ABSTRACT
Introduction: Significant neurologic morbidity is caused by pediatric cerebrospinal fluid (CSF) shunt infections. The underlying mechanisms leading to impaired school performance and increased risk of seizures are unknown, however, a better understanding of these mechanisms may allow us to temper their consequences. Recent evidence has demonstrated important roles for complement proteins in neurodevelopment and neuroinflammation. Methods: We examined complement activation throughout Staphylococcus epidermidis (S. epidermidis) central nervous system (CNS) catheter infection. In addition, based on accumulating evidence that C3 plays a role in synaptic pruning in other neuroinflammatory states we determined if C3 and downstream C5 led to alterations in synaptic protein levels. Using our murine model of S. epidermidis catheter infection we quantified levels of the complement components C1q, Factor B, MASP2, C3, and C5 over the course of infection along with bacterial burdens. Results: We found that MASP2 predominated early in catheter infection, but that Factor B was elevated at intermediate time points. Unexpectedly C1q was elevated at late timepoints when bacterial burdens were low or undetectable. Based on these findings and the wealth of information regarding the emerging roles of C1q in the CNS, this suggests functions beyond pathogen elimination during S. epidermidis CNS catheter infection. To identify if C3 impacted synaptic protein levels we performed synaptosome isolation and quantified levels of VGLUT1 and PSD95 as well as pre-, post- and total synaptic puncta in cortical layer V of C3 knockout (KO) and wild type mice. We also used C5 KO and wild type mice to determine if there was any difference in pre-, post- and total synaptic puncta. Discussion: Neither C3 nor C5 impacted synaptic protein abundance. These findings suggest that chronic elevations in C1q in the brain that persist once CNS catheter infection has resolved may be modulating disease sequalae.
Subject(s)
Catheter-Related Infections , Complement C1q , Staphylococcal Infections , Staphylococcus epidermidis , Animals , Staphylococcus epidermidis/physiology , Mice , Complement C1q/metabolism , Staphylococcal Infections/immunology , Staphylococcal Infections/microbiology , Catheter-Related Infections/microbiology , Catheter-Related Infections/immunology , Disease Models, Animal , Mice, Inbred C57BL , Male , Complement Activation , Female , Chronic Disease , Mice, KnockoutABSTRACT
Fetal alcohol spectrum disorders are one of the leading causes of developmental abnormalities worldwide. Maternal consumption of alcohol during pregnancy leads to a diverse range of cognitive and neurobehavioral deficits. Although moderate-to-heavy levels of prenatal alcohol exposure (PAE) have been associated with adverse offspring outcomes, there is limited data on the consequences of chronic low-level PAE. Here, we use a model of maternal voluntary alcohol consumption throughout gestation in a mouse model to investigate the effects of PAE on behavioral phenotypes during late adolescence and early adulthood in male and female offspring. Body composition was measured by dual-energy X-ray absorptiometry. Baseline behaviors, including feeding, drinking, and movement, were examined by performing home cage monitoring studies. The impact of PAE on motor function, motor skill learning, hyperactivity, acoustic reactivity, and sensorimotor gating was investigated by performing a battery of behavioral tests. PAE was found to be associated with altered body composition. No differences in overall movement, food, or water consumption were observed between control and PAE mice. Although PAE offspring of both sexes exhibited deficits in motor skill learning, no differences were observed in basic motor skills such as grip strength and motor coordination. PAE females exhibited a hyperactive phenotype in a novel environment. PAE mice exhibited increased reactivity to acoustic stimuli, and PAE females showed disrupted short-term habituation. Sensorimotor gating was not altered in PAE mice. Collectively, our data show that chronic low-level exposure to alcohol in utero results in behavioral impairments.
Subject(s)
Fetal Alcohol Spectrum Disorders , Prenatal Exposure Delayed Effects , Humans , Mice , Pregnancy , Animals , Female , Male , Learning , Ethanol/toxicity , PhenotypeABSTRACT
Motor skill learning induces changes in synaptic structure and function in the primary motor cortex (M1). In the fragile X syndrome (FXS) mouse model an impairment in motor skill learning and associated formation of new dendritic spines was previously reported. However, whether modulation of synaptic strength through trafficking of AMPA receptors (AMPARs) with motor skill training is impaired in FXS is not known. Here, we performed in vivo imaging of a tagged AMPA receptor subunit, GluA2, in layer (L)2/3 neurons in the primary motor cortex of wild-type (WT) and Fmr1 knock-out (KO) male mice at different stages of learning a single forelimb-reaching task. Surprisingly, in the Fmr1 KO mice, despite impairments in learning there was no deficit in motor skill training-induced spine formation. However, the gradual accumulation of GluA2 in WT stable spines, which persists after training is completed and past the phase of spine number normalization, is absent in the Fmr1 KO mouse. These results demonstrate that motor skill learning not only reorganizes circuits through formation of new synapses, but also strengthens existing synapses through accumulation of AMPA receptors and GluA2 changes are better associated with learning than new spine formation.
