1
|
Nachtigall EG, de C Myskiw J, Izquierdo I, Furini CRG. Cellular mechanisms of contextual fear memory reconsolidation: Role of hippocampal SFKs, TrkB receptors and GluN2B-containing NMDA receptors. Psychopharmacology (Berl) 2024; 241:61-73. [PMID: 37700085 DOI: 10.1007/s00213-023-06463-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 08/31/2023] [Indexed: 09/14/2023]
Abstract
Memories are stored into long-term representations through a process that depends on protein synthesis. However, a consolidated memory is not static and inflexible and can be reactivated under certain circumstances, the retrieval is able to reactivate memories and destabilize them engaging a process of restabilization known as reconsolidation. Although the molecular mechanisms that mediate fear memory reconsolidation are not entirely known, so here we investigated the molecular mechanisms in the hippocampus involved in contextual fear conditioning memory (CFC) reconsolidation in male Wistar rats. We demonstrated that the blockade of Src family kinases (SFKs), GluN2B-containing NMDA receptors and TrkB receptors (TrkBR) in the CA1 region of the hippocampus immediately after the reactivation session impaired contextual fear memory reconsolidation. These impairments were blocked by the neurotrophin BDNF and the NMDAR agonist, D-Serine. Considering that the study of the link between synaptic proteins is crucial for understanding memory processes, targeting the reconsolidation process may provide new ways of disrupting maladaptive memories, such as those seen in post-traumatic stress disorder. Here we provide new insights into the cellular mechanisms involved in contextual fear memory reconsolidation, demonstrating that SFKs, GluN2B-containing NMDAR, and TrkBR are necessary for the reconsolidation process. Our findings suggest a link between BDNF and SFKs and GluN2B-containing NMDAR as well as a link between NMDAR and SFKs and TrkBR in fear memory reconsolidation. These preliminary pharmacological findings provide new evidence of the mechanisms involved in the reconsolidation of fear memory and have the potential to contribute to the development of treatments for psychiatric disorders involving maladaptive memories.
Collapse
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 - 3rd floor, Porto Alegre, RS, 90610-000, Brazil
- Memory Center, Brain Institute, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - 2nd floor - HSL, Porto Alegre, RS, 90610-000, Brazil
| | - Jociane de C Myskiw
- Memory Center, Brain Institute, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - 2nd floor - HSL, Porto Alegre, RS, 90610-000, Brazil
| | - Ivan Izquierdo
- Memory Center, Brain Institute, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - 2nd floor - HSL, Porto Alegre, RS, 90610-000, 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 - 3rd floor, Porto Alegre, RS, 90610-000, Brazil.
- Memory Center, Brain Institute, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Av. Ipiranga, 6690 - 2nd floor - HSL, Porto Alegre, RS, 90610-000, Brazil.
| |
Collapse
|
2
|
Gonzalez MC, Radiske A, Cammarota M. On the Involvement of BDNF Signaling in Memory Reconsolidation. Front Cell Neurosci 2019; 13:383. [PMID: 31507380 PMCID: PMC6713924 DOI: 10.3389/fncel.2019.00383] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 08/06/2019] [Indexed: 01/24/2023] Open
Abstract
When retrieval occurs concomitantly with novelty detection, mismatch perception or reactivation of conflicting information, consolidated memories can enter into a labile state, and to persist, must be restabilized through a protein synthesis-dependent reconsolidation process during which their strength and content can be modified. Extensive literature implicates brain-derived neurotrophic factor (BDNF), a key regulator of synaptogenesis and synaptic plasticity, in the acquisition, consolidation and extinction of several memory types. However, the participation of BDNF in memory reconsolidation has been less studied. In this review, we discuss recent reports supporting the involvement of BDNF signaling in reactivation-induced memory updating.
