Reversal of cocaine addiction by environmental enrichment

Abstract

Environmental conditions can dramatically influence the behavioral and neurochemical effects of drugs of abuse. For example, stress increases the reinforcing effects of drugs and plays an important role in determining the vulnerability to develop drug addiction. On the other hand, positive conditions, such as environmental enrichment, can reduce the reinforcing effects of psychostimulants and may provide protection against the development of drug addiction. However, whether environmental enrichment can be used to ''treat'' drug addiction has not been investigated. In this study, we first exposed mice to drugs and induced addiction-related behaviors and only afterward exposed them to enriched environments. We found that 30 days of environmental enrichment completely eliminates behavioral sensitization and conditioned place preference to cocaine. In addition, housing mice in enriched environments after the development of conditioned place preference prevents cocaine-induced reinstatement of conditioned place preference and reduces activation of the brain circuitry involved in cocaine-induced reinstatement. Altogether, these results demonstrate that environmental enrichment can eliminate already established addiction-related behaviors in mice and suggest that environmental stimulation may be a fundamental factor in facilitating abstinence and preventing relapse to cocaine addiction.dopamine ͉ drug abuse ͉ environment ͉ stress ͉ treatment

Individual Differences and Social Influences on the Neurobehavioral Pharmacology of Abused Drugs

“…As discussed earlier, cocaine CPP is reversed in rats that are given social interaction episodes after the establishment of CPP (Fritz et al, 2011b). Cocaine CPP established in isolate housed mice also is reversed by a period of living in enriched housing before the CPP test (Solinas et al, 2008). Similarly, when rats that have been trained to self-administer cocaine while isolate housed and are then are moved to enriched housing, they show an attenuation in cocaine-seeking behavior induced by drug-associated cues and stressors (Chauvet et al, 2009;Fritz et al, 2011c;Thiel et al, 2011).…”

The Use of the Puzzle Box as a Means of Assessing the Efficacy of Environmental Enrichment

“…Environmental enrichment (EE) may be defined as surroundings that provide animals with increased opportunity for social interaction, motor activity, and greater sensory stimulation than usually experienced in a standard laboratory environment.EE has been shown to consistently affect the behavior of animals, bringing about changes such as reduction of stress and anxiety-related activity [8][9][10] , improved performance in learning and memory tasks 8,11 , early onset of motor coordination and exploratory activity 11 , changes in maternal care 8 as well as resistance to addictive substances [12][13][14][15] . Further, EE has been revealed to ameliorate the effects of neurodegenerative disorders, delaying the onset and decreasing the severity of symptoms in animal models of Huntington's [1][2][3][4]16 , Parkinson's 17 and Alzheimer's disease 18 .…”

Undoing cocaine's consequences on behavior and brain

“…The findings of Solinas et al (6) are important in that they provide some of the first evidence in an animal model for successful behavioral treatment of addiction-related behaviors. However, several questions remain.…”

“…Indeed, such nondrug alternatives (such as highly palatable food or exercise opportunities in animal subjects and money or token equivalents in humans) are effective at reducing drug intake (3, 9, 10). However, the enriched housing environment used by Solinas et al (6) cannot easily be conceptualized as an ''alternative'' to any of the drug-related behaviors examined in their mice, suggesting that enriched housing exerted its effects in other ways. One likely possibility that is suggested by the authors is through effects on stress.…”

“…Some of this latter work has shown that the acquisition of addictionrelated behaviors such as sensitization and drug self-administration is attenuated in animals housed in ''enriched'' environments (containing novel toys, food, and conspecifics with which to interact) compared with those housed in standard laboratory conditions (4,5), but such findings do not present a practical guide to treating drug-addicted humans, who present for treatment only after drug use is acquired. However, in this issue of PNAS, Solinas et al (6) suggest that environmental enrichment can still exert its beneficial effects on addiction-related behaviors even after they are established.…”