 8–10 dendrites (from 5 – 10 neurons/group, n = 39 neurons) were measured for each treatment, resulting in 150–238 dendritic spines/treatment group for a total of 1,007 dendritic spines measured. Log transformation was performed on original data to achieved normality. One-way repeated measures ANOVA suggests a significant difference between five treatment groups [F(4,34)= 9.342, p<0.001]. Newman-Keuls multiple comparison test indicates * p ≤ 0.001 compared with vehicle treatment group, and groups treated with DOI for 5min, 15min and 60min.

C. Cystamine inhibits the DOI-induced dendritic spine enlargement. Bars represent absolute value of dendritic spine area. The number of spines measured in each group was 154 for vehicle, vehicle treated, 223 for vehicle, DOI treated, 122 for cystamine, vehicle treated and 164 for cystamine, DOI treated cells. Since log transformation did not result in a normal distribution of the data, analysis was performed on the original data using a non-parametric test. Kruskal-Wallis one-way ANOVA on Ranks indicates a significant difference between four treatment groups (p<0.001, n = 21 neurons). Post hoc Dunn’s test suggests * p<0.05 compared with vehicle-vehicle treatment; # p<0.05 compared with vehicle-DOI treatment.

D. DOI and cystamine have no significant effects on dendritic spine density. Bars represent absolute value of dendritic spine density. Log transformation was performed on original data to achieved normality. Two-way ANOVA test indicates that neither cystamine nor DOI has a significant effect on dendritic spine density.