Figure 1.

Striatal mAChRs enhance activity dependence of dopamine release. a–d, Mean peak [DA]_o ± SEM versus frequency during four pulse trains (1–100 Hz) in controls (filled circles) or Oxo-M (triangles) normalized to [DA]_o released by a single pulse in control conditions (a, c) or each individual condition (b, d), in CPu (n = 9–12) (a, b) and NAc (n = 9–14) (c, d). Significant effects of frequency: Kruskal–Wallis, p < 0.001. Curve fits are Gaussian (controls, R² > 0.7) or sigmoidal curves (Oxo-M, R² > 0.99). Significance of post hoc t tests for comparisons of Oxo-M versus controls are indicated by asterisks (**p < 0.01; ***p < 0.001). e, g, Profiles of mean [DA]_o ± SEM versus time in CPu after stimuli (arrows) of either a single pulse (1p) or a high-frequency burst (4p/100 Hz) in controls versus drug conditions (Oxo-M, 10 μm; atropine, 2 μm). Data are normalized to peak [DA]_o released by 1p in controls. n = 9. f, h, Mean peak [DA]_o ± SEM versus number of pulses at 100 Hz normalized to release by a single pulse in own condition in CPu. e, f, The enhanced sensitivity of DA release to burst versus nonburst stimuli in Oxo-M (***p < 0.001 vs control; post hoc Tukey's t tests; n = 9) was reversed by addition of atropine (^†††p < 0.001, Oxo-M vs Oxo-M+atropine; post hoc Tukey's t tests; n = 9) to a ratio not different from controls. g, h, Atropine alone does not modify DA release (post hoc Tukey's t tests; n = 9) but prevents Oxo-M-induced change in DA release probability (post hoc Tukey's t tests; n = 9).