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Hyppönen VEA, Rosa J, Kettunen MI. Simultaneous fMRI and metabolic MRS of hyperpolarized [1- 13C]pyruvate during nicotine stimulus in rat. NMR IN BIOMEDICINE 2024; 37:e5108. [PMID: 38273732 DOI: 10.1002/nbm.5108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 12/05/2023] [Accepted: 01/04/2024] [Indexed: 01/27/2024]
Abstract
Functional MRI (fMRI) and MRS (fMRS) can be used to noninvasively map cerebral activation and metabolism. Recently, hyperpolarized 13C spectroscopy and metabolic imaging have provided an alternative approach to assess metabolism. In this study, we combined 1H fMRI and hyperpolarized [1-13C]pyruvate MRS to compare cerebral blood oxygenation level-dependent (BOLD) response and real-time cerebral metabolism, as assessed with lactate and bicarbonate labelling, during nicotine stimulation. Simultaneous 1H fMRI (multislice gradient echo echo-planar imaging) and 13C spectroscopic (single slice pulse-acquire) data were collected in urethane-anaesthetized female Sprague-Dawley rats (n = 12) at 9.4 T. Animals received an intravenous (i.v.) injection of either nicotine (stimulus; 88 μg/kg, n = 7, or 300 μg/kg, n = 5) or 0.9% saline (matching volume), followed by hyperpolarized [1-13C]pyruvate injection 60 s later. Three hours later, a second injection was administered: the animals that had previously received saline were injected with nicotine and vice versa, both followed by another hyperpolarized [1-13C]pyruvate i.v. injection 60 s later. The low-dose (88 μg/kg) nicotine injection led to a 12% ± 4% (n = 7, t-test, p ~ 0.0006 (t-value -5.8, degrees of freedom 6), Wilcoxon p ~ 0.0078 (test statistic 0)) increase in BOLD signal. At the same time, an increase in 13C-bicarbonate signal was seen in four out of six animals. Bicarbonate-to-total carbon ratios were 0.010 ± 0.004 and 0.018 ± 0.010 (n = 6, t-test, p ~ 0.03 (t-value -2.3, degrees of freedom 5), Wilcoxon p ~ 0.08 (test statistic 3)) for saline and nicotine experiments, respectively. No increase in the lactate signal was seen; lactate-to-total carbon was 0.16 ± 0.02 after both injections. The high (300 μg/kg) nicotine dose (n = 5) caused highly variable BOLD and metabolic responses, possibly due to the apparent respiratory distress. Simultaneous detection of 1H fMRI and hyperpolarized 13C-MRS is feasible. A comparison of metabolic response between control and stimulated states showed differences in bicarbonate signal, implying that the hyperpolarization technique could offer complimentary information on brain activation.
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Affiliation(s)
- Viivi-Elina A Hyppönen
- Metabolic MR Imaging, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Jessica Rosa
- Metabolic MR Imaging, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Mikko I Kettunen
- Metabolic MR Imaging, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
- Kuopio Biomedical Imaging Unit, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
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Asim M, Wang H, Chen X. Shedding light on cholecystokinin's role in hippocampal neuroplasticity and memory formation. Neurosci Biobehav Rev 2024; 159:105615. [PMID: 38437975 DOI: 10.1016/j.neubiorev.2024.105615] [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: 01/18/2024] [Revised: 02/26/2024] [Accepted: 03/01/2024] [Indexed: 03/06/2024]
Abstract
The hippocampus is a crucial brain region involved in the process of forming and consolidating memories. Memories are consolidated in the brain through synaptic plasticity, and a key mechanism underlying this process is called long-term potentiation (LTP). Recent research has shown that cholecystokinin (CCK) plays a role in facilitating the formation of LTP, as well as learning and memory consolidation. However, the specific mechanisms by which CCK is involved in hippocampal neuroplasticity and memory formation are complicated or poorly understood. This literature review aims to explore the role of LTP in memory formation, particularly in relation to hippocampal memory, and to discuss the implications of CCK and its receptors in the formation of hippocampal memories. Additionally, we will examine the circuitry of CCK in the hippocampus and propose potential CCK-dependent mechanisms of synaptic plasticity that contribute to memory formation.
