Figure 4.
mAChRs control of DA release is attenuated by M2/M4 antagonists. a, c, e, g, Profiles of mean [DA]o ± SEM versus time after stimuli (arrows) of either a single pulse (1p) or a high-frequency burst (4p; 100 Hz) in increasing concentrations of Oxo-M in CPu (a, c) and NAc (e, g) in either the absence (a, e) or presence (c, g) of M2/M4 antagonist himbacine (50 nm; solid horizontal line). Data are normalized to peak [DA]o released by 1p in drug-free controls. Post hoc Bonferroni's t tests for burst versus single pulse are all p < 0.001; n = 9. b, d, f, h, Mean peak [DA]o ± SEM versus number of pulses at 100 Hz normalized to release by a single pulse in each condition. Although either 1 or 10 μm Oxo-M significantly modifies relationship between release and activity without himbacine (b, f) (post hoc Tukey's t tests, ***p < 0.001 compared with control), the previous presence of himbacine prevents the effects of 1 μm Oxo-M and limits the effects of 10 μm (d, h) (post hoc Tukey's t tests, ***p < 0.001 compared with himbacine alone).