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Sanguino-Gómez J, Huijgens S, den Hartog M, J M Schenk I, Kluck W, Versluis TD, Krugers HJ. Neural correlates of learning and memory are altered by early-life stress. Neurobiol Learn Mem 2024:107952. [PMID: 38906243 DOI: 10.1016/j.nlm.2024.107952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 04/12/2024] [Accepted: 06/09/2024] [Indexed: 06/23/2024]
Abstract
The ability to learning and remember, which is fundamental for behavioral adaptation, is susceptible to stressful experiences during the early postnatal period, such as abnormal levels of maternal care. The exact mechanisms underlying these effects still remain elusive. This study examined in male mice whether early life stress (ELS) alters memory and brain activation patterns, by studying the expression of the immediate early genes (IEGs) c-Fos and Arc in the dentate gyrus (DG) and basolateral amygdala (BLA) after training and memory retrieval in a fear conditioning task. Furthermore, we examined the potential of RU38486 (RU486), a glucocorticoid receptor antagonist, to mitigate ELS-induced memory deficits by blocking stress signalling during adolescence. Arc::dVenus reporter mice, which allow investigating experience-dependent expression of the immediate early gene Arc also at more remote time points, were exposed to ELS by housing dams and offspring with limited bedding and nesting material (LBN) between postnatal days (PND) 2-9 and trained in a fear conditioning task at adult age. We found that ELS reduced both fear acquisition and contextual memory retrieval. RU486 did not prevent these effects. ELS reduced the number of Arc::dVenus+ cells in DG and BLA after training, while the number of c-Fos+ cells were left unaffected. After memory retrieval, ELS decreased c-Fos+ cells in the ventral DG and BLA. ELS also disrupted the colocalization of c-Fos+ cells with (training activated) Arc::dVenus+ cells in the ventral DG, possibly indicating impaired engram allocation in the ventral DG after memory retrieval. Altered correlated activity during training and changes in IEG expression over time were also found in ELS animals. In conclusion, this study shows that ELS alters neuronal activation patterns after fear acquisition and retrieval, which may provide mechanistic insights into enduring impact of early-life stress on the processing of fear memories, possibly via changes in cell (co-) activation and engram cell allocation.
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Affiliation(s)
| | - Stefan Huijgens
- Brain Plasticity Group, SILS-CNS, University of Amsterdam, Amsterdam, The Netherlands
| | - Maxine den Hartog
- Brain Plasticity Group, SILS-CNS, University of Amsterdam, Amsterdam, The Netherlands
| | - Inim J M Schenk
- Brain Plasticity Group, SILS-CNS, University of Amsterdam, Amsterdam, The Netherlands
| | - Wenya Kluck
- Brain Plasticity Group, SILS-CNS, University of Amsterdam, Amsterdam, The Netherlands
| | - Tamara D Versluis
- Brain Plasticity Group, SILS-CNS, University of Amsterdam, Amsterdam, The Netherlands
| | - Harm J Krugers
- Brain Plasticity Group, SILS-CNS, University of Amsterdam, Amsterdam, The Netherlands.
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Dirven BCJ, van Melis L, Daneva T, Dillen L, Homberg JR, Kozicz T, Henckens MJAG. Hippocampal Trauma Memory Processing Conveying Susceptibility to Traumatic Stress. Neuroscience 2024; 540:87-102. [PMID: 38220126 DOI: 10.1016/j.neuroscience.2024.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 12/04/2023] [Accepted: 01/10/2024] [Indexed: 01/16/2024]
Abstract
While the majority of the population is ever exposed to a traumatic event during their lifetime, only a fraction develops posttraumatic stress disorder (PTSD). Disrupted trauma memory processing has been proposed as a core factor underlying PTSD symptomatology. We used transgenic Targeted-Recombination-in-Active-Populations (TRAP) mice to investigate potential alterations in trauma-related hippocampal memory engrams associated with the development of PTSD-like symptomatology. Mice were exposed to a stress-enhanced fear learning paradigm, in which prior exposure to a stressor affects the learning of a subsequent fearful event (contextual fear conditioning using foot shocks), during which neuronal activity was labeled. One week later, mice were behaviorally phenotyped to identify mice resilient and susceptible to developing PTSD-like symptomatology. Three weeks post-learning, mice were re-exposed to the conditioning context to induce remote fear memory recall, and associated hippocampal neuronal activity was assessed. While no differences in the size of the hippocampal neuronal ensemble activated during fear learning were observed between groups, susceptible mice displayed a smaller ensemble activated upon remote fear memory recall in the ventral CA1, higher regional hippocampal parvalbuminneuronal density and a relatively lower activity of parvalbumininterneurons upon recall. Investigation of potential epigenetic regulators of the engram revealed rather generic (rather than engram-specific) differences between groups, with susceptible mice displaying lower hippocampal histone deacetylase 2 expression, and higher methylation and hydroxymethylation levels. These finding implicate variation in epigenetic regulation within the hippocampus, as well as reduced regional hippocampal activity during remote fear memory recall in interindividual differences in susceptibility to traumatic stress.
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Affiliation(s)
- Bart C J Dirven
- Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands; Department of Medical Imaging, Anatomy, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands
| | - Lennart van Melis
- Department of Medical Imaging, Anatomy, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands
| | - Teya Daneva
- Department of Medical Imaging, Anatomy, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands
| | - Lieke Dillen
- Department of Medical Imaging, Anatomy, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands
| | - Judith R Homberg
- Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands
| | - Tamas Kozicz
- Department of Medical Imaging, Anatomy, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands; Center for Individualized Medicine, Department of Clinical Genomics, and Biochemical Genetics Laboratory, Mayo Clinic, Rochester, MN 55905, USA; University of Pecs Medical School, Department of Anatomy, Pecs, Hungary
| | - Marloes J A G Henckens
- Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
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