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Sample records for single dendritic spine

  1. The Spread of Ras Activity Triggered by Activation of a Single Dendritic Spine

    PubMed Central

    Harvey, Christopher D.; Yasuda, Ryohei; Zhong, Haining; Svoboda, Karel

    2009-01-01

    In neurons, individual dendritic spines isolate NMDA receptor-mediated Ca2+ accumulations from the dendrite and other spines. However, it is not known to what extent spines compartmentalize signaling events downstream of Ca2+ influx. We combined two-photon fluorescence lifetime imaging (FLIM) with two-photon glutamate uncaging to image the activity of the small GTPase Ras following NMDA receptor activation at individual spines. Induction of long-term potentiation (LTP) triggered robust Ca2+-dependent Ras activation in single spines that decayed in approximately 5 minutes. Ras activity spread over approximately 10 micrometers of dendrite and invaded neighboring spines by diffusion. The spread of Ras-dependent signaling was necessary for the local regulation of the threshold for LTP induction. Thus Ca2+-dependent synaptic signals can spread to couple multiple synapses on short stretches of dendrite. PMID:18556515

  2. Imaging ERK and PKA Activation in Single Dendritic Spines during Structural Plasticity.

    PubMed

    Tang, Shen; Yasuda, Ryohei

    2017-03-22

    Extracellular signal-regulated kinase (ERK) and protein kinase A (PKA) play important roles in LTP and spine structural plasticity. While fluorescence resonance energy transfer (FRET)-based sensors for these kinases had previously been developed, they did not provide sufficient sensitivity for imaging small neuronal compartments, such as single dendritic spines in brain slices. Here we improved the sensitivity of FRET-based kinase sensors for monitoring kinase activity under two-photon fluorescence lifetime imaging microscopy (2pFLIM). Using these improved sensors, we succeeded in imaging ERK and PKA activation in single dendritic spines during structural long-term potentiation (sLTP) in hippocampal CA1 pyramidal neurons, revealing that the activation of these kinases spreads widely with length constants of more than 10 μm. The strategy for improvement of sensors used here should be applicable for developing highly sensitive biosensors for various protein kinases. VIDEO ABSTRACT.

  3. Autocrine BDNF-TrkB signalling within a single dendritic spine.

    PubMed

    Harward, Stephen C; Hedrick, Nathan G; Hall, Charles E; Parra-Bueno, Paula; Milner, Teresa A; Pan, Enhui; Laviv, Tal; Hempstead, Barbara L; Yasuda, Ryohei; McNamara, James O

    2016-10-06

    Brain-derived neurotrophic factor (BDNF) and its receptor TrkB are crucial for many forms of neuronal plasticity, including structural long-term potentiation (sLTP), which is a correlate of an animal's learning. However, it is unknown whether BDNF release and TrkB activation occur during sLTP, and if so, when and where. Here, using a fluorescence resonance energy transfer-based sensor for TrkB and two-photon fluorescence lifetime imaging microscopy, we monitor TrkB activity in single dendritic spines of CA1 pyramidal neurons in cultured murine hippocampal slices. In response to sLTP induction, we find fast (onset < 1 min) and sustained (>20 min) activation of TrkB in the stimulated spine that depends on NMDAR (N-methyl-d-aspartate receptor) and CaMKII signalling and on postsynaptically synthesized BDNF. We confirm the presence of postsynaptic BDNF using electron microscopy to localize endogenous BDNF to dendrites and spines of hippocampal CA1 pyramidal neurons. Consistent with these findings, we also show rapid, glutamate-uncaging-evoked, time-locked BDNF release from single dendritic spines using BDNF fused to superecliptic pHluorin. We demonstrate that this postsynaptic BDNF-TrkB signalling pathway is necessary for both structural and functional LTP. Together, these findings reveal a spine-autonomous, autocrine signalling mechanism involving NMDAR-CaMKII-dependent BDNF release from stimulated dendritic spines and subsequent TrkB activation on these same spines that is crucial for structural and functional plasticity.

  4. Single-Molecule Discrimination within Dendritic Spines of Discrete Perisynaptic Sites of Actin Filament Assembly Driving Postsynaptic Reorganization

    NASA Astrophysics Data System (ADS)

    Blanpied, Thomas A.

    2013-03-01

    In the brain, the strength of synaptic transmission between neurons is principally set by the organization of proteins within the receptive, postsynaptic cell. Synaptic strength at an individual site of contact can remain remarkably stable for months or years. However, it also can undergo diverse forms of plasticity which change the strength at that contact independent of changes to neighboring synapses. Such activity-triggered neural plasticity underlies memory storage and cognitive development, and is disrupted in pathological physiology such as addiction and schizophrenia. Much of the short-term regulation of synaptic plasticity occurs within the postsynaptic cell, in small subcompartments surrounding the synaptic contact. Biochemical subcompartmentalization necessary for synapse-specific plasticity is achieved in part by segregation of synapses to micron-sized protrusions from the cell called dendritic spines. Dendritic spines are heavily enriched in the actin cytoskeleton, and regulation of actin polymerization within dendritic spines controls both basal synaptic strength and many forms of synaptic plasticity. However, understanding the mechanism of this control has been difficult because the submicron dimensions of spines limit examination of actin dynamics in the spine interior by conventional confocal microscopy. To overcome this, we developed single-molecule tracking photoactivated localization microscopy (smtPALM) to measure the movement of individual actin molecules within living spines. This revealed inward actin flow from broad areas of the spine plasma membrane, as well as a dense central core of heterogeneous filament orientation. The velocity of single actin molecules along filaments was elevated in discrete regions within the spine, notably near the postsynaptic density but surprisingly not at the endocytic zone which is involved in some forms of plasticity. We conclude that actin polymerization is initiated at many well-separated foci within

  5. Intravital imaging of dendritic spine plasticity

    PubMed Central

    Sau Wan Lai, Cora

    2014-01-01

    Abstract Dendritic spines are the postsynaptic part of most excitatory synapses in the mammalian brain. Recent works have suggested that the structural and functional plasticity of dendritic spines have been associated with information coding and memories. Advances in imaging and labeling techniques enable the study of dendritic spine dynamics in vivo. This perspective focuses on intravital imaging studies of dendritic spine plasticity in the neocortex. I will introduce imaging tools for studying spine dynamics and will further review current findings on spine structure and function under various physiological and pathological conditions. PMID:28243511

  6. Non-synaptic dendritic spines in neocortex.

    PubMed

    Arellano, J I; Espinosa, A; Fairén, A; Yuste, R; DeFelipe, J

    2007-03-16

    A long-held assumption states that each dendritic spine in the cerebral cortex forms a synapse, although this issue has not been systematically investigated. We performed complete ultrastructural reconstructions of a large (n=144) population of identified spines in adult mouse neocortex finding that only 3.6% of the spines clearly lacked synapses. Nonsynaptic spines were small and had no clear head, resembling dendritic filopodia, and could represent a source of new synaptic connections in the adult cerebral cortex.

  7. Dendritic spine dysgenesis in neuropathic pain.

    PubMed

    Tan, Andrew M; Waxman, Stephen G

    2015-08-05

    Neuropathic pain is a significant unmet medical need in patients with variety of injury or disease insults to the nervous system. Neuropathic pain often presents as a painful sensation described as electrical, burning, or tingling. Currently available treatments have limited effectiveness and narrow therapeutic windows for safety. More powerful analgesics, e.g., opioids, carry a high risk for chemical dependence. Thus, a major challenge for pain research is the elucidation of the mechanisms that underlie neuropathic pain and developing targeted strategies to alleviate pathological pain. The mechanistic link between dendritic spine structure and circuit function could explain why neuropathic pain is difficult to treat, since nociceptive processing pathways are adversely "hard-wired" through the reorganization of dendritic spines. Several studies in animal models of neuropathic pain have begun to reveal the functional contribution of dendritic spine dysgenesis in neuropathic pain. Previous reports have demonstrated three primary changes in dendritic spine structure on nociceptive dorsal horn neurons following injury or disease, which accompany chronic intractable pain: (I) increased density of dendritic spines, particularly mature mushroom-spine spines, (II) redistribution of spines toward dendritic branch locations close to the cell body, and (III) enlargement of the spine head diameter, which generally presents as a mushroom-shaped spine. Given the important functional implications of spine distribution, density, and shape for synaptic and neuronal function, the study of dendritic spine abnormality may provide a new perspective for investigating pain, and the identification of specific molecular players that regulate spine morphology may guide the development of more effective and long-lasting therapies.

  8. Dendritic spine dysgenesis in Autism Related Disorders

    PubMed Central

    Phillips, Mary; Pozzo-Miller, Lucas

    2015-01-01

    The activity-dependent structural and functional plasticity of dendritic spines has led to the long-standing belief that these neuronal compartments are the subcellular sites of learning and memory. Of relevance to human health, central neurons in several neuropsychiatric illnesses, including autism related disorders, have atypical numbers and morphologies of dendritic spines. These so-called dendritic spine dysgeneses found in individuals with autism related disorders are consistently replicated in experimental mouse models. Dendritic spine dysgenesis reflects the underlying synaptopathology that drives clinically relevant behavioral deficits in experimental mouse models, providing a platform for testing new therapeutic approaches. By examining molecular signaling pathways, synaptic deficits, and spine dysgenesis in experimental mouse models of autism related disorders we find strong evidence for mTOR to be a critical point of convergence and promising therapeutic target. PMID:25578949

  9. Ultrastructure of Dendritic Spines: Correlation Between Synaptic and Spine Morphologies

    PubMed Central

    Arellano, Jon I.; Benavides-Piccione, Ruth; DeFelipe, Javier; Yuste, Rafael

    2007-01-01

    Dendritic spines are critical elements of cortical circuits, since they establish most excitatory synapses. Recent studies have reported correlations between morphological and functional parameters of spines. Specifically, the spine head volume is correlated with the area of the postsynaptic density (PSD), the number of postsynaptic receptors and the ready-releasable pool of transmitter, whereas the length of the spine neck is proportional to the degree of biochemical and electrical isolation of the spine from its parent dendrite. Therefore, the morphology of a spine could determine its synaptic strength and learning rules. To better understand the natural variability of neocortical spine morphologies, we used a combination of gold-toned Golgi impregnations and serial thin-section electron microscopy and performed three-dimensional reconstructions of spines from layer 2/3 pyramidal cells from mouse visual cortex. We characterized the structure and synaptic features of 144 completed reconstructed spines, and analyzed their morphologies according to their positions. For all morphological parameters analyzed, spines exhibited a continuum of variability, without clearly distinguishable subtypes of spines or clear dependence of their morphologies on their distance to the soma. On average, the spine head volume was correlated strongly with PSD area and weakly with neck diameter, but not with neck length. The large morphological diversity suggests an equally large variability of synaptic strength and learning rules. PMID:18982124

  10. Dendritic spine dysgenesis in Rett syndrome

    PubMed Central

    Xu, Xin; Miller, Eric C.; Pozzo-Miller, Lucas

    2014-01-01

    Spines are small cytoplasmic extensions of dendrites that form the postsynaptic compartment of the majority of excitatory synapses in the mammalian brain. Alterations in the numerical density, size, and shape of dendritic spines have been correlated with neuronal dysfunction in several neurological and neurodevelopmental disorders associated with intellectual disability, including Rett syndrome (RTT). RTT is a progressive neurodevelopmental disorder associated with intellectual disability that is caused by loss of function mutations in the transcriptional regulator methyl CpG-binding protein 2 (MECP2). Here, we review the evidence demonstrating that principal neurons in RTT individuals and Mecp2-based experimental models exhibit alterations in the number and morphology of dendritic spines. We also discuss the exciting possibility that signaling pathways downstream of brain-derived neurotrophic factor (BDNF), which is transcriptionally regulated by MeCP2, offer promising therapeutic options for modulating dendritic spine development and plasticity in RTT and other MECP2-associated neurodevelopmental disorders. PMID:25309341

  11. Learning rules and persistence of dendritic spines.

    PubMed

    Kasai, Haruo; Hayama, Tatsuya; Ishikawa, Motoko; Watanabe, Satoshi; Yagishita, Sho; Noguchi, Jun

    2010-07-01

    Structural plasticity of dendritic spines underlies learning, memory and cognition in the cerebral cortex. We here summarize fifteen rules of spine structural plasticity, or 'spine learning rules.' Together, they suggest how the spontaneous generation, selection and strengthening (SGSS) of spines represents the physical basis for learning and memory. This SGSS mechanism is consistent with Hebb's learning rule but suggests new relations between synaptic plasticity and memory. We describe the cellular and molecular bases of the spine learning rules, such as the persistence of spine structures and the fundamental role of actin, which polymerizes to form a 'memory gel' required for the selection and strengthening of spine synapses. We also discuss the possible link between transcriptional and translational regulation of structural plasticity. The SGSS mechanism and spine learning rules elucidate the integral nature of synaptic plasticity in neuronal network operations within the actual brain tissue.

  12. EPSPs Measured in Proximal Dendritic Spines of Cortical Pyramidal Neurons.

    PubMed

    Acker, Corey D; Hoyos, Erika; Loew, Leslie M

    2016-01-01

    EPSPs occur when the neurotransmitter glutamate binds to postsynaptic receptors located on small pleomorphic membrane protrusions called dendritic spines. To transmit the synaptic signal, these potentials must travel through the spine neck and the dendritic tree to reach the soma. Due to their small size, the electrical behavior of spines and their ability to compartmentalize electrical signals has been very difficult to assess experimentally. In this study, we developed a method to perform simultaneous two-photon voltage-sensitive dye recording with two-photon glutamate uncaging in order to measure the characteristics (amplitude and duration) of uncaging-evoked EPSPs in single spines on the basal dendrites of L5 pyramidal neurons in acute brain slices from CD1 control mice. We were able to record uncaging-evoked spine potentials that resembled miniature EPSPs at the soma from a wide range of spine morphologies. In proximal spines, these potentials averaged 13.0 mV (range, 6.5-30.8 mV; N = 20) for an average somatic EPSP of 0.59 mV, whereas the mean attenuation ratio (spine/soma) was found to be 25.3. Durations of spine EPSP waveforms were found to be 11.7 ms on average. Modeling studies demonstrate the important role that spine neck resistance (Rneck) plays in spine EPSP amplitudes. Simulations used to estimate Rneck by fits to voltage-sensitive dye measurements produced a mean of 179 MΩ (range, 23-420 MΩ; N = 19). Independent measurements based on fluorescence recovery after photobleaching of a cytosolic dye from spines of the same population of neurons produced a mean R eck estimate of 204 MΩ (range, 52-521 MΩ; N = 34).

  13. The discovery of dendritic spines by Cajal

    PubMed Central

    Yuste, Rafael

    2015-01-01

    Dendritic spines were considered an artifact of the Golgi method until a brash Spanish histologist, Santiago Ramón y Cajal, bet his scientific career arguing that they were indeed real, correctly deducing their key role in mediating synaptic connectivity. This article reviews the historical context of the discovery of spines and the reasons behind Cajal's obsession with them, all the way till his deathbed. PMID:25954162

  14. Single-cell genetic expression of mutant GABAA receptors causing Human genetic epilepsy alters dendritic spine and GABAergic bouton formation in a mutation-specific manner.

    PubMed

    Lachance-Touchette, Pamela; Choudhury, Mayukh; Stoica, Ana; Di Cristo, Graziella; Cossette, Patrick

    2014-01-01

    Mutations in genes encoding for GABAA receptor subunits is a well-established cause of genetic generalized epilepsy. GABA neurotransmission is implicated in several developmental processes including neurite outgrowth and synapse formation. Alteration in excitatory/inhibitory synaptic activities plays a critical role in epilepsy, thus here we investigated whether mutations in α1 subunit of GABAA receptor may affect dendritic spine and GABAergic bouton formation. In particular, we examined the effects of three mutations of the GABRA1 gene (D219N, A322D and K353delins18X) that were found in a cohort of French Canadian families with genetic generalized epilepsy. We used a novel single-cell genetic approach, by preparing cortical organotypic cultures from GABRA1 (flox/flox) mice and simultaneously inactivating endogenous GABRA1 and transfecting mutant α1 subunits in single glutamatergic pyramidal cells and basket GABAergic interneurons by biolistic transfection. We found that GABRA1 (-/-) GABAergic cells showed reduced innervation field, which was rescued by co-expressing α1-A322D and α1-WT but not α1-D219N. We further found that the expression of the most severe GABRA1 missense mutation (α1-A322D) induced a striking increase of spine density in pyramidal cells along with an increase in the number of mushroom-like spines. In addition, α1-A322D expression in GABAergic cells slightly increased perisomatic bouton density, whereas other mutations did not alter bouton formation. All together, these results suggest that the effects of different GABAAR mutations on GABAergic bouton and dendritic spine formation are specific to the mutation and cannot be always explained by a simple loss-of-function gene model. The use of single cell genetic manipulation in organotypic cultures may provide a better understanding of the specific and distinct neural circuit alterations caused by different GABAA receptor subunit mutations and will help define the pathophysiology of genetic

  15. Single-cell genetic expression of mutant GABAA receptors causing Human genetic epilepsy alters dendritic spine and GABAergic bouton formation in a mutation-specific manner

    PubMed Central

    Lachance-Touchette, Pamela; Choudhury, Mayukh; Stoica, Ana; Di Cristo, Graziella; Cossette, Patrick

    2014-01-01

    Mutations in genes encoding for GABAA receptor subunits is a well-established cause of genetic generalized epilepsy. GABA neurotransmission is implicated in several developmental processes including neurite outgrowth and synapse formation. Alteration in excitatory/inhibitory synaptic activities plays a critical role in epilepsy, thus here we investigated whether mutations in α1 subunit of GABAA receptor may affect dendritic spine and GABAergic bouton formation. In particular, we examined the effects of three mutations of the GABRA1 gene (D219N, A322D and K353delins18X) that were found in a cohort of French Canadian families with genetic generalized epilepsy. We used a novel single-cell genetic approach, by preparing cortical organotypic cultures from GABRA1flox/flox mice and simultaneously inactivating endogenous GABRA1 and transfecting mutant α1 subunits in single glutamatergic pyramidal cells and basket GABAergic interneurons by biolistic transfection. We found that GABRA1−/− GABAergic cells showed reduced innervation field, which was rescued by co-expressing α1-A322D and α1-WT but not α1-D219N. We further found that the expression of the most severe GABRA1 missense mutation (α1-A322D) induced a striking increase of spine density in pyramidal cells along with an increase in the number of mushroom-like spines. In addition, α1-A322D expression in GABAergic cells slightly increased perisomatic bouton density, whereas other mutations did not alter bouton formation. All together, these results suggest that the effects of different GABAAR mutations on GABAergic bouton and dendritic spine formation are specific to the mutation and cannot be always explained by a simple loss-of-function gene model. The use of single cell genetic manipulation in organotypic cultures may provide a better understanding of the specific and distinct neural circuit alterations caused by different GABAA receptor subunit mutations and will help define the pathophysiology of genetic

  16. Random positions of dendritic spines in human cerebral cortex.

    PubMed

    Morales, Juan; Benavides-Piccione, Ruth; Dar, Mor; Fernaud, Isabel; Rodríguez, Angel; Anton-Sanchez, Laura; Bielza, Concha; Larrañaga, Pedro; DeFelipe, Javier; Yuste, Rafael

    2014-07-23

    Dendritic spines establish most excitatory synapses in the brain and are located in Purkinje cell's dendrites along helical paths, perhaps maximizing the probability to contact different axons. To test whether spine helixes also occur in neocortex, we reconstructed >500 dendritic segments from adult human cortex obtained from autopsies. With Fourier analysis and spatial statistics, we analyzed spine position along apical and basal dendrites of layer 3 pyramidal neurons from frontal, temporal, and cingulate cortex. Although we occasionally detected helical positioning, for the great majority of dendrites we could not reject the null hypothesis of spatial randomness in spine locations, either in apical or basal dendrites, in neurons of different cortical areas or among spines of different volumes and lengths. We conclude that in adult human neocortex spine positions are mostly random. We discuss the relevance of these results for spine formation and plasticity and their functional impact for cortical circuits.

