Inactivation of the paraventricular thalamus abolishes the expression of cocaine conditioned place preference in rats

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BackgroundThe paraventricular thalamus (PVT) is rapidly becoming recognized as part of the addiction circuitry. In addition to its strong anatomical connection to most of the brain regions underlying addiction, such as the nucleus accumbens, prefrontal cortex, amygdala, and hippocampus, the PVT has recently been shown to contribute to cocaine sensitization and reinstatement. In the present study, we examined the role of the PVT in the expression of cocaine conditioned place preference (CPP). MethodsWe tested the impact of PVT inactivation by baclofen/muscimol (bac-mus) microinjection on the expression of cocaine-induced CPP in rats. Rats were implanted with guide cannulae into the PVT. Bac-mus (GABAB–GABAA agonists) or saline was injected into the PVT prior to CPP testing. ResultsInactivation of the PVT by bac-mus prevented the expression of CPP, while placements outside the PVT did not affect CPP. Intra-PVT injections of bac-mus did not affect locomotor activity during the session. ConclusionsIn the present study, we contribute to the growing body of research supporting a role for the PVT in addiction by demonstrating that the PVT is necessary for the expression of cocaine CPP.