Reduced sensitivity to reward in CB1 knockout mice.
Psychopharmacology. 2004-04-09; 176(2): 223-232
DOI: 10.1007/s00213-004-1877-8
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1. Psychopharmacology (Berl). 2004 Nov;176(2):223-32. Epub 2004 Apr 9.
Reduced sensitivity to reward in CB1 knockout mice.
Sanchis-Segura C(1), Cline BH, Marsicano G, Lutz B, Spanagel R.
Author information:
(1)Department of Psychopharmacology, Central Institute for Mental Health, CIMH,
University of Heidelberg, 68159 Mannheim, Germany.
RATIONALE: Previous studies have demonstrated that the activation and blockade of
the cannabinoid type 1 receptor (CB1) leads to an enhancement and decrease of the
consumption of food and other orally ingested reinforcers, respectively.
OBJECTIVE: To gain further knowledge about the role of CB1 in sucrose/saccharin
reinforcing efficacy and intake, we tested CB1 knockout (CB1-KO) and littermate
wild-type (WT) control mice in several self-administration experimental
protocols.
METHODS: Operant (fixed or progressive ratio schedule) and non-operant
conditioning procedures were used. In addition, a choice analysis based on the
“matching law” as well as a microstructural analysis of the intra-session pattern
of self-administration was performed.
RESULTS: CB1-KO mice consume less sucrose under operant conditions or when using
a two-bottle free choice procedure. Moreover, as revealed by additional
behavioural analysis, CB1-KO mice exhibit a decreased sensitivity to the
rewarding properties of sucrose. In agreement with this finding, the differences
between WT and CB1-KO mice faded away when the palatability of sucrose was
devaluated by adding quinine, but not when a non-caloric sweetener, saccharin,
was available.
CONCLUSIONS: These results demonstrate a modulatory role of CB1 in the
determination of the rewarding properties of sucrose and probably, as suggested
by previous studies, other reinforcers.
DOI: 10.1007/s00213-004-1877-8
PMID: 15083252 [Indexed for MEDLINE]