A Lack of Changes in the Transcriptomic Response in the Hippocampus or Amygdala After Developmental Exposure to Mild Variable Stress
Citation:
Franklin, J., B. Chorley, V. Moser, W. Oshiro, T. Beasley, Kathy Mcdaniel, AND D. Herr. A Lack of Changes in the Transcriptomic Response in the Hippocampus or Amygdala After Developmental Exposure to Mild Variable Stress. Society of Toxicology Annual Meeting, Baltimore, Maryland, March 10 - 14, 2019.
Impact/Purpose:
This is an abstract to describe my research at the annual Society of Toxicology Conference.
Description:
Early developmental exposure to stress has been reported to influence learning and memory mechanisms. Changes in the gene expression of brain-derived neurotrophic factor (Bdnf), Ca2+/calmodulin-dependent protein kinase II alpha (Camk2a), and cyclic adenosine monophosphate (cAMP) response element binding (Creb1) have been associated with learning in rodent models. We utilized perinatal exposure to a variable stress paradigm to examine changes in learning and expression of these gene targets after trace fear conditioning. Pregnant Long Evans rats were exposed to an unpredictable series of mild stressful events, which had previously been shown to increase maternal corticosterone levels. These nonchemical factors were presented daily from gestational day (GD) 13 through GD 21 with a postnatal group that also included maternal separation. Starting at postnatal day 97, male and female adult offspring were trained with a trace fear conditioning (TFC) 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 training day. Hippocampus and amygdala were removed and flash frozen at 3 or 6 hours after TFC. All treatment groups displayed learning during context testing. Quantitative RT-PCR data generated from hippocampus or amygdala showed a lack of significant change in the expression of Bdnf, Camk2a, or Creb1 at either time point, or for either sex, regardless of stress exposure. This lack of change may indicate that these genes are influenced at different time points than when these tissues were collected, or that other gene targets could be responding to this learning task for these rats. On-going research will examine a wider range of RNA targets using RNAseq in adult rats that have completed TFC compared to controls that have not undergone testing, to isolate RNA targets that are influenced by TFC. Additional work will examine treatment-related changes in the offspring of dams concurrently exposed to manganese and variable prenatal stress, including transcriptional changes in the hippocampus and amygdala of adult rats after learning the TFC task. This abstract does not necessarily reflect EPA policy.