PKA is required for establishing CPP for several drugs of abuse. The acquisition of amphetamine CPP is decreased in a dose-dependent manner when the PKA inhibitor Rp-cAMPS is co-administered with amphetamine into the NAc during CPP conditioning sessions.124 Intracerebroventricular injection of the PKA inhibitor H89 immediately after each CPP conditioning session decreases consolidation of cocaine CPP during training.125 Similarly, microinjections of Rp-cAMPS into the VTA126 or of H89 into the hippocampal CA1 region127 after each conditioning session decrease consolidation of morphine CPP.126,127 Administration of H89 into CA1 hippocampus before each training session or just before the preference test does not inhibit morphine CPP in rats. Hippocampal PKA thus regulates consolidation but not acquisition or expression of morphine CPP.127 However, Rp-cAMPS, administered into the VTA immediately prior to preference tests, blocks the expression of morphine CPP. VTA PKA can thus regulate both consolidation and expression of morphine CPP.126 These results indicate that PKA acts within specific brain regions that mediate drug reward to help mediate acquisition, consolidation, and expression of drug-induced CPP. Acquisition of amphetamine CPP is also decreased by co-injection
