Post-traumatic stress disorder (PTSD) is characterized by fear extinction deficit; chronic stress worsens this deficit. Using a Chronic Unpredictable Stress (CUS) model, we previously found that CUS increased fear extinction deficit in female mice and knockout of Ciliary Neurotrophic Factor (CNTF) attenuated it. The amygdala, specifically the medial amygdala, is strongly associated with fear conditioning and extinction. CUS increased CNTF and reduced Urocortin 3 (UCN3) in the medial amygdala, suggesting CNTF-mediated UCN3 inhibition may be involved in CUS-induced deficit of fear extinction. The medial amygdala connects to the hypothalamic paraventricular nucleus (PVN) via posterior bed nucleus of stria terminalis (pBNST) and mediates the stress response (Fig. 1). The objective of this project is to determine whether CUS affects CNTF, UCN3, and CNTF-related cytokine leukemia inhibitory factor (LIF) and interleukin-6 (IL-6) in the pBNST and hypothalamic PVN. Hippocampal CNTF expression was also examined as a brain region outside of the medial amygdala-pBNST-hypothalamic PVN circuitry. 4 groups (5 mice/group) of CNTF+/+ and CNTF-/- mice were treated with 4 weeks of CUS or control handling. At the end, fresh brain samples were collected. The hypothalamic PVN, pBNST and hippocampus were punched out from 600-700 um cryostat frozen sections. CUS was applied for 4 weeks. The control mice were handled daily for 4 weeks. RNA was extracted from tissue using QIANGEN Rneasy mini kit. BCA assay was performed to analyze protein concentration, then 10% SDS gel was used to run the protein samples. Statistical analysis included one-way ANOVA followed by Bonferroni multiple comparison or 2-tailed T test. p <0.05 was defined as significant difference. In the pBNST, CUS did not affect CNTF and UCN3 mRNA expression. However, UCN3 protein was upregulated by CUS in CNTF+/+ but not CNTF-/- mice, suggesting CNTF inhibits UCN3 expression, possibly through post-transcriptional mechanism. CUS did not alter LIF and IL-3 in the pBNST. CUS did not alter CNTF mRNA expression in the PVN and further study will measure UCN3 mRNA and protein in the PVN. Finally, there was no CUS effect on CNTF, LIF and IL-6 mRNA in the hippocampus. These results and further studies are useful in development of therapeutic medications and drug targets in the case of chronic stress.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:asrf-1936 |
| Date | 07 April 2022 |
| Creators | Siddiqui, Nausheen, Jia, Cuihong, Hagg, Theodoor |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Source | Appalachian Student Research Forum & Jay S. Boland Undergraduate Research Symposium |
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