  17. Random Positions of Dendritic Spines in Human Cerebral Cortex

    PubMed Central

    Morales, Juan; Benavides-Piccione, Ruth; Dar, Mor; Fernaud, Isabel; Rodríguez, Angel; Anton-Sanchez, Laura; Bielza, Concha; Larrañaga, Pedro; DeFelipe, Javier

    2014-01-01

    Dendritic spines establish most excitatory synapses in the brain and are located in Purkinje cell's dendrites along helical paths, perhaps maximizing the probability to contact different axons. To test whether spine helixes also occur in neocortex, we reconstructed >500 dendritic segments from adult human cortex obtained from autopsies. With Fourier analysis and spatial statistics, we analyzed spine position along apical and basal dendrites of layer 3 pyramidal neurons from frontal, temporal, and cingulate cortex. Although we occasionally detected helical positioning, for the great majority of dendrites we could not reject the null hypothesis of spatial randomness in spine locations, either in apical or basal dendrites, in neurons of different cortical areas or among spines of different volumes and lengths. We conclude that in adult human neocortex spine positions are mostly random. We discuss the relevance of these results for spine formation and plasticity and their functional impact for cortical circuits. PMID:25057209

  18. Synaptic amplification by dendritic spines enhances input cooperativity.

    PubMed

    Harnett, Mark T; Makara, Judit K; Spruston, Nelson; Kath, William L; Magee, Jeffrey C

    2012-11-22

    Dendritic spines are the nearly ubiquitous site of excitatory synaptic input onto neurons and as such are critically positioned to influence diverse aspects of neuronal signalling. Decades of theoretical studies have proposed that spines may function as highly effective and modifiable chemical and electrical compartments that regulate synaptic efficacy, integration and plasticity. Experimental studies have confirmed activity-dependent structural dynamics and biochemical compartmentalization by spines. However, there is a longstanding debate over the influence of spines on the electrical aspects of synaptic transmission and dendritic operation. Here we measure the amplitude ratio of spine head to parent dendrite voltage across a range of dendritic compartments and calculate the associated spine neck resistance (R(neck)) for spines at apical trunk dendrites in rat hippocampal CA1 pyramidal neurons. We find that R(neck) is large enough (~500 MΩ) to amplify substantially the spine head depolarization associated with a unitary synaptic input by ~1.5- to ~45-fold, depending on parent dendritic impedance. A morphologically realistic compartmental model capable of reproducing the observed spatial profile of the amplitude ratio indicates that spines provide a consistently high-impedance input structure throughout the dendritic arborization. Finally, we demonstrate that the amplification produced by spines encourages electrical interaction among coactive inputs through an R(neck)-dependent increase in spine head voltage-gated conductance activation. We conclude that the electrical properties of spines promote nonlinear dendritic processing and associated forms of plasticity and storage, thus fundamentally enhancing the computational capabilities of neurons.

  19. Epac2-mediated dendritic spine remodeling: implications for disease

    PubMed Central

    Woolfrey, Kevin M.; Srivastava, Deepak P.

    2010-01-01

    In the mammalian forebrain, most glutamatergic excitatory synapses occur on small dendritic protrusions called dendritic spines. Dendritic spines are highly plastic and can rapidly change morphology in response to numerous stimuli. This dynamic remodeling of dendritic spines is thought to be critical for information processing, memory and cognition. Conversely, multiple studies have revealed that neuropathologies such as autism spectrum disorders (ASDs) are linked with alterations in dendritic spine morphologies and miswiring of neural circuitry. One compelling hypothesis is that abnormal dendritic spine remodeling is a key contributing factor for this miswiring. Ongoing research has identified a number of mechanisms that are critical for the control of dendritic spine remodeling. Among these mechanisms, regulation of small GTPase signaling by guanine-nucleotide exchange factors (GEFs) is emerging as a critical mechanism for integrating physiological signals in the control of dendritic spine remodeling. Furthermore, multiple proteins associated with regulation of dendritic spine remodeling have also been implicated with multiple neuropathologies, including ASDs. Epac2, a GEF for the small GTPase Rap, has recently been described as a novel cAMP(yet PKA-independent) target localized to dendritic spines. Signaling via this protein in response to pharmacological stimulation or cAMP accumulation, via the dopamine D1/5 receptor, results in Rap activation, promotes structural destabilization, in the form of dendritic spine shrinkage, and functional depression due to removal of GluR2/3-containing AMPA receptors. In addition, Epac2 forms macromolecular complexes with ASD-associated proteins, which are sufficient to regulate Epac2 localization and function. Furthermore, rare nonsynonymous variants of the EPAC2 gene associated with the ASD phenotype alter protein function, synaptic protein distribution, and spine morphology. We review here the role of Epac2 in the remodeling

  20. Astrocytes refine cortical connectivity at dendritic spines

    PubMed Central

    Risher, W Christopher; Patel, Sagar; Kim, Il Hwan; Uezu, Akiyoshi; Bhagat, Srishti; Wilton, Daniel K; Pilaz, Louis-Jan; Singh Alvarado, Jonnathan; Calhan, Osman Y; Silver, Debra L; Stevens, Beth; Calakos, Nicole; Soderling, Scott H; Eroglu, Cagla

    2014-01-01

    During cortical synaptic development, thalamic axons must establish synaptic connections despite the presence of the more abundant intracortical projections. How thalamocortical synapses are formed and maintained in this competitive environment is unknown. Here, we show that astrocyte-secreted protein hevin is required for normal thalamocortical synaptic connectivity in the mouse cortex. Absence of hevin results in a profound, long-lasting reduction in thalamocortical synapses accompanied by a transient increase in intracortical excitatory connections. Three-dimensional reconstructions of cortical neurons from serial section electron microscopy (ssEM) revealed that, during early postnatal development, dendritic spines often receive multiple excitatory inputs. Immuno-EM and confocal analyses revealed that majority of the spines with multiple excitatory contacts (SMECs) receive simultaneous thalamic and cortical inputs. Proportion of SMECs diminishes as the brain develops, but SMECs remain abundant in Hevin-null mice. These findings reveal that, through secretion of hevin, astrocytes control an important developmental synaptic refinement process at dendritic spines. DOI: http://dx.doi.org/10.7554/eLife.04047.001 PMID:25517933

  1. Olfactory experiences dynamically regulate plasticity of dendritic spines in granule cells of Xenopus tadpoles in vivo

    PubMed Central

    Zhang, Li; Huang, Yubin; Hu, Bing

    2016-01-01

    Granule cells, rich in dendrites with densely punctated dendritic spines, are the most abundant inhibitory interneurons in the olfactory bulb. The dendritic spines of granule cells undergo remodeling during the development of the nervous system. The morphological plasticity of the spines’ response to different olfactory experiences in vivo is not fully known. In initial studies, a single granule cell in Xenopus tadpoles was labeled with GFP plasmids via cell electroporation; then, morphologic changes of the granule cell spines were visualized by in vivo confocal time-lapse imaging. With the help of long-term imaging, the total spine density, dynamics, and stability of four types of dendritic spines (mushroom, stubby, thin and filopodia) were obtained. Morphological analysis demonstrated that odor enrichment produced a remarkable increase in the spine density and stability of large mushroom spine. Then, with the help of short-term imaging, we analyzed the morphological transitions among different spines. We found that transitions between small spines (thin and filopodia) were more easily influenced by odor stimulation or olfactory deprivation. These results indicate that different olfactory experiences can regulate the morphological plasticity of different dendritic spines in the granule cell. PMID:27713557

  2. Organization of TNIK in dendritic spines.

    PubMed

    Burette, Alain C; Phend, Kristen D; Burette, Susan; Lin, Qingcong; Liang, Musen; Foltz, Gretchen; Taylor, Noël; Wang, Qi; Brandon, Nicholas J; Bates, Brian; Ehlers, Michael D; Weinberg, Richard J

    2015-09-01

    Tumor necrosis factor receptor-associated factor 2 (TRAF2)- and noncatalytic region of tyrosine kinase (NCK)-interacting kinase (TNIK) has been identified as an interactor in the psychiatric risk factor, Disrupted in Schizophrenia 1 (DISC1). As a step toward deciphering its function in the brain, we performed high-resolution light and electron microscopic immunocytochemistry. We demonstrate here that TNIK is expressed in neurons throughout the adult mouse brain. In striatum and cerebral cortex, TNIK concentrates in dendritic spines, especially in the vicinity of the lateral edge of the synapse. Thus, TNIK is highly enriched at a microdomain critical for glutamatergic signaling.

  3. Ca2+ signalling in postsynaptic dendrites and spines of mammalian neurons in brain slice.

    PubMed

    Müller, W; Connor, J A

    1992-01-01

    Postsynaptic Ca2+ changes are involved in control of cellular excitability and induction of synaptic long-term changes. We monitored Ca2+ changes in dendrites and spines during synaptic and direct stimulation using high resolution microfluorometry of fura-2 injected into CA3 pyramidal neurons in guinea pig hippocampal slice. When driven by current injection from an intracellular electrode or with synaptic stimulation, postsynaptic Ca2+ accumulations were highest in the proximal dendrites with a pronounced fall-off towards the soma and some fall-off towards more distal dendrites. Muscarinic activation by low concentrations of carbachol strongly increased intradendritic Ca2+ accumulation during directly-evoked repetitive firing. This enhancement occurred in large part because muscarinic activation suppressed the normal Ca(2+)-dependent activation of K-channels that mediates adaptation of firing. Repetitive firing of cholinergic fibers in the slice reproduced the effects of carbachol. Inhibition of acetylcholine-esterase activity by eserine enhanced the effects of repetitive stimulation of chlolinergic fibers. All effects were reversible and were blocked by the muscarinic antagonist atropine. Ca2+ accumulations in postsynaptic spines might be the basis of specificity of synaptic plasticity. With selective stimulation of few associative/comissural fibers, Ca2+ accumulated in single postsynaptic spines but not in the parent dendrite. With strong stimulation, dendrite levels also increased but spine levels were considerably higher. The NMDA-receptor antagonist AP-5 blocked Ca(2+)-peaks in spines, but left Ca2+ changes in dendrite shafts largely unaffected. Sustained steep Ca2+ gradients between single spines and the parent dendrite, often lasting several minutes, developed with repeated stimulation. Our results demonstrate a spine entity that can act independent from the dendrite with respect to Ca(2+)-dependent processes. Muscarinic augmentation of dendritic Ca2+ levels

  4. Dendritic spines as individual neuronal compartments for synaptic Ca2+ responses.

    PubMed

    Müller, W; Connor, J A

    1991-11-07

    The possibility that postsynaptic spines on neuronal dendrites are discrete biochemical compartments for Ca(2+)-activated processes involved in synaptic plasticity is a widely proposed concept that has eluded experimental demonstration. Using microfluorometry on CA3 neurons in hippocampal slices, we show here that with weak presynaptic stimulation of associative/commissural fibres, Ca2+ accumulates in single postsynaptic spines but not in the parent dendrite. Stronger stimulation also promotes changes in dendrites. The NMDA-receptor antagonist AP-5 blocks changes in Ca2+ in spines. Sustained steep Ca2+ gradients between single spines and the parent dendrite, often lasting several minutes, develop with repeated stimulation. The observed compartmentalization allows for the specificity, cooperativity and associativity displayed by memory models such as long-term potentiation.

  5. Cold-induced exodus of postsynaptic proteins from dendritic spines.

    PubMed

    Cheng, Hui-Hsuan; Huang, Zu-Han; Lin, Wei-Hsiang; Chow, Wei-Yuan; Chang, Yen-Chung

    2009-02-01

    Dendritic spines are small protrusions on neuronal dendrites and the major target of the excitatory inputs in mammalian brains. Cultured neurons and brain slices are important tools in studying the biochemical and cellular properties of dendritic spines. During the processes of immunocytochemical studies of neurons and the preparation of brain slices, neurons were often kept at temperatures lower than 37 degrees C for varied lengths of time. This study sought to investigate whether and how cold treatment would affect the protein composition of dendritic spines. The results indicated that upon cold treatment four postsynaptic proteins, namely, alpha,beta-tubulins, calcium, calmodulin-dependent protein kinase IIalpha, and cytoplasmic dynein heavy chain and microtubule-associated protein 2, but not PSD-95 or AMPA receptors, exited from the majority of dendritic spines of cultured rat hippocampal neurons in a Gd(3+)-sensitive manner. The cold-induced exit of tubulins from dendritic spines was further found to be an energy-dependent process involving the activation of Gd(3+)-sensitive calcium channels and ryanodine receptors. The results thus indicate that changes in temperature, calcium concentration, and energy supply of the medium surrounding neurons would affect the protein composition of the dendritic spines and conceivably the protein composition of the subcellular organizations, such as the postsynaptic density, in the cytoplasm of dendritic spines.

  6. Synaptic amplification by dendritic spines enhances input cooperativity

    PubMed Central

    Harnett, Mark T.; Makara, Judit K.; Spruston, Nelson; Kath, William L.; Magee, Jeffrey C.

    2012-01-01

    Dendritic spines are the nearly ubiquitous site of excitatory synaptic input onto neurons1–2 and as such are critically positioned to influence diverse aspects of neuronal signaling. Decades of theoretical studies have proposed that spines may function as highly effective and modifiable chemical and electrical compartments that regulate synaptic efficacy, integration, and plasticity3–8. Experimental studies have confirmed activity-dependent structural dynamics and biochemical compartmentalization by spines9–12. However, a longstanding debate remains over the influence of spines on the electrical aspects of synaptic transmission and dendritic operation3–8,13–18. Here, we measured the amplitude ratio (AR) of spine head to parent dendrite voltage across a range of dendritic compartments and calculated the associated Rneck for spines at apical trunk dendrites in hippocampal CA1 pyramidal neurons. We found that Rneck is large enough (~500 MΩ) to substantially amplify the spine head depolarization associated with a unitary synaptic input by ~1.5- to ~45-fold depending on parent dendritic impedance. A morphologically realistic compartmental model capable of reproducing the observed spatial profile of AR indicates that spines provide a consistently high impedance input structure throughout the dendritic arbor. Finally, we demonstrate that the amplification produced by spines encourages electrical interaction among coactive inputs through an Rneck-dependent increase in spine head voltage- dependent conductance activation. We conclude that the electrical properties of spines promote nonlinear dendritic processing and associated forms of plasticity and storage, thus fundamentally enhancing the computational capabilities of neurons19–21. PMID:23103868

  7. Dendritic spine geometry can localize GTPase signaling in neurons

    PubMed Central

    Ramirez, Samuel A.; Raghavachari, Sridhar; Lew, Daniel J.