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Affiliation(s)
- Muhammad Asim
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong; Department of Biomedical Science, City University of Hong Kong, Kowloon Tong, Hong Kong; Centre for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Chinese Academy of Sciences, Hong Kong.
| | - Huajie Wang
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Xi Chen
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong; Department of Biomedical Science, City University of Hong Kong, Kowloon Tong, Hong Kong; Centre for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Chinese Academy of Sciences, Hong Kong
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MacCallum PE, Cooze JB, Ward J, Moore KA, Blundell J. Evaluating the effects of single, multiple, and delayed systemic rapamycin injections to contextual fear reconsolidation: Implications for the neurobiology of memory and the treatment of PTSD-like re-experiencing. Behav Brain Res 2024; 461:114855. [PMID: 38185381 DOI: 10.1016/j.bbr.2024.114855] [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: 09/28/2023] [Revised: 12/18/2023] [Accepted: 01/03/2024] [Indexed: 01/09/2024]
Abstract
The mechanistic target of rapamycin (mTOR) kinase is known to mediate the formation and persistence of aversive memories. Rapamycin, an mTOR inhibitor, administered around the time of reactivation blocks retrieval-induced mTOR activity and de novo protein synthesis in the brains of rodents, while correspondingly diminishing subsequent fear memory. The goal of the current experiments was to further explore rapamycin's effects on fear memory persistence. First, we examined whether mTOR blockade at different time-points after reactivation attenuates subsequent contextual fear memory. We show that rapamycin treatment 3 or 12 h post-reactivation disrupts memory persistence. Second, we examined whether consecutive days of reactivation paired with rapamycin had additive effects over a single pairing at disrupting a contextual fear memory. We show that additional reactivation-rapamycin pairings exacerbates the reconsolidation impairment. Finally, we examined if impaired reconsolidation of a contextual fear memory from rapamycin treatment had any after-effects on learning and recalling a new fear association. We show that rapamycin-impaired reconsolidation does not affect new learning or recall and protects against fear generalization. Our findings improve our understanding of mTOR- dependent fear memory processes, as well as provide insight into potentially novel treatment options for stress-related psychopathologies such as posttraumatic stress disorder.
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Affiliation(s)
- Phillip E MacCallum
- Department of Psychology, Memorial University of Newfoundland, 232 Elizabeth Ave, St. John's, Newfoundland and Labrador A1B 3X9, Canada
| | - Jane B Cooze
- Department of Psychology, Memorial University of Newfoundland, 232 Elizabeth Ave, St. John's, Newfoundland and Labrador A1B 3X9, Canada
| | - Joshua Ward
- Department of Psychology, Memorial University of Newfoundland, 232 Elizabeth Ave, St. John's, Newfoundland and Labrador A1B 3X9, Canada
| | - Kelsey Am Moore
- Department of Psychology, Memorial University of Newfoundland, 232 Elizabeth Ave, St. John's, Newfoundland and Labrador A1B 3X9, Canada
| | - Jacqueline Blundell
- Department of Psychology, Memorial University of Newfoundland, 232 Elizabeth Ave, St. John's, Newfoundland and Labrador A1B 3X9, Canada.
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Nachtigall EG, D R de Freitas J, de C Myskiw J, R G Furini C. Role of hippocampal Wnt signaling pathways on contextual fear memory reconsolidation. Neuroscience 2023:S0306-4522(23)00248-8. [PMID: 37286160 DOI: 10.1016/j.neuroscience.2023.05.028] [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: 07/25/2022] [Revised: 05/15/2023] [Accepted: 05/27/2023] [Indexed: 06/09/2023]
Abstract
Memories already consolidated when reactivated return to a labile state and can be modified, this process is known as reconsolidation. It is known the Wnt signaling pathways can modulate hippocampal synaptic plasticity as well as learning and memory. Yet, Wnt signaling pathways interact with NMDA (N-methyl-D-aspartate) receptors. However, whether canonical Wnt/β-catenin and non-canonical Wnt/Ca2+ signaling pathways are required in the CA1 region of hippocampus for contextual fear memory reconsolidation remains unclear. So, here we verified that the inhibition of canonical Wnt/β-catenin pathway with DKK1 (Dickkopf-1) into CA1 impaired the reconsolidation of contextual fear conditioning (CFC) memory when administered immediately and 2h after reactivation session but not 6h later, while the inhibition of non-canonical Wnt/Ca2+ signaling pathway with SFRP1 (Secreted frizzled-related protein-1) into CA1 immediately after reactivation session had no effect. Moreover, the impairment induced by DKK1 was blocked by the administration of the agonist of the NMDA receptors glycine site, D-Serine, immediately and 2h after reactivation session. We found that hippocampal canonical Wnt/β-catenin is necessary to the reconsolidation of CFC memory at least two hours after reactivation, while non-canonical Wnt/Ca2+ signaling pathway is not involved in this process and, that there is a link between Wnt/β-catenin signaling pathway and NMDA receptors. In view of this, this study provides new evidence regarding the neural mechanisms underlying contextual fear memory reconsolidation and contributes to provide a new possible target for the treatment of fear related disorders.
