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Abdulmalek S, Connole LM, O'Sullivan NC, Beyna M, Pangalos MN, von Schack D, Ring RH, Murphy KJ. Midkine is upregulated in the hippocampus following both spatial and olfactory reward association learning and enhances memory. J Neurochem 2024; 168:2832-2847. [PMID: 39361112 DOI: 10.1111/jnc.16151] [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] [Received: 11/24/2023] [Revised: 06/03/2024] [Accepted: 06/05/2024] [Indexed: 10/06/2024]
Abstract
Hippocampal neuronal plasticity is a fundamental process underpinning learning and memory formation and requiring elaborate molecular mechanisms that result in the dynamic remodelling of synaptic connectivity. The neurotrophic properties of midkine (Mdk) have been implicated in the development and repair of the nervous system, while Mdk knockout resulted in deficits in the formation of certain types of memory. The role of Mdk in the process of memory-associated neuronal plasticity, however, remains poorly understood. We investigated the learning-induced regulation of Mdk in spatial navigation and association learning using the water maze and the odour reward association learning paradigms, characterising a temporal profile of Mdk protein expression post-learning. Both learning events revealed similar patterns of upregulation of expression of the protein in the rat hippocampal dentate gyrus, which were rapid and transient. Moreover, administration of recombinant Mdk during the endogenous Mdk upregulation following learning enhanced memory in the water maze task revealing a pro-cognitive action of Mdk. We further show that, within the adult hippocampus, Mdk mRNA is predominantly expressed in granular and pyramidal neurons and that hippocampal neuronal Mdk expression is regulated by the canonical plasticity-associated neurotransmitter glutamate. Finally, we confirm that the positive action of Mdk on neurite outgrowth previously noted in cortical and cerebellar neurons extends to hippocampal neurons. Together, our findings suggest a role for Mdk in glutamate-mediated hippocampal neuronal plasticity important for long-term memory consolidation.
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Affiliation(s)
- Sarah Abdulmalek
- Neurotherapeutics Research Group, UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - Laura M Connole
- Neurotherapeutics Research Group, UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - Niamh C O'Sullivan
- Neurotherapeutics Research Group, UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - Mercedes Beyna
- Inflammation Research Unit, Pfizer Worldwide Research & Development, Cambridge, Massachusetts, USA
| | | | - David von Schack
- Inflammation Research Unit, Pfizer Worldwide Research & Development, Cambridge, Massachusetts, USA
| | | | - Keith J Murphy
- Neurotherapeutics Research Group, UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin, Ireland
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Rolls ET, Treves A. A theory of hippocampal function: New developments. Prog Neurobiol 2024; 238:102636. [PMID: 38834132 DOI: 10.1016/j.pneurobio.2024.102636] [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: 01/27/2024] [Revised: 04/15/2024] [Accepted: 05/30/2024] [Indexed: 06/06/2024]
Abstract
We develop further here the only quantitative theory of the storage of information in the hippocampal episodic memory system and its recall back to the neocortex. The theory is upgraded to account for a revolution in understanding of spatial representations in the primate, including human, hippocampus, that go beyond the place where the individual is located, to the location being viewed in a scene. This is fundamental to much primate episodic memory and navigation: functions supported in humans by pathways that build 'where' spatial view representations by feature combinations in a ventromedial visual cortical stream, separate from those for 'what' object and face information to the inferior temporal visual cortex, and for reward information from the orbitofrontal cortex. Key new computational developments include the capacity of the CA3 attractor network for storing whole charts of space; how the correlations inherent in self-organizing continuous spatial representations impact the storage capacity; how the CA3 network can combine continuous spatial and discrete object and reward representations; the roles of the rewards that reach the hippocampus in the later consolidation into long-term memory in part via cholinergic pathways from the orbitofrontal cortex; and new ways of analysing neocortical information storage using Potts networks.
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Affiliation(s)
- Edmund T Rolls
- Oxford Centre for Computational Neuroscience, Oxford, UK; Department of Computer Science, University of Warwick, Coventry CV4 7AL, UK.
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Mira RG, Quintanilla RA, Cerpa W. Mild Traumatic Brain Injury Induces Mitochondrial Calcium Overload and Triggers the Upregulation of NCLX in the Hippocampus. Antioxidants (Basel) 2023; 12:antiox12020403. [PMID: 36829963 PMCID: PMC9952386 DOI: 10.3390/antiox12020403] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 02/10/2023] Open
Abstract
Traumatic brain injury (TBI) is brain damage due to external forces. Mild TBI (mTBI) is the most common form of TBI, and repeated mTBI is a risk factor for developing neurodegenerative diseases. Several mechanisms of neuronal damage have been described in the cortex and hippocampus, including mitochondrial dysfunction. However, up until now, there have been no studies evaluating mitochondrial calcium dynamics. Here, we evaluated mitochondrial calcium dynamics in an mTBI model in mice using isolated hippocampal mitochondria for biochemical studies. We observed that 24 h after mTBI, there is a decrease in mitochondrial membrane potential and an increase in basal matrix calcium levels. These findings are accompanied by increased mitochondrial calcium efflux and no changes in mitochondrial calcium uptake. We also observed an increase in NCLX protein levels and calcium retention capacity. Our results suggest that under mTBI, the hippocampal cells respond by incrementing NCLX levels to restore mitochondrial function.
