Figure 2.

D2 and D4 receptor modulation of evoked firing of pyramidal neurons was absent following CIE exposure. A, D, Bath application of the D1 receptor agonist SKF38393 (SKF) increased evoked firing in pyramidal neurons from control and CIE rats 1 week after the last day of exposure. B, D, D2 receptor stimulation with quinpirole (Quin) decreased firing in control slices, but this effect is abolished in slices from CIE rats following 1 week of withdrawal. C, D, Bath application of a D4 receptor agonist (PD168077; PD) had little effect on firing rate and this was not changed by CIE. E, Quinpirole had no effect in slices obtained immediately following the last day of CIE exposure and this effect persisted in slices from rats following 4 weeks of withdrawal from CIE. *p < 0.05 versus baseline, #p < 0.05 control versus CIE, n = 7–8 cells from 4 to 5 rats/group.