Collapse
Affiliation(s)
- Maria Carolina Gonzalez
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Andressa Radiske
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Martín Cammarota
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
| |
Collapse
|
3
|
Extinction of aversive taste memory homeostatically prevents the maintenance of in vivo insular cortex LTP: Calcineurin participation. Neurobiol Learn Mem 2018; 154:54-61. [DOI: 10.1016/j.nlm.2018.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 02/14/2018] [Accepted: 04/05/2018] [Indexed: 12/27/2022]
|
4
|
Abstract
Scientific advances in the last decades uncovered that memory is not a stable, fixed entity. Apparently stable memories may become transiently labile and susceptible to modifications when retrieved due to the process of reconsolidation. Here, we review the initial evidence and the logic on which reconsolidation theory is based, the wide range of conditions in which it has been reported and recent findings further revealing the fascinating nature of this process. Special focus is given to conceptual issues of when and why reconsolidation happen and its possible outcomes. Last, we discuss the potential clinical implications of memory modifications by reconsolidation.
Collapse
Affiliation(s)
- Josue Haubrich
- Department of Psychology, McGill University, Montreal, Canada
- Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Karim Nader
- Department of Psychology, McGill University, Montreal, Canada.
| |
Collapse
|
5
|
Arguello AA, Wang R, Lyons CM, Higginbotham JA, Hodges MA, Fuchs RA. Role of the agranular insular cortex in contextual control over cocaine-seeking behavior in rats. Psychopharmacology (Berl) 2017; 234:2431-2441. [PMID: 28462472 PMCID: PMC5538945 DOI: 10.1007/s00213-017-4632-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 04/15/2017] [Indexed: 11/30/2022]
Abstract
RATIONALE Environmental stimulus control over drug relapse requires the retrieval of context-response-cocaine associations, maintained in long-term memory through active reconsolidation processes. Identifying the neural substrates of these phenomena is important from a drug addiction treatment perspective. OBJECTIVES The present study evaluated whether the agranular insular cortex (AI) plays a role in drug context-induced cocaine-seeking behavior and cocaine memory reconsolidation. METHODS Rats were trained to lever press for cocaine infusions in a distinctive context, followed by extinction training in a different context. Rats in experiment 1 received bilateral microinfusions of vehicle or a GABA agonist cocktail (baclofen and muscimol (BM)) into the AI or the overlying somatosensory cortex (SSJ, anatomical control region) immediately before a test of drug-seeking behavior (i.e., non-reinforced lever presses) in the previously cocaine-paired context. The effects of these manipulations on locomotor activity were also assessed in a novel context. Rats in experiment 2 received vehicle or BM into the AI after a 15-min reexposure to the cocaine-paired context, intended to reactivate context-response-cocaine memories and initiate their reconsolidation. The effects of these manipulations on drug context-induced cocaine-seeking behavior were assessed 72 h later. RESULTS BM-induced pharmacological inactivation of the AI, but not the SSJ, attenuated drug context-induced reinstatement of cocaine-seeking behavior without altering locomotor activity. Conversely, AI inactivation after memory reactivation failed to impair subsequent drug-seeking behavior and thus cocaine memory reconsolidation. CONCLUSIONS These findings suggest that the AI is a critical element of the neural circuitry that mediates contextual control over cocaine-seeking behavior.
Collapse
Affiliation(s)
- Amy A. Arguello
- Department of Psychology, Michigan State University, East Lansing, MI, 48824, USA
| | - Rong Wang
- Integrative Physiology and Neuroscience, Washington State University, VBRB #231 Pullman, WA, 99164-7620, USA
| | - Carey M. Lyons
- Integrative Physiology and Neuroscience, Washington State University, VBRB #231 Pullman, WA, 99164-7620, USA
| | - Jessica A. Higginbotham
- Integrative Physiology and Neuroscience, Washington State University, VBRB #231 Pullman, WA, 99164-7620, USA
| | - Matthew A. Hodges
- Integrative Physiology and Neuroscience, Washington State University, VBRB #231 Pullman, WA, 99164-7620, USA
| | - Rita A. Fuchs
- Integrative Physiology and Neuroscience, Washington State University, VBRB #231 Pullman, WA, 99164-7620, USA,Corresponding Author: Dr. Rita A. Fuchs, Washington State University, College of Veterinary Medicine, Integrative Physiology and Neuroscience, P.O. Box 647620, Pullman, WA 99164-7620, USA, Phone: 509-335-6164, Fax: 509-335-4650,
| |
Collapse
|
6
|
Spermidine improves the persistence of reconsolidated fear memory and neural differentiation in vitro: Involvement of BDNF. Neurobiol Learn Mem 2017; 140:82-91. [DOI: 10.1016/j.nlm.2017.02.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 02/02/2017] [Accepted: 02/20/2017] [Indexed: 11/22/2022]
|
7
|
Radiske A, Rossato JI, Gonzalez MC, Köhler CA, Bevilaqua LR, Cammarota M. BDNF controls object recognition memory reconsolidation. Neurobiol Learn Mem 2017; 142:79-84. [PMID: 28274823 DOI: 10.1016/j.nlm.2017.02.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/20/2017] [Accepted: 02/25/2017] [Indexed: 01/16/2023]
Abstract
Reconsolidation restabilizes memory after reactivation. Previously, we reported that the hippocampus is engaged in object recognition memory reconsolidation to allow incorporation of new information into the original engram. Here we show that BDNF is sufficient for this process, and that blockade of BDNF function in dorsal CA1 impairs updating of the reactivated recognition memory trace.