Subject(s)
Fragile X Syndrome , Motor Skills , Mice , Animals , Male , Motor Skills/physiology , Receptors, AMPA , Fragile X Mental Retardation Protein/genetics , Dendritic Spines/physiology , Learning/physiology , Mice, Knockout , Disease Models, Animal , Fragile X Syndrome/genetics , Synapses/physiologyABSTRACT
Fragile X syndrome (FXS), the most prevalent heritable form of intellectual disability, is caused by the transcriptional silencing of the FMR1 gene. While neuronal contribution to FXS has been extensively studied in both animal and human-based models of FXS, the roles of astrocytes, a type of glial cells in the brain, are largely unknown. Here, we generated a human-based FXS model via differentiation of astrocytes from human-induced pluripotent stem cells (hiPSCs) and human embryonic stem cells (hESCs) and characterized their development, function, and proteomic profiles. We identified shortened cell cycle, enhanced Ca2+ signaling, impaired sterol biosynthesis, and pervasive alterations in the proteome of FXS astrocytes. Our work identified astrocytic impairments that could contribute to the pathogenesis of FXS and highlight astrocytes as a novel therapeutic target for FXS treatment.
Subject(s)
Fragile X Syndrome , Animals , Humans , Fragile X Syndrome/genetics , Fragile X Syndrome/metabolism , Astrocytes/metabolism , Proteomics , Fragile X Mental Retardation Protein/genetics , Fragile X Mental Retardation Protein/metabolism , Cell Cycle , Cholesterol/metabolismABSTRACT
To fully understand the cellular physiology of neurons and glia in behaving animals, it is necessary to visualize their morphology and record their activity in vivo in behaving mice. This paper describes a method for the implantation of a chronic cranial window to allow for the longitudinal imaging of brain cells in awake, head-restrained mice. In combination with genetic strategies and viral injections, it is possible to label specific cells and regions of interest with structural or physiological markers. This protocol demonstrates how to combine viral injections to label neurons in the vicinity of GCaMP6-expressing astrocytes in the cortex for simultaneous imaging of both cells through a cranial window. Multiphoton imaging of the same cells can be performed for days, weeks, or months in awake, behaving animals. This approach provides researchers with a method for viewing cellular dynamics in real time and can be applied to answer a number of questions in neuroscience.
Subject(s)
Skull , Wakefulness , Animals , Cerebral Cortex , Diagnostic Imaging , Mice , Neurons , Skull/diagnostic imagingABSTRACT
Accumulating studies demonstrate the morphological and functional diversity of astrocytes, a subtype of glial cells in the central nervous system. Animal models are instrumental in advancing our understanding of the role of astrocytes in brain development and their contribution to neurological disease; however, substantial interspecies differences exist between rodent and human astrocytes, underscoring the importance of studying human astrocytes. Human pluripotent stem cell differentiation approaches allow the study of patient-specific astrocytes in the etiology of neurological disorders. In this review, we summarize the structural and functional properties of astrocytes, including the unique features of human astrocytes; demonstrate the necessity of the stem cell platform; and discuss how this platform has been applied to the research of neurodevelopmental and neuropsychiatric diseases.
