Environmental enrichment decreases intravenous amphetamine self-administration in rats: dose-response functions for fixed- and progressive-ratio schedules

Green, Thomas; Gehrke, Brenda J.; Bardo, Michael T.

doi:10.1007/s00213-002-1134-y

Cited by 155 publications

(186 citation statements)

References 12 publications

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“…In conclusion, the current results show that, similar to the results obtained with amphetamine self-administration (Bardo et al, 2001;Green et al, 2002), environmental enrichment decreases the incentive salience of a novel non-drug reinforcer. Since novelty and drugs of abuse are thought to share similar neural substrates (Feenstra and Botterblom, 1996;Rebec et al, 1997;Beaufour et al, 2001), it is possible that repeated exposure to enriching novel stimulation during development may activate these substrates repeatedly, thus reducing the relative reinforcing strength of subsequent reinforcers.…”

Section: Discussionsupporting

confidence: 90%

“…If the contingent light is controlling responding, then responding should only increase to the active lever. Such a discrimination procedure has been used previously to demonstrate that environmental enrichment decreases the reinforcing effect of amphetamine (Bardo et al, 2001;Green et al, 2002). Therefore, the current experiment used a two-lever discrimination procedure to assess the reinforcing effect of novel light reward in EC and IC rats.…”

Section: Methodsmentioning

confidence: 98%

“…arrival, rats were assigned randomly to EC or IC home cage rearing for the duration of the study using methods described previously (Green et al, 2002;Zhu et al, 2004). EC rats were housed in a large metal cage (60 cm × 120 cm × 45 cm) with cohorts (8-10 per cage).…”

Section: Environmental Conditions-uponmentioning

confidence: 99%

“…For example, EC rats self-administer less amphetamine at low unit doses than do IC rats (Bardo et al, 2001;Green et al, 2002). However, it is not known currently if the enrichment-induced decrease in operant responding is specific to stimulant drugs or whether it generalizes to novelty reward.…”

mentioning

confidence: 99%

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Environmental enrichment decreases responding for visual novelty

Cain

Green

Bardo

2006

Behavioural Processes

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Previous research has demonstrated that rats reared in an enriched condition (EC) with novel objects and social partners self-administer less amphetamine compared to rats raised in an isolated condition (IC). However, it is unclear if the enrichment-induced decrease in stimulant self-administration generalizes to non-drug rewards such as those provided by novel environmental stimuli. In the current study, EC, IC, and social condition (SC) rats were raised from 21 to 51 days of age before being tested in a two-lever operant conditioning chamber in which responding on one lever (active lever) resulted in illumination of a cue light. In Experiment 1, rats were initially assessed for baseline responding (no contingency) and then the contingent light was introduced. EC rats responded less than IC rats for the contingent light stimulus; however, EC rats also displayed a lower rate of baseline responding. In Experiment 2, rats were trained initially to lever press for a sucrose reward to decrease differences in baseline responding. While sucrose pretraining decreased baseline response differences between groups, EC rats still responded less for the contingent light stimulus than IC or SC rats. These results suggest that environmental enrichment decreases the incentive value of visual novelty.

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Section: Discussionsupporting

confidence: 90%

Section: Methodsmentioning

confidence: 98%

Section: Environmental Conditions-uponmentioning

confidence: 99%

mentioning

confidence: 99%

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Environmental enrichment decreases responding for visual novelty

Cain

Green

Bardo

2006

Behavioural Processes

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“…Finally, genes that belong to cellular signalling such as the protein kinase PKC lambda and mitogen-activated protein kinase kinase kinase 12 (MAP3K12) were also regulated by enriched environment. We have mostly focused on these later genes because protein kinases and MAP kinases are known to play a crucial role in the effects of stimulant drugs and may be responsible for the differential response to drugs in EE mice in comparison to SE mice that others and we have previously reported (Bardo et al, 2001;Bezard et al, 2003;Green et al, 2002;Solinas et al, in press). …”

Section: Several Families Of Genes Are Regulated By Environmental Stimentioning

confidence: 99%

Environmental enrichment during adolescence regulates gene expression in the striatum of mice

et al. 2008

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We have previously shown that environmental enrichment decreases the activating and rewarding effects of the psych psychostimulant cocaine and increases resistance to the neurotoxic effect of the Parkinson-inducing drug MPTP. These effects were accompanied by an increase in the striatal expression of the neurotrophin BDNF, an increase in the striatal levels of delta-Fos B and by a decrease in striatal levels of the dopamine transporter, the main molecular target for cocaine and MPTP. Here, we used cDNA arrays to investigate the effects of rearing mice in enriched environments from weaning to adulthood on the profile of expression of genes in the striatum focusing on genes involved in intracellular signalling and functioning. We found that mice reared in an enriched environment show several alterations in the levels of mRNA coding for proteins involved in cell proliferation, cell differentiation, signal transduction, transcription and translation, cell structure and meta metabolism. Several of these findings were further confirmed by real-time quantitative PCR and, in the case of protein kinase C lambda, also by western blot. These findings are the first description of alterations in striatal gene expression by an enriched environment. The striatal gene expression regulation by environment that we report here may play a role in the resistance to the effects of drugs of abuse and dopaminergic neurotoxins previously reported.

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