• 1Reseach Group Developmental Neuropsychopharmacology, Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
• 2Institute of Molecular Psychiatry, University of Bonn, Germany.

The endocannabinoid (ECB) system has emerged recently as a key mediator for reward processing. It is well known thatcannabinoids affect appetitive learning processes and can induce reinforcing and rewarding effects. However, the involvement of the ECB system in hedonic aspects of reward-related behavior is not completely understood. With the present study we investigated the modulatory role of the ECB system on hedonic perception, measured by the pleasure attenuated startle (PAS) paradigm for a palatable food reward. Here, a conditioned odor is thought to induce a pleasant affective state which attenuates an aversive reflex – the acoustic startle response (ASR). Modulatory effects effects of the CB1 receptor antagonist/inverse agonist SR1411716 and the cannabinoid agonist WIN 55,212-2 on PAS were examined in rats. PAS was also measured in CB1 receptor knockout (KO) and wild-type (WT) mice. Pharmacological inhibition, as well as the absence of CB1 receptors was found to reduce PAS, whereas WIN 55,212-2 administration increased PAS. Finally, presentation of a conditioned reward-cue was found to induce striatal FosB/ΔFosB expression in WT, but not KO mice, indicating a reduced stimulation of reward-related brain regions in conditioned KO mice by odor presentation. We here show that in addition to our previous studies in rats, PAS may also serve as a valuable and suitable measure to assess hedonic processing in mice. Our data further indicate that the ECB system, and in particular CB1 receptor signaling, appear to be highly important for the mediation of hedonic aspects of reward processing.Neuropsychopharmacology accepted article peview online, 10 April 2014; doi:10.1038/npp.2014.86.

PMID:

 

24718372

 

[PubMed – as supplied by publisher]