    2015-01-01

    Dendritic spines are the postsynaptic terminals of most excitatory synapses in the mammalian brain. Learning and memory are associated with long-lasting structural remodeling of dendritic spines through an actin-mediated process regulated by the Rho-family GTPases RhoA, Rac, and Cdc42. These GTPases undergo sustained activation after synaptic stimulation, but whereas Rho activity can spread from the stimulated spine, Cdc42 activity remains localized to the stimulated spine. Because Cdc42 itself diffuses rapidly in and out of the spine, the basis for the retention of Cdc42 activity in the stimulated spine long after synaptic stimulation has ceased is unclear. Here we model the spread of Cdc42 activation at dendritic spines by means of reaction-diffusion equations solved on spine-like geometries. Excitable behavior arising from positive feedback in Cdc42 activation leads to spreading waves of Cdc42 activity. However, because of the very narrow neck of the dendritic spine, wave propagation is halted through a phenomenon we term geometrical wave-pinning. We show that this can account for the localization of Cdc42 activity in the stimulated spine, and, of interest, retention is enhanced by high diffusivity of Cdc42. Our findings are broadly applicable to other instances of signaling in extreme geometries, including filopodia and primary cilia. PMID:26337387

  8. Musical representation of dendritic spine distribution: a new exploratory tool.

    PubMed

    Toharia, Pablo; Morales, Juan; de Juan, Octavio; Fernaud, Isabel; Rodríguez, Angel; DeFelipe, Javier

    2014-04-01

    Dendritic spines are small protrusions along the dendrites of many types of neurons in the central nervous system and represent the major target of excitatory synapses. For this reason, numerous anatomical, physiological and computational studies have focused on these structures. In the cerebral cortex the most abundant and characteristic neuronal type are pyramidal cells (about 85 % of all neurons) and their dendritic spines are the main postsynaptic target of excitatory glutamatergic synapses. Thus, our understanding of the synaptic organization of the cerebral cortex largely depends on the knowledge regarding synaptic inputs to dendritic spines of pyramidal cells. Much of the structural data on dendritic spines produced by modern neuroscience involves the quantitative analysis of image stacks from light and electron microscopy, using standard statistical and mathematical tools and software developed to this end. Here, we present a new method with musical feedback for exploring dendritic spine morphology and distribution patterns in pyramidal neurons. We demonstrate that audio analysis of spiny dendrites with apparently similar morphology may "sound" quite different, revealing anatomical substrates that are not apparent from simple visual inspection. These morphological/music translations may serve as a guide for further mathematical analysis of the design of the pyramidal neurons and of spiny dendrites in general.

  9. Automated Remote Focusing, Drift Correction, and Photostimulation to Evaluate Structural Plasticity in Dendritic Spines

    PubMed Central

    Evans, Paul R.; Garrett, Tavita R.; Yan, Long; Yasuda, Ryohei

    2017-01-01

    Long-term structural plasticity of dendritic spines plays a key role in synaptic plasticity, the cellular basis for learning and memory. The biochemical step is mediated by a complex network of signaling proteins in spines. Two-photon imaging techniques combined with two-photon glutamate uncaging allows researchers to induce and quantify structural plasticity in single dendritic spines. However, this method is laborious and slow, making it unsuitable for high throughput screening of factors necessary for structural plasticity. Here we introduce a MATLAB-based module built for Scanimage to automatically track, image, and stimulate multiple dendritic spines. We implemented an electrically tunable lens in combination with a drift correction algorithm to rapidly and continuously track targeted spines and correct sample movements. With a straightforward user interface to design custom multi-position experiments, we were able to adequately image and produce targeted plasticity in multiple dendritic spines using glutamate uncaging. Our methods are inexpensive, open source, and provides up to a five-fold increase in throughput for quantifying structural plasticity of dendritic spines. PMID:28114380

  10. Dendritic Spines as Tunable Regulators of Synaptic Signals

    PubMed Central

    Tønnesen, Jan; Nägerl, U. Valentin

    2016-01-01

    Neurons are perpetually receiving vast amounts of information in the form of synaptic input from surrounding cells. The majority of input occurs at thousands of dendritic spines, which mediate excitatory synaptic transmission in the brain, and is integrated by the dendritic and somatic compartments of the postsynaptic neuron. The functional role of dendritic spines in shaping biochemical and electrical signals transmitted via synapses has long been intensely studied. Yet, many basic questions remain unanswered, in particular regarding the impact of their nanoscale morphology on electrical signals. Here, we review our current understanding of the structure and function relationship of dendritic spines, focusing on the controversy of electrical compartmentalization and the potential role of spine structural changes in synaptic plasticity. PMID:27340393

  11. Electrical behaviour of dendritic spines as revealed by voltage imaging

    PubMed Central

    Popovic, Marko A.; Carnevale, Nicholas; Rozsa, Balazs; Zecevic, Dejan

    2015-01-01

    Thousands of dendritic spines on individual neurons process information and mediate plasticity by generating electrical input signals using a sophisticated assembly of transmitter receptors and voltage-sensitive ion channel molecules. Our understanding, however, of the electrical behaviour of spines is limited because it has not been possible to record input signals from these structures with adequate sensitivity and spatiotemporal resolution. Current interpretation of indirect data and speculations based on theoretical considerations are inconclusive. Here we use an electrochromic voltage-sensitive dye which acts as a transmembrane optical voltmeter with a linear scale to directly monitor electrical signals from individual spines on thin basal dendrites. The results show that synapses on these spines are not electrically isolated by the spine neck to a significant extent. Electrically, they behave as if they are located directly on dendrites. PMID:26436431

  12. Input transformation by dendritic spines of pyramidal neurons

    PubMed Central

    Araya, Roberto

    2014-01-01

    In the mammalian brain, most inputs received by a neuron are formed on the dendritic tree. In the neocortex, the dendrites of pyramidal neurons are covered by thousands of tiny protrusions known as dendritic spines, which are the major recipient sites for excitatory synaptic information in the brain. Their peculiar morphology, with a small head connected to the dendritic shaft by a slender neck, has inspired decades of theoretical and more recently experimental work in an attempt to understand how excitatory synaptic inputs are processed, stored and integrated in pyramidal neurons. Advances in electrophysiological, optical and genetic tools are now enabling us to unravel the biophysical and molecular mechanisms controlling spine function in health and disease. Here I highlight relevant findings, challenges and hypotheses on spine function, with an emphasis on the electrical properties of spines and on how these affect the storage and integration of excitatory synaptic inputs in pyramidal neurons. In an attempt to make sense of the published data, I propose that the raison d'etre for dendritic spines lies in their ability to undergo activity-dependent structural and molecular changes that can modify synaptic strength, and hence alter the gain of the linearly integrated sub-threshold depolarizations in pyramidal neuron dendrites before the generation of a dendritic spike. PMID:25520626

  13. Analysis of dendritic spine morphology in cultured CNS neurons.

    PubMed

    Srivastava, Deepak P; Woolfrey, Kevin M; Penzes, Peter

    2011-07-13

    Dendritic spines are the sites of the majority of excitatory connections within the brain, and form the post-synaptic compartment of synapses. These structures are rich in actin and have been shown to be highly dynamic. In response to classical Hebbian plasticity as well as neuromodulatory signals, dendritic spines can change shape and number, which is thought to be critical for the refinement of neural circuits and the processing and storage of information within the brain. Within dendritic spines, a complex network of proteins link extracellular signals with the actin cyctoskeleton allowing for control of dendritic spine morphology and number. Neuropathological studies have demonstrated that a number of disease states, ranging from schizophrenia to autism spectrum disorders, display abnormal dendritic spine morphology or numbers. Moreover, recent genetic studies have identified mutations in numerous genes that encode synaptic proteins, leading to suggestions that these proteins may contribute to aberrant spine plasticity that, in part, underlie the pathophysiology of these disorders. In order to study the potential role of these proteins in controlling dendritic spine morphologies/number, the use of cultured cortical neurons offers several advantages. Firstly, this system allows for high-resolution imaging of dendritic spines in fixed cells as well as time-lapse imaging of live cells. Secondly, this in vitro system allows for easy manipulation of protein function by expression of mutant proteins, knockdown by shRNA constructs, or pharmacological treatments. These techniques allow researchers to begin to dissect the role of disease-associated proteins and to predict how mutations of these proteins may function in vivo.

  14. Abl2/Arg controls dendritic spine and dendrite arbor stability via distinct cytoskeletal control pathways.

    PubMed

    Lin, Yu-Chih; Yeckel, Mark F; Koleske, Anthony J

    2013-01-30

    Rho family GTPases coordinate cytoskeletal rearrangements in neurons, and mutations in their regulators are associated with mental retardation and other neurodevelopmental disorders (Billuart et al., 1998; Kutsche et al., 2000; Newey et al., 2005; Benarroch, 2007). Chromosomal microdeletions encompassing p190RhoGAP or its upstream regulator, the Abl2/Arg tyrosine kinase, have been observed in cases of mental retardation associated with developmental defects (Scarbrough et al., 1988; James et al., 1996; Takano et al., 1997; Chaabouni et al., 2006; Leal et al., 2009). Genetic knock-out of Arg in mice leads to synapse, dendritic spine, and dendrite arbor loss accompanied by behavioral deficits (Moresco et al., 2005; Sfakianos et al., 2007). To elucidate the cell-autonomous mechanisms by which Arg regulates neuronal stability, we knocked down Arg in mouse hippocampal neuronal cultures. We find that Arg knockdown significantly destabilizes dendrite arbors and reduces dendritic spine density by compromising dendritic spine stability. Inhibiting RhoA prevents dendrite arbor loss following Arg knockdown in neurons, but does not block spine loss. Interestingly, Arg-deficient neurons exhibit increased miniature EPSC amplitudes, and their remaining spines exhibit larger heads deficient in the actin stabilizing protein cortactin. Spine destabilization in Arg knockdown neurons is prevented by blocking NMDA receptor-dependent relocalization of cortactin from spines, or by forcing cortactin into spines via fusion to an actin-binding region of Arg. Thus, Arg employs distinct mechanisms to selectively regulate spine and dendrite stability: Arg dampens activity-dependent disruption of cortactin localization to stabilize spines and attenuates Rho activity to stabilize dendrite arbors.

  15. Neurotensin promotes the dendrite elongation and the dendritic spine maturation of the cerebral cortex in vitro.

    PubMed

    Gandou, Chihiro; Ohtani, Akiko; Senzaki, Kouji; Shiga, Takashi

    2010-03-01

    We examined roles of neurotensin in the dendrite formation and the maturation of dendritic spines in the rat cerebral cortex. Embryonic day (E) 18 cortical neurons were cultured for 2 or 4 days in the presence of neurotensin. The chronic treatment of cortical neurons with neurotensin for 4 days increased the dendritic length of non-GABAergic neurons. In addition, the acute treatment of cortical neurons for 24h at 3 days in vitro also increased the dendritic length of non-GABAergic neurons similarly but more strongly than the chronic treatment. In contrast, the acute treatment for 4h had no effects on the dendrite formation. Next, we examined the effects of neurotensin on the maturation of dendritic spines. E16 cortical neurons were cultured for 10 or 14 days in a basal medium and then treated with neurotensin for 24h. At 11 days in vitro, neurotensin increased the postsynaptic density (PSD) 95-positive dendritic protrusions (filopodia, puncta and spines) together with the increase of spine density and the decrease of puncta density. At 15 days in vitro, neurotensin decreased the puncta density. In addition, the immunohistochemical localization of neurotensin type 1 and type 3 receptors in cultured neurons suggested the differential contribution of the receptors in these effects. These findings suggest that neurotensin promotes the dendrite outgrowth and the maturation of dendritic spines of cultured cortical neurons, although further studies are needed to conclude that these roles of neurotensin are also the case in vivo.

  16. Dendritic spine formation and synaptic function require neurobeachin

    PubMed Central

    Niesmann, Katharina; Breuer, Dorothee; Brockhaus, Johannes; Born, Gesche; Wolff, Ilka; Reissner, Carsten; Kilimann, Manfred W.; Rohlmann, Astrid; Missler, Markus

    2011-01-01

    A challenge in neuroscience is to understand the mechanisms underlying synapse formation. Most excitatory synapses in the brain are built on spines, which are actin-rich protrusions from dendrites. Spines are a major substrate of brain plasticity, and spine pathologies are observed in various mental illnesses. Here we investigate the role of neurobeachin (Nbea), a multidomain protein previously linked to cases of autism, in synaptogenesis. We show that deletion of Nbea leads to reduced numbers of spinous synapses in cultured neurons from complete knockouts and in cortical tissue from heterozygous mice, accompanied by altered miniature postsynaptic currents. In addition, excitatory synapses terminate mostly at dendritic shafts instead of spine heads in Nbea mutants, and actin becomes less enriched synaptically. As actin and synaptopodin, a spine-associated protein with actin-bundling activity, accumulate ectopically near the Golgi apparatus of mutant neurons, a role emerges for Nbea in trafficking important cargo to pre- and postsynaptic compartments. PMID:22109531

  17. EPSPs Measured in Proximal Dendritic Spines of Cortical Pyramidal Neurons123

    PubMed Central

    2016-01-01

    Abstract EPSPs occur when the neurotransmitter glutamate binds to postsynaptic receptors located on small pleomorphic membrane protrusions called dendritic spines. To transmit the synaptic signal, these potentials must travel through the spine neck and the dendritic tree to reach the soma. Due to their small size, the electrical behavior of spines and their ability to compartmentalize electrical signals has been very difficult to assess experimentally. In this study, we developed a method to perform simultaneous two-photon voltage-sensitive dye recording with two-photon glutamate uncaging in order to measure the characteristics (amplitude and duration) of uncaging-evoked EPSPs in single spines on the basal dendrites of L5 pyramidal neurons in acute brain slices from CD1 control mice. We were able to record uncaging-evoked spine potentials that resembled miniature EPSPs at the soma from a wide range of spine morphologies. In proximal spines, these potentials averaged 13.0 mV (range, 6.5–30.8 mV; N = 20) for an average somatic EPSP of 0.59 mV, whereas the mean attenuation ratio (spine/soma) was found to be 25.3. Durations of spine EPSP waveforms were found to be 11.7 ms on average. Modeling studies demonstrate the important role that spine neck resistance (Rneck) plays in spine EPSP amplitudes. Simulations used to estimate Rneck by fits to voltage-sensitive dye measurements produced a mean of 179 MΩ (range, 23–420 MΩ; N = 19). Independent measurements based on fluorescence recovery after photobleaching of a cytosolic dye from spines of the same population of neurons produced a mean Rneck estimate of 204 MΩ (range, 52–521 MΩ; N = 34). PMID:27257618

  18. Dendritic Spines in Depression: What We Learned from Animal Models

    PubMed Central

    Qiao, Hui; Li, Ming-Xing; Xu, Chang; Chen, Hui-Bin; An, Shu-Cheng; Ma, Xin-Ming

    2016-01-01

    Depression, a severe psychiatric disorder, has been studied for decades, but the underlying mechanisms still remain largely unknown. Depression is closely associated with alterations in dendritic spine morphology and spine density. Therefore, understanding dendritic spines is vital for uncovering the mechanisms underlying depression. Several chronic stress models, including chronic restraint stress (CRS), chronic unpredictable mild stress (CUMS), and chronic social defeat stress (CSDS), have been used to recapitulate depression-like behaviors in rodents and study the underlying mechanisms. In comparison with CRS, CUMS overcomes the stress habituation and has been widely used to model depression-like behaviors. CSDS is one of the most frequently used models for depression, but it is limited to the study of male mice. Generally, chronic stress causes dendritic atrophy and spine loss in the neurons of the hippocampus and prefrontal cortex. Meanwhile, neurons of the amygdala and nucleus accumbens exhibit an increase in spine density. These alterations induced by chronic stress are often accompanied by depression-like behaviors. However, the underlying mechanisms are poorly understood. This review summarizes our current understanding of the chronic stress-induced remodeling of dendritic spines in the hippocampus, prefrontal cortex, orbitofrontal cortex, amygdala, and nucleus accumbens and also discusses the putative underlying mechanisms. PMID:26881133

  19. Computational Approach to Dendritic Spine Taxonomy and Shape Transition Analysis

    PubMed Central

    Bokota, Grzegorz; Magnowska, Marta; Kuśmierczyk, Tomasz; Łukasik, Michał; Roszkowska, Matylda; Plewczynski, Dariusz

    2016-01-01

    The common approach in morphological analysis of dendritic spines of mammalian neuronal cells is to categorize spines into subpopulations based on whether they are stubby, mushroom, thin, or filopodia shaped. The corresponding cellular models of synaptic plasticity, long-term potentiation, and long-term depression associate the synaptic strength with either spine enlargement or spine shrinkage. Although a variety of automatic spine segmentation and feature extraction methods were developed recently, no approaches allowing for an automatic and unbiased distinction between dendritic spine subpopulations and detailed computational models of spine behavior exist. We propose an automatic and statistically based method for the unsupervised construction of spine shape taxonomy based on arbitrary features. The taxonomy is then utilized in the newly introduced computational model of behavior, which relies on transitions between shapes. Models of different populations are compared using supplied bootstrap-based statistical tests. We compared two populations of spines at two time points. The first population was stimulated with long-term potentiation, and the other in the resting state was used as a control. The comparison of shape transition characteristics allowed us to identify the differences between population behaviors. Although some extreme changes were observed in the stimulated population, statistically significant differences were found only when whole models were compared. The source code of our software is freely available for non-commercial use1. Contact: d.plewczynski@cent.uw.edu.pl. PMID:28066226

  20. Principles of Long-Term Dynamics of Dendritic Spines

    PubMed Central

    Yasumatsu, Nobuaki; Matsuzaki, Masanori; Miyazaki, Takashi; Noguchi, Jun; Kasai, Haruo

    2008-01-01

    Long-term potentiation (LTP) of synapse strength requires enlargement of dendritic spines on cerebral pyramidal neurons. Long-term depression (LTD) is linked to spine shrinkage. Indeed, spines are dynamic structures: they form, change their shapes and volumes or can disappear in the space of hours. Do all such changes result from synaptic activity, or do some changes result from intrinsic processes? How do enlargement and shrinkage of spines relate to elimination and generation of spines, and how do these processes contribute to the stationary distribution of spine volumes? To answer these questions, we recorded the volumes of many individual spines daily for several days using two-photon imaging of CA1 pyramidal neurons in cultured slices of rat hippocampus between postnatal day 17 to 23. With normal synaptic transmission, spines often changed volume or were created or eliminated, thereby showing activity-dependent plasticity. However, we found that spines changed volume even after we blocked synaptic activity, reflecting a native instability of these small structures over the long term. Such “intrinsic fluctuations” showed unique dependence on spine volume. A mathematical model constructed from these data and the theory of random fluctuations explains population behaviors of spines, such as rates of elimination and generation, stationary distribution of volumes and the long-term persistence of large spines. Our study finds that generation and elimination of spines are more prevalent than previously believed, and spine volume shows significant correlation with its age and life expectancy. The population dynamics of spines also predict key psychological features of memory. PMID:19074033

  1. Fluorescence imaging of dendritic spines of Golgi-Cox-stained neurons using brightening background

    NASA Astrophysics Data System (ADS)

    Ai, Min; Xiong, Hanqing; Yang, Tao; Shang, Zhenhua; Chen, Muqing; Liu, Xiuli; Zeng, Shaoqun

    2015-01-01

    We report a novel fluorescence imaging approach to imaging nonfluorescence-labeled biological tissue samples. The method was demonstrated by imaging neurons in Golgi-Cox-stained and epoxy-resin-embedded samples through the excitation of the background fluorescence of the specimens. The dark neurons stood out clearly against background fluorescence in the images, enabling the tracing of a single dendritic spine using both confocal and wide-field fluorescence microscopy. The results suggest that the reported fluorescence imaging method would provide an effective alternative solution to image nonfluorescence-labeled samples, and it allows tracing the dendritic spine structure of neurons.

