Figure 5.

The DA D₂ receptor antagonist, L-741,626, blocks RO5256390’s effects on cocaine-induced changes in DA transport. Co-application of cocaine (Co) with the DA D₂ receptor antagonist, L-741,626 (L-741), dose-dependently increased cocaine effects on DA release (a). This effect was also observed with the perfusion of the lower concentration of L-741 alone. Sumanirole (Suman), DA D₂ receptor agonist dose-dependently produced a significant attenuation of cocaine’s effect on tau whereas L-741,626 significantly potentiated cocaine’s effect on tau (b). The lower concentration of L-741,626 (30 nM), which did not affect cocaine-induced changes in DA clearance when perfused with RO5256390 and cocaine, completely blocked RO5256390’s ability to inhibit cocaine’s effects on DA uptake (d). SB216763 (SB), a GSK-3 inhibitor, increased peak at the lower concentration (e) and significantly attenuated cocaine-induced DA increases in tau at the higher concentration (f). (*p < 0.05, **p < 0.01 vs baseline; ^#p < 0.05, ^##p < 0.01 vs cocaine values; n = 5–19).