Collapse
Affiliation(s)
- Andressa Radiske
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, RN 59056-450 Natal, Brazil
| | - Janine I Rossato
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, RN 59056-450 Natal, Brazil
| | - Maria Carolina Gonzalez
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, RN 59056-450 Natal, Brazil
| | - Cristiano A Köhler
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, RN 59056-450 Natal, Brazil
| | - Lia R Bevilaqua
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, RN 59056-450 Natal, Brazil
| | - Martín Cammarota
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, RN 59056-450 Natal, Brazil.
| |
Collapse
|
8
|
Blank M, Petry FS, Lichtenfels M, Valiati FE, Dornelles AS, Roesler R. TrkB blockade in the hippocampus after training or retrieval impairs memory: protection from consolidation impairment by histone deacetylase inhibition. J Neural Transm (Vienna) 2015; 123:159-65. [DOI: 10.1007/s00702-015-1464-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 09/16/2015] [Indexed: 01/07/2023]
|
9
|
Abstract
Therapies based on the impairment of reconsolidation or the enhancement of extinction offer the possibility of decreasing the persistent recollection of distressing memories. However, the direct interplay between reconsolidation and extinction has rarely been considered. Previously, we reported that reactivation induces reconsolidation of fear extinction memory. Here, using a step-down inhibitory avoidance learning paradigm in rats, we show that intrahippocampus infusion of function-blocking anti-BDNF antibody immediately or 6 h after extinction memory reactivation impairs the reconsolidation of extinction. Extinction memory reactivation increases proBDNF, BDNF, and tropomyosin receptor kinase B (TrkB) phosphorylation levels in dorsal CA1, while blocking BDNF maturation in the hippocampus with plasminogen activator inhibitor 1 hinders the persistence of extinction and induces the recurrence of fear. Moreover, coinfusion of recombinant BDNF (0.25 μg/side) after extinction memory reactivation impedes the recovery of the avoidance response induced by inhibiting gene expression and protein synthesis in the dorsal hippocampus. Our findings unravel a new role for BDNF, suggesting that this neurotrophin is necessary and sufficient to maintain the reactivated fear extinction engram.
Collapse
|
10
|
Exton-McGuinness MT, Lee JL, Reichelt AC. Updating memories—The role of prediction errors in memory reconsolidation. Behav Brain Res 2015; 278:375-84. [DOI: 10.1016/j.bbr.2014.10.011] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 10/08/2014] [Accepted: 10/10/2014] [Indexed: 10/24/2022]
|
11
|
Abstract
Many psychiatric disorders are characterized by intrusive, distracting, and disturbing memories that either perpetuate the illness or hinder successful treatment. For example, posttraumatic stress disorder (PTSD) involves such strong reemergence of memories associated with a traumatic event that the individual feels like the event is happening again. Furthermore, drug addiction is characterized by compulsive use and repeated relapse that is often driven by internal memories of drug use and/or by exposure to external stimuli that were associated with drug use. Therefore, identifying pharmacological methods to weaken the strength of maladaptive memories is a major goal of research efforts aimed at finding new treatments for these disorders. The primary mechanism by which memories could be pharmacologically disrupted or altered is through manipulation of memory reconsolidation. Reconsolidation occurs when an established memory is remembered or reactivated, reentering a labile state before again being consolidated into long-term memory storage. Memories are subject to disruption during this labile state. In this chapter we will discuss the preclinical and clinical studies identifying potential pharmacological methods for disrupting the integrity of maladaptive memory to treat mental illness.
