Figure 6.

Chronic cocaine exposure increases nNOS activity, S-nitrosylation of MMP-2, and MMP activity. A, Representative examples of gelantinolytic fluorescence corresponding to MMP-2 and MMP-9 activity. Each of two groups, extinguished from cocaine self-administration or cocaine-extinguished plus 15 min of cued reinstatement were microinjected bilaterally into the NAcore with FITC-quenched gelatin in combination with either NPLA (1 nmol) or vehicle into contralateral hemispheres. Tissue was obtained 15 min after microinjection and 100 μm sections were analyzed for fluorescence. Scale bar, 1 mm. Dashed lines outline microinjection track and anterior commissure (ac), both of which were masked out for quantification. B, NPLA reduced both constitutive MMP-2 activity in extinguished (Ext) and transient MMP-9 activity (Smith et al., 2014). C, nNOS serine-847 was dephosphorylated after extinction and cued reinstatement of cocaine seeking. D, E, MMP-2 S-nitrosylation was increased after 15 min of cued reinstatement (D), but MMP-9 was not (E). *p < 0.05 compared with vehicle (B) or yoked saline (C–E). n is shown inside each bar.