Figure 4
High cue reactive (HCR) rats exhibit lower 5-HT2CR protein expression in medial prefrontal cortex (mPFC) relative to low cue reactive (LCR) rats. (a) Mean total lever presses (±s.e.m.) on the previously-active and inactive levers are presented for the cue reactivity test session. Each previously-active lever press resulted in the presentation of the discrete cue complex in the absence of cocaine delivery on an FR1. Rats identified as HCR (n=5) displayed significantly higher lever presses for cocaine-associated cues vs LCR rats (n=6; *P<0.01). Inactive lever presses did not differ between HCR and LCR rats. (b) Qualitative and (c) quantitative data demonstrate phenotypic differences in mPFC 5-HT2CR synaptosomal protein expression. HCR rats displayed lower cortical synaptosomal 5-HT2CR protein levels relative to LCR rats (*P<0.05). (d) An inverse correlation was observed between mPFC 5-HT2CR synaptosomal protein and responses on the previously-active lever for cocaine-associated cues in individual rats (r=0.815; P<0.01). The differential protein expression observed in HCR (0.051±0.002 arbitrary units) and LCR (0.076±0.008 arbitrary units) rats was not related to the cue reactivity test itself as comparable 5-HT2CR mPFC protein levels were observed in HCR (n=6; 0.049±0.01 arbitrary units) and LCR rats (n=6; 0.087±0.02 arbitrary units) that remained in their home cage until sacrifice.