  2. Paradoxical signaling regulates structural plasticity in dendritic spines

    PubMed Central

    Rangamani, Padmini; Levy, Michael G.; Khan, Shahid; Oster, George

    2016-01-01

    Transient spine enlargement (3- to 5-min timescale) is an important event associated with the structural plasticity of dendritic spines. Many of the molecular mechanisms associated with transient spine enlargement have been identified experimentally. Here, we use a systems biology approach to construct a mathematical model of biochemical signaling and actin-mediated transient spine expansion in response to calcium influx caused by NMDA receptor activation. We have identified that a key feature of this signaling network is the paradoxical signaling loop. Paradoxical components act bifunctionally in signaling networks, and their role is to control both the activation and the inhibition of a desired response function (protein activity or spine volume). Using ordinary differential equation (ODE)-based modeling, we show that the dynamics of different regulators of transient spine expansion, including calmodulin-dependent protein kinase II (CaMKII), RhoA, and Cdc42, and the spine volume can be described using paradoxical signaling loops. Our model is able to capture the experimentally observed dynamics of transient spine volume. Furthermore, we show that actin remodeling events provide a robustness to spine volume dynamics. We also generate experimentally testable predictions about the role of different components and parameters of the network on spine dynamics. PMID:27551076

  3. In Vivo Study of Dynamics and Stability of Dendritic Spines on Olfactory Bulb Interneurons in Xenopus laevis Tadpoles

    PubMed Central

    Huang, Yu-Bin; Hu, Chun-Rui; Zhang, Li; Yin, Wu; Hu, Bing

    2015-01-01

    Dendritic spines undergo continuous remodeling during development of the nervous system. Their stability is essential for maintaining a functional neuronal circuit. Spine dynamics and stability of cortical excitatory pyramidal neurons have been explored extensively in mammalian animal models. However, little is known about spiny interneurons in non-mammalian vertebrate models. In the present study, neuronal morphology was visualized by single-cell electroporation. Spiny neurons were surveyed in the Xenopus tadpole brain and observed to be widely distributed in the olfactory bulb and telencephalon. DsRed- or PSD95-GFP-expressing spiny interneurons in the olfactory bulb were selected for in vivo time-lapse imaging. Dendritic protrusions were classified as filopodia, thin, stubby, or mushroom spines based on morphology. Dendritic spines on the interneurons were highly dynamic, especially the filopodia and thin spines. The stubby and mushroom spines were relatively more stable, although their stability significantly decreased with longer observation intervals. The 4 spine types exhibited diverse preferences during morphological transitions from one spine type to others. Sensory deprivation induced by severing the olfactory nerve to block the input of mitral/tufted cells had no significant effects on interneuron spine stability. Hence, a new model was established in Xenopus laevis tadpoles to explore dendritic spine dynamics in vivo. PMID:26485435

  4. Reduced Purkinje cell dendritic arborization and loss of dendritic spines in essential tremor.

    PubMed

    Louis, Elan D; Lee, Michelle; Babij, Rachel; Ma, Karen; Cortés, Etty; Vonsattel, Jean-Paul G; Faust, Phyllis L

    2014-12-01

    Based on accumulating post-mortem evidence of abnormalities in Purkinje cell biology in essential tremor, we hypothesized that regressive changes in dendritic morphology would be apparent in the Purkinje cell population in essential tremor cases versus age-matched controls. Cerebellar cortical tissue from 27 cases with essential tremor and 27 age-matched control subjects was processed by the Golgi-Kopsch method. Purkinje cell dendritic anatomy was quantified using a Neurolucida microscopic system interfaced with a motorized stage. In all measures, essential tremor cases demonstrated significant reductions in dendritic complexity compared with controls. Median values in essential tremor cases versus controls were: 5712.1 versus 10 403.2 µm (total dendrite length, P=0.01), 465.9 versus 592.5 µm (branch length, P=0.01), 22.5 versus 29.0 (maximum branch order, P=0.001), and 165.3 versus 311.7 (number of terminations, P=0.008). Furthermore, the dendritic spine density was reduced in essential tremor cases (medians=0.82 versus 1.02 µm(-1), P=0.03). Our demonstration of regressive changes in Purkinje cell dendritic architecture and spines in essential tremor relative to control brains provides additional evidence of a pervasive abnormality of Purkinje cell biology in this disease, which affects multiple neuronal cellular compartments including their axon, cell body, dendrites and spines.

  5. Rapid Loss of Dendritic Spines after Stress Involves Derangement of Spine Dynamics by Corticotropin-Releasing Hormone

    PubMed Central

    Chen, Yuncai; Dubé, Céline M.; Rice, Courtney J.; Baram, Tallie Z.

    2008-01-01

    Chronic stress causes dendritic regression and loss of dendritic spines in hippocampal neurons that is accompanied by deficits in synaptic plasticity and memory. However, the responsible mechanisms remain unresolved. Here, we found that within hours of the onset of stress, the density of dendritic spines declined in vulnerable dendritic domains. This rapid, stress-induced spine loss was abolished by blocking the receptor (CRFR1) of corticotropin-releasing hormone (CRH), a hippocampal neuropeptide released during stress. Exposure to CRH provoked spine loss and dendritic regression in hippocampal organotypic cultures, and selective blockade of the CRFR1 receptor had the opposite effect. Live, time-lapse imaging revealed that CRH reduced spine density by altering dendritic spine dynamics: the peptide selectively and reversibly accelerated spine retraction, and this mechanism involved destabilization of spine F-actin. In addition, mice lacking the CRFR1 receptor had augmented spine density. These findings support a mechanistic role for CRH–CRFR1 signaling in stress-evoked spine loss and dendritic remodeling. PMID:18337421

  6. The dendritic spine story: an intriguing process of discovery.

    PubMed

    DeFelipe, Javier

    2015-01-01

    Dendritic spines are key components of a variety of microcircuits and they represent the majority of postsynaptic targets of glutamatergic axon terminals in the brain. The present article will focus on the discovery of dendritic spines, which was possible thanks to the application of the Golgi technique to the study of the nervous system, and will also explore the early interpretation of these elements. This discovery represents an interesting chapter in the history of neuroscience as it shows us that progress in the study of the structure of the nervous system is based not only on the emergence of new techniques but also on our ability to exploit the methods already available and correctly interpret their microscopic images.

  7. High Actin Concentrations in Brain Dendritic Spines and Postsynaptic Densities

    NASA Astrophysics Data System (ADS)

    Matus, Andrew; Ackermann, Marcel; Pehling, Gundula; Randolph Byers, H.; Fujiwara, Keigi

    1982-12-01

    Antibodies against actin were used to corroborate the presence of actin as a major component protein of isolated brain postsynaptic densities. The same antibodies also were used as an immunohistochemical stain to study the distribution of actin in sections of intact brain tissue. This showed two major sites where actin is concentrated: smooth muscle cells around blood vessels and postsynaptic sites. In the postsynaptic area the highest concentration of actin occurs in postsynaptic densities and there also is intense staining in the surrounding cytoplasm, especially within dendritic spines. Antiactin staining was much weaker in other parts of neurons and in glial cells. The high concentration of actin in dendritic spines may be related to shape changes that these structures have been found to undergo in response to prolonged afferent stimulation.

  8. The dendritic spine story: an intriguing process of discovery

    PubMed Central

    DeFelipe, Javier

    2015-01-01

    Dendritic spines are key components of a variety of microcircuits and they represent the majority of postsynaptic targets of glutamatergic axon terminals in the brain. The present article will focus on the discovery of dendritic spines, which was possible thanks to the application of the Golgi technique to the study of the nervous system, and will also explore the early interpretation of these elements. This discovery represents an interesting chapter in the history of neuroscience as it shows us that progress in the study of the structure of the nervous system is based not only on the emergence of new techniques but also on our ability to exploit the methods already available and correctly interpret their microscopic images. PMID:25798090

  9. Polarity Determinants in Dendritic Spine Development and Plasticity.

    PubMed

    Zhang, Huaye

    2016-01-01

    The asymmetric distribution of various proteins and RNAs is essential for all stages of animal development, and establishment and maintenance of this cellular polarity are regulated by a group of conserved polarity determinants. Studies over the last 10 years highlight important functions for polarity proteins, including apical-basal polarity and planar cell polarity regulators, in dendritic spine development and plasticity. Remarkably, many of the conserved polarity machineries function in similar manners in the context of spine development as they do in epithelial morphogenesis. Interestingly, some polarity proteins also utilize neuronal-specific mechanisms. Although many questions remain unanswered in our understanding of how polarity proteins regulate spine development and plasticity, current and future research will undoubtedly shed more light on how this conserved group of proteins orchestrates different pathways to shape the neuronal circuitry.

  10. Morphological analysis of dendrites and spines by hybridization of ridge detection with twin support vector machine.

    PubMed

    Wang, Shuihua; Chen, Mengmeng; Li, Yang; Shao, Ying; Zhang, Yudong; Du, Sidan; Wu, Jane

    2016-01-01

    Dendritic spines are described as neuronal protrusions. The morphology of dendritic spines and dendrites has a strong relationship to its function, as well as playing an important role in understanding brain function. Quantitative analysis of dendrites and dendritic spines is essential to an understanding of the formation and function of the nervous system. However, highly efficient tools for the quantitative analysis of dendrites and dendritic spines are currently undeveloped. In this paper we propose a novel three-step cascaded algorithm-RTSVM- which is composed of ridge detection as the curvature structure identifier for backbone extraction, boundary location based on differences in density, the Hu moment as features and Twin Support Vector Machine (TSVM) classifiers for spine classification. Our data demonstrates that this newly developed algorithm has performed better than other available techniques used to detect accuracy and false alarm rates. This algorithm will be used effectively in neuroscience research.

  11. Morphological analysis of dendrites and spines by hybridization of ridge detection with twin support vector machine

    PubMed Central

    Wang, Shuihua; Chen, Mengmeng; Li, Yang; Shao, Ying; Zhang, Yudong

    2016-01-01

    Dendritic spines are described as neuronal protrusions. The morphology of dendritic spines and dendrites has a strong relationship to its function, as well as playing an important role in understanding brain function. Quantitative analysis of dendrites and dendritic spines is essential to an understanding of the formation and function of the nervous system. However, highly efficient tools for the quantitative analysis of dendrites and dendritic spines are currently undeveloped. In this paper we propose a novel three-step cascaded algorithm–RTSVM— which is composed of ridge detection as the curvature structure identifier for backbone extraction, boundary location based on differences in density, the Hu moment as features and Twin Support Vector Machine (TSVM) classifiers for spine classification. Our data demonstrates that this newly developed algorithm has performed better than other available techniques used to detect accuracy and false alarm rates. This algorithm will be used effectively in neuroscience research. PMID:27547530

  12. Paternal deprivation during infancy results in dendrite- and time-specific changes of dendritic development and spine formation in the orbitofrontal cortex of the biparental rodent Octodon degus.

    PubMed

    Helmeke, C; Seidel, K; Poeggel, G; Bredy, T W; Abraham, A; Braun, K

    2009-10-20

    The aim of this study in the biparental rodent Octodon degus was to assess the impact of paternal deprivation on neuronal and synaptic development in the orbitofrontal cortex, a prefrontal region which is essential for emotional and cognitive function. On the behavioral level the quantitative comparison of parental behaviors in biparental and single-mother families revealed that (i) degu fathers significantly participate in parental care and (ii) single-mothers do not increase their maternal care to compensate the lack of paternal care. On the brain structural level we show in three-week-old father-deprived animals that layer II/III pyramidal neurons in the orbitofrontal cortex displayed significantly lower spine densities on apical and basal dendrites. Whereas biparentally raised animals have reached adult spine density values at postnatal day 21, fatherless animals seem "to catch up" by a delayed increase of spine density until reaching similar values as biparentally raised animals in adulthood. However, in adulthood reduced apical spine numbers together with shorter apical dendrites were observed in father-deprived animals, which indicates that dendritic growth and synapse formation (seen in biparental animals between postnatal day 21 and adulthood) were significantly suppressed. These results demonstrate that paternal deprivation delays and partly suppresses the development of orbitofrontal circuits. The retarded dendritic and synaptic development of the apical dendrites of layer II/III pyramidal neurons in the orbitofrontal cortex of adult fatherless animals may reflect a reduced excitatory connectivity of this cortical subregion.

  13. Dendritic BDNF synthesis is required for late-phase spine maturation and recovery of cortical responses following sensory deprivation.

    PubMed

    Kaneko, Megumi; Xie, Yuxiang; An, Juan Ji; Stryker, Michael P; Xu, Baoji

    2012-04-04

    Sensory experience in early postnatal life shapes neuronal connections in the brain. Here we report that the local synthesis of brain-derived neurotrophic factor (BDNF) in dendrites plays an important role in this process. We found that dendritic spines of layer 2/3 pyramidal neurons of the visual cortex in mutant mice lacking dendritic Bdnf mRNA and thus local BDNF synthesis were normal at 3 weeks of age, but thinner, longer, and more closely spaced (morphological features of immaturity) at 4 months of age than in wild-type (WT) littermates. Layer 2/3 of the visual cortex in these mutant animals also had fewer GABAergic presynaptic terminals at both ages. The overall size and shape of dendritic arbors were, however, similar in mutant and WT mice at both ages. By using optical imaging of intrinsic signals and single-unit recordings, we found that mutant animals failed to recover cortical responsiveness following monocular deprivation (MD) during the critical period, although they displayed normally the competitive loss of responsiveness to an eye briefly deprived of vision. Furthermore, MD still induced a loss of responsiveness to the closed eye in adult mutant mice, but not in adult WT mice. These results indicate that dendritic BDNF synthesis is required for spine pruning, late-phase spine maturation, and recovery of cortical responsiveness following sensory deprivation. They also suggest that maturation of dendritic spines is required for the maintenance of cortical responsiveness following sensory deprivation in adulthood.

  14. Nanoscale segregation of actin nucleation and elongation factors determines dendritic spine protrusion

    PubMed Central

    Chazeau, Anaël; Mehidi, Amine; Nair, Deepak; Gautier, Jérémie J; Leduc, Cécile; Chamma, Ingrid; Kage, Frieda; Kechkar, Adel; Thoumine, Olivier; Rottner, Klemens; Choquet, Daniel; Gautreau, Alexis; Sibarita, Jean-Baptiste; Giannone, Grégory

    2014-01-01

    Actin dynamics drive morphological remodeling of neuronal dendritic spines and changes in synaptic transmission. Yet, the spatiotemporal coordination of actin regulators in spines is unknown. Using single protein tracking and super-resolution imaging, we revealed the nanoscale organization and dynamics of branched F-actin regulators in spines. Branched F-actin nucleation occurs at the PSD vicinity, while elongation occurs at the tip of finger-like protrusions. This spatial segregation differs from lamellipodia where both branched F-actin nucleation and elongation occur at protrusion tips. The PSD is a persistent confinement zone for IRSp53 and the WAVE complex, an activator of the Arp2/3 complex. In contrast, filament elongators like VASP and formin-like protein-2 move outwards from the PSD with protrusion tips. Accordingly, Arp2/3 complexes associated with F-actin are immobile and surround the PSD. Arp2/3 and Rac1 GTPase converge to the PSD, respectively, by cytosolic and free-diffusion on the membrane. Enhanced Rac1 activation and Shank3 over-expression, both associated with spine enlargement, induce delocalization of the WAVE complex from the PSD. Thus, the specific localization of branched F-actin regulators in spines might be reorganized during spine morphological remodeling often associated with synaptic plasticity. PMID:25293574

  15. From Synaptic Transmission to Cognition: An Intermediary Role for Dendritic Spines

    ERIC Educational Resources Information Center

    Gonzalez-Burgos, Ignacio

    2012-01-01

    Dendritic spines are cytoplasmic protrusions that develop directly or indirectly from the filopodia of neurons. Dendritic spines mediate excitatory neurotransmission and they can isolate the electrical activity generated by synaptic impulses, enabling them to translate excitatory afferent information via several types of plastic changes, including…

  16. Periodic F-actin structures shape the neck of dendritic spines.

    PubMed

    Bär, Julia; Kobler, Oliver; van Bommel, Bas; Mikhaylova, Marina

    2016-11-14

    Most of the excitatory synapses on principal neurons of the forebrain are located on specialized structures called dendritic spines. Their morphology, comprising a spine head connected to the dendritic branch via a thin neck, provides biochemical and electrical compartmentalization during signal transmission. Spine shape is defined and tightly controlled by the organization of the actin cytoskeleton. Alterations in synaptic strength correlate with changes in the morphological appearance of the spine head and neck. Therefore, it is important to get a better understanding of the nanoscale organization of the actin cytoskeleton in dendritic spines. A periodic organization of the actin/spectrin lattice was recently discovered in axons and a small fraction of dendrites using super-resolution microscopy. Here we use a small probe phalloidin-Atto647N, to label F-actin in mature hippocampal primary neurons and in living hippocampal slices. STED nanoscopy reveals that in contrast to β-II spectrin antibody labelling, phalloidin-Atto647N stains periodic actin structures in all dendrites and the neck of nearly all dendritic spines, including filopodia-like spines. These findings extend the current view on F-actin organization in dendritic spines and may provide new avenues for understanding the structural changes in the spine neck during induction of synaptic plasticity, active organelle transport or tethering.