Subject(s)
Astrocytes/pathology , Induced Pluripotent Stem Cells/pathology , Neurodevelopmental Disorders/etiology , Psychotic Disorders/etiology , Animals , Cell Differentiation , Humans , Models, Biological , Neurodevelopmental Disorders/pathology , Psychotic Disorders/pathologyABSTRACT
Following traumatic or ischemic brain injury, rapid cell death and extracellular matrix degradation lead to the formation of a cavity at the brain lesion site, which is responsible for prolonged neurological deficits and permanent disability. Transplantation of neural stem/progenitor cells (NSCs) represents a promising strategy for reconstructing the lesion cavity and promoting tissue regeneration. In particular, the promotion of neuronal migration, organization, and integration of transplanted NSCs is critical to the success of stem cell-based therapy. This is particularly important for the cerebral cortex, the most common area involved in brain injuries, because the highly organized structure of the cerebral cortex is essential to its function. Biomaterials-based strategies show some promise for conditioning the lesion site microenvironment to support transplanted stem cells, but the progress in demonstrating organized cell engraftment and integration into the brain is very limited. An effective approach to sufficiently address these challenges has not yet been developed. Here, we have implemented a digital light-processing-based 3D printer and printed hydrogel scaffolds with a designed shape, uniaxially aligned microchannels, and tunable mechanical properties. We demonstrated the capacity to achieve high shape precision to the lesion site with brain tissue-matching mechanical properties. We also established spatial control of bioactive molecule distribution within 3D printed hydrogel scaffolds. These printed hydrogel scaffolds have shown high neuro-compatibility with aligned neuronal outgrowth along with the microchannels. This study will provide a biomaterial-based approach that can serve as a protective and guidance vehicle for transplanted NSC organization and integration for brain tissue regeneration after injuries.
Subject(s)
Hydrogels , Neural Stem Cells , Neurogenesis , Printing, Three-Dimensional , Tissue ScaffoldsABSTRACT
Astrocytes, a highly heterogeneous population of glial cells, serve as essential regulators of brain development and homeostasis. The heterogeneity of astrocyte populations underlies the diversity in their functions. In addition to the typical mammalian astrocyte architecture, the cerebral cortex of humans exhibits a radial distribution of interlaminar astrocytes in the supragranular layers. These primate-specific interlaminar astrocytes are located in the superficial layer and project long processes traversing multiple layers of the cerebral cortex. However, due to the lack of accessible experimental models, their functional properties and their role in regulating neuronal circuits remain unclear. Here we modeled human interlaminar astrocytes in humanized glial chimeric mice by engrafting astrocytes differentiated from human-induced pluripotent stem cells into the mouse cortex. This model provides a novel platform for understanding neuron-glial interaction and its alterations in neurological diseases.
Subject(s)
Astrocytes/chemistry , Astrocytes/physiology , Cerebral Cortex/chemistry , Cerebral Cortex/physiology , Induced Pluripotent Stem Cells/chemistry , Induced Pluripotent Stem Cells/physiology , Adolescent , Animals , Cells, Cultured , Cerebral Cortex/cytology , Female , Humans , Male , Mice , Mice, 129 Strain , Mice, TransgenicABSTRACT
Motor skill training induces functional and structural changes in the primary motor cortex. New dendritic spines are formed with training and the horizontal connections in the layer II/III area of the primary motor cortex are strengthened. Here we investigated the functional synaptic properties of pyramidal neurons following motor skill training. We trained mice on a single forelimb-reaching task for five days and performed whole cell recordings from layer II/III pyramidal neurons in the forelimb representation area of the primary motor cortex in the ipsilateral (untrained) and contralateral (trained) hemispheres in acute brain slices. Success rate in the forelimb-reaching task rapidly improved over the first 3 days and stabilized on subsequent days. After five days of training, a time at which learning has peaked and synaptic strengthening with field potential recordings show enhancement, we observed an increase in mEPSC frequency while increases in mEPSC amplitudes was only observed in 20% of the cells. Increase in excitatory synaptic properties were correlated with improved motor skill. Measurement of miniature IPSC (mIPSC) after five days of training showed no difference in either frequency or amplitude between the trained and untrained hemispheres. Our present results indicate dynamic changes in excitatory but not inhibitory synapses in M1 layer II/III pyramidal neurons at the late stages of motor skill learning.
Subject(s)
Excitatory Postsynaptic Potentials/physiology , Inhibitory Postsynaptic Potentials/physiology , Learning/physiology , Motor Cortex/physiology , Motor Skills/physiology , Synapses/physiology , Animals , Male , Mice , Mice, Inbred C57BLABSTRACT
The process of oligodendrogenesis has been relatively well delineated in the rodent brain. However, it remains unknown whether analogous developmental processes are manifested in the human brain. Here we report oligodendrogenesis in forebrain organoids, generated by using OLIG2-GFP knockin human pluripotent stem cell (hPSC) reporter lines. OLIG2/GFP exhibits distinct temporal expression patterns in ventral forebrain organoids (VFOs) versus dorsal forebrain organoids (DFOs). Interestingly, oligodendrogenesis can be induced in both VFOs and DFOs after neuronal maturation. Assembling VFOs and DFOs to generate fused forebrain organoids (FFOs) promotes oligodendroglia maturation. Furthermore, dorsally derived oligodendroglial cells outcompete ventrally derived oligodendroglia and become dominant in FFOs after long-term culture. Thus, our organoid models reveal human oligodendrogenesis with ventral and dorsal origins. These models will serve to study the phenotypic and functional differences between human ventrally and dorsally derived oligodendroglia and to reveal mechanisms of diseases associated with cortical myelin defects.