Collapse
Affiliation(s)
- Jane R Taylor
- Department of Psychiatry, Yale University, New Haven, CT, USA
| | | |
Collapse
|
12
|
Jarome TJ, Lubin FD. Epigenetic mechanisms of memory formation and reconsolidation. Neurobiol Learn Mem 2014; 115:116-27. [PMID: 25130533 PMCID: PMC4250295 DOI: 10.1016/j.nlm.2014.08.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 08/02/2014] [Accepted: 08/05/2014] [Indexed: 10/24/2022]
Abstract
Memory consolidation involves transcriptional control of genes in neurons to stabilize a newly formed memory. Following retrieval, a once consolidated memory destabilizes and again requires gene transcription changes in order to restabilize, a process referred to as reconsolidation. Understanding the molecular mechanisms of gene transcription during the consolidation and reconsolidation processes could provide crucial insights into normal memory formation and memory dysfunction associated with psychiatric disorders. In the past decade, modifications of epigenetic markers such as DNA methylation and posttranslational modifications of histone proteins have emerged as critical transcriptional regulators of gene expression during initial memory formation and after retrieval. In light of the rapidly growing literature in this exciting area of research, we here examine the most recent and latest evidence demonstrating how memory acquisition and retrieval trigger epigenetic changes during the consolidation and reconsolidation phases to impact behavior. In particular we focus on the reconsolidation process, where we discuss the already identified epigenetic regulators of gene transcription during memory reconsolidation, while exploring other potential epigenetic modifications that may also be involved, and expand on how these epigenetic modifications may be precisely and temporally controlled by important signaling cascades critical to the reconsolidation process. Finally, we explore the possibility that epigenetic mechanisms may serve to regulate a system or circuit level reconsolidation process and may be involved in retrieval-dependent memory updating. Hence, we propose that epigenetic mechanisms coordinate changes in neuronal gene transcription, not only during the initial memory consolidation phase, but are triggered by retrieval to regulate molecular and cellular processes during memory reconsolidation.
Collapse
Affiliation(s)
- Timothy J Jarome
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Farah D Lubin
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
| |
Collapse
|
13
|
Involvement of BDNF signaling transmission from basolateral amygdala to infralimbic prefrontal cortex in conditioned taste aversion extinction. J Neurosci 2014; 34:7302-13. [PMID: 24849362 DOI: 10.1523/jneurosci.5030-13.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin-related kinase receptor B (TrkB), play a critical role in memory extinction. However, the detailed role of BDNF in memory extinction on the basis of neural circuit has not been fully understood. Here, we aim to investigate the role of BDNF signaling circuit in mediating conditioned taste aversion (CTA) memory extinction of the rats. We found region-specific changes in BDNF gene expression during CTA extinction. CTA extinction led to increased BDNF gene expression in the basolateral amygdala (BLA) and infralimbic prefrontal cortex (IL) but not in the central amygdaloid nucleus (CeA) and hippocampus (HIP). Moreover, blocking BDNF signaling or exogenous microinjection of BDNF into the BLA or IL could disrupt or enhance CTA extinction, which suggested that BDNF signaling in the BLA and IL is necessary and sufficient for CTA extinction. Interestingly, we found that microinjection of BDNF-neutralizing antibody into the BLA could abolish the extinction training-induced BDNF mRNA level increase in the IL, but not vice versa, demonstrating that BDNF signaling is transmitted from the BLA to IL during extinction. Finally, the accelerated extinction learning by infusion of exogenous BDNF in the BLA could also be blocked by IL infusion of BDNF-neutralizing antibody rather than vice versa, indicating that the IL, but not BLA, is the primary action site of BDNF in CTA extinction. Together, these data suggest that BLA-IL circuit regulates CTA memory extinction by identifying BDNF as a key regulator.