  17. Periodic F-actin structures shape the neck of dendritic spines

    PubMed Central

    Bär, Julia; Kobler, Oliver; van Bommel, Bas; Mikhaylova, Marina

    2016-01-01

    Most of the excitatory synapses on principal neurons of the forebrain are located on specialized structures called dendritic spines. Their morphology, comprising a spine head connected to the dendritic branch via a thin neck, provides biochemical and electrical compartmentalization during signal transmission. Spine shape is defined and tightly controlled by the organization of the actin cytoskeleton. Alterations in synaptic strength correlate with changes in the morphological appearance of the spine head and neck. Therefore, it is important to get a better understanding of the nanoscale organization of the actin cytoskeleton in dendritic spines. A periodic organization of the actin/spectrin lattice was recently discovered in axons and a small fraction of dendrites using super-resolution microscopy. Here we use a small probe phalloidin-Atto647N, to label F-actin in mature hippocampal primary neurons and in living hippocampal slices. STED nanoscopy reveals that in contrast to β-II spectrin antibody labelling, phalloidin-Atto647N stains periodic actin structures in all dendrites and the neck of nearly all dendritic spines, including filopodia-like spines. These findings extend the current view on F-actin organization in dendritic spines and may provide new avenues for understanding the structural changes in the spine neck during induction of synaptic plasticity, active organelle transport or tethering. PMID:27841352

  18. The ROR2 tyrosine kinase receptor regulates dendritic spine morphogenesis in hippocampal neurons.

    PubMed

    Alfaro, Iván E; Varela-Nallar, Lorena; Varas-Godoy, Manuel; Inestrosa, Nibaldo C

    2015-07-01

    Wnt signaling regulates synaptic development and function and contributes to the fine-tuning of the molecular and morphological differentiation of synapses. We have shown previously that Wnt5a activates non-canonical Wnt signaling to stimulate postsynaptic differentiation in excitatory hippocampal neurons promoting the clustering of the postsynaptic scaffold protein PSD-95 and the development of dendritic spines. At least three different kinds of Wnt receptors have been associated with Wnt5a signaling: seven trans-membrane Frizzled receptors and the tyrosine kinase receptors Ryk and ROR2. We report here that ROR2 is distributed in the dendrites of hippocampal neurons in close proximity to synaptic contacts and it is contained in dendritic spine protrusions. We demonstrate that ROR2 is necessary to maintain dendritic spine number and morphological distribution in cultured hippocampal neurons. ROR2 overexpression increased dendritic spine growth without affecting the density of dendritic spine protrusions in a form dependent on its extracellular Wnt binding cysteine rich domain (CRD) and kinase domain. Overexpression of dominant negative ROR2 lacking the extracellular CRD decreased spine density and the proportion of mushroom like spines, while ROR2 lacking the C-terminal and active kinase domains only affected spine morphology. Our results indicate a crucial role of the ROR2 in the formation and maturation of the postsynaptic dendritic spines in hippocampal neurons.

  19. Of microtubules and memory: implications for microtubule dynamics in dendrites and spines

    PubMed Central

    Dent, Erik W.

    2017-01-01

    Microtubules (MTs) are cytoskeletal polymers composed of repeating subunits of tubulin that are ubiquitously expressed in eukaryotic cells. They undergo a stochastic process of polymerization and depolymerization from their plus ends termed dynamic instability. MT dynamics is an ongoing process in all cell types and has been the target for the development of several useful anticancer drugs, which compromise rapidly dividing cells. Recent studies also suggest that MT dynamics may be particularly important in neurons, which develop a highly polarized morphology, consisting of a single axon and multiple dendrites that persist throughout adulthood. MTs are especially dynamic in dendrites and have recently been shown to polymerize directly into dendritic spines, the postsynaptic compartment of excitatory neurons in the CNS. These transient polymerization events into dendritic spines have been demonstrated to play important roles in synaptic plasticity in cultured neurons. Recent studies also suggest that MT dynamics in the adult brain function in the essential process of learning and memory and may be compromised in degenerative diseases, such as Alzheimer’s disease. This raises the possibility of targeting MT dynamics in the design of new therapeutic agents. PMID:28035040

  20. Cortical regulation of dopamine depletion-induced dendritic spine loss in striatal medium spiny neurons.

    PubMed

    Neely, M D; Schmidt, D E; Deutch, A Y

    2007-10-26

    The proximate cause of Parkinson's disease is striatal dopamine depletion. Although no overt toxicity to striatal neurons has been reported in Parkinson's disease, one of the consequences of striatal dopamine loss is a decrease in the number of dendritic spines on striatal medium spiny neurons (MSNs). Dendrites of these neurons receive cortical glutamatergic inputs onto the dendritic spine head and dopaminergic inputs from the substantia nigra onto the spine neck. This synaptic arrangement suggests that dopamine gates corticostriatal glutamatergic drive onto spines. Using triple organotypic slice cultures composed of ventral mesencephalon, striatum, and cortex of the neonatal rat, we examined the role of the cortex in dopamine depletion-induced dendritic spine loss in MSNs. The striatal dopamine innervation was lesioned by treatment of the cultures with the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium (MPP+) or by removing the mesencephalon. Both MPP+ and mesencephalic ablation decreased MSN dendritic spine density. Analysis of spine morphology revealed that thin spines were preferentially lost after dopamine depletion. Removal of the cortex completely prevented dopamine depletion-induced spine loss. These data indicate that the dendritic remodeling of MSNs seen in parkinsonism occurs secondary to increases in corticostriatal glutamatergic drive, and suggest that modulation of cortical activity may be a useful therapeutic strategy in Parkinson's disease.

  1. Laser-induced microlesion of single dendrites in living mice

    NASA Astrophysics Data System (ADS)

    Sacconi, L.; Panteri, R.; Masi, A.; Diana, G.; Buffelli, M.; Keller, F.; Pavone, F. S.

    2007-02-01

    Recently, two-photon microscopy has been used to perform high spatial resolution imaging of spine plasticity in the intact neocortex in living mice. In this work we study the in vivo spine rearrangements after an acute and selective damage. For this purpose, we have used a near-IR femtosecond pulsed laser to combine two-photon microscopy imaging with microdissection operation on fluorescently-labeled neurons. Three-dimensional reconstructions of dendrites expressing fluorescence protein have been performed in the cortex of YFP-H and GFP-M transgenic living mice. Afterwards, single dendrites have been laser-dissected irradiating the structure with a high femtosecond laser energy dose. By using a chronically implanted glass window we performed long-term imaging in the area of the dissected dendrite. We will show that laser ablation can be performed with micrometric precision and without visible collateral damage to nearby neuronal structures. Also, we will evidence the morphological changes of the dendritic branches and dendritic spines after this specific perturbation inside the intact neuronal network. Laser microdissection of selected structures of the neuronal branching in vivo represents a promising tool for neurobiological research.

  2. Activity-dependent dendritic spine neck changes are correlated with synaptic strength

    PubMed Central

    Araya, Roberto; Vogels, Tim P.; Yuste, Rafael

    2014-01-01

    Most excitatory inputs in the mammalian brain are made on dendritic spines, rather than on dendritic shafts. Spines compartmentalize calcium, and this biochemical isolation can underlie input-specific synaptic plasticity, providing a raison d’etre for spines. However, recent results indicate that the spine can experience a membrane potential different from that in the parent dendrite, as though the spine neck electrically isolated the spine. Here we use two-photon calcium imaging of mouse neocortical pyramidal neurons to analyze the correlation between the morphologies of spines activated under minimal synaptic stimulation and the excitatory postsynaptic potentials they generate. We find that excitatory postsynaptic potential amplitudes are inversely correlated with spine neck lengths. Furthermore, a spike timing-dependent plasticity protocol, in which two-photon glutamate uncaging over a spine is paired with postsynaptic spikes, produces rapid shrinkage of the spine neck and concomitant increases in the amplitude of the evoked spine potentials. Using numerical simulations, we explore the parameter regimes for the spine neck resistance and synaptic conductance changes necessary to explain our observations. Our data, directly correlating synaptic and morphological plasticity, imply that long-necked spines have small or negligible somatic voltage contributions, but that, upon synaptic stimulation paired with postsynaptic activity, they can shorten their necks and increase synaptic efficacy, thus changing the input/output gain of pyramidal neurons. PMID:24982196

  3. Spines slow down dendritic chloride diffusion and affect short-term ionic plasticity of GABAergic inhibition

    PubMed Central

    Mohapatra, Namrata; Tønnesen, Jan; Vlachos, Andreas; Kuner, Thomas; Deller, Thomas; Nägerl, U. Valentin; Santamaria, Fidel; Jedlicka, Peter

    2016-01-01

    Cl− plays a crucial role in neuronal function and synaptic inhibition. However, the impact of neuronal morphology on the diffusion and redistribution of intracellular Cl− is not well understood. The role of spines in Cl− diffusion along dendritic trees has not been addressed so far. Because measuring fast and spatially restricted Cl− changes within dendrites is not yet technically possible, we used computational approaches to predict the effects of spines on Cl− dynamics in morphologically complex dendrites. In all morphologies tested, including dendrites imaged by super-resolution STED microscopy in live brain tissue, spines slowed down longitudinal Cl− diffusion along dendrites. This effect was robust and could be observed in both deterministic as well as stochastic simulations. Cl− extrusion altered Cl− diffusion to a much lesser extent than the presence of spines. The spine-dependent slowing of Cl− diffusion affected the amount and spatial spread of changes in the GABA reversal potential thereby altering homosynaptic as well as heterosynaptic short-term ionic plasticity at GABAergic synapses in dendrites. Altogether, our results suggest a fundamental role of dendritic spines in shaping Cl− diffusion, which could be of relevance in the context of pathological conditions where spine densities and neural excitability are perturbed. PMID:26987404

  4. Role of dendritic spines in action potential backpropagation: a numerical simulation study.

    PubMed

    Tsay, David; Yuste, Rafael

    2002-11-01

    Two remarkable aspects of pyramidal neurons are their complex dendritic morphologies and the abundant presence of spines, small structures that are the sites of excitatory input. Although the channel properties of the dendritic shaft membrane have been experimentally probed, the influence of spine properties in dendritic signaling and action potential propagation remains unclear. To explore this we have performed multi-compartmental numerical simulations investigating the degree of consistency between experimental data on dendritic channel densities and backpropagation behavior, as well as the necessity and degree of influence of excitable spines. Our results indicate that measured densities of Na(+) channels in dendritic shafts cannot support effective backpropagation observed in apical dendrites due to suprathreshold inactivation. We demonstrate as a potential solution that Na(+) channels in spines at higher densities than those measured in the dendritic shaft can support extensive backpropagation. In addition, clustering of Na(+) channels in spines appears to enhance their effect due to their unique morphology. Finally, we show that changes in spine morphology significantly influence backpropagation efficacy. These results suggest that, by clustering sodium channels, spines may serve to control backpropagation.

  5. Spines slow down dendritic chloride diffusion and affect short-term ionic plasticity of GABAergic inhibition

    NASA Astrophysics Data System (ADS)

    Mohapatra, Namrata; Tønnesen, Jan; Vlachos, Andreas; Kuner, Thomas; Deller, Thomas; Nägerl, U. Valentin; Santamaria, Fidel; Jedlicka, Peter

    2016-03-01

    Cl‑ plays a crucial role in neuronal function and synaptic inhibition. However, the impact of neuronal morphology on the diffusion and redistribution of intracellular Cl‑ is not well understood. The role of spines in Cl‑ diffusion along dendritic trees has not been addressed so far. Because measuring fast and spatially restricted Cl‑ changes within dendrites is not yet technically possible, we used computational approaches to predict the effects of spines on Cl‑ dynamics in morphologically complex dendrites. In all morphologies tested, including dendrites imaged by super-resolution STED microscopy in live brain tissue, spines slowed down longitudinal Cl‑ diffusion along dendrites. This effect was robust and could be observed in both deterministic as well as stochastic simulations. Cl‑ extrusion altered Cl‑ diffusion to a much lesser extent than the presence of spines. The spine-dependent slowing of Cl‑ diffusion affected the amount and spatial spread of changes in the GABA reversal potential thereby altering homosynaptic as well as heterosynaptic short-term ionic plasticity at GABAergic synapses in dendrites. Altogether, our results suggest a fundamental role of dendritic spines in shaping Cl‑ diffusion, which could be of relevance in the context of pathological conditions where spine densities and neural excitability are perturbed.

  6. Spines slow down dendritic chloride diffusion and affect short-term ionic plasticity of GABAergic inhibition.

    PubMed

    Mohapatra, Namrata; Tønnesen, Jan; Vlachos, Andreas; Kuner, Thomas; Deller, Thomas; Nägerl, U Valentin; Santamaria, Fidel; Jedlicka, Peter

    2016-03-18

    Cl(-) plays a crucial role in neuronal function and synaptic inhibition. However, the impact of neuronal morphology on the diffusion and redistribution of intracellular Cl(-) is not well understood. The role of spines in Cl(-) diffusion along dendritic trees has not been addressed so far. Because measuring fast and spatially restricted Cl(-) changes within dendrites is not yet technically possible, we used computational approaches to predict the effects of spines on Cl(-) dynamics in morphologically complex dendrites. In all morphologies tested, including dendrites imaged by super-resolution STED microscopy in live brain tissue, spines slowed down longitudinal Cl(-) diffusion along dendrites. This effect was robust and could be observed in both deterministic as well as stochastic simulations. Cl(-) extrusion altered Cl(-) diffusion to a much lesser extent than the presence of spines. The spine-dependent slowing of Cl(-) diffusion affected the amount and spatial spread of changes in the GABA reversal potential thereby altering homosynaptic as well as heterosynaptic short-term ionic plasticity at GABAergic synapses in dendrites. Altogether, our results suggest a fundamental role of dendritic spines in shaping Cl(-) diffusion, which could be of relevance in the context of pathological conditions where spine densities and neural excitability are perturbed.

  7. Age-Based Comparison of Human Dendritic Spine Structure Using Complete Three-Dimensional Reconstructions

    PubMed Central

    Benavides-Piccione, Ruth; Fernaud-Espinosa, Isabel; Robles, Victor; Yuste, Rafael; DeFelipe, Javier

    2013-01-01

    Dendritic spines of pyramidal neurons are targets of most excitatory synapses in the cerebral cortex. Recent evidence suggests that the morphology of the dendritic spine could determine its synaptic strength and learning rules. However, unfortunately, there are scant data available regarding the detailed morphology of these structures for the human cerebral cortex. In the present study, we analyzed over 8900 individual dendritic spines that were completely 3D reconstructed along the length of apical and basal dendrites of layer III pyramidal neurons in the cingulate cortex of 2 male humans (aged 40 and 85 years old), using intracellular injections of Lucifer Yellow in fixed tissue. We assembled a large, quantitative database, which revealed a major reduction in spine densities in the aged case. Specifically, small and short spines of basal dendrites and long spines of apical dendrites were lost, regardless of the distance from the soma. Given the age difference between the cases, our results suggest selective alterations in spines with aging in humans and indicate that the spine volume and length are regulated by different biological mechanisms. PMID:22710613

  8. Biophysical model of the role of actin remodeling on dendritic spine morphology

    PubMed Central

    Miermans, C. A.; Kusters, R. P. T.; Hoogenraad, C. C.; Storm, C.

    2017-01-01

    Dendritic spines are small membranous structures that protrude from the neuronal dendrite. Each spine contains a synaptic contact site that may connect its parent dendrite to the axons of neighboring neurons. Dendritic spines are markedly distinct in shape and size, and certain types of stimulation prompt spines to evolve, in fairly predictable fashion, from thin nascent morphologies to the mushroom-like shapes associated with mature spines. It is well established that the remodeling of spines is strongly dependent upon the actin cytoskeleton inside the spine. A general framework that details the precise role of actin in directing the transitions between the various spine shapes is lacking. We address this issue, and present a quantitative, model-based scenario for spine plasticity validated using realistic and physiologically relevant parameters. Our model points to a crucial role for the actin cytoskeleton. In the early stages of spine formation, the interplay between the elastic properties of the spine membrane and the protrusive forces generated in the actin cytoskeleton propels the incipient spine. In the maturation stage, actin remodeling in the form of the combined dynamics of branched and bundled actin is required to form mature, mushroom-like spines. Importantly, our model shows that constricting the spine-neck aids in the stabilization of mature spines, thus pointing to a role in stabilization and maintenance for additional factors such as ring-like F-actin structures. Taken together, our model provides unique insights into the fundamental role of actin remodeling and polymerization forces during spine formation and maturation. PMID:28158194

  9. Postsynaptic PDLIM5 / Enigma Homolog binds SPAR and causes dendritic spine shrinkage

    PubMed Central

    Herrick, Scott; Evers, Danielle M.; Lee, Ji-Yun; Udagawa, Noriko; Pak, Daniel T.S.

    2009-01-01

    Dendritic spine morphology is thought to play important roles in synaptic development and plasticity, and morphological derangements in spines are correlated with several neurological disorders. Here, we identified an interaction between Spine-Associated RapGAP (SPAR), a postsynaptic protein that reorganizes actin cytoskeleton and drives dendritic spine head growth, and PDLIM5 / Enigma Homolog (ENH), a PDZ-LIM (postsynaptic density-95/Discs large/zona occludens 1-Lin11/Isl-1/Mec3) family member. PDLIM5 has been implicated in susceptibility to bipolar disorder, major depression and schizophrenia but its function in neurological disease is poorly understood. We show that PDLIM5 is present in the postsynaptic density, where it promotes decreased dendritic spine head size and longer, filopodia-like morphology. Conversely, RNA interference against PDLIM5 or loss of PDLIM5 interaction with SPAR caused increased spine head diameter. Furthermore, PKC activation promoted delivery of PDLIM5 into dendritic spines and increased its spine colocalization with SPAR. These data reveal new postsynaptic functions for PDLIM5 in shrinkage of dendritic spines that may be relevant to its association with psychiatric illness. PMID:19900557

  10. Molecular architecture of synaptic actin cytoskeleton in hippocampal neurons reveals a mechanism of dendritic spine morphogenesis.

