RESUMO
In people with multiple sclerosis (MS), newborn and surviving oligodendrocytes (OLs) can contribute to remyelination, however, current therapies are unable to enhance or sustain endogenous repair. Low intensity repetitive transcranial magnetic stimulation (LI-rTMS), delivered as an intermittent theta burst stimulation (iTBS), increases the survival and maturation of newborn OLs in the healthy adult mouse cortex, but it is unclear whether LI-rTMS can promote remyelination. To examine this possibility, we fluorescently labelled oligodendrocyte progenitor cells (OPCs; Pdgfrα-CreER transgenic mice) or mature OLs (Plp-CreER transgenic mice) in the adult mouse brain and traced the fate of each cell population over time. Daily sessions of iTBS (600 pulses; 120 mT), delivered during cuprizone (CPZ) feeding, did not alter new or pre-existing OL survival but increased the number of myelin internodes elaborated by new OLs in the primary motor cortex (M1). This resulted in each new M1 OL producing ~ 471 µm more myelin. When LI-rTMS was delivered after CPZ withdrawal (during remyelination), it significantly increased the length of the internodes elaborated by new M1 and callosal OLs, increased the number of surviving OLs that supported internodes in the corpus callosum (CC), and increased the proportion of axons that were myelinated. The ability of LI-rTMS to modify cortical neuronal activity and the behaviour of new and surviving OLs, suggests that it may be a suitable adjunct intervention to enhance remyelination in people with MS.
Assuntos
Cuprizona , Doenças Desmielinizantes , Bainha de Mielina , Oligodendroglia , Remielinização , Estimulação Magnética Transcraniana , Animais , Estimulação Magnética Transcraniana/métodos , Oligodendroglia/metabolismo , Doenças Desmielinizantes/terapia , Doenças Desmielinizantes/induzido quimicamente , Doenças Desmielinizantes/patologia , Camundongos , Bainha de Mielina/metabolismo , Modelos Animais de Doenças , Camundongos Transgênicos , Córtex Motor/patologia , Córtex Motor/metabolismo , Sobrevivência Celular , Camundongos Endogâmicos C57BL , Esclerose Múltipla/terapia , Esclerose Múltipla/patologiaRESUMO
During cortical development and throughout adulthood, oligodendrocytes add myelin internodes to glutamatergic projection neurons and GABAergic inhibitory neurons. In addition to directing node of Ranvier formation, to enable saltatory conduction and influence action potential transit time, oligodendrocytes support axon health by communicating with axons via the periaxonal space and providing metabolic support that is particularly critical for healthy ageing. In this review we outline the timing of oligodendrogenesis in the developing mouse and human cortex and describe the important role that oligodendrocytes play in sustaining and modulating neuronal function. We also provide insight into the known and speculative impact that myelination has on cortical axons and their associated circuits during the developmental critical periods and throughout life, particularly highlighting their life-long role in learning and remembering.
Assuntos
Córtex Cerebelar/crescimento & desenvolvimento , Bainha de Mielina/fisiologia , Plasticidade Neuronal/fisiologia , Oligodendroglia/fisiologia , Animais , Humanos , CamundongosRESUMO
Primary cilia are small microtubule-based organelles capable of transducing signals from growth factor receptors embedded in the cilia membrane. Developmentally, oligodendrocyte progenitor cells (OPCs) express genes associated with primary cilia assembly, disassembly, and signaling, however, the importance of primary cilia for adult myelination has not been explored. We show that OPCs are ciliated in vitro and in vivo, and that they disassemble their primary cilia as they progress through the cell cycle. OPC primary cilia are also disassembled as OPCs differentiate into oligodendrocytes. When kinesin family member 3a (Kif3a), a gene critical for primary cilium assembly, was conditionally deleted from adult OPCs in vivo (Pdgfrα-CreER™:: Kif3a fl/fl transgenic mice), OPCs failed to assemble primary cilia. Kif3a-deletion was also associated with reduced OPC proliferation and oligodendrogenesis in the corpus callosum and motor cortex and a progressive impairment of fine motor coordination.