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Affiliation(s)
- Rodrigo G. Mira
- Laboratorio de Función y Patología Neuronal, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontifica Universidad Católica de Chile, Santiago 8331150, Chile
- Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas 6213515, Chile
| | - Rodrigo A. Quintanilla
- Laboratory of Neurodegenerative Diseases, Universidad Autónoma de Chile, Santiago 8910060, Chile
| | - Waldo Cerpa
- Laboratorio de Función y Patología Neuronal, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontifica Universidad Católica de Chile, Santiago 8331150, Chile
- Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas 6213515, Chile
- Correspondence:
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de Morais VAC, de Oliveira-Pinto AV, Mello Neto AF, Freitas JS, da Silva MM, Suemoto CK, Leite RP, Grinberg LT, Jacob-Filho W, Pasqualucci C, Nitrini R, Caramelli P, Lent R. Resilience of Neural Cellularity to the Influence of Low Educational Level. Brain Sci 2023; 13:brainsci13010104. [PMID: 36672086 PMCID: PMC9857353 DOI: 10.3390/brainsci13010104] [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: 10/21/2022] [Revised: 12/28/2022] [Accepted: 12/30/2022] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Education is believed to contribute positively to brain structure and function, as well as to cognitive reserve. One of the brain regions most impacted by education is the medial temporal lobe (MTL), a region that houses the hippocampus, which has an important role in learning processes and in consolidation of memories, and is also known to undergo neurogenesis in adulthood. We aimed to investigate the influence of education on the absolute cell numbers of the MTL (comprised by the hippocampal formation, amygdala, and parahippocampal gyrus) of men without cognitive impairment. METHODS The Isotropic Fractionator technique was used to allow the anisotropic brain tissue to be transformed into an isotropic suspension of nuclei, and therefore assess the absolute cell composition of the MTL. We dissected twenty-six brains from men aged 47 to 64 years, with either low or high education. RESULTS A significant difference between groups was observed in brain mass, but not in MTL mass. No significant difference was found between groups in the number of total cells, number of neurons, and number of non-neuronal cells. Regression analysis showed that the total number of cells, number of neurons, and number of non-neuronal cells in MTL were not affected by education. CONCLUSIONS The results indicate a resilience of the absolute cellular composition of the MTL of typical men to low schooling, suggesting that the cellularity of brain regions is not affected by formal education.
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Affiliation(s)
- Viviane A. Carvalho de Morais
- Neuroplasticity Laboratory, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil
| | - Ana V. de Oliveira-Pinto
- Neuroplasticity Laboratory, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil
| | - Arthur F. Mello Neto
- Neuroplasticity Laboratory, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil
| | - Jaqueline S. Freitas
- Neuroplasticity Laboratory, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil
| | - Magnólia M. da Silva
- Biobank for Aging Studies, Faculdade de Medicina, Universidade de São Paulo, São Paulo 01246-903, SP, Brazil
| | - Claudia Kimie Suemoto
- Biobank for Aging Studies, Faculdade de Medicina, Universidade de São Paulo, São Paulo 01246-903, SP, Brazil
| | - Renata P. Leite
- Biobank for Aging Studies, Faculdade de Medicina, Universidade de São Paulo, São Paulo 01246-903, SP, Brazil
| | - Lea T. Grinberg
- Memory and Aging Center, University of California San Francisco, San Francisco, CA 94158, USA
| | - Wilson Jacob-Filho
- Biobank for Aging Studies, Faculdade de Medicina, Universidade de São Paulo, São Paulo 01246-903, SP, Brazil
- Laboratory of Medical Research in Aging (LIM-66), Faculdade de Medicina, Universidade de São Paulo, São Paulo 01246-903, SP, Brazil
| | - Carlos Pasqualucci
- Biobank for Aging Studies, Faculdade de Medicina, Universidade de São Paulo, São Paulo 01246-903, SP, Brazil
| | - Ricardo Nitrini
- Biobank for Aging Studies, Faculdade de Medicina, Universidade de São Paulo, São Paulo 01246-903, SP, Brazil
| | - Paulo Caramelli
- Behavioral and Cognitive Neurology Research Group, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, MG, Brazil
| | - Roberto Lent
- Neuroplasticity Laboratory, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil
- D’Or Institute of Research and Education, Rio de Janeiro 22281-100, RJ, Brazil
- Correspondence:
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