Deletion of the GABAA α2-subunit does not alter self dministration of cocaine or reinstatement of cocaine seeking

Dixon, C I, Halbout, B, King, S L and Stephens, D N (2014) Deletion of the GABAA α2-subunit does not alter self dministration of cocaine or reinstatement of cocaine seeking. Psychopharmacology, 231 (13). pp. 2695-2703. ISSN 0033-3158

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Abstract

Rationale
GABAA receptors containing α2-subunits are highly represented in brain areas that are involved in motivation and reward, and have been associated with addiction to several drugs, including cocaine. We have shown previously that a deletion of the α2-subunit results in an absence of sensitisation to cocaine.
Objective
We investigated the reinforcing properties of cocaine in GABAA α2-subunit knockout (KO) mice using an intravenous self-administration procedure.
Methods
α2-subunit wildtype (WT), heterozygous (HT) and KO mice were trained to lever press for a 30 % condensed milk solution. After implantation with a jugular catheter, mice were trained to lever press for cocaine (0.5 mg/kg/infusion) during ten daily sessions. Responding was extinguished and the mice tested for cue- and cocaine-primed reinstatement. Separate groups of mice were trained to respond for decreasing doses of cocaine (0.25, 0.125, 0.06 and 0.03 mg/kg).
Results
No differences were found in acquisition of lever pressing for milk. All genotypes acquired self-administration of cocaine and did not differ in rates of self-administration, dose dependency or reinstatement. However, whilst WT and HT mice showed a dose-dependent increase in lever pressing during the cue presentation, KO mice did not.
Conclusions
Despite a reported absence of sensitisation, motivation to obtain cocaine remains unchanged in KO and HT mice. Reinstatement of cocaine seeking by cocaine and cocaine-paired cues is also unaffected. We postulate that whilst not directly involved in reward perception, the α2-subunit may be involved in modulating the “energising” aspect of cocaine’s effects on reward-seeking.

Item Type: Article
Schools and Departments: School of Psychology > Psychology
Subjects: B Philosophy. Psychology. Religion > BF Psychology > BF0180 Experimental psychology
Depositing User: Jill Kirby
Date Deposited: 02 Jul 2014 11:36
Last Modified: 06 Mar 2017 04:29
URI: http://sro.sussex.ac.uk/id/eprint/49178

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