Assuntos
Células-Tronco Adultas , Células Precursoras de Oligodendrócitos , Animais , Diferenciação Celular , Cílios , Cinesinas/genética , Camundongos , Camundongos Transgênicos , OligodendrogliaRESUMO
Myelin and axon losses are associated with cognitive decline in healthy ageing but are worse in people diagnosed with tauopathy. To determine whether tauopathy is also associated with enhanced myelin plasticity, we evaluated the behaviour of OPCs in mice that expressed a human pathological variant of microtubule-associated protein tau (MAPTP301S ). By 6 months of age (P180), MAPTP301S mice overexpressed hyperphosphorylated tau and had developed reactive gliosis in the hippocampus but had not developed overt locomotor or memory impairment. By performing cre-lox lineage tracing of adult OPCs, we determined that the number of newborn oligodendrocytes added to the hippocampus, entorhinal cortex and fimbria was equivalent in control and MAPTP301S mice prior to P150. However, between P150 and P180, significantly more new oligodendrocytes were added to these regions in the MAPTP301S mouse brain. This large increase in new oligodendrocyte number was not the result of increased OPC proliferation, nor did it alter oligodendrocyte density in the hippocampus, entorhinal cortex or fimbria, which was equivalent in P180 wild-type and MAPTP301S mice. Furthermore, the proportion of hippocampal and fimbria axons with myelin was unaffected by tauopathy. However, the proportion of myelinated axons that were ensheathed by immature myelin internodes was significantly increased in the hippocampus and fimbria of P180 MAPTP301S mice, when compared with their wild-type littermates. These data suggest that MAPTP301S transgenic mice experience significant oligodendrocyte turnover, with newborn oligodendrocytes compensating for myelin loss early in the development of tauopathy.
Assuntos
Tauopatias , Substância Branca , Animais , Modelos Animais de Doenças , Hipocampo/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Oligodendroglia/metabolismo , Proteínas tau/genética , Proteínas tau/metabolismoRESUMO
In Alzheimer's disease, amyloid plaque formation is associated with the focal death of oligodendrocytes and soluble amyloid ß impairs the survival of oligodendrocytes in vitro. However, the response of oligodendrocyte progenitor cells (OPCs) to early amyloid pathology remains unclear. To explore this, we performed a histological, electrophysiological, and behavioral characterization of transgenic mice expressing a pathological form of human amyloid precursor protein (APP), containing three single point mutations associated with the development of familial Alzheimer's disease (PDGFB-APPSw.Ind , also known as J20 mice). PDGFB-APPSw.Ind transgenic mice had impaired survival from weaning, were hyperactive by 2 months of age, and developed amyloid plaques by 6 months of age, however, their spatial memory remained intact over this time course. Hippocampal OPC density was normal in P60-P180 PDGFB-APPSw.Ind transgenic mice and, by performing whole-cell patch-clamp electrophysiology, we found that their membrane properties, including their response to kainate (100 µM), were largely normal. However, by P100, the response of hippocampal OPCs to GABA was elevated in PDGFB-APPSw.Ind transgenic mice. We also found that the nodes of Ranvier were shorter, the paranodes longer, and the myelin thicker for hippocampal axons in young adult PDGFB-APPSw.Ind transgenic mice compared with wildtype littermates. Additionally, oligodendrogenesis was normal in young adulthood, but increased in the hippocampus, entorhinal cortex, and fimbria of PDGFB-APPSw.Ind transgenic mice as pathology developed. As the new oligodendrocytes were not associated with a change in total oligodendrocyte number, these cells are likely required for cell replacement.
Assuntos
Amiloidose/patologia , Encéfalo/patologia , Bainha de Mielina/patologia , Neurogênese/fisiologia , Oligodendroglia/patologia , Fatores Etários , Amiloidose/genética , Animais , Feminino , Humanos , Masculino , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Bainha de Mielina/genéticaRESUMO
Neuronal activity is a potent extrinsic regulator of oligodendrocyte generation and central nervous system myelination. Clinically, repetitive transcranial magnetic stimulation (rTMS) is delivered to noninvasively modulate neuronal activity; however, the ability of rTMS to facilitate adaptive myelination has not been explored. By performing cre-lox lineage tracing, to follow the fate of oligodendrocyte progenitor cells in the adult mouse brain, we determined that low intensity rTMS (LI-rTMS), administered as an intermittent theta burst stimulation, but not as a continuous theta burst or 10 Hz stimulation, increased the number of newborn oligodendrocytes in the adult mouse cortex. LI-rTMS did not alter oligodendrogenesis per se, but instead increased cell survival and enhanced myelination. These data suggest that LI-rTMS can be used to noninvasively promote myelin addition to the brain, which has potential implications for the treatment of demyelinating diseases such as multiple sclerosis.