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Affiliation(s)
- Eduarda G Nachtigall
- Laboratory of Cognition and Memory Neurobiology, Brain Institute, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - Bldg. 63, 3(rd) floor, 90610-000, Porto Alegre, RS, Brazil
| | - Júlia D R de Freitas
- Laboratory of Cognition and Memory Neurobiology, Brain Institute, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - Bldg. 63, 3(rd) floor, 90610-000, Porto Alegre, RS, Brazil
| | - Jociane de C Myskiw
- Psychobiology and Neurocomputation Laboratory (LPBNC), Department of Biophysics, Institute of Biosciences, Federal University of Rio Grande do Sul (UFRGS). Av. Bento Gonçalves, 9500, Bldg. 43422, room 208A, 91501-970, Porto Alegre, RS, Brazil
| | - Cristiane R G Furini
- Laboratory of Cognition and Memory Neurobiology, Brain Institute, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - Bldg. 63, 3(rd) floor, 90610-000, Porto Alegre, RS, Brazil; Institute of Geriatrics and Gerontology, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6681 - Bldg. 40, 8(th) floor, 90610-000, Porto Alegre, RS, Brazil.
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Echeverria V, Mendoza C, Iarkov A. Nicotinic acetylcholine receptors and learning and memory deficits in Neuroinflammatory diseases. Front Neurosci 2023; 17:1179611. [PMID: 37255751 PMCID: PMC10225599 DOI: 10.3389/fnins.2023.1179611] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Accepted: 04/07/2023] [Indexed: 06/01/2023] Open
Abstract
Animal survival depends on cognitive abilities such as learning and memory to adapt to environmental changes. Memory functions require an enhanced activity and connectivity of a particular arrangement of engram neurons, supported by the concerted action of neurons, glia, and vascular cells. The deterioration of the cholinergic system is a common occurrence in neurological conditions exacerbated by aging such as traumatic brain injury (TBI), posttraumatic stress disorder (PTSD), Alzheimer's disease (AD), and Parkinson's disease (PD). Cotinine is a cholinergic modulator with neuroprotective, antidepressant, anti-inflammatory, antioxidant, and memory-enhancing effects. Current evidence suggests Cotinine's beneficial effects on cognition results from the positive modulation of the α7-nicotinic acetylcholine receptors (nAChRs) and the inhibition of the toll-like receptors (TLRs). The α7nAChR affects brain functions by modulating the function of neurons, glia, endothelial, immune, and dendritic cells and regulates inhibitory and excitatory neurotransmission throughout the GABA interneurons. In addition, Cotinine acting on the α7 nAChRs and TLR reduces neuroinflammation by inhibiting the release of pro-inflammatory cytokines by the immune cells. Also, α7nAChRs stimulate signaling pathways supporting structural, biochemical, electrochemical, and cellular changes in the Central nervous system during the cognitive processes, including Neurogenesis. Here, the mechanisms of memory formation as well as potential mechanisms of action of Cotinine on memory preservation in aging and neurological diseases are discussed.
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Affiliation(s)
- Valentina Echeverria
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Concepción, Chile
- Research and Development Department, Bay Pines VAHCS, Bay Pines, FL, United States
| | - Cristhian Mendoza
- Facultad de Odontologia y Ciencias de la Rehabilitacion, Universidad San Sebastián, Concepción, Chile
| | - Alex Iarkov
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Concepción, Chile
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