Article (Scientific journals)
The magnitude and the extinction duration of the cocaine-induced conditioned locomotion-activated response are related to the number of cocaine injections paired with the testing context in C57BL/6J mice
Michel, Anne; Tambour, Sophie; Tirelli, Ezio
2003In Behavioural Brain Research, 145 (1-2), p. 113-123
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Keywords :
C57BL/6J mice; cocaine; conditioned drug effects; conditioning; contextual sensitisation; number of drug-context pairings; US-CS associations; placebo effect
Abstract :
[en] Behavioural activation repeatedly induced by a stimulant in rodents can persist in the absence of the drug if the animals are tested in the context where the drug was previously given, a phenomenon often explained in terms of Pavlovian conditioning. The aim of this study was to verify whether the amplitude of the putative CR (the drug-like activity) increases with the number of the US-CS associations (the number of drug-context pairings), one of the most representative rules of Pavlovian conditioning. The effect of the number of trials on the speed of extinction was also considered. C57BL/6J mice received 3, 6 or 12 once-daily injections of either saline or 12 mg/kg (-)-cocaine hydrochloride (s.c.) in the same test context, a photocell activity-box in which they were tested for 60 min after every injection. Other groups received the same treatments outside of the test context (being placed in a novel cage tub after each injection). Twenty-four hours after the last treatment session, all mice were challenged with saline in the test context (test for conditioned activity), extinction sessions taking place on the three subsequent days. Sensitisation to the locomotor-activating effect of cocaine developed only amongst the animals injected 6 or 12 times, the magnitude of the last sensitised response being comparable for these two injections regimen. On saline challenge, only the animals that had received 6 or 12 cocaine injections showed significant conditioned activity (CR), with the greatest response occurring following 12 injections. The 6-trial group reached the level of non-significance after fewer extinction sessions than the 12-trial group; however, the rates of extinction did not differ (comparable regression coefficients and quasi-parallel curves). These results suggest that the amplitude of the CR (cocaine-like stimulation after saline), and perhaps less convincingly the duration of extinction, are functions of the number of the US-CS (cocaine-context) pairings, supporting the Pavlovian nature of post-sensitisation placebo drug-like effects. (C) 2003 Elsevier Science B.V. All rights reserved.
Disciplines :
Neurosciences & behavior
Author, co-author :
Michel, Anne
Tambour, Sophie ;  Université de Liège - ULiège > Département des sciences cognitives > Neuroscience comportementale et psychopharmacologie expér.
Tirelli, Ezio ;  Université de Liège - ULiège > Département des sciences cognitives > Neuroscience comportementale et psychopharmacologie expér.
Language :
English
Title :
The magnitude and the extinction duration of the cocaine-induced conditioned locomotion-activated response are related to the number of cocaine injections paired with the testing context in C57BL/6J mice
Publication date :
17 October 2003
Journal title :
Behavioural Brain Research
ISSN :
0166-4328
eISSN :
1872-7549
Publisher :
Elsevier Science Bv, Amsterdam, Netherlands
Volume :
145
Issue :
1-2
Pages :
113-123
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 17 November 2009

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