    PubMed

    Korobova, Farida; Svitkina, Tatyana

    2010-01-01

    Excitatory synapses in the brain play key roles in learning and memory. The formation and functions of postsynaptic mushroom-shaped structures, dendritic spines, and possibly of presynaptic terminals, rely on actin cytoskeleton remodeling. However, the cytoskeletal architecture of synapses remains unknown hindering the understanding of synapse morphogenesis. Using platinum replica electron microscopy, we characterized the cytoskeletal organization and molecular composition of dendritic spines, their precursors, dendritic filopodia, and presynaptic boutons. A branched actin filament network containing Arp2/3 complex and capping protein was a dominant feature of spine heads and presynaptic boutons. Surprisingly, the spine necks and bases, as well as dendritic filopodia, also contained a network, rather than a bundle, of branched and linear actin filaments that was immunopositive for Arp2/3 complex, capping protein, and myosin II, but not fascin. Thus, a tight actin filament bundle is not necessary for structural support of elongated filopodia-like protrusions. Dynamically, dendritic filopodia emerged from densities in the dendritic shaft, which by electron microscopy contained branched actin network associated with dendritic microtubules. We propose that dendritic spine morphogenesis begins from an actin patch elongating into a dendritic filopodium, which tip subsequently expands via Arp2/3 complex-dependent nucleation and which length is modulated by myosin II-dependent contractility.

  11. Dendritic spines disappear with chilling but proliferate excessively upon rewarming of mature hippocampus.

    PubMed

    Kirov, S A; Petrak, L J; Fiala, J C; Harris, K M

    2004-01-01

    More dendritic spine synapses occur on mature neurons in hippocampal slices by 2 h of incubation in vitro, than in perfusion-fixed hippocampus. What conditions initiate this spinogenesis and how rapidly do the spines begin to proliferate on mature neurons? To address these questions, CA1 field of the hippocampus neurons expressing green fluorescent protein in living slices from mature mice were imaged with two-photon microscopy. Spines disappeared and dendrites were varicose immediately after slice preparation in ice-cold artificial cerebrospinal fluid (ACSF). Electron microscopy (EM) revealed disrupted dendritic cytoplasm, enlarged or free-floating postsynaptic densities, and excessive axonal endocytosis. Upon warming dendritic varicosities shrank and spines rapidly reappeared within a few minutes illustrating the remarkable resilience of mature hippocampal neurons in slices. When membrane impermeant sucrose was substituted for NaCl in ACSF dendrites remained spiny at ice-cold temperatures and EM revealed less disruption. Nevertheless, spine number and length increased within 30 min in warm ACSF even when the extracellular calcium concentration was zero and synaptic transmission was blocked. When slices were first recovered for several hours and then chilled in 6 degrees C ACSF many spines disappeared and the dendrites became varicose. Upon re-warming varicosities shrank and spines reemerged in the same position from which they disappeared. In addition, new spines formed and spines were longer suggesting that chilling, not the initial injury from slicing, caused the spines to disappear while re-warming triggered the spine proliferation on mature neurons. The new spines might be a substrate for neuronal recovery of function, when neurons have been chilled or exposed to other traumatic conditions that disrupt ionic homeostasis.

  12. Imaging dendritic spines of rat primary hippocampal neurons using structured illumination microscopy.

    PubMed

    Schouten, Marijn; De Luca, Giulia M R; Alatriste González, Diana K; de Jong, Babette E; Timmermans, Wendy; Xiong, Hui; Krugers, Harm; Manders, Erik M M; Fitzsimons, Carlos P

    2014-05-04

    Dendritic spines are protrusions emerging from the dendrite of a neuron and represent the primary postsynaptic targets of excitatory inputs in the brain. Technological advances have identified these structures as key elements in neuron connectivity and synaptic plasticity. The quantitative analysis of spine morphology using light microscopy remains an essential problem due to technical limitations associated with light's intrinsic refraction limit. Dendritic spines can be readily identified by confocal laser-scanning fluorescence microscopy. However, measuring subtle changes in the shape and size of spines is difficult because spine dimensions other than length are usually smaller than conventional optical resolution fixed by light microscopy's theoretical resolution limit of 200 nm. Several recently developed super resolution techniques have been used to image cellular structures smaller than the 200 nm, including dendritic spines. These techniques are based on classical far-field operations and therefore allow the use of existing sample preparation methods and to image beyond the surface of a specimen. Described here is a working protocol to apply super resolution structured illumination microscopy (SIM) to the imaging of dendritic spines in primary hippocampal neuron cultures. Possible applications of SIM overlap with those of confocal microscopy. However, the two techniques present different applicability. SIM offers higher effective lateral resolution, while confocal microscopy, due to the usage of a physical pinhole, achieves resolution improvement at the expense of removal of out of focus light. In this protocol, primary neurons are cultured on glass coverslips using a standard protocol, transfected with DNA plasmids encoding fluorescent proteins and imaged using SIM. The whole protocol described herein takes approximately 2 weeks, because dendritic spines are imaged after 16-17 days in vitro, when dendritic development is optimal. After completion of the

  13. BDNF over-expression increases olfactory bulb granule cell dendritic spine density in vivo

    PubMed Central

    McDole, Brittnee; Isgor, Ceylan; Pare, Christopher; Guthrie, Kathleen

    2015-01-01

    Olfactory bulb granule cells are axon-less, inhibitory interneurons that regulate the activity of the excitatory output neurons, the mitral and tufted cells, through reciprocal dendrodendritic synapses located on granule cell spines. These contacts are established in the distal apical dendritic compartment, while granule cell basal dendrites and more proximal apical segments bear spines that receive glutamatergic inputs from the olfactory cortices. This synaptic connectivity is vital to olfactory circuit function and is remodeled during development, and in response to changes in sensory activity and lifelong granule cell neurogenesis. Manipulations that alter levels of the neurotrophin brain-derived neurotrophic factor (BDNF) in vivo have significant effects on dendritic spine morphology, maintenance and activity-dependent plasticity for a variety of CNS neurons, yet little is known regarding BDNF effects on bulb granule cell spine maturation or maintenance. Here we show that, in vivo, sustained bulbar over-expression of BDNF produces a marked increase in granule cell spine density that includes an increase in mature spines on their apical dendrites. Morphometric analysis demonstrated that changes in spine density were most notable in the distal and proximal apical domains, indicating that multiple excitatory inputs are potentially modified by BDNF. Our results indicate that increased levels of endogenous BDNF can promote the maturation and/or maintenance of dendritic spines on granule cells, suggesting a role for this factor in modulating granule cell functional connectivity within adult olfactory circuitry. PMID:26211445

  14. BDNF over-expression increases olfactory bulb granule cell dendritic spine density in vivo.

    PubMed

    McDole, B; Isgor, C; Pare, C; Guthrie, K

    2015-09-24

    Olfactory bulb granule cells (GCs) are axon-less, inhibitory interneurons that regulate the activity of the excitatory output neurons, the mitral and tufted cells, through reciprocal dendrodendritic synapses located on GC spines. These contacts are established in the distal apical dendritic compartment, while GC basal dendrites and more proximal apical segments bear spines that receive glutamatergic inputs from the olfactory cortices. This synaptic connectivity is vital to olfactory circuit function and is remodeled during development, and in response to changes in sensory activity and lifelong GC neurogenesis. Manipulations that alter levels of the neurotrophin brain-derived neurotrophic factor (BDNF) in vivo have significant effects on dendritic spine morphology, maintenance and activity-dependent plasticity for a variety of CNS neurons, yet little is known regarding BDNF effects on bulb GC spine maturation or maintenance. Here we show that, in vivo, sustained bulbar over-expression of BDNF in transgenic mice produces a marked increase in GC spine density that includes an increase in mature spines on their apical dendrites. Morphometric analysis demonstrated that changes in spine density were most notable in the distal and proximal apical domains, indicating that multiple excitatory inputs are potentially modified by BDNF. Our results indicate that increased levels of endogenous BDNF can promote the maturation and/or maintenance of dendritic spines on GCs, suggesting a role for this factor in modulating GC functional connectivity within adult olfactory circuitry.

  15. The dendritic spines of interneurons are dynamic structures influenced by PSA-NCAM expression.

    PubMed

    Guirado, Ramon; Perez-Rando, Marta; Sanchez-Matarredona, David; Castillo-Gómez, Esther; Liberia, Teresa; Rovira-Esteban, Laura; Varea, Emilio; Crespo, Carlos; Blasco-Ibáñez, José Miguel; Nacher, Juan

    2014-11-01

    Excitatory neurons undergo dendritic spine remodeling in response to different stimuli. However, there is scarce information about this type of plasticity in interneurons. The polysialylated form of the neural cell adhesion molecule (PSA-NCAM) is a good candidate to mediate this plasticity as it participates in neuronal remodeling and is expressed by some mature cortical interneurons, which have reduced dendritic arborization, spine density, and synaptic input. To study the connectivity of the dendritic spines of interneurons and the influence of PSA-NCAM on their dynamics, we have analyzed these structures in a subpopulation of fluorescent spiny interneurons in the hippocampus of glutamic acid decarboxylase-enhanced green fluorescent protein transgenic mice. Our results show that these spines receive excitatory synapses. The depletion of PSA in vivo using the enzyme Endo-Neuraminidase-N (Endo-N) increases spine density when analyzed 2 days after, but decreases it 7 days after. The dendritic spine turnover was also analyzed in real time using organotypic hippocampal cultures: 24 h after the addition of EndoN, we observed an increase in the apparition rate of spines. These results indicate that dendritic spines are important structures in the control of the synaptic input of hippocampal interneurons and suggest that PSA-NCAM is relevant in the regulation of their morphology and connectivity.

  16. Casting a Net on Dendritic Spines: The Extracellular Matrix and its Receptors

    PubMed Central

    Dansie, Lorraine E.; Ethell, Iryna M.

    2011-01-01

    Dendritic spines are dynamic structures that accommodate the majority of excitatory synapses in the brain and are influenced by extracellular signals from presynaptic neurons, glial cells and the extracellular matrix (ECM). The ECM surrounds dendritic spines and extends into the synaptic cleft, maintaining synapse integrity as well as mediating trans-synaptic communications between neurons. Several scaffolding proteins and glycans that compose the ECM form a lattice-like network, which serves as an attractive ground for various secreted glycoproteins, lectins, growth factors and enzymes. ECM components can control dendritic spines through the interactions with their specific receptors or by influencing the functions of other synaptic proteins. In this review, we focus on ECM components and their receptors that regulate dendritic spine development and plasticity in the normal and diseased brain. PMID:21834084

  17. Methods of dendritic spine detection: from Golgi to high-resolution optical imaging.

    PubMed

    Mancuso, J J; Chen, Y; Li, X; Xue, Z; Wong, S T C

    2013-10-22

    Dendritic spines, the bulbous protrusions that form the postsynaptic half of excitatory synapses, are one of the most prominent features of neurons and have been imaged and studied for over a century. In that time, changes in the number and morphology of dendritic spines have been correlated to the developmental process as well as the pathophysiology of a number of neurodegenerative diseases. Due to the sheer scale of synaptic connectivity in the brain, work to date has merely scratched the surface in the study of normal spine function and pathology. This review will highlight traditional approaches to the imaging of dendritic spines and newer approaches made possible by advances in microscopy, protein engineering, and image analysis. The review will also describe recent work that is leading researchers toward the possibility of a systematic and comprehensive study of spine anatomy throughout the brain.

  18. Dendritic spine dysgenesis in superficial dorsal horn sensory neurons after spinal cord injury.

    PubMed

    Cao, Xiaoyu C; Pappalardo, Laura W; Waxman, Stephen G; Tan, Andrew M

    2017-01-01

    Neuropathic pain is a major complication of spinal cord injury, and despite aggressive efforts, this type of pain is refractory to available clinical treatment. Our previous work has demonstrated a structure-function link between dendritic spine dysgenesis on nociceptive sensory neurons in the intermediate zone, laminae IV/V, and chronic pain in central nervous system and peripheral nervous system injury models of neuropathic pain. To extend these findings, we performed a follow-up structural analysis to assess whether dendritic spine remodeling occurs on superficial dorsal horn neurons located in lamina II after spinal cord injury. Lamina II neurons are responsible for relaying deep, delocalized, often thermally associated pain commonly experienced in spinal cord injury pathologies. We analyzed dendritic spine morphometry and localization in tissue obtained from adult rats exhibiting neuropathic pain one-month following spinal cord injury. Although the total density of dendritic spines on lamina II neurons did not change after spinal cord injury, we observed an inverse relationship between the densities of thin- and mushroom-shaped spines: thin-spine density decreased while mushroom-spine density increased. These structural changes were specifically noted along dendritic branches within 150 µm from the soma, suggesting a possible adverse contribution to nociceptive circuit function. Intrathecal treatment with NSC23766, a Rac1-GTPase inhibitor, significantly reduced spinal cord injury-induced changes in both thin- and mushroom-shaped dendritic spines. Overall, these observations demonstrate that dendritic spine remodeling occurs in lamina II, regulated in part by the Rac1-signaling pathway, and suggests that structural abnormalities in this spinal cord region may also contribute to abnormal nociception after spinal cord injury.

  19. Dendritic spine dysgenesis in superficial dorsal horn sensory neurons after spinal cord injury

    PubMed Central

    Cao, Xiaoyu C; Pappalardo, Laura W; Waxman, Stephen G

    2017-01-01

    Neuropathic pain is a major complication of spinal cord injury, and despite aggressive efforts, this type of pain is refractory to available clinical treatment. Our previous work has demonstrated a structure–function link between dendritic spine dysgenesis on nociceptive sensory neurons in the intermediate zone, laminae IV/V, and chronic pain in central nervous system and peripheral nervous system injury models of neuropathic pain. To extend these findings, we performed a follow-up structural analysis to assess whether dendritic spine remodeling occurs on superficial dorsal horn neurons located in lamina II after spinal cord injury. Lamina II neurons are responsible for relaying deep, delocalized, often thermally associated pain commonly experienced in spinal cord injury pathologies. We analyzed dendritic spine morphometry and localization in tissue obtained from adult rats exhibiting neuropathic pain one-month following spinal cord injury. Although the total density of dendritic spines on lamina II neurons did not change after spinal cord injury, we observed an inverse relationship between the densities of thin- and mushroom-shaped spines: thin-spine density decreased while mushroom-spine density increased. These structural changes were specifically noted along dendritic branches within 150 µm from the soma, suggesting a possible adverse contribution to nociceptive circuit function. Intrathecal treatment with NSC23766, a Rac1-GTPase inhibitor, significantly reduced spinal cord injury-induced changes in both thin- and mushroom-shaped dendritic spines. Overall, these observations demonstrate that dendritic spine remodeling occurs in lamina II, regulated in part by the Rac1-signaling pathway, and suggests that structural abnormalities in this spinal cord region may also contribute to abnormal nociception after spinal cord injury. PMID:28326929

  20. Ibuprofen Protects from Cypermethrin-Induced Changes in the Striatal Dendritic Length and Spine Density.

    PubMed

    Tripathi, Pratibha; Singh, Ashish; Bala, Lakshmi; Patel, Devendra Kumar; Singh, Mahendra Pratap

    2017-03-25

    Microgliosis and inflammation are major wrongdoers in cypermethrin-induced Parkinsonism along with oxidative stress, mitochondrial dysfunction and α-synuclein aggregation. Dopamine depletion could alter dendritic morphology, length and spine number in the striatum. Present study investigated the effect of ibuprofen on the dendritic morphology, length and spine density in cypermethrin PD model. Male pups were treated intraperitoneally with cypermethrin during postnatal days followed by adulthood to induce Parkinsonism using standard procedure along with controls. Subsets of animals were pre-treated with ibuprofen 2 h prior to cypermethrin treatment during adulthood. Standard methods were used to confirm Parkinsonism/neuroprotection. Striatal dendritic morphology, length, spine number and expression of synaptophysin and postsynaptic density protein-95 (PSD-95) along with the nigrostriatal pro-inflammatory and apoptotic proteins were measured. Cypermethrin induced Parkinsonian traits and attenuated the dendritic length, spine number and expression of synaptophysin and PSD-95. While cypermethrin increased the expression of interleukin-1β, interleukin-4, interferon-γ, inducible nitric oxide synthase, caspase-3, caspase-9 and B-cell lymphoma (Bcl)-xl proteins, it attenuated Bcl-2 expression. Ibuprofen normalized the changes in dendritic morphology, length, spine number and expression of synaptophysin, PSD-95, and pro-inflammatory and apoptotic proteins. Results demonstrate that cypermethrin induces inflammation and alters dendritic morphology, length and spine number, which are encountered by ibuprofen.

  1. Repetitive motor learning induces coordinated formation of clustered dendritic spines in vivo.

    PubMed

    Fu, Min; Yu, Xinzhu; Lu, Ju; Zuo, Yi

    2012-02-19

    Many lines of evidence suggest that memory in the mammalian brain is stored with distinct spatiotemporal patterns. Despite recent progresses in identifying neuronal populations involved in memory coding, the synapse-level mechanism is still poorly understood. Computational models and electrophysiological data have shown that functional clustering of synapses along dendritic branches leads to nonlinear summation of synaptic inputs and greatly expands the computing power of a neural network. However, whether neighbouring synapses are involved in encoding similar memory and how task-specific cortical networks develop during learning remain elusive. Using transcranial two-photon microscopy, we followed apical dendrites of layer 5 pyramidal neurons in the motor cortex while mice practised novel forelimb skills. Here we show that a third of new dendritic spines (postsynaptic structures of most excitatory synapses) formed during the acquisition phase of learning emerge in clusters, and that most such clusters are neighbouring spine pairs. These clustered new spines are more likely to persist throughout prolonged learning sessions, and even long after training stops, than non-clustered counterparts. Moreover, formation of new spine clusters requires repetition of the same motor task, and the emergence of succedent new spine(s) accompanies the strengthening of the first new spine in the cluster. We also show that under control conditions new spines appear to avoid existing stable spines, rather than being uniformly added along dendrites. However, succedent new spines in clusters overcome such a spatial constraint and form in close vicinity to neighbouring stable spines. Our findings suggest that clustering of new synapses along dendrites is induced by repetitive activation of the cortical circuitry during learning, providing a structural basis for spatial coding of motor memory in the mammalian brain.

