Date of Award
Increased attention has been directed towards determining how environment interacts with genetics on the manifestation of stress-related disorders. This study investigates the differential effects of an enriched versus impoverished environment on behavioral and biochemical endpoints of depression between stress-vulnerable and stress-resilient strains in the chick anxiety-depression model. Black Australorp and Production Red strains were housed in either enriched or impoverished conditions for 4 days and then socially isolated for 90 min. Rate of distress vocalizations (DVocs) were recorded throughout the isolation period and latency to behavioral despair was calculated. Immediately following testing, bilateral hippocampal tissue was harvested and brain-derived neurotrophic factor (BDNF) levels were analyzed via an ELISA assay. A no-test group of chicks removed directly from the home cage was used as a control. Regardless of housing conditions, stress-vulnerable Black Australorps entered behavioral despair more quickly than the Production Reds. Significant decreases in BDNF were seen as a result of an isolation stressor, but were dependent on the complex interaction of genetic line and housing stress conditions. Decreases were only detected in Black Australorps housed in impoverished conditions and the Production Red housed in enriched conditions, a finding we explain in terms of differences between predictable, mild stress and an acute stressor. Because of the nuanced nature of current research regarding the effects of both acute and mild stress, we urge researchers to begin to develop methods to integrate both differing genetic predispositions to stress as well as differences in environmental modifiers.
Anchor, Sydney M., "Biochemical And Behavioral Effects Of Environmental Enrichment On Strain-Dependent Vulnerability To Anxiety And Depression In The Chick Separation Stress Paradigm" (2016). Honors Theses. 882.