Abstract
Neurotransmission at dopamine (DA) and glutamate synapses has been implicated in conditioning place preference (CPP) in rats, but different receptor subtypes may be differentially involved in acquisition and expression. A balanced CPP was used to study the role of DA D2 and D3 and glutamatergic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptors in acquisition and expression of amphetamine (2.0 mg/kg) CPP. We tested the DA D3 receptor-preferring antagonist nafadotride, the AMPA/kainate glutamate-receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione disodium salt (CNQX), and the DA D2 receptor-preferring antagonist haloperidol. The results revealed that nafadotride (0.5 mg/kg) and CNQX (0.05 mg/kg) blocked the expression of amphetamine CPP at a dose that failed to block acquisition. In contrast, haloperidol (0.1 mg/kg) blocked the acquisition of CPP at a dose that failed to block expression. Cotreatment with subthreshold doses of nafadotride (0.1 mg/kg) and CNQX (0.01 mg/kg) before the test session failed to block the expression of CPP. The results suggest that AMPA/kainate and DA D3 receptors are more strongly involved in the expression of amphetamine CPP and D2 receptors are more strongly involved in the acquisition of amphetamine CPP.