Figure 5.

Arousal effect of caffeine was abolished in rats with site-specific deletion of A_2ARs in the shell of the NAc. A, The loss of the arousal response to caffeine (15 mg/kg, i.p.) in rats that had received AAV–shA_2AR injections (black circles) into the NAc correlated closely with the knockdown of A_2ARs in the NAc, whereas there was very little variation in caffeine-induced wakefulness in control animals injected with shCTRL (white triangles). B, Caffeine-induced wakefulness for 3 h in AAV-untreated rats and in rats that received injection of AAV–shCTRL into the NAc or injection of AAV–shA_2AR into the NAc shell and core, OLT, CPu, and GP. Caffeine was given intraperitoneally at 15 mg/kg. C, D, Typical sections from two rats injected bilaterally with AAV carrying shA_2AR into the shell or core of the NAc that were stained with mouse monoclonal antibody against A_2AR showed dominant depletion of A_2ARs either in the shell (D, right photomicrograph) or the core (C, left photomicrograph) of the NAc. Adjacent sections to C and D were stained with rabbit polyclonal antibody against mCherry (Clontech) to confirm the extent to which neural cells in the NAc were transfected with AAV–shA_2AR (C, D, right photomicrographs). The red circles in the photomicrographs in D outline the entire NAc, including both the core and shell region, whereas the green circles in the photomicrographs in C delineate the core of the NAc. The polysomnographic recordings in C and D show typical examples of EEG, EMG, LMA, and hypnograms after administration of caffeine at a dose of 15 mg/kg (top polysomnographic panel) or vehicle (bottom polysomnographic panel) in two rats with AAV–shA_2AR infections of the shell (D) or the core (C) of the NAc. Data are presented as mean ± SEM (n = 5–6 per AAV-treatment). **p < 0.01 compared with AAV-untreated or AAV–shCTRL-injected rats, assessed by one-way ANOVA. Scale bars: C, D, 300 μm.