Figure 3.

Reduction of dopamine release in NAc while transitioning from immobility to struggling during tail suspension. A, Schematic diagram of a mouse engaging in a FSCV recording during tail suspension (left). Histologically verified recording sites in the NAc (right) for all animals. B, A representative color plot of cyclic voltammogram showing dopamine release while the mouse's behavior changed from the immobility to the struggling stage. Inset represents the background-subtracted cyclic voltammogram of dopamine. C, Synchronization of dopamine concentration change (top) and body movement of mice under the TST (bottom). D, Event-triggered average of body movement (top) and extracellular dopamine concentration (bottom) during the transition from the immobile to the struggling stage (N = 5 mice; 55 trials). Shaded areas represent the mean ± SEM. E, Quantification of dopamine concentration before and after the onset of struggling behavior. Summation of dopamine concentration in the NAc for 10 s before (blue bar) and after (red bar) the transition from immobile to struggling behavior was calculated as the area under the curve in all trials (N = 5 mice; 55 trials, **p < 0.001, two-tailed Student's t test). Error bars represent the SEM. Scale bar: 1 mm (A).