Subject(s)
Neural Stem Cells/cytology , Oligodendroglia/cytology , Organoids/cytology , Pluripotent Stem Cells/cytology , Cell Differentiation/genetics , Gene Expression Profiling/methods , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Humans , Neural Stem Cells/metabolism , Neurogenesis/genetics , Oligodendrocyte Transcription Factor 2/genetics , Oligodendrocyte Transcription Factor 2/metabolism , Oligodendroglia/metabolism , Organoids/metabolism , Pluripotent Stem Cells/metabolismABSTRACT
The developing brain is sensitive to a variety of insults. Epidemiological studies have identified prenatal exposure to infection as a risk factor for a range of neurological disorders, including autism spectrum disorder and schizophrenia. Animal models corroborate this association and have been used to probe the contribution of gene-environment interactions to the etiology of neurodevelopmental disorders. Here we review the behavior and brain phenotypes that have been characterized in MIA offspring, including the studies that have looked at the interaction between maternal immune activation and genetic risk factors for autism spectrum disorder or schizophrenia. These phenotypes include behaviors relevant to autism, schizophrenia, and other neurological disorders, alterations in brain anatomy, and structural and functional neuronal impairments. The link between maternal infection and these phenotypic changes is not fully understood, but there is increasing evidence that maternal immune activation induces prolonged immune alterations in the offspring's brain which could underlie epigenetic alterations which in turn may mediate the behavior and brain changes. These concepts will be discussed followed by a summary of the pharmacological interventions that have been tested in the maternal immune activation model.
Subject(s)
Brain/pathology , Gene-Environment Interaction , Neurodevelopmental Disorders/immunology , Pregnancy Complications, Infectious/immunology , Prenatal Exposure Delayed Effects/immunology , Animals , Autism Spectrum Disorder/immunology , Autism Spectrum Disorder/pathology , Disease Models, Animal , Female , Humans , Neurodevelopmental Disorders/pathology , Pregnancy , Pregnancy Complications, Infectious/pathology , Prenatal Exposure Delayed Effects/pathology , Schizophrenia/immunology , Schizophrenia/pathologyABSTRACT
Structural dynamics of dendritic spines are important for memory and learning and are impaired in neurodevelopmental disorders such as fragile X syndrome. Spine dynamics are regulated by activity-dependent mechanisms that involve modulation of AMPA receptors (AMPAR); however, the relationship between AMPAR and spine dynamics in vivo and how these are altered in FXS mouse model is not known. Here, we tracked AMPAR and spines over multiple days in vivo in the cortex and found that dendritic spines in the fmr1 KO mouse were denser, smaller, had higher turnover rates and contained less sGluA2 compared to littermate controls. Although, KO spines maintained the relationship between AMPAR and spine stability, AMPAR levels in the KO were more dynamic with larger proportion of spines showing multiple dynamic events of AMPAR. Directional changes in sGluA2 were also observed in newly formed and eliminated spines, with KO spines displaying greater loss of AMPAR before elimination. Thus, we demonstrate that AMPAR levels within spines not are only continuously dynamic, but are also predictive of spine behavior, with impairments observed in the fmr1 KO mice.
Subject(s)
Dendritic Spines/metabolism , Fragile X Mental Retardation Protein/metabolism , Fragile X Syndrome/metabolism , Receptors, AMPA/metabolism , Synapses/metabolism , Animals , Dendritic Spines/pathology , Disease Models, Animal , Fragile X Mental Retardation Protein/genetics , Fragile X Syndrome/pathology , Male , Mice, Inbred C57BL , Mice, Knockout , Motor Cortex/metabolism , Motor Cortex/pathology , Pyramidal Cells/metabolism , Pyramidal Cells/pathology , Synapses/pathology , Time FactorsABSTRACT
Emerging epidemiology studies indicate that maternal immune activation (MIA) resulting from inflammatory stimuli such as viral or bacterial infections during pregnancy serves as a risk factor for multiple neurodevelopmental disorders including autism spectrum disorders and schizophrenia. Although alterations in the cortex and hippocampus of MIA offspring have been described, less evidence exists on the impact on the cerebellum. Here, we report altered expression of cytokines and chemokines in the cerebellum of MIA offspring, including increase in the neuroinflammatory cytokine TNFα and its receptor TNFR1. We also report reduced expression of the synaptic organizing proteins cerebellin-1 and GluRδ2. These synaptic protein alterations are associated with a deficit in the ability of cerebellar neurons to form synapses and an increased number of dendritic spines that are not in contact with a presynaptic terminal. These impairments are likely contributing to the behavioral deficits in the MIA exposed offspring.
