Cannabinoid CB1 receptor is dispensable for memory extinction in an appetitively-motivated learning task.

Sabine M. Hölter, Magdalena Kallnik, Wolfgang Wurst, Giovanni Marsicano, Beat Lutz, Carsten T. Wotjak
European Journal of Pharmacology. 2005-03-01; 510(1-2): 69-74
DOI: 10.1016/j.ejphar.2005.01.008

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1. Eur J Pharmacol. 2005 Mar 7;510(1-2):69-74.

Cannabinoid CB1 receptor is dispensable for memory extinction in an
appetitively-motivated learning task.

Hölter SM(1), Kallnik M, Wurst W, Marsicano G, Lutz B, Wotjak CT.

Author information:
(1)Max-Planck-Institut für Psychiatrie, AG Neuronale Plastizität/Mausverhalten,
Kraepelinstr. 2, D-80804 München, Germany.

The interaction of the cannabinoid CB1 receptor with its endogenous ligands plays
an essential role in extinction of aversive memories (Marsicano, G., Wotjak,
C.T., Azad, S.C., Bisogno, T., Rammes, G., Cascio, M.G., Hermann, H., Tang, J.,
Hofmann, C., Zieglgansberger, W., Di, M., V, Lutz, B., 2002. The endogenous
cannabinoid system controls extinction of aversive memories. Nature 418,
530-534). The present study tested the generality of this observation in respect
to positively-reinforced memories. To this end, male cannabinoid CB1 receptor
deficient mice (CB1R-/-) and their wild-type littermate controls (CB1R+/+) were
trained in an appetitively-motivated operant conditioning task, in which
food-deprived animals received a food reward on nose-poking into an illuminated
hole. During training, CB1R-/- turned out to be less motivated to participate in
the task. After further restriction of daily food consumption, however, CB1R-/-
reached the same level of performance as CB1R+/+ as far as number of correct
responses and errors of omission are concerned. The accuracy of performance
served as a measure for the memory of the light-reward association and was stable
at similarly high levels over a retention period of 9 days without additional
training (97.6+/-0.5% vs. 97.0+/-0.9% correct responses). During subsequent
extinction training, the positive reinforcement was omitted. As a consequence,
both CB1R-/- and CB1R+/+ showed a similar decline in accuracy of performance and
total number of correct responses, accompanied by an increase in errors of
omission. These data demonstrate that the cannabinoid CB1 receptor is not
essential for extinction of the stimulus-response association in an
appetitively-motivated learning task.

DOI: 10.1016/j.ejphar.2005.01.008
PMID: 15740726 [Indexed for MEDLINE]

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