Here, we studied drug-induced state-dependency using morphine as a state-forming stimulus in place conditioning setting. In GluA1−/− mice, the expression of morphine-conditioned place preference was tested with or without morphine to assess state-dependent testing conditions. We also studied the detection of morphine stimulus in drug discrimination paradigm, and morphine action in various brain regions using opioid-stimulated G-protein neurochemical assay. VTA DA neuronal plasticity induced by a single morphine injection was examined by electrophysiological ex vivo slice recordings. Our results suggest a role of AMPA receptors in morphine-induced state-dependency.