Subject(s)
Cerebellum/immunology , Cytokines/immunology , Nerve Tissue Proteins/immunology , Prenatal Exposure Delayed Effects/immunology , Protein Precursors/immunology , Receptors, Glutamate/immunology , Synapses/immunology , Animals , Cerebellum/metabolism , Cytokines/biosynthesis , Female , Male , Maternal Exposure/adverse effects , Mice, Transgenic , Nerve Tissue Proteins/biosynthesis , Pregnancy , Prenatal Exposure Delayed Effects/metabolism , Protein Biosynthesis/physiology , Protein Precursors/biosynthesis , Receptors, Glutamate/biosynthesis , Synapses/metabolismABSTRACT
Motor-skill learning induces changes in synaptic structure and function in the primary motor cortex through the involvement of a long-term potentiation- (LTP-) like mechanism. Although there is evidence that calcium-dependent release of gliotransmitters by astrocytes plays an important role in synaptic transmission and plasticity, the role of astrocytes in motor-skill learning is not known. To test the hypothesis that astrocytic activity is necessary for motor-skill learning, we perturbed astrocytic function using pharmacological and genetic approaches. We find that perturbation of astrocytes either by selectively attenuating IP3R2 mediated astrocyte Ca(2+) signaling or using an astrocyte specific metabolic inhibitor fluorocitrate (FC) results in impaired motor-skill learning of a forelimb reaching-task in mice. Moreover, the learning impairment caused by blocking astrocytic activity using FC was rescued by administration of the gliotransmitter D-serine. The learning impairments are likely caused by impaired LTP as FC blocked LTP in slices and prevented motor-skill training-induced increases in synaptic AMPA-type glutamate receptor in vivo. These results support the conclusion that normal astrocytic Ca(2+) signaling during a reaching task is necessary for motor-skill learning.
Subject(s)
Astrocytes/physiology , Learning/physiology , Motor Skills/physiology , Animals , Antimetabolites/pharmacology , Astrocytes/drug effects , Citrates/pharmacology , Estrogen Antagonists/pharmacology , Forelimb , In Vitro Techniques , Injections, Intraventricular , Inositol 1,4,5-Trisphosphate Receptors/drug effects , Inositol 1,4,5-Trisphosphate Receptors/genetics , Learning/drug effects , Long-Term Potentiation/drug effects , Long-Term Potentiation/physiology , Mice , Mice, Inbred C57BL , Motor Skills/drug effects , Mutation , Psychomotor Performance/drug effects , Receptors, AMPA/drug effects , Serine/pharmacology , Synaptic Transmission/drug effects , Synaptic Transmission/physiology , Tamoxifen/pharmacologyABSTRACT
Both genetic and environmental factors are thought to contribute to neurodevelopmental and neuropsychiatric disorders with maternal immune activation (MIA) being a risk factor for both autism spectrum disorders and schizophrenia. Although MIA mouse offspring exhibit behavioral impairments, the synaptic alterations in vivo that mediate these behaviors are not known. Here we employed in vivo multiphoton imaging to determine that in the cortex of young MIA offspring there is a reduction in number and turnover rates of dendritic spines, sites of majority of excitatory synaptic inputs. Significantly, spine impairments persisted into adulthood and correlated with increased repetitive behavior, an ASD relevant behavioral phenotype. Structural analysis of synaptic inputs revealed a reorganization of presynaptic inputs with a larger proportion of spines being contacted by both excitatory and inhibitory presynaptic terminals. These structural impairments were accompanied by altered excitatory and inhibitory synaptic transmission. Finally, we report that a postnatal treatment of MIA offspring with the anti-inflammatory drug ibudilast, prevented both synaptic and behavioral impairments. Our results suggest that a possible altered inflammatory state associated with maternal immune activation results in impaired synaptic development that persists into adulthood but which can be prevented with early anti-inflammatory treatment.
