Figure 4.

Functional confirmation of α4 deletion from dopaminergic neurons. A, B, α4β2*-nAChR-mediated (α-CtxMII-resistant; A) and α6β2*-nAChR-mediated (α-CtxMII-sensitive; B) dopamine release from two dopaminergic projection regions, OT and ST. C, α4β2*-nAChR-mediated GABA release from ST and CX. For both dopamine and GABA release, full dose–response curves were measured; representative concentrations are reported here (units normalized to baseline). K⁺-stimulated neurotransmitter release did not differ across genotypes (data not shown). D–F, ¹²⁵I-Epibatidine binding (femtomoles per milligram of protein) in OT, ST, and CX. D, Cytistine-sensitive component (representing α4β2*-nAChRs). E, α-CtxMII-sensitive component (α6β2*-nAChRs). F, Total (representing all high-affinity heteromeric nAChRs). *p < 0.05.