↵F2-a Baseline extracellular dopamine in the nucleus accumbens shell (uncorrected for recovery). These values represent the mean (SE) fmol/sample of the average of the last two baseline samples (60–100 min from the onset of the experiment).

↵F2-b Alterations in baseline extracellular dopamine induced by calcium channel antagonists KN-93, KN-92, or botulinum toxin. These values represent the mean (SE) fmol/sample of the average of the last two samples taken 60–100 min after one of these compounds was included in the microdialysis buffer (160–200 min from the onset of the experiment).

↵F2-c The baseline and drug data from the botulinum toxin experiments are from separate groups of rats. The baseline amphetamine group represents the combination of subjects that either did (n = 8) or did not (n = 17) receive a saline microinfusion (0.3 μl/60 sec) into the nucleus accumbens the day before the microdialysis experiment. The data from these subjects did not significantly differ and were pooled. All of the animals in the baseline GBR-12909 group received an intra-accumbens microinfusion of saline before the implantation of the microdialysis probe. These baseline samples correspond to the amphetamine and GBR-12909 baseline data presented in Figure 1. The “drug” column represents animals that received an intra-accumbal microinfusion of botulinum toxin (1.0 ng/μl, 0.3 μl) the day before the microdialysis experiment (i.e., the baseline values of the amphetamine and GBR-12909 experiments summarized in Fig. 3).

↵* Significant difference between the drug and baseline dopamine values (p < 0.05, t test).