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Developmental Exposure to Mild Variable Stress: Adult Offspring Performance in Trace Fear Conditioning after Prenatal and Postnatal Stress
Franklin, J., V. Moser, W. Oshiro, T. Beasley, Kathy Mcdaniel, AND D. Herr. Developmental Exposure to Mild Variable Stress: Adult Offspring Performance in Trace Fear Conditioning after Prenatal and Postnatal Stress. Developmental Neurotoxicology Conference, Denver, Colorado, June 24 - 28, 2017.
Abstract for Developmental Neurotoxicology Conference poster presentation
In utero exposure to mild variable stress has been reported to influence learning and memory formation in offspring. Our research aims to examine whether nonchemical environmental stressors will exacerbate effects to chemical exposure. This study utilized a varying stress paradigm to simulate human psychosocial stress incurred during and after pregnancy to identify phenotypic learning changes in adult offspring that are potential stress markers. We additionally wanted to compare these behavioral outcomes to rat performance induced by perinatal exposure to manganese (Mn), a neurotoxic environmental element, at 2 or 5 g/l in drinking water throughout gestation and lactation. Pregnant Long Evans rats were exposed to an unpredictable series of mild stressful events which had previously been shown to increase maternal corticosterone levels. Nonchemical stressors were presented from GD 13 through GD 21 and included varying noise, light, housing, and confinement during both sleep and wake cycles. A subgroup of offspring was also exposed to periods of maternal separation. Starting at PND 97 offspring were trained with a trace fear conditioning protocol whereby rats were exposed to a compound cue (light and tone) followed by 30 seconds (trace period) and a mild foot shock (1mA, 0.5 seconds). Five paired training sessions occurred on the first day. The following day, context and cue learning were assessed by measuring motor activity. Preliminary data suggests adult offspring learned the task and exhibited reduced movement in response to both context and cue regardless of stress or Mn exposure. Ongoing research will continue to look for treatment differences in offspring of dams concurrently exposed to Mn and prenatal stress and if there are molecular changes to RNA in the hippocampus or amygdala of adult offspring after learning the trace fear conditioning task. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.