Collapse
|
14
|
Intranigral lipopolysaccharide induced anxiety and depression by altered BDNF mRNA expression in rat hippocampus. Prog Neuropsychopharmacol Biol Psychiatry 2014; 51:126-32. [PMID: 24508447 DOI: 10.1016/j.pnpbp.2014.01.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 01/15/2014] [Accepted: 01/26/2014] [Indexed: 01/15/2023]
Abstract
It is known that lipopolysaccharide (LPS) treatment induces neuroinflammation and memory deterioration. One of the mechanisms may be the interference with brain-derived neurotrophic factor (BDNF) gene expression and function. Lipopolysaccharide (3 μg/kg and 10 μg/kg) was unilaterally injected into the substantia nigra of adult male Wistar rats. Pergolide-induced rotational behavior test was employed to validate unilateral damage to the dopamine nigrostriatal neurons. Anxiety-depression-like behaviors were studied by means of elevated plus-maze task and forced swimming test, as animal models of anxiety and depression. Rats given LPS exhibited the following: decrease of the percentage of the time spent and the number of entries in the open arm within elevated plus-maze test and decrease of swimming and increase of immobility times within forced swimming test. In addition, these behaviors are associated with decreased BDNF mRNA expression in rat hippocampus. Taken together, these data indicate that intranigral LPS infusion influences the induction of BDNF mRNA expression within hippocampus which contributes to observed behavioral responses in rats, with relevance for Parkinson's disease conditions.
Collapse
|
15
|
Wang Y, Feng Y, Fu Q, Li L. Panax notoginsenoside Rb1 ameliorates Alzheimer's disease by upregulating brain-derived neurotrophic factor and downregulating Tau protein expression. Exp Ther Med 2013; 6:826-830. [PMID: 24137274 PMCID: PMC3786787 DOI: 10.3892/etm.2013.1215] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 06/26/2013] [Indexed: 12/20/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder and the main cause of dementia. Panax notoginsenoside Rb1 (PNRb1), which is also known as (3β,12β)-20-[(6-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy]-12-hydroxydammar-24-en-3-yl 2-O-β-D-glucopyranosyl-β-D-glucopyranoside and is the main active component of the plant Panax notoginseng, is effective in treating AD. However, the mechanisms of PNRb1 remain unknown. In the present study, rat brain tissue sections were pretreated with PNRb1 and then induced by okadaic acid to establish brain slice models of AD. The results of qPCR and immunoblot analyses demonstrated that PNRb1 suppressed the protein expression of phosphorylated Tau and upregulated the expression levels of brain-derived neurotrophic factor (BDNF). These results suggest that PNRb1 is able to upregulate the protein level of BDNF and downregulate Tau protein phosphorylation in AD.
Collapse
Affiliation(s)
- Yu Wang
- Department of Neurology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110015, P.R. China
| | | | | | | |
Collapse
|
16
|
London A, Cohen M, Schwartz M. Microglia and monocyte-derived macrophages: functionally distinct populations that act in concert in CNS plasticity and repair. Front Cell Neurosci 2013; 7:34. [PMID: 23596391 PMCID: PMC3625831 DOI: 10.3389/fncel.2013.00034] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 03/18/2013] [Indexed: 11/25/2022] Open
Abstract
Functional macrophage heterogeneity is recognized outside the central nervous system (CNS), where alternatively activated macrophages can perform immune-resolving functions. Such functional heterogeneity was largely ignored in the CNS, with respect to the resident microglia and the myeloid-derived cells recruited from the blood following injury or disease, previously defined as blood-derived microglia; both were indistinguishably perceived detrimental. Our studies have led us to view the myeloid-derived infiltrating cells as functionally distinct from the resident microglia, and accordingly, to name them monocyte-derived macrophages (mo-MΦ). Although microglia perform various maintenance and protective roles, under certain conditions when they can no longer provide protection, mo-MΦ are recruited to the damaged CNS; there, they act not as microglial replacements but rather assistant cells, providing activities that cannot be timely performed by the resident cells. Here, we focus on the functional heterogeneity of microglia/mo-MΦ, emphasizing that, as opposed to the mo-MΦ, microglia often fail to timely acquire the phenotype essential for CNS repair.
Collapse
Affiliation(s)
- Anat London
- Department of Neurobiology, Weizmann Institute of Science Rehovot, Israel
| | | | | |
Collapse
|