Assuntos
Encéfalo/fisiologia , Oligodendroglia/fisiologia , Estimulação Magnética Transcraniana , Animais , Encéfalo/citologia , Tamanho Celular , Sobrevivência Celular/fisiologia , Feminino , Masculino , Camundongos Transgênicos , Neurogênese/fisiologia , Oligodendroglia/citologia , Distribuição Aleatória , Estimulação Magnética Transcraniana/métodosRESUMO
The amyloid-ß precursor protein (APP) is a transmembrane protein that is widely expressed within the central nervous system (CNS). While the pathogenic dysfunction of this protein has been extensively studied in the context of Alzheimer's disease, its normal function is poorly understood, and reports have often appeared contradictory. In this study we have examined the role of APP in regulating neurogenesis in the adult mouse brain by comparing neural stem cell proliferation, as well as new neuron number and morphology between APP knockout mice and C57bl6 controls. Short-term EdU administration revealed that the number of proliferating EdU+ neural progenitor cells and the number of PSA-NCAM+ neuroblasts produced in the SVZ and dentate gyrus were not affected by the life-long absence of APP. However, by labelling newborn cells with EdU and then following their fate over-time, we determined that ~48% more newly generated EdU+ NeuN+ neurons accumulated in the granule cell layer of the olfactory bulb and ~57% more in the dentate gyrus of young adult APP knockout mice relative to C57bl6 controls. Furthermore, proportionally fewer of the adult-born olfactory bulb granule neurons were calretinin+. To determine whether APP was having an effect on neuronal maturation, we administered tamoxifen to young adult Nestin-CreERT2::Rosa26-YFP and Nestin-CreERT2::Rosa26-YFP::APP-knockout mice, fluorescently labelling ~80% of newborn (EdU+) NeuN+ dentate granule neurons formed between P75 and P105. Our analysis of their morphology revealed that neurons added to the hippocampus of APP knockout mice have shorter dendritic arbors and only half the number of branch points as those generated in C57bl6 mice. We conclude that APP reduces the survival of newborn neurons in the olfactory bulb and hippocampus, but that it does not influence all neuronal subtypes equally. Additionally, APP influences dentate granule neuron maturation, acting as a robust regulator of dendritic extension and arborisation.
Assuntos
Precursor de Proteína beta-Amiloide/metabolismo , Hipocampo/metabolismo , Células-Tronco Neurais/metabolismo , Neurogênese , Bulbo Olfatório/metabolismo , Precursor de Proteína beta-Amiloide/genética , Animais , Células Cultivadas , Hipocampo/citologia , Hipocampo/crescimento & desenvolvimento , Camundongos , Camundongos Endogâmicos C57BL , Células-Tronco Neurais/citologia , Bulbo Olfatório/citologia , Bulbo Olfatório/crescimento & desenvolvimentoRESUMO
BACKGROUND: Multiple sclerosis (MS) is a chronic neurological condition and the leading cause of non-traumatic disability in young adults. MS pathogenesis leads to the death of oligodendrocytes, demyelination, and progressive central nervous system neurodegeneration. Endogenous remyelination occurs in people with MS (PwMS) but is insufficient to repair the damage. Our preclinical studies in mice indicate that endogenous remyelination can be supported by the delivery of repetitive transcranial magnetic stimulation (rTMS). Our phase I trial concluded that 20 sessions of rTMS, delivered over 5 weeks, are safe and feasible for PwMS. This phase II trial aims to investigate the safety and preliminary efficacy of rTMS for PwMS. METHODS: Participants must be aged 18-65 years, diagnosed with MS by a neurologist, stable and relapse free for 6 months, have an Extended Disability Status Scale (EDSS) between 1.5 and 6 (inclusive), willing to travel to a study site every weekday for 4 consecutive weeks, and able to provide informed consent and access the internet. Participants from multiple centres will be randomised 2:1 (rTMS to sham) stratified by sex. The intervention will be delivered with a Magstim Rapid2 stimulator device and circular 90-mm coil or MagVenture MagPro stimulator device with C100 circular coil, positioned to stimulate a broad area including frontal and parietal cortices. For the rTMS group, pulse intensity will be set at 18% (MagVenture) or 25% (Magstim) of maximum stimulator output (MSO), and rTMS applied as intermittent theta burst stimulation (iTBS) (~ 3 min per side; 600 pulses). For the sham group, the procedure will be the same, but the intensity is set at 0%. Each participant will attend 20 intervention sessions over a maximum of 5 weeks. Outcome measures include MS Functional Composite Score (primary), Fatigue Severity Scale, Hospital Anxiety and Depression Scale, Quality of Life, and Pittsburgh Sleep Quality Index/Numeric Rating Scale and adverse events (secondary) and advanced MRI metrics (tertiary). Outcomes will be measured at baseline and after completing the intervention. DISCUSSION: This study will determine if rTMS can improve functional outcomes or other MS symptoms and determine whether rTMS has the potential to promote remyelination in PwMS. TRIAL REGISTRATION: Registered with Australian New Zealand Clinical Trials Registry, 20 January 2022; ACTRN12622000064707.
