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Smies CW, Bellfy L, Wright DS, Bennetts SG, Urban MW, Brunswick CA, Shu G, Kwapis JL. Pharmacological HDAC3 inhibition alters memory updating in young and old male mice. Front Mol Neurosci 2024; 17:1429880. [PMID: 38989157 PMCID: PMC11234845 DOI: 10.3389/fnmol.2024.1429880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Accepted: 06/17/2024] [Indexed: 07/12/2024] Open
Abstract
Long-term memories are not stored in a stable state but must be flexible and dynamic to maintain relevance in response to new information. Existing memories are thought to be updated through the process of reconsolidation, in which memory retrieval initiates destabilization and updating to incorporate new information. Memory updating is impaired in old age, yet little is known about the mechanisms that go awry. One potential mechanism is the repressive histone deacetylase 3 (HDAC3), which is a powerful negative regulator of memory formation that contributes to age-related impairments in memory formation. Here, we tested whether HDAC3 also contributes to age-related impairments in memory updating using the Objects in Updated Locations (OUL) paradigm. We show that blocking HDAC3 immediately after updating with the pharmacological inhibitor RGFP966 ameliorated age-related impairments in memory updating in 18-m.o. male mice. Surprisingly, we found that post-update HDAC3 inhibition in young (3-m.o.) male mice had no effect on memory updating but instead impaired memory for the original information, suggesting that the original and updated information may compete for expression at test and HDAC3 helps regulate which information is expressed. To test this idea, we next assessed whether HDAC3 inhibition would improve memory updating in young male mice given a weak, subthreshold update. Consistent with our hypothesis, we found that HDAC3 blockade strengthened the subthreshold update without impairing memory for the original information, enabling balanced expression of the original and updated information. Together, this research suggests that HDAC3 may contribute to age-related impairments in memory updating and may regulate the strength of a memory update in young mice, shifting the balance between the original and updated information at test.
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Affiliation(s)
- Chad W. Smies
- Department of Biology, Pennsylvania State University, University Park, PA, United States
- Center for the Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States
| | - Lauren Bellfy
- Department of Biology, Pennsylvania State University, University Park, PA, United States
- Center for the Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States
| | - Destiny S. Wright
- Department of Biology, Pennsylvania State University, University Park, PA, United States
- Center for the Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States
| | - Sofia G. Bennetts
- Department of Biology, Pennsylvania State University, University Park, PA, United States
- Center for the Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States
| | - Mark W. Urban
- Department of Biology, Pennsylvania State University, University Park, PA, United States
- Center for the Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States
| | - Chad A. Brunswick
- Department of Biology, Pennsylvania State University, University Park, PA, United States
- Center for the Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States
| | - Guanhua Shu
- Department of Biology, Pennsylvania State University, University Park, PA, United States
- Center for the Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States
| | - Janine L. Kwapis
- Department of Biology, Pennsylvania State University, University Park, PA, United States
- Center for the Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States
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Smies CW, Bellfy L, Wright DS, Bennetts SS, Urban MW, Brunswick CA, Shu G, Kwapis JL. Pharmacological HDAC3 inhibition alters memory updating in young and old mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.08.593015. [PMID: 38766057 PMCID: PMC11100699 DOI: 10.1101/2024.05.08.593015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Long-term memories are not stored in a stable state but must be flexible and dynamic to maintain relevance in response to new information. Existing memories are thought to be updated through the process of reconsolidation, in which memory retrieval initiates destabilization and updating to incorporate new information. Memory updating is impaired in old age, yet little is known about the mechanisms that go awry. One potential mechanism is the repressive histone deacetylase 3 (HDAC3), which is a powerful negative regulator of memory formation that contributes to age-related impairments in memory formation. Here, we tested whether HDAC3 also contributes to age-related impairments in memory updating using the Objects in Updated Locations (OUL) paradigm. We show that blocking HDAC3 immediately after updating with the pharmacological inhibitor RGFP966 ameliorated age-related impairments in memory updating in 18-m.o. mice. Surprisingly, we found that post-update HDAC3 inhibition in young (3-m.o.) mice had no effect on memory updating but instead impaired memory for the original information, suggesting that the original and updated information may compete for expression at test and HDAC3 helps regulate which information is expressed. To test this idea, we next assessed whether HDAC3 inhibition would improve memory updating in young mice given a weak, subthreshold update. Consistent with our hypothesis, we found that HDAC3 blockade strengthened the subthreshold update without impairing memory for the original information, enabling balanced expression of the original and updated information. Together, this research suggests that HDAC3 may contribute to age-related impairments in memory updating and may regulate the strength of a memory update in young mice, shifting the balance between the original and updated information at test.
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Haubrich J, Nader K. Network-level changes in the brain underlie fear memory strength. eLife 2023; 12:RP88172. [PMID: 38047914 PMCID: PMC10695559 DOI: 10.7554/elife.88172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2023] Open
Abstract
The strength of a fear memory significantly influences whether it drives adaptive or maladaptive behavior in the future. Yet, how mild and strong fear memories differ in underlying biology is not well understood. We hypothesized that this distinction may not be exclusively the result of changes within specific brain regions, but rather the outcome of collective changes in connectivity across multiple regions within the neural network. To test this, rats were fear conditioned in protocols of varying intensities to generate mild or strong memories. Neuronal activation driven by recall was measured using c-fos immunohistochemistry in 12 brain regions implicated in fear learning and memory. The interregional coordinated brain activity was computed and graph-based functional networks were generated to compare how mild and strong fear memories differ at the systems level. Our results show that mild fear recall is supported by a well-connected brain network with small-world properties in which the amygdala is well-positioned to be modulated by other regions. In contrast, this connectivity is disrupted in strong fear memories and the amygdala is isolated from other regions. These findings indicate that the neural systems underlying mild and strong fear memories differ, with implications for understanding and treating disorders of fear dysregulation.
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Affiliation(s)
- Josue Haubrich
- Department of Psychology, McGill UniversityMontréalCanada
- Department of Neurophysiology, Ruhr-University BochumBochumGermany
| | - Karim Nader
- Department of Psychology, McGill UniversityMontréalCanada
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Kéri S. Trauma and Remembering: From Neuronal Circuits to Molecules. Life (Basel) 2022; 12:1707. [PMID: 36362862 PMCID: PMC9699199 DOI: 10.3390/life12111707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 10/23/2022] [Accepted: 10/24/2022] [Indexed: 08/10/2023] Open
Abstract
Individuals with posttraumatic stress disorder (PTSD) experience intrusions of vivid traumatic memories, heightened arousal, and display avoidance behavior. Disorders in identity, emotion regulation, and interpersonal relationships are also common. The cornerstone of PTSD is altered learning, memory, and remembering, regulated by a complex neuronal and molecular network. We propose that the essential feature of successful treatment is the modification of engrams in their unstable state during retrieval. During psychedelic psychotherapy, engrams may show a pronounced instability, which enhances modification. In this narrative review, we outline the clinical characteristics of PTSD, its multifaceted neuroanatomy, and the molecular pathways that regulate memory destabilization and reconsolidation. We propose that psychedelics, acting by serotonin-glutamate interactions, destabilize trauma-related engrams and open the door to change them during psychotherapy.
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Affiliation(s)
- Szabolcs Kéri
- Department of Cognitive Science, Budapest University of Technology and Economics, 1111 Budapest, Hungary; ; Tel.: +36-1463-1273
- National Institute of Mental Health, Neurology, and Neurosurgery, 1145 Budapest, Hungary
- Department of Physiology, Albert Szent-Györgyi Medical School, University of Szeged, 6720 Szeged, Hungary
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