  2. A surface-based 3-D dendritic spine detection approach from confocal microscopy images.

    PubMed

    Li, Qing; Deng, Zhigang

    2012-03-01

    Determining the relationship between the dendritic spine morphology and its functional properties is a fundamental challenge in neurobiology research. In particular, how to accurately and automatically analyse meaningful structural information from a large microscopy image data set is far away from being resolved. As pointed out in existing literature, one remaining challenge in spine detection and segmentation is how to automatically separate touching spines. In this paper, based on various global and local geometric features of the dendrite structure, we propose a novel approach to detect and segment neuronal spines, in particular, a breaking-down and stitching-up algorithm to accurately separate touching spines. Extensive performance comparisons show that our approach is more accurate and robust than two state-of-the-art spine detection and segmentation algorithms.

  3. Conductance transients onto dendritic spines in a segmental cable model of hippocampal neurons.

    PubMed Central

    Turner, D A

    1984-01-01

    Dendritic shaft (Zd) and spine (Zsp) input impedances were computed numerically for sites on hippocampal neurons, using a segmental format of cable calculations. The Zsp values for a typical spine appended onto a dendritic shaft averaged less than 2% higher than the Zd values for the adjacent dendritic shaft. Spine synaptic inputs were simulated by a brief conductance transient, which possessed a time integral of 12 X 10(-10)S X ms. This input resulted in an average peak spine response of 20 mV for both dentate granule neurons and CA1 pyramidal cells. The average spine transient was attenuated less than 2% in conduction across the spine neck, considering peak voltage, waveform parameters, and charge transfer. The spine conductance transient resulted in an average somatic response of 100 microV in the dentate granule neurons, because of passive electrotonic propagation. The same input transient was also applied to proximal and distal sites on CA1 pyramidal cells. The predicted responses at the soma demonstrated a clear difference between the proximal and distal inputs, in terms of both peak voltage and waveform parameters. Thus, the main determinant of the passive propagation of transient electrical signals in these neurons appears to be dendritic branching rather than signal attenuation through the spine neck. PMID:6743760

  4. Vortioxetine promotes maturation of dendritic spines in vitro: A comparative study in hippocampal cultures.

    PubMed

    Waller, Jessica A; Chen, Fenghua; Sánchez, Connie

    2016-04-01

    Cognitive dysfunction is prevalent in patients with major depressive disorder (MDD), and cognitive impairments can persist after relief of depressive symptoms. The multimodal-acting antidepressant vortioxetine is an antagonist at 5-HT3, 5-HT7, and 5-HT1D receptors, a partial agonist at 5-HT1B receptors, an agonist at 5-HT1A receptors, and an inhibitor of the serotonin (5-HT) transporter (SERT) and has pro-cognitive properties. In preclinical studies, vortioxetine enhances long-term potentiation (LTP), a cellular correlate of neuroplasticity, and enhances memory in various cognitive tasks. However, the molecular mechanisms by which vortioxetine augments LTP and memory remain unknown. Dendritic spines are specialized, actin-rich microdomains on dendritic shafts and are major sites of most excitatory synapses. Since dendritic spine remodeling is implicated in synaptic plasticity and spine size dictates the strength of synaptic transmission, we assessed if vortioxetine, relative to other antidepressants including ketamine, duloxetine, and fluoxetine, plays a role in the maintenance of dendritic spine architecture in vitro. We show that vortioxetine, ketamine, and duloxetine induce spine enlargement. However, only vortioxetine treatment increased the number of spines in contact with presynaptic terminals. In contrast, fluoxetine had no effect on spine remodeling. These findings imply that the various 5-HT receptor mechanisms of vortioxetine may play a role in its effect on spine dynamics and in increasing the proportion of potentially functional synaptic contacts.

  5. BDNF pro-peptide regulates dendritic spines via caspase-3

    PubMed Central

    Guo, J; Ji, Y; Ding, Y; Jiang, W; Sun, Y; Lu, B; Nagappan, G

    2016-01-01

    The precursor of brain-derived neurotrophic factor (BDNF) (proBDNF) is enzymatically cleaved, by either intracellular (furin/PC1) or extracellular proteases (tPA/plasmin/MMP), to generate mature BDNF (mBDNF) and its pro-peptide (BDNF pro-peptide). Little is known about the function of BDNF pro-peptide. We have developed an antibody that specifically detects cleaved BDNF pro-peptide, but not proBDNF or mBDNF. Neuronal depolarization elicited a marked increase in extracellular BDNF pro-peptide, suggesting activity-dependent regulation of its extracellular levels. Exposure of BDNF pro-peptide to mature hippocampal neurons in culture dramatically reduced dendritic spine density. This effect was mediated by caspase-3, as revealed by studies with pharmacological inhibitors and genetic knockdown. BDNF pro-peptide also increased the number of ‘elongated' mitochondria and cytosolic cytochrome c, suggesting the involvement of mitochondrial-caspase-3 pathway. These results, along with BDNF pro-peptide effects recently reported on growth cones and long-term depression (LTD), suggest that BDNF pro-peptide is a negative regulator of neuronal structure and function. PMID:27310873

  6. Electrical and Ca2+ signaling in dendritic spines of substantia nigra dopaminergic neurons

    PubMed Central

    Hage, Travis A; Sun, Yujie; Khaliq, Zayd M

    2016-01-01

    Little is known about the density and function of dendritic spines on midbrain dopamine neurons, or the relative contribution of spine and shaft synapses to excitability. Using Ca2+ imaging, glutamate uncaging, fluorescence recovery after photobleaching and transgenic mice expressing labeled PSD-95, we comparatively analyzed electrical and Ca2+ signaling in spines and shaft synapses of dopamine neurons. Dendritic spines were present on dopaminergic neurons at low densities in live and fixed tissue. Uncaging-evoked potential amplitudes correlated inversely with spine length but positively with the presence of PSD-95. Spine Ca2+ signals were less sensitive to hyperpolarization than shaft synapses, suggesting amplification of spine head voltages. Lastly, activating spines during pacemaking, we observed an unexpected enhancement of spine Ca2+ midway throughout the spike cycle, likely involving recruitment of NMDA receptors and voltage-gated conductances. These results demonstrate functionality of spines in dopamine neurons and reveal a novel modulation of spine Ca2+ signaling during pacemaking. DOI: http://dx.doi.org/10.7554/eLife.13905.001 PMID:27163179

  7. Large and Small Dendritic Spines Serve Different Interacting Functions in Hippocampal Synaptic Plasticity and Homeostasis

    PubMed Central

    Paulin, Joshua J. W.; Haslehurst, Peter; Fellows, Alexander D.; Liu, Wenfei; Jackson, Joshua D.; Joel, Zelah; Cummings, Damian M.; Edwards, Frances A.

    2016-01-01

    The laying down of memory requires strong stimulation resulting in specific changes in synaptic strength and corresponding changes in size of dendritic spines. Strong stimuli can also be pathological, causing a homeostatic response, depressing and shrinking the synapse to prevent damage from too much Ca2+ influx. But do all types of dendritic spines serve both of these apparently opposite functions? Using confocal microscopy in organotypic slices from mice expressing green fluorescent protein in hippocampal neurones, the size of individual spines along sections of dendrite has been tracked in response to application of tetraethylammonium. This strong stimulus would be expected to cause both a protective homeostatic response and long-term potentiation. We report separation of these functions, with spines of different sizes reacting differently to the same strong stimulus. The immediate shrinkage of large spines suggests a homeostatic protective response during the period of potential danger. In CA1, long-lasting growth of small spines subsequently occurs consolidating long-term potentiation but only after the large spines return to their original size. In contrast, small spines do not change in dentate gyrus where potentiation does not occur. The separation in time of these changes allows clear functional differentiation of spines of different sizes. PMID:26881123

  8. Automated 4D analysis of dendritic spine morphology: applications to stimulus-induced spine remodeling and pharmacological rescue in a disease model.

    PubMed

    Swanger, Sharon A; Yao, Xiaodi; Gross, Christina; Bassell, Gary J

    2011-10-07

    Uncovering the mechanisms that regulate dendritic spine morphology has been limited, in part, by the lack of efficient and unbiased methods for analyzing spines. Here, we describe an automated 3D spine morphometry method and its application to spine remodeling in live neurons and spine abnormalities in a disease model. We anticipate that this approach will advance studies of synapse structure and function in brain development, plasticity, and disease.

  9. CD44: a novel synaptic cell adhesion molecule regulating structural and functional plasticity of dendritic spines

    PubMed Central

    Roszkowska, Matylda; Skupien, Anna; Wójtowicz, Tomasz; Konopka, Anna; Gorlewicz, Adam; Kisiel, Magdalena; Bekisz, Marek; Ruszczycki, Blazej; Dolezyczek, Hubert; Rejmak, Emilia; Knapska, Ewelina; Mozrzymas, Jerzy W.; Wlodarczyk, Jakub; Wilczynski, Grzegorz M.; Dzwonek, Joanna

    2016-01-01

    Synaptic cell adhesion molecules regulate signal transduction, synaptic function, and plasticity. However, their role in neuronal interactions with the extracellular matrix (ECM) is not well understood. Here we report that the CD44, a transmembrane receptor for hyaluronan, modulates synaptic plasticity. High-resolution ultrastructural analysis showed that CD44 was localized at mature synapses in the adult brain. The reduced expression of CD44 affected the synaptic excitatory transmission of primary hippocampal neurons, simultaneously modifying dendritic spine shape. The frequency of miniature excitatory postsynaptic currents decreased, accompanied by dendritic spine elongation and thinning. These structural and functional alterations went along with a decrease in the number of presynaptic Bassoon puncta, together with a reduction of PSD-95 levels at dendritic spines, suggesting a reduced number of functional synapses. Lack of CD44 also abrogated spine head enlargement upon neuronal stimulation. Moreover, our results indicate that CD44 contributes to proper dendritic spine shape and function by modulating the activity of actin cytoskeleton regulators, that is, Rho GTPases (RhoA, Rac1, and Cdc42). Thus CD44 appears to be a novel molecular player regulating functional and structural plasticity of dendritic spines. PMID:27798233

  10. DSCAM contributes to dendrite arborization and spine formation in the developing cerebral cortex.

    PubMed

    Maynard, Kristen R; Stein, Elke

    2012-11-21

    Down syndrome cell adhesion molecule, or DSCAM, has been implicated in many neurodevelopmental processes including axon guidance, dendrite arborization, and synapse formation. Here we show that DSCAM plays an important role in regulating the morphogenesis of cortical pyramidal neurons in the mouse. We report that DSCAM expression is developmentally regulated and localizes to synaptic plasma membranes during a time of robust cortical dendrite arborization and spine formation. Analysis of mice that carry a spontaneous mutation in DSCAM (DSCAM(del17)) revealed gross morphological changes in brain size and shape in addition to subtle changes in cortical organization, volume, and lamination. Early postnatal mutant mice displayed a transient decrease in cortical thickness, but these reductions could not be attributed to changes in neuron production or cell death. DSCAM(del17) mutants showed temporary impairments in the branching of layer V pyramidal neuron dendrites at P10 and P17 that recovered to normal by adulthood. Defects in DSCAM(del17) dendrite branching correlated with a temporal increase in apical branch spine density and lasting changes in spine morphology. At P15 and P42, mutant mice displayed a decrease in the percentage of large, stable spines and an increase in the percentage of small, immature spines. Together, our findings suggest that DSCAM contributes to pyramidal neuron morphogenesis by regulating dendrite arborization and spine formation during cortical circuit development.

  11. Selective Estrogen Receptor Modulators Regulate Dendritic Spine Plasticity in the Hippocampus of Male Rats

    PubMed Central

    González-Burgos, Ignacio; Rivera-Cervantes, Martha C.; Velázquez-Zamora, Dulce A.; Feria-Velasco, Alfredo; Garcia-Segura, Luis Miguel

    2012-01-01

    Some selective estrogen receptor modulators, such as raloxifene and tamoxifen, are neuroprotective and reduce brain inflammation in several experimental models of neurodegeneration. In addition, raloxifene and tamoxifen counteract cognitive deficits caused by gonadal hormone deprivation in male rats. In this study, we have explored whether raloxifene and tamoxifen may regulate the number and geometry of dendritic spines in CA1 pyramidal neurons of the rat hippocampus. Young adult male rats were injected with raloxifene (1 mg/kg), tamoxifen (1 mg/kg), or vehicle and killed 24 h after the injection. Animals treated with raloxifene or tamoxifen showed an increased numerical density of dendritic spines in CA1 pyramidal neurons compared to animals treated with vehicle. Raloxifene and tamoxifen had also specific effects in the morphology of spines. These findings suggest that raloxifene and tamoxifen may influence the processing of information by hippocampal pyramidal neurons by affecting the number and shape of dendritic spines. PMID:22164341

  12. Castration alters the number and structure of dendritic spines in the male posterodorsal medial amygdala.

    PubMed

    Zancan, Mariana; Dall'Oglio, Aline; Quagliotto, Edson; Rasia-Filho, Alberto A

    2017-02-01

    The posterodorsal medial amygdala (MePD) is responsive to androgens and participates in the integration of olfactory/vomeronasal stimuli for the display of sexual behavior in rats. Adult gonadectomy (GDX) affects the MePD structural integrity at the same time that impairs male mating behavior. At the cellular level, dendritic spines modulate excitatory synaptic transmission, strength, and plasticity. Here, we describe the effect of GDX on the number and shape of dendritic spines in the right and left MePD using confocal microscopy and 3D image reconstruction. Age-matched adult rats were intact (n = 6), submitted to a sham procedure (n = 4) or castrated and studied 90 days after GDX (n = 5). The MePD neurons have a density of 1.1 spines/dendritic μm composed of thin, mushroom-like, stubby/wide, and few ramified or atypical spines. Irrespective of brain hemisphere, GDX decreased the dendritic spine density in the MePD, but induced different effects on each spine type. That is, compared to control groups, GDX reduced (i) the number (up to 50%) of thin, mushroom-like, and ramified spines, and (ii) the size and the neck length of thin spines as well as the head diameter of ramified spines. Besides, GDX increased the number of stubby/wide and atypical spines (up to 140% and 400%, respectively). These data show that GDX promotes a cellular and synaptic reorganization in a spine-specific manner in the MePD. By altering the number and shape of these connectional elements, GDX can affect the neural transmission and hinder the function of integrated brain circuitries in the male brain.

  13. VCP and ATL1 regulate endoplasmic reticulum and protein synthesis for dendritic spine formation.

    PubMed

    Shih, Yu-Tzu; Hsueh, Yi-Ping

    2016-03-17

    Imbalanced protein homeostasis, such as excessive protein synthesis and protein aggregation, is a pathogenic hallmark of a range of neurological disorders. Here, using expression of mutant proteins, a knockdown approach and disease mutation knockin mice, we show that VCP (valosin-containing protein), together with its cofactor P47 and the endoplasmic reticulum (ER) morphology regulator ATL1 (Atlastin-1), regulates tubular ER formation and influences the efficiency of protein synthesis to control dendritic spine formation in neurons. Strengthening the significance of protein synthesis in dendritic spinogenesis, the translation blocker cyclohexamide and the mTOR inhibitor rapamycin reduce dendritic spine density, while a leucine supplement that increases protein synthesis ameliorates the dendritic spine defects caused by Vcp and Atl1 deficiencies. Because VCP and ATL1 are the causative genes of several neurodegenerative and neurodevelopmental disorders, we suggest that impaired ER formation and inefficient protein synthesis are significant in the pathogenesis of multiple neurological disorders.

  14. VCP and ATL1 regulate endoplasmic reticulum and protein synthesis for dendritic spine formation

    PubMed Central

    Shih, Yu-Tzu; Hsueh, Yi-Ping

    2016-01-01

    Imbalanced protein homeostasis, such as excessive protein synthesis and protein aggregation, is a pathogenic hallmark of a range of neurological disorders. Here, using expression of mutant proteins, a knockdown approach and disease mutation knockin mice, we show that VCP (valosin-containing protein), together with its cofactor P47 and the endoplasmic reticulum (ER) morphology regulator ATL1 (Atlastin-1), regulates tubular ER formation and influences the efficiency of protein synthesis to control dendritic spine formation in neurons. Strengthening the significance of protein synthesis in dendritic spinogenesis, the translation blocker cyclohexamide and the mTOR inhibitor rapamycin reduce dendritic spine density, while a leucine supplement that increases protein synthesis ameliorates the dendritic spine defects caused by Vcp and Atl1 deficiencies. Because VCP and ATL1 are the causative genes of several neurodegenerative and neurodevelopmental disorders, we suggest that impaired ER formation and inefficient protein synthesis are significant in the pathogenesis of multiple neurological disorders. PMID:26984393

  15. Brain-derived neurotrophic factor mediates estradiol-induced dendritic spine formation in hippocampal neurons.

    PubMed

    Murphy, D D; Cole, N B; Segal, M

    1998-09-15

    Dendritic spines are of major importance in information processing and memory formation in central neurons. Estradiol has been shown to induce an increase of dendritic spine density on hippocampal neurons in vivo and in vitro. The neurotrophin brain-derived neurotrophic factor (BDNF) recently has been implicated in neuronal maturation, plasticity, and regulation of GABAergic interneurons. We now demonstrate that estradiol down-regulates BDNF in cultured hippocampal neurons to 40% of control values within 24 hr of exposure. This, in turn, decreases inhibition and increases excitatory tone in pyramidal neurons, leading to a 2-fold increase in dendritic spine density. Exogenous BDNF blocks the effects of estradiol on spine formation, and BDNF depletion with a selective antisense oligonucleotide mimics the effects of estradiol. Addition of BDNF antibodies also increases spine density, and diazepam, which facilitates GABAergic neurotransmission, blocks estradiol-induced spine formation. These observations demonstrate a functional link between estradiol, BDNF as a potent regulator of GABAergic interneurons, and activity-dependent formation of dendritic spines in hippocampal neurons.