Assuntos
Ensaios Clínicos Fase II como Assunto , Esclerose Múltipla , Estimulação Magnética Transcraniana , Humanos , Estimulação Magnética Transcraniana/métodos , Estimulação Magnética Transcraniana/efeitos adversos , Adulto , Pessoa de Meia-Idade , Esclerose Múltipla/terapia , Resultado do Tratamento , Masculino , Feminino , Adolescente , Adulto Jovem , Idoso , Estudos Multicêntricos como Assunto , Ensaios Clínicos Controlados Aleatórios como Assunto , Fatores de Tempo , Avaliação da Deficiência , Qualidade de VidaRESUMO
Background: Low-intensity repetitive transcranial magnetic stimulation (rTMS), delivered as a daily intermittent theta burst stimulation (iTBS) for four consecutive weeks, increased the number of new oligodendrocytes in the adult mouse brain. Therefore, rTMS holds potential as a remyelinating intervention for people with multiple sclerosis (MS). Objective: Primarily to determine the safety and tolerability of our rTMS protocol in people with MS. Secondary objectives include feasibility, blinding and an exploration of changes in magnetic resonance imaging (MRI) metrics, patient-reported outcome measures (PROMs) and cognitive or motor performance. Methods: A randomised (2:1), placebo controlled, single blind, parallel group, phase 1 trial of 20 rTMS sessions (600 iTBS pulses per hemisphere; 25% maximum stimulator output), delivered over 4-5 weeks. Twenty participants were randomly assigned to 'sham' (n = 7) or active rTMS (n = 13), with the coil positioned at 90° or 0°, respectively. Results: Five adverse events (AEs) including one serious AE reported. None were related to treatment. Protocol compliance was high (85%) and blinding successful. Within participant MRI metrics, PROMs and cognitive or motor performance were unchanged over time. Conclusion: Twenty sessions of rTMS is safe and well tolerated in a small group of people with MS. The study protocol and procedures are feasible. Improvement of sham is warranted before further investigating safety and efficacy.
RESUMO
BACKGROUND: Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease, characterised by oligodendrocyte death and demyelination. Oligodendrocyte progenitor cells can differentiate into new replacement oligodendrocytes; however, remyelination is insufficient to protect neurons from degeneration in people with MS. We previously reported that 4 weeks of daily low-intensity repetitive transcranial magnetic stimulation (rTMS) in an intermittent theta-burst stimulation (iTBS) pattern increased the number of new myelinating oligodendrocytes in healthy adult mice. This study translates this rTMS protocol and aims to determine its safety and tolerability for people living with MS. We will also perform magnetic resonance imaging (MRI) and symptom assessments as preliminary indicators of myelin addition following rTMS. METHODS: Participants (N = 30, aged 18-65 years) will have a diagnosis of relapsing-remitting or secondary progressive MS. ≤2 weeks before the intervention, eligible, consenting participants will complete a physical exam, baseline brain MRI scan and participant-reported MS symptom assessments [questionnaires: Fatigue Severity Scale, Quality of Life (AQoL-8D), Hospital Anxiety and Depression Scale; and smartphone-based measures of cognition (electronic symbol digit modalities test), manual dexterity (pinching test, draw a shape test) and gait (U-Turn test)]. Participants will be pseudo-randomly allocated to rTMS (n=20) or sham (placebo; n=10), stratified by sex. rTMS or sham will be delivered 5 days per week for 4 consecutive weeks (20 sessions, 6 min per day). rTMS will be applied using a 90-mm circular coil at low-intensity (25% maximum stimulator output) in an iTBS pattern. For sham, the coil will be oriented 90° to the scalp, preventing the magnetic field from stimulating the brain. Adverse events will be recorded daily. We will evaluate participant blinding after the first, 10th and final session. After the final session, participants will repeat symptom assessments and brain MRI, for comparison with baseline. Participant-reported assessments will be repeated at 4-month post-allocation follow-up. DISCUSSION: This study will determine whether this rTMS protocol is safe and tolerable for people with MS. MRI and participant-reported symptom assessments will serve as preliminary indications of rTMS efficacy for myelin addition to inform further studies. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN12619001196134 . Registered on 27 August 2019.
