Figure 5.

Extracellular dopamine concentrations in the accumbal shell (A) and core (B) dialysates obtained from SD male rats treated with (S)-MK-26 (1, 10 mg/kg) or vehicle (Kolliphor EL 30%). Rats stereotaxically implanted with a microdialysis probe aimed at the accumbal shell or core were placed individually into the experimental cage and perfused with dialysis buffer. During the experiment, four initial dialysate aliquots were collected, one every 15 min, before intraperitoneal administration (indicated by arrows) of either the vehicle (Kolliphor EL 30% 1.5 mL/kg) or (S)-MK-26 (1 or 10 mg/kg) and collection of subsequent 10 dialysate aliquots for dopamine determination commenced. Values are percentages (with 100% as the average of the last four dopamine basal values before treatment) and expressed as means ± SEM of the values obtained by 3–5 rats per group. *: p < 0.05 with respect to basal values (before treatment); #: p < 0.05 with respect to vehicle-treated rats (two-way ANOVA for repeated measures followed by Tukey’s multicomparison test). Basal dopamine levels in NAc were 6.53 pg (in shell) and 7.29 pg (in core) per 20 µL of dialysate, corresponding to extracellular dopamine concentrations of approximately 2.13 nM and 2.38 nM, in shell and core, respectively.