Subject(s)
Dendritic Spines/immunology , Maternal-Fetal Exchange , Neurodevelopmental Disorders/immunology , Synapses/immunology , Animals , Anti-Inflammatory Agents/pharmacology , Dendritic Spines/drug effects , Disease Models, Animal , Excitatory Postsynaptic Potentials , Female , Mice , Mice, Inbred C57BL , Neurodevelopmental Disorders/etiology , Neurons/drug effects , Neurons/immunology , Pregnancy , Pyridines/pharmacology , Somatosensory Cortex/drug effects , Somatosensory Cortex/growth & development , Somatosensory Cortex/immunology , Synapses/drug effectsABSTRACT
Fragile X Syndrome is the most common inherited intellectual disability, and Fragile X Syndrome patients often exhibit motor and learning deficits. It was previously shown that the fmr1 knock-out mice, a common mouse model of Fragile X Syndrome, recapitulates this motor learning deficit and that the deficit is associated with altered plasticity of dendritic spines. Here, we investigated the motor learning-induced turnover, stabilization and clustering of dendritic spines in the fmr1 knock-out mouse using a single forelimb reaching task and in vivo multiphoton imaging. We report that fmr1 knock-out mice have deficits in motor learning-induced changes in dendritic spine turnover and new dendritic spine clustering, but not the motor learning-induced long-term stabilization of new dendritic spines. These results suggest that a failure to establish the proper synaptic connections in both number and location, but not the stabilization of the connections that are formed, contributes to the motor learning deficit seen in the fmr1 knock-out mouse.
Subject(s)
Dendritic Spines/genetics , Fragile X Mental Retardation Protein/genetics , Gene Knockout Techniques , Motor Skills , Animals , Dendritic Spines/pathology , Dendritic Spines/physiology , Female , Fragile X Mental Retardation Protein/metabolism , Fragile X Syndrome/genetics , Fragile X Syndrome/metabolism , Fragile X Syndrome/pathology , Humans , Learning , Mice, Inbred C57BL , Mice, Knockout , Motor ActivityABSTRACT
Learning and memory are thought to occur due to changes in synaptic strength. Strengthening of synapses due to Long Term Potentiation mechanisms are mediated by increases in synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) levels. Here we describe a protocol to isolate and quantify synaptic AMPAR subunit GluA1 levels from the motor cortex of mice which have undergone motor skill training.
ABSTRACT
Fragile X syndrome (FXS) is the most common inherited intellectual disability. FXS results from a mutation that causes silencing of the FMR1 gene, which encodes the fragile X mental retardation protein. Patients with FXS exhibit a range of neurological deficits, including motor skill deficits. Here, we have investigated motor skill learning and its synaptic correlates in the fmr1 knock-out (KO) mouse. We find that fmr1 KO mice have impaired motor skill learning of a forelimb-reaching task, compared with their wild-type (WT) littermate controls. Electrophysiological recordings from the forelimb region of the primary motor cortex demonstrated reduced, training-induced synaptic strengthening in the trained hemisphere. Moreover, long-term potentiation (LTP) is impaired in the fmr1 KO mouse, and motor skill training does not occlude LTP as it does in the WT mice. Whereas motor skill training induces an increase of synaptic AMPA-type glutamate receptor subunit 1 (GluA1), there is a delay in GluA1 increase in the trained hemisphere of the fmr1 KO mice. Using transcranial in vivo multiphoton microscopy, we find that fmr1 KO mice have similar spine density but increased dendritic spine turnover compared with WT mice. Finally, we report that motor skill training-induced formation of dendritic spines is impaired in fmr1 KO mice. We conclude that FMRP plays a role in motor skill learning and that reduced functional and structural synaptic plasticity might underlie the behavioral deficit in the fmr1 KO mouse.
Subject(s)
Fragile X Syndrome/physiopathology , Learning/physiology , Motor Skills/physiology , Neuronal Plasticity/physiology , Synapses/physiology , Animals , Disease Models, Animal , Fragile X Mental Retardation Protein/genetics , Fragile X Mental Retardation Protein/metabolism , Fragile X Syndrome/genetics , Long-Term Potentiation/genetics , Long-Term Potentiation/physiology , Mice , Mice, Knockout , Receptors, AMPA/metabolism , Synapses/metabolismABSTRACT
Biolistic transfection and diolistic labeling are techniques in which subcellular-sized particles, coated with DNA and lipophilic dyes, respectively, are propelled into cells. The gene-gun approach is particularly applicable for use on ex vivo organized tissue such as brain slices, where cells are not accessible for transfection with methods used in dissociated cell preparations. This simple and rapid method results in targeting of individual cells in a Golgi-like manner, allowing investigating structural and functional aspects of neuronal development.