Assuntos
Esclerose Múltipla , Estimulação Magnética Transcraniana , Adolescente , Adulto , Idoso , Austrália , Encéfalo , Humanos , Pessoa de Meia-Idade , Esclerose Múltipla/terapia , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Estimulação Magnética Transcraniana/efeitos adversos , Resultado do Tratamento , Adulto JovemRESUMO
Oligodendrocyte progenitor cells (OPCs) express protocadherin 15 (Pcdh15), a member of the cadherin superfamily of transmembrane proteins. Little is known about the function of Pcdh15 in the central nervous system (CNS), however, Pcdh15 expression can predict glioma aggression and promote the separation of embryonic human OPCs immediately following a cell division. Herein, we show that Pcdh15 knockdown significantly increases extracellular signal-related kinase (ERK) phosphorylation and activation to enhance OPC proliferation in vitro. Furthermore, Pcdh15 knockdown elevates Cdc42-Arp2/3 signalling and impairs actin kinetics, reducing the frequency of lamellipodial extrusion and slowing filopodial withdrawal. Pcdh15 knockdown also reduces the number of processes supported by each OPC and new process generation. Our data indicate that Pcdh15 is a critical regulator of OPC proliferation and process motility, behaviours that characterise the function of these cells in the healthy CNS, and provide mechanistic insight into the role that Pcdh15 might play in glioma progression.
Assuntos
Glioma , Células Precursoras de Oligodendrócitos , Proteínas Relacionadas a Caderinas , Proliferação de Células , Glioma/genética , Glioma/metabolismo , Humanos , Oligodendroglia , ProtocaderinasRESUMO
Central nervous system myelination increases action potential conduction velocity. However, it is unclear how myelination is coordinated to ensure the temporally precise arrival of action potentials and facilitate information processing within cortical and associative circuits. Here, we show that myelin sheaths, supported by mature oligodendrocytes, remain plastic in the adult mouse brain and undergo subtle structural modifications to influence action potential conduction velocity. Repetitive transcranial magnetic stimulation and spatial learning, two stimuli that modify neuronal activity, alter the length of the nodes of Ranvier and the size of the periaxonal space within active brain regions. This change in the axon-glial configuration is independent of oligodendrogenesis and robustly alters action potential conduction velocity. Because aptitude in the spatial learning task was found to correlate with action potential conduction velocity in the fimbria-fornix pathway, modifying the axon-glial configuration may be a mechanism that facilitates learning in the adult mouse brain.
Assuntos
Potenciais de Ação/genética , Axônios/metabolismo , Encéfalo/fisiopatologia , Animais , CamundongosRESUMO
Low-density lipoprotein receptor-related protein 1 (LRP1) is a large, endocytic cell surface receptor that is highly expressed by oligodendrocyte progenitor cells (OPCs) and LRP1 expression is rapidly downregulated as OPCs differentiate into oligodendrocytes (OLs). We report that the conditional deletion of Lrp1 from adult mouse OPCs (Pdgfrα-CreER :: Lrp1 fl/fl ) increases the number of newborn, mature myelinating OLs added to the corpus callosum and motor cortex. As these additional OLs extend a normal number of internodes that are of a normal length, Lrp1-deletion increases adult myelination. OPC proliferation is also elevated following Lrp1 deletion in vivo, however, this may be a secondary, homeostatic response to increased OPC differentiation, as our in vitro experiments show that LRP1 is a direct negative regulator of OPC differentiation, not proliferation. Deleting Lrp1 from adult OPCs also increases the number of newborn mature OLs added to the corpus callosum in response to cuprizone-induced demyelination. These data suggest that the selective blockade of LRP1 function on adult OPCs may enhance myelin repair in demyelinating diseases such as multiple sclerosis.
