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Chronic Adolescent Exposure to Cannabinoids and Environmental Factors Interact to Change Vulnerability for Later Development of Psychopathology

Furrow, Amy (2012) Chronic Adolescent Exposure to Cannabinoids and Environmental Factors Interact to Change Vulnerability for Later Development of Psychopathology. Masters thesis, Radford University.

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Abstract

Exposure to exogenous cannabinoids during adolescence has been shown to disrupt subsequent neuronal processes of development and functioning compared to chronic adult administration (e.g., Bambico et al., 2010). Age of first encounter with a psychoactive compound is critical due to the heightened sensitivity during this period. The current study examined the interaction of environmental conditions in rats exposed to a synthetic cannabinoid during puberty. Environmental enrichment (EE) mimics positive early life experiences by providing enhanced social and physical stimulation, whereas isolation environments mimic negative early life experiences and provide decreased physical and social stimulation. Rosenzweig, Krech, and Bennett (1961) were the first to provide evidence suggesting that EE could lead to structural changes in the brain. The present study investigates the influence of EE in rats chronically exposed to cannabinoids during adolescence by assessing symptomology of anxiety and depression in adulthood. Seventy-three naïve, male Long-Evans rats were divided into one of three environmental conditions: enriched environment (EE), social environment (SE) or isolation environment (IE) following weaning on postnatal day 22 (PND). Half of the rats in each environment received daily injections (i.p., .35 mg/kg) of CP 55, 940 from PND 35 to 48, while the other half received comparable vehicle injections. Behavioral testing began on PND 77, after a 28-day wash-out period. Subjects were tested in successive order on four behavioral tasks assessing symptoms of anxiety and depression: the elevated plus maze (EPM), a test of social interaction (SI), a sucrose preference task, and the forced swim test (FST). Behavioral alterations observed in adulthood resulting from chronic cannabinoid exposure during adolescence included, reduced weight gain, increased anxiety-related behaviors in the open-field (boli), and decreased sucrose consumption. The results supported the original hypothesis concerning increased emotionality among subjects housed in the isolation environment. Overall, the effects of chronic adolescent cannabinoid exposure were more severe and long-term for subjects that were housed in an impoverished environment growing up. Specifically, the IE animals displayed increased anxiety related behaviors in the open-field (boli), and in the forced swim test (boli). Exposure to the cannabinoid drug induced changes that persisted into adulthood including: reduced weight gain, increased anxiety-related behaviors on the EPM, in the open-field (boli), as well as some evidence of depression on the sucrose preference test. Environmental enrichment was found to reduce weight gain that persisted into late adulthood and decrease anxiety displayed by the drug rats on the FST. The EE and SE animals displayed similar behavioral characteristics such as, a decreased stress response and increased habituation to novelty, suggesting a beneficial effect of social housing. Although some protective effects of EE were found, the results of the study suggest an overall beneficial effect of social housing rather than a specific effect of enrichment on the EPM and social interaction task. Thus, EE may provide some protection against the effects of cannabinoid exposure, but the amount of social stimulation provided during early development is probably more important.

Item Type: Thesis (Masters)
Subjects: B Philosophy. Psychology. Religion > BF Psychology
Divisions: UNSPECIFIED
Depositing User: Amy Furrow
Date Deposited: 29 May 2013 14:11
Last Modified: 29 May 2013 14:11
URI: http://wagner.radford.edu/id/eprint/87

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