Ultrasonic vocalization in rats self-administering heroin and cocaine in different settings: evidence of substance-specific interactions between drug and setting

Avvisati, Riccardo, Contu, Laura, Stendardo, Emiliana, Michetti, Caterina, Montanari, Christian, Scattoni, Maria and Badiani, Aldo (2016) Ultrasonic vocalization in rats self-administering heroin and cocaine in different settings: evidence of substance-specific interactions between drug and setting. Psychopharmacology, 233 (8). pp. 1501-1511. ISSN 0033-3158

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Abstract

Rationale
Clinical and preclinical evidence indicates that the setting of drug use affects drug reward in a substance-specific manner. Heroin and cocaine co-abusers, for example, indicated distinct settings for the two drugs: heroin being used preferentially at home and cocaine preferentially outside the home. Similar results were obtained in rats that were given the opportunity to self-administer intravenously both heroin and cocaine.

Objectives
The goal of the present study was to investigate the possibility that the positive affective state induced by cocaine is enhanced when the drug is taken at home relative to a non-home environment, and vice versa for heroin.

Methods
To test this hypothesis, we trained male rats to self-administer both heroin and cocaine on alternate days and simultaneously recorded the emission of ultrasonic vocalizations (USVs), as it has been reported that rats emit 50-kHz USVs when exposed to rewarding stimuli, suggesting that these USVs reflect positive affective states.

Results
We found that Non-Resident rats emitted more 50-kHz USVs when they self-administered cocaine than when self-administered heroin whereas Resident rats emitted more 50-kHz USVs when self-administering heroin than when self-administering cocaine. Differences in USVs in Non-Resident rats were more pronounced during the first self-administration (SA) session, when the SA chambers were completely novel to them. In contrast, the differences in USVs in Resident rats were more pronounced during the last SA sessions.

Conclusion
These findings indicate that the setting of drug taking exerts a substance-specific influence on the ability of drugs to induce positive affective states.

Item Type: Article
Keywords: Ultrasonic vocalizations, USVs, Drug abuse, Cocaine, Heroin, Self-administration, Emotion, Environment, Context, Setting, Reward, Affect
Schools and Departments: School of Psychology > Psychology
Subjects: B Philosophy. Psychology. Religion
Depositing User: Lene Hyltoft
Date Deposited: 11 Mar 2016 14:09
Last Modified: 11 Mar 2017 02:21
URI: http://sro.sussex.ac.uk/id/eprint/59668

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