RESUMO
Oligodendrocyte progenitor cells (OPCs) are immature cells in the central nervous system (CNS) that can rapidly respond to changes within their environment by modulating their proliferation, motility and differentiation. OPCs differentiate into myelinating oligodendrocytes throughout life, and both cell types have been implicated in maintaining and modulating neuronal function to affect motor performance, cognition and emotional state. However, questions remain about the mechanisms employed by OPCs and oligodendrocytes to regulate circuit function, including whether OPCs can only influence circuits through their generation of new oligodendrocytes, or can play other regulatory roles within the CNS. In this review, we detail the molecular and cellular mechanisms that allow OPCs, newborn oligodendrocytes and pre-existing oligodendrocytes to regulate circuit function and ultimately influence behavioral outcomes.
RESUMO
Transcranial magnetic stimulation (TMS) is widely used in the clinic, and while it has a direct effect on neuronal excitability, the beneficial effects experienced by patients are likely to include the indirect activation of other cell types. Research conducted over the past two decades has made it increasingly clear that a population of non-neuronal cells, collectively known as glia, respond to and facilitate neuronal signaling. Each glial cell type has the ability to respond to electrical activity directly or indirectly, making them likely cellular effectors of TMS. TMS has been shown to enhance adult neural stem and progenitor cell (NSPC) proliferation, but the effect on cell survival and differentiation is less certain. Furthermore there is limited information regarding the response of astrocytes and microglia to TMS, and a complete paucity of data relating to the response of oligodendrocyte-lineage cells to this treatment. However, due to the critical and yet multifaceted role of glial cells in the central nervous system (CNS), the influence that TMS has on glial cells is certainly an area that warrants careful examination.
Assuntos
Sistema Nervoso Central/citologia , Neuroglia/fisiologia , Estimulação Magnética Transcraniana , Animais , Sistema Nervoso Central/fisiologia , HumanosRESUMO
The low density lipoprotein-receptor related protein 1 (LRP1) is a large endocytic cell surface receptor that is known to interact with a variety of ligands, intracellular adaptor proteins and other cell surface receptors to regulate cellular behaviours ranging from proliferation to cell fate specification, migration, axon guidance, and lipid metabolism. A number of studies have demonstrated that LRP1 is expressed in the brain, yet it is unclear which central nervous system cell types express LRP1 during development and in adulthood. Herein we undertake a detailed study of LRP1 expression within the mouse brain and spinal cord, examining a number of developmental stages ranging from embryonic day 13.5 to postnatal day 60. We report that LRP1 expression in the brain peaks during postnatal development. On a cellular level, LRP1 is expressed by radial glia, neuroblasts, microglia, oligodendrocyte progenitor cells (OPCs), astrocytes and neurons, with the exception of parvalbumin+ interneurons in the cortex. Most cell populations exhibit stable expression of LRP1 throughout development; however, the proportion of OPCs that express LRP1 increases significantly from ~69% at E15.5 to ~99% in adulthood. We also report that LRP1 expression is rapidly lost as OPCs differentiate, and is absent from all oligodendrocytes, including newborn oligodendrocytes. While LRP1 function has been primarily examined in mature neurons, these expression data suggest it plays a more critical role in glial cell regulation-where expression levels are much higher.
Assuntos
Sistema Nervoso Central/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Neuroglia/metabolismo , Neurônios/metabolismo , Receptores de LDL/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Animais , Células Cultivadas , Feminino , Proteína-1 Relacionada a Receptor de Lipoproteína de Baixa Densidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neuroglia/citologia , Neurônios/citologiaRESUMO
In the central nervous system (CNS) platelet derived growth factor receptor alpha (PDGFRα) is expressed exclusively by oligodendrocyte progenitor cells (OPCs), making the Pdgfrα promoter an ideal tool for directing transgene expression in this cell type. Two Pdgfrα-CreERT2 mouse lines have been generated for this purpose which, when crossed with cre-sensitive reporter mice, allow the temporally restricted labelling of OPCs for lineage-tracing studies. These mice have also been used to achieve the deletion of CNS-specific genes from OPCs. However the ability of Pdgfrα-CreERT2 mice to induce cre-mediated recombination in PDGFRα+ cell populations located outside of the CNS has not been examined. Herein we quantify the proportion of PDGFRα+ cells that become YFP-labelled following Tamoxifen administration to adult Pdgfrα-CreERT2::Rosa26-YFP transgenic mice. We report that the vast majority (>90%) of PDGFRα+ OPCs in the CNS, and a significant proportion of PDGFRα+ stromal cells within the bone marrow (~38%) undergo recombination and become YFP-labelled. However, only a small proportion of the PDGFRα+ cell populations found in the sciatic nerve, adrenal gland, pituitary gland, heart, gastrocnemius muscle, kidney, lung, liver or intestine become YFP-labelled. These data suggest that Pdgfrα-CreERT2 transgenic mice can be used to achieve robust recombination in OPCs, while having a minimal effect on most PDGFRα+ cell populations outside of the CNS.
