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Psychopharmacology (Berl). 2016 Apr;233(8):1501-11. doi: 10.1007/s00213-016-4247-4. Epub 2016 Mar 10.

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

Author information

1
Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Rome, Italy.
2
Istituto Superiore di Sanità, Rome, Italy.
3
Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Rome, Italy. aldo.badiani@uniroma1.it.
4
Sussex Addiction Research and Intervention Centre (SARIC), School of Psychology, University of Sussex, Brighton, UK. aldo.badiani@uniroma1.it.

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.

KEYWORDS:

Affect; Cocaine; Context; Drug abuse; Emotion; Environment; Heroin; Reward; Self-administration; Setting; USVs; Ultrasonic vocalizations

PMID:
26960696
PMCID:
PMC4819852
DOI:
10.1007/s00213-016-4247-4
[Indexed for MEDLINE]
Free PMC Article

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