Figure 3. Quantitative isolation of MMP-2,9 activity around the dendritic spine heads versus dentrite shaft of D1- and D2-MSNs.

A) Merge of filament 3D remodel and isolated dendritic segment from Figure 2e. B) The 3D filament remodel recapitulates the dendritic shaft (white), spine neck (green), and spine head (red) (middle panel). White dashed box highlights region of dendrite conveyed in bottom panel. C) The 3D space-filling model of spine heads or shaft was used to mask MMP-2/9 puncta not associated to either the spine head (left panel) or dendrite shaft (right panel) compartments in order to calculate 1) spine head-specific and 2) shaft-specific MMP puncta localization. Scale bar=5μm. D) D1 MSNs exhibit potentiated spine head diameter during transient heroin seeking (nested 1-way ANOVA; F_{(2, 12)}=8.28; p=0.006). E) MMP gelatinolytic puncta was increased in both spine head and shaft subcompartments of D1 dendritic segments during transient heroin seeking (nested 1-way ANOVA; spine head F_{(2, 12)}=11.80; p=0.002; shaft F_{(2, 12)}=7.77; p=0.007). Spine head:Shaft MMP ratio revealed increased spine head-specific MMP gelatinolytic puncta around D1-MSNs during cue-induced RST (nested 1-way ANOVA, F_{(2, 12)}=7.49; p=0.008). c) No difference D2-MSN spine head diameter across groups (nested ANOVA; F_{(2, 13)}=2.455; p=0.1246). F) MMP gelatinolytic puncta was increased in both spine head and shaft subcompartments of D2-MSN dendritic segments under extinguished conditions (nested 1-way ANOVA; spine head F_{(2, 53)}=25.08; p<0.001; shaft F_{(2, 13)}=11.69; p=0.001). G) Spine head:Shaft MMP ratio revealed increased spine head-specific MMP gelatinolytic puncta around D2-MSNs following extinction (nested 1-way ANOVA; F_{(2, 54)}=15.66; p<0.001). Data are shown as mean ± SEM. N represents number of neurons quantified over number of animals in each condition. *p<0.05 comparing RST or EXT to SAL, ⁺p<0.05 comparing RST to EXT using a Sidak post hoc test.