Assuntos
Oligodendroglia/metabolismo , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Receptores de Estrogênio/metabolismo , Recombinação Genética , Células-Tronco/metabolismo , Animais , Linhagem Celular , Linhagem da Célula/genética , Feminino , Integrases/genética , Integrases/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/genética , Receptores de Estrogênio/genética , Proteínas Recombinantes/metabolismo , Células de Schwann/metabolismo , Nervo Isquiático/citologia , Tamoxifeno/farmacologiaRESUMO
Consumption of alcohol during pregnancy can have detrimental impacts on the developing hippocampus, which can lead to deficits in learning and memory function. Although high levels of alcohol exposure can lead to severe deficits, there is a lack of research examining the effects of low levels of exposure. This study used a rat model to determine if prenatal exposure to chronic low dose ethanol would result in deficits in learning and memory performance and if this was associated with morphological changes within the hippocampus. Sprague Dawley rats were fed a liquid diet containing 6% (vol/vol) ethanol (EtOH) or an isocaloric control diet throughout gestation. Male and Female offspring underwent behavioural testing at 8 (Adult) or 15 months (Aged) of age. Brains from these animals were collected for stereological analysis of pyramidal neuron number and dendritic morphology within the CA1 and CA3 regions of the dorsal hippocampus. Prenatal ethanol exposed animals did not differ in spatial learning or memory performance in the Morris water maze or Y maze tasks compared to Control offspring. There was no effect of prenatal ethanol exposure on pyramidal cell number or density within the dorsal hippocampus. Overall, this study indicates that chronic low dose prenatal ethanol exposure in this model does not have long term detrimental effects on pyramidal cells within the dorsal hippocampus or impair spatial learning and memory performance.
Assuntos
Etanol/toxicidade , Hipocampo/efeitos dos fármacos , Aprendizagem em Labirinto , Memória , Efeitos Tardios da Exposição Pré-Natal , Animais , Etanol/administração & dosagem , Feminino , Hipocampo/citologia , Hipocampo/embriologia , Hipocampo/crescimento & desenvolvimento , Masculino , Gravidez , Células Piramidais/citologia , Células Piramidais/efeitos dos fármacos , Ratos , Ratos Sprague-DawleyRESUMO
Prenatal exposure to high levels of alcohol is strongly associated with poor cognitive outcomes particularly in relation to learning and memory. It is also becoming more evident that anxiety disorders and anxiety-like behaviour can be associated with prenatal alcohol exposure. This study used a rat model to determine if prenatal exposure to a relatively small amount of alcohol would result in anxiety-like behaviour and to determine if this was associated with morphological changes in the basolateral amygdala. Pregnant Sprague Dawley rats were fed a liquid diet containing either no alcohol (Control) or 6% (vol/vol) ethanol (EtOH) throughout gestation. Male and Female offspring underwent behavioural testing at 8 months (Adult) or 15 months (Aged) of age. Rats were perfusion fixed and brains were collected at the end of behavioural testing for morphological analysis of pyramidal neuron number and dendritic morphology within the basolateral amygdala. EtOH exposed offspring displayed anxiety-like behaviour in the elevated plus maze, holeboard and emergence tests. Although sexually dimorphic behaviour was apparent, sex did not impact anxiety-like behaviour induced by prenatal alcohol exposure. This increase in anxiety - like behaviour could not be attributed to a change in pyramidal cell number within the BLA but rather was associated with an increase in dendritic spines along the apical dendrite which is indicative of an increase in synaptic connectivity and activity within these neurons. This study is the first to link increases in anxiety like behaviour to structural changes within the basolateral amygdala in a model of prenatal ethanol exposure. In addition, this study has shown that exposure to even a relatively small amount of alcohol during development leads to long term alterations in anxiety-like behaviour.