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The Benefits and Costs of Environmental Enrichment

Smith, Brittany L
http://orcid.org/0000-0003-2745-1461
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479815083298321

Abstract Details

2016, PhD, University of Cincinnati, Medicine: Neuroscience/Medical Science Scholars Interdisciplinary.
Environmental enrichment is largely beneficial, especially for the limbic system as it prevents and reverses the effects of stress, addiction, and subsequent depression-like and anxiety-like behaviors. Enrichment is beneficial to many brain regions that control stress and emotion, such as the hippocampus, amygdala, and medial prefrontal cortex. Specifically, enrichment protects against the effects of stress through the infralimbic prefrontal cortex (IL PFC), a brain region involved in the etiology of substance abuse and affective disorders. This strongly suggests enrichment as ideal for preventing and treating psychiatric illness. One major caveat is that enrichment removal may actually precipitate a negative mood state and increase vulnerability to drug addiction. However, it is unknown if enrichment removal induces stress or if enrichment would still protect against the effects of stress even if it is not maintained. Therefore, we assessed the benefits and costs of environmental enrichment as they relate to stress responding and depression-like behavior. We found that enrichment is costly for adult male rats if it cannot be maintained, indicated by depression-like behavior, blunted peak glucocorticoid responses to stress, hyperphagia, and weight gain when the rats are removed from their enriched environment. Conversely, we found that enrichment is beneficial to adolescent female rats undergoing subsequent stress because it prevents adulthood development of stress-induced depression-like behavior and adrenal hyporesponsivity. These findings suggest that the benefits and costs of enrichment in rats are highly dependent on age, sex, and stress. Because of the marked physiological and behavioral changes, we demonstrate that enrichment removal serves as an appropriate model for significant loss. Loss is heavily involved in precipitating psychiatric (and physical) illness in humans and is underrepresented in rodent models. We sought to identify molecular mediators for the loss phenotype by analyzing IL PFC gene expression with enrichment and enrichment removal. Enrichment influenced gene expression in a pattern consistent with stress protection, but enrichment removal yielded few unique gene changes. This confirms that enrichment exerts many beneficial effects through the IL PFC, but enrichment loss may be acting through more complex interactions with downstream targets, with future studies likely addressing other brain regions. Together, this work shows that it is possible to harness the benefits of environmental enrichment while avoiding potentially detrimental costs by targeting enrichment to specific populations. Finally, enrichment removal represents a novel model for loss that has the potential to improve our understanding of a broader range of psychological and physiological disorders.
Renu Sah, Ph.D. (Committee Chair)
Stephen Benoit, Ph.D. (Committee Member)
James Herman, Ph.D. (Committee Member)
Robert McNamara, Ph.D. (Committee Member)
Matia Solomon, Ph.D. (Committee Member)
Charles Vorhees, Ph.D. (Committee Member)
180 p.
Neurology
environmental enrichment; depression; stress; prefrontal cortex; loss

Recommended Citations

Citations

  • Smith, B. L. (2016). The Benefits and Costs of Environmental Enrichment [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479815083298321

    APA Style (7th edition)

  • Smith, Brittany. The Benefits and Costs of Environmental Enrichment. 2016. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479815083298321.

    MLA Style (8th edition)

  • Smith, Brittany. "The Benefits and Costs of Environmental Enrichment." Doctoral dissertation, University of Cincinnati, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479815083298321

    Chicago Manual of Style (17th edition)

ucin1479815083298321
440
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This open access ETD is published by University of Cincinnati and OhioLINK.