Contextual Fear Conditioning Alter Microglia Number and Morphology in the Rat Dorsal Hippocampus
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Description
Contextual fear conditioning is a Pavlovian conditioning paradigm capable of rapidly creating fear memories to contexts, such as rooms or chambers. Contextual fear conditioning protocols have long been utilized to evaluate how fear memories are consolidated, maintained, expressed, recalled, and extinguished within the brain. These studies have identified the lateral portion of the amygdala and the dorsal portion of the hippocampus as essential for contextual fear memory consolidation. The current study was designed to evaluate how two different contextual fear memories alter amygdala and hippocampus microglia, brain derived neurotrophic factor (BDNF), and phosphorylated cyclic-AMP response element binding (pCREB). We find rats provided with standard contextual fear conditioning to have more microglia and more cells expressing BDNF in the dentate gyrus as compared to a context only control group. Additionally, standard contextual fear conditioning altered microglia morphology to become amoeboid in shape – a common response to central nervous system insult, such as traumatic brain injury, infection, ischemia, and more. The unpaired fear conditioning procedure (whereby non-reinforced and non-overlapping auditory tones were provided at random intervals during conditioning), despite producing equivalent levels of fear as the standard procedure, did not alter microglia, BDNF or pCREB number in any dorsal hippocampus or lateral amygdala brain regions. Despite this, the unpaired fear conditioning protocol produced some alterations in microglia morphology, but less compared to rats provided with standard contextual fear conditioning. Results from this study demonstrate that contextual fear conditioning is capable of producing large alterations to dentate gyrus plasticity and microglia, whereas unpaired fear conditioning only produces minor changes to microglia morphology. These data show, for the first time, that Pavlovian fear conditioning protocols can induce similar responses as trauma, infection or other insults within the central nervous system.
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ID Code: | 150952 | ||||||
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Item Type: | Contribution to Journal (Journal Article) | ||||||
Refereed: | Yes | ||||||
ORCID iD: |
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Measurements or Duration: | 17 pages | ||||||
Keywords: | BDNF, contextual fear conditioning, dentate gyrus, hippocampus and amygdala, microglia | ||||||
DOI: | 10.3389/fncel.2019.00214 | ||||||
ISSN: | 1662-5102 | ||||||
Pure ID: | 44082595 | ||||||
Divisions: | Past > QUT Faculties & Divisions > Faculty of Health Past > Institutes > Institute of Health and Biomedical Innovation Current > Schools > School of Clinical Sciences Current > Schools > School of Biomedical Sciences Current > Schools > School of Psychology & Counselling |
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Copyright Owner: | 2019 Chaaya, Jacques, Belmer, Beecher, Ali, Chehrehasa, Battle, Johnson and Bartlett. | ||||||
Copyright Statement: | This work is covered by copyright. Unless the document is being made available under a Creative Commons Licence, you must assume that re-use is limited to personal use and that permission from the copyright owner must be obtained for all other uses. If the document is available under a Creative Commons License (or other specified license) then refer to the Licence for details of permitted re-use. It is a condition of access that users recognise and abide by the legal requirements associated with these rights. If you believe that this work infringes copyright please provide details by email to qut.copyright@qut.edu.au | ||||||
Deposited On: | 07 Feb 2020 06:33 | ||||||
Last Modified: | 11 May 2024 06:42 |
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