Heroin versus cocaine: opposite choice as a function of context but not of drug history in the rat.

Rationale: Previous studies have shown that rats trained to self-administer heroin and cocaine exhibit opposite preferences, as a function of setting, when tested in a choice paradigm. Rats tested at home prefer heroin to cocaine, whereas rats tested outside the home prefer cocaine to heroin. Here, we investigated whether drug history would influence subsequent drug preference in distinct settings.

Ambience and drug choice: cocaine- and heroin-taking as a function of environmental context in humans and rats.

Background: We have recently observed an unforeseen dissociation in the effect of environmental context on heroin versus cocaine self-administration in rats. Rats housed in the self-administration chambers (Residents) took more heroin than rats that were transferred to the self-administration chambers only for the test sessions (Nonresidents). The contrary was found for cocaine.

Drug context differently regulates cocaine versus heroin self-administration and cocaine- versus heroin-induced Fos mRNA expression in the rat.

Rationale: We have previously reported that cocaine self-administration is facilitated in male rats not residing in the test chambers (Non Resident rats) relative to rats living in the test chambers at all times (Resident rats). Surprisingly, the opposite was found for heroin.

Materials And Methods: We predicted that, when given access to both cocaine and heroin on alternate days, Non Resident rats would take more cocaine relative to heroin than Resident rats.

Opposite environmental regulation of heroin and amphetamine self-administration in the rat.

Rationale: The circumstances of drug taking are thought to play a role in drug abuse but the evidence of it is anecdotal. Previous studies have shown that the intravenous self-administration of cocaine is facilitated in rats non-residing in the test chambers relative to rats that live in the test chambers at all times. We investigated here whether environmental context could exert its modulatory influence on heroin and amphetamine self-administration as well.

Modeling the role of environment in addiction.

The aim of this review is to provide an overview of the main types of animal models used to investigate the modulatory role of environment on drug addiction. The environment can alter the responsiveness to addictive drugs in at least three major ways. First, adverse life experiences can make an individual more vulnerable to develop drug addiction or to relapse into drug seeking.

Environmental modulation of cocaine self-administration in the rat.

Rationale: Previous studies have shown that environmental context can powerfully modulate the induction of psychomotor sensitization to cocaine in the rat. Rats that receive repeated administrations of cocaine in association with environmental novelty exhibit greater psychomotor sensitization than animals that receive the same treatments in their home cages.

Objectives: The goal of the present study was to investigate whether environmental context can exert its modulatory influence also on cocaine self-administration.