  16. Morphologic evidence for spatially clustered spines in apical dendrites of monkey neocortical pyramidal cells.

    PubMed

    Yadav, Aniruddha; Gao, Yuan Z; Rodriguez, Alfredo; Dickstein, Dara L; Wearne, Susan L; Luebke, Jennifer I; Hof, Patrick R; Weaver, Christina M

    2012-09-01

    The general organization of neocortical connectivity in rhesus monkey is relatively well understood. However, mounting evidence points to an organizing principle that involves clustered synapses at the level of individual dendrites. Several synaptic plasticity studies have reported cooperative interaction between neighboring synapses on a given dendritic branch, which may potentially induce synapse clusters. Additionally, theoretical models have predicted that such cooperativity is advantageous, in that it greatly enhances a neuron's computational repertoire. However, largely because of the lack of sufficient morphologic data, the existence of clustered synapses in neurons on a global scale has never been established. The majority of excitatory synapses are found within dendritic spines. In this study, we demonstrate that spine clusters do exist on pyramidal neurons by analyzing the three-dimensional locations of ∼40,000 spines on 280 apical dendritic branches in layer III of the rhesus monkey prefrontal cortex. By using clustering algorithms and Monte Carlo simulations, we quantify the probability that the observed extent of clustering does not occur randomly. This provides a measure that tests for spine clustering on a global scale, whenever high-resolution morphologic data are available. Here we demonstrate that spine clusters occur significantly more frequently than expected by pure chance and that spine clustering is concentrated in apical terminal branches. These findings indicate that spine clustering is driven by systematic biological processes. We also found that mushroom-shaped and stubby spines are predominant in clusters on dendritic segments that display prolific clustering, independently supporting a causal link between spine morphology and synaptic clustering.

  17. Rat-strain dependent changes of dendritic and spine morphology in the hippocampus after cocaine self-administration.

    PubMed

    Selvas, Abraham; Coria, Santiago M; Kastanauskaite, Asta; Fernaud-Espinosa, Isabel; DeFelipe, Javier; Ambrosio, Emilio; Miguéns, Miguel

    2017-01-01

    We previously showed that cocaine self-administration increases spine density in CA1 hippocampal neurons in Lewis (LEW) but not in Fischer 344 (F344) rats. Dendritic spine morphology is intimately related to its function. Thus, we conducted a 3D morphological analysis of CA1 dendrites and dendritic spines in these two strains of rats. Strain-specific differences were observed prior to cocaine self-administration: LEW rats had significantly larger dendritic diameters but lower spine density than the F344 strain. After cocaine self-administration, proximal dendritic volume, dendritic surface area and spine density were increased in LEW rats, where a higher percentage of larger spines were also observed. In addition, we found a strong positive correlation between dendritic volume and spine morphology, and a moderate correlation between dendritic volume and spine density in cocaine self-administered LEW rats, an effect that was not evident in any other condition. By contrast, after cocaine self-administration, F334 rats showed decreased spine head volumes. Our findings suggest that genetic differences could play a key role in the structural plasticity induced by cocaine in CA1 pyramidal neurons. These cocaine-induced alterations could be related to differences in the memory processing of drug reward cues that could potentially explain differential individual vulnerability to cocaine addiction.

  18. Extracellular matrix control of dendritic spine and synapse structure and plasticity in adulthood

    PubMed Central

    Levy, Aaron D.; Omar, Mitchell H.; Koleske, Anthony J.

    2014-01-01

    Dendritic spines are the receptive contacts at most excitatory synapses in the central nervous system. Spines are dynamic in the developing brain, changing shape as they mature as well as appearing and disappearing as they make and break connections. Spines become much more stable in adulthood, and spine structure must be actively maintained to support established circuit function. At the same time, adult spines must retain some plasticity so their structure can be modified by activity and experience. As such, the regulation of spine stability and remodeling in the adult animal is critical for normal function, and disruption of these processes is associated with a variety of late onset diseases including schizophrenia and Alzheimer’s disease. The extracellular matrix (ECM), composed of a meshwork of proteins and proteoglycans, is a critical regulator of spine and synapse stability and plasticity. While the role of ECM receptors in spine regulation has been extensively studied, considerably less research has focused directly on the role of specific ECM ligands. Here, we review the evidence for a role of several brain ECM ligands and remodeling proteases in the regulation of dendritic spine and synapse formation, plasticity, and stability in adults. PMID:25368556

  19. Dietary cholesterol concentration affects synaptic plasticity and dendrite spine morphology of rabbit hippocampal neurons.

    PubMed

    Wang, Desheng; Zheng, Wen

    2015-10-05

    Previous studies have shown dietary cholesterol can enhance learning but retard memory which may be partly due to increased cholesterol levels in hippocampus and reduced afterhyperpolarization (AHP) amplitude of hippocampal CA1 neurons. This study explored the dose-dependent effect of dietary cholesterol on synaptic plasticity of rabbit hippocampal CA1 neurons and spine morphology, the postsynaptic structures responsible for synaptic plasticity. Field potential recordings revealed a low concentration of dietary cholesterol increased long-term potentiation (LTP) expression while high concentrations produced a pronounced reduction in LTP expression. Dietary cholesterol facilitated basal synaptic transmission but did not influence presynaptic function. DiI staining showed dietary cholesterol induced alterations in dendrite spine morphology characterized by increased mushroom spine density and decreased thin spine density, two kinds of dendritic spines that may be linked to memory consolidation and learning acquisition. Dietary cholesterol also modulated the geometric measures of mushroom spines. Therefore, dietary cholesterol dose-dependently modulated both synaptic plasticity and dendrite spine morphologies of hippocampal CA1 neurons that could mediate learning and memory changes previously seen to result from feeding a cholesterol diet.

  20. Sleep promotes branch-specific formation of dendritic spines after learning.

    PubMed

    Yang, Guang; Lai, Cora Sau Wan; Cichon, Joseph; Ma, Lei; Li, Wei; Gan, Wen-Biao

    2014-06-06

    How sleep helps learning and memory remains unknown. We report in mouse motor cortex that sleep after motor learning promotes the formation of postsynaptic dendritic spines on a subset of branches of individual layer V pyramidal neurons. New spines are formed on different sets of dendritic branches in response to different learning tasks and are protected from being eliminated when multiple tasks are learned. Neurons activated during learning of a motor task are reactivated during subsequent non-rapid eye movement sleep, and disrupting this neuronal reactivation prevents branch-specific spine formation. These findings indicate that sleep has a key role in promoting learning-dependent synapse formation and maintenance on selected dendritic branches, which contribute to memory storage.

  1. Voxel-based morphometry predicts shifts in dendritic spine density and morphology with auditory fear conditioning.

    PubMed

    Keifer, O P; Hurt, R C; Gutman, D A; Keilholz, S D; Gourley, S L; Ressler, K J

    2015-07-07

    Neuroimaging has provided compelling data about the brain. Yet the underlying mechanisms of many neuroimaging techniques have not been elucidated. Here we report a voxel-based morphometry (VBM) study of Thy1-YFP mice following auditory fear conditioning complemented by confocal microscopy analysis of cortical thickness, neuronal morphometric features and nuclei size/density. Significant VBM results included the nuclei of the amygdala, the insula and the auditory cortex. There were no significant VBM changes in a control brain area. Focusing on the auditory cortex, confocal analysis showed that fear conditioning led to a significantly increased density of shorter and wider dendritic spines, while there were no spine differences in the control area. Of all the morphology metrics studied, the spine density was the only one to show significant correlation with the VBM signal. These data demonstrate that learning-induced structural changes detected by VBM may be partially explained by increases in dendritic spine density.

  2. Dlg5 Regulates Dendritic Spine Formation and Synaptogenesis by Controlling Subcellular N-Cadherin Localization

    PubMed Central

    Wang, Shih-Hsiu J.; Celic, Ivana; Choi, Se-Young; Riccomagno, Martin; Wang, Qiang; Sun, Lu O.; Mitchell, Sarah P.; Vasioukhin, Valera; Huganir, Richard L.

    2014-01-01

    Most excitatory synapses in the mammalian brain are formed on dendritic spines, and spine density has a profound impact on synaptic transmission, integration, and plasticity. Membrane-associated guanylate kinase (MAGUK) proteins are intracellular scaffolding proteins with well established roles in synapse function. However, whether MAGUK proteins are required for the formation of dendritic spines in vivo is unclear. We isolated a novel disc large-5 (Dlg5) allele in mice, Dlg5LP, which harbors a missense mutation in the DLG5 SH3 domain, greatly attenuating its ability to interact with the DLG5 GUK domain. We show here that DLG5 is a MAGUK protein that regulates spine formation, synaptogenesis, and synaptic transmission in cortical neurons. DLG5 regulates synaptogenesis by enhancing the cell surface localization of N-cadherin, revealing a key molecular mechanism for regulating the subcellular localization of this cell adhesion molecule during synaptogenesis. PMID:25232112

  3. Pathogenic SYNGAP1 mutations impair cognitive development by disrupting maturation of dendritic spine synapses.

    PubMed

    Clement, James P; Aceti, Massimiliano; Creson, Thomas K; Ozkan, Emin D; Shi, Yulin; Reish, Nicholas J; Almonte, Antoine G; Miller, Brooke H; Wiltgen, Brian J; Miller, Courtney A; Xu, Xiangmin; Rumbaugh, Gavin

    2012-11-09

    Mutations that cause intellectual disability (ID) and autism spectrum disorder (ASD) are commonly found in genes that encode for synaptic proteins. However, it remains unclear how mutations that disrupt synapse function impact intellectual ability. In the SYNGAP1 mouse model of ID/ASD, we found that dendritic spine synapses develop prematurely during the early postnatal period. Premature spine maturation dramatically enhanced excitability in the developing hippocampus, which corresponded with the emergence of behavioral abnormalities. Inducing SYNGAP1 mutations after critical developmental windows closed had minimal impact on spine synapse function, whereas repairing these pathogenic mutations in adulthood did not improve behavior and cognition. These data demonstrate that SynGAP protein acts as a critical developmental repressor of neural excitability that promotes the development of life-long cognitive abilities. We propose that the pace of dendritic spine synapse maturation in early life is a critical determinant of normal intellectual development.

  4. Control of Spine Maturation and Pruning through ProBDNF Synthesized and Released in Dendrites

    PubMed Central

    Orefice, Lauren L.; Shih, Chien-Cheng; Xu, Haifei; Waterhouse, Emily G.; Xu, Baoji

    2015-01-01

    Excess synapses formed during early postnatal development are pruned over an extended period, while the remaining synapses mature. Synapse pruning is critical for activity-dependent refinement of neuronal connections and its dysregulation has been found in neurodevelopmental disorders such as autism spectrum disorders; however, the mechanism underlying synapse pruning remains largely unknown. As dendritic spines are the postsynaptic sites for the vast majority of excitatory synapses, spine maturation and pruning are indicators for maturation and elimination of these synapses. Our previous studies have found that dendritically localized mRNA for brain-derived neurotrophic factor (BDNF) regulates spine maturation and pruning. Here we investigated the mechanism by which dendritic Bdnf mRNA, but not somatically restricted Bdnf mRNA, promotes spine maturation and pruning. We found that neuronal activity stimulates both translation of dendritic Bdnf mRNA and secretion of its translation product mainly as proBDNF. The secreted proBDNF promotes spine maturation and pruning, and its effect on spine pruning is in part mediated by the p75NTR receptor via RhoA activation. Furthermore, some proBDNF is extracellularly converted to mature BDNF and then promotes maturation of stimulated spines by activating Rac1 through the TrkB receptor. In contrast, translation of somatic Bdnf mRNA and the release of its translation product mainly as mature BDNF are independent of action potentials. These results not only reveal a biochemical pathway regulating synapse pruning, but also suggest that BDNF synthesized in the soma and dendrites is released through distinct secretory pathways. PMID:26705735

  5. Effects of lead exposure on dendrite and spine development in hippocampal dentate gyrus areas of rats.

    PubMed

    Hu, Fan; Ge, Meng-Meng; Chen, Wei-Heng

    2016-03-01

    Lead exposure has been implicated in the impairment of synaptic plasticity in the hippocampal dentate gyrus (DG) areas of rats. However, whether the degradation of physiological properties is based on the morphological alteration of granule neurons in DG areas remains elusive. Here, we examined the dendritic branch extension and spine formation of granule neurons after lead exposure during development in rats. Dendritic morphology was studied using Golgi-Cox stain method, which was followed by Sholl analysis at postnatal days 14 and 21. Our results indicated that, for both ages, lead exposure significantly decreased the total dendritic length and spine density of granule neurons in the DG of the rat hippocampus. Further branch order analysis revealed that the decrease of dendritic length was observed only at the second branch order. Moreover, there were obvious deficits in the proportion and size of mushroom-type spines. These deficits in spine formation and maturity were accompanied by a decrease in Arc/Arg3.1 expression. Our present findings are the first to show that developmental lead exposure disturbs branch and spine formation in hippocampal DG areas. Arc/Arg3.1 may have a critical role in the disruption of neuronal morphology and synaptic plasticity in lead-exposed rats.

  6. Emerging Roles of Filopodia and Dendritic Spines in Motoneuron Plasticity during Development and Disease

    PubMed Central

    Kanjhan, Refik; Noakes, Peter G.; Bellingham, Mark C.

    2016-01-01

    Motoneurons develop extensive dendritic trees for receiving excitatory and inhibitory synaptic inputs to perform a variety of complex motor tasks. At birth, the somatodendritic domains of mouse hypoglossal and lumbar motoneurons have dense filopodia and spines. Consistent with Vaughn's synaptotropic hypothesis, we propose a developmental unified-hybrid model implicating filopodia in motoneuron spinogenesis/synaptogenesis and dendritic growth and branching critical for circuit formation and synaptic plasticity at embryonic/prenatal/neonatal period. Filopodia density decreases and spine density initially increases until postnatal day 15 (P15) and then decreases by P30. Spine distribution shifts towards the distal dendrites, and spines become shorter (stubby), coinciding with decreases in frequency and increases in amplitude of excitatory postsynaptic currents with maturation. In transgenic mice, either overexpressing the mutated human Cu/Zn-superoxide dismutase (hSOD1G93A) gene or deficient in GABAergic/glycinergic synaptic transmission (gephyrin, GAD-67, or VGAT gene knockout), hypoglossal motoneurons develop excitatory glutamatergic synaptic hyperactivity. Functional synaptic hyperactivity is associated with increased dendritic growth, branching, and increased spine and filopodia density, involving actin-based cytoskeletal and structural remodelling. Energy-dependent ionic pumps that maintain intracellular sodium/calcium homeostasis are chronically challenged by activity and selectively overwhelmed by hyperactivity which eventually causes sustained membrane depolarization leading to excitotoxicity, activating microglia to phagocytose degenerating neurons under neuropathological conditions. PMID:26843990

  7. Aluminum chloride induces neuroinflammation, loss of neuronal dendritic spine and cognition impairment in developing rat.

    PubMed

    Cao, Zheng; Yang, Xu; Zhang, Haiyang; Wang, Haoran; Huang, Wanyue; Xu, Feibo; Zhuang, Cuicui; Wang, Xiaoguang; Li, Yanfei

    2016-05-01

    Aluminum (Al) is present in the daily life of humans, and the incidence of Al contamination increased in recent years. Long-term excessive Al intake induces neuroinflammation and cognition impairment. Neuroinflammation alter density of dendritic spine, which, in turn, influence cognition function. However, it is unknown whether increased neuroinflammation is associated with altered density of dendritic spine in Al-treated rats. In the present study, AlCl3 was orally administrated to rat at 50, 150 and 450 mg/kg for 90d. We examined the effects of AlCl3 on the cognition function, density of dendritic spine in hippocampus of CA1 and DG region and the mRNA levels of IL-1β, IL-6, TNF-α, MHC II, CX3CL1 and BNDF in developing rat. These results showed exposure to AlCl3 lead to increased mRNA levels of IL-1β, IL-6, TNF-α and MCH II, decreased mRNA levels of CX3CL1 and BDNF, decreased density of dendritic spine and impaired learning and memory in developing rat. Our results suggest AlCl3 can induce neuroinflammation that may result in loss of spine, and thereby leads to learning and memory deficits.

  8. Motherhood and the hormones of pregnancy modify concentrations of hippocampal neuronal dendritic spines.

    PubMed

    Kinsley, Craig H; Trainer, Regina; Stafisso-Sandoz, Graciela; Quadros, Princy; Marcus, Lori Keyser; Hearon, Christa; Meyer, Elizabeth Ann Amory; Hester, Naomi; Morgan, Melissa; Kozub, Frederick J; Lambert, Kelly G

    2006-02-01

    Short-term fluctuations in steroid hormones such as estradiol (E2) and progesterone (P) can affect the concentration of hippocampal dendritic spines in adult, cycling nulliparous female rats. Pregnancy is characterized by a significantly longer duration of substantially elevated E2 and P compared to the estrous cycle. Thus, even greater changes than those reported during estrus may be evident. In two experiments, we examined the extent to which reproductive and hormonal state altered the concentration of apical neuronal dendritic spines of the CA1 region of the hippocampus in the following age-matched groups (N's = 7-10/group) of rats: in Exp. 1., CA1 dendritic spine density was examined in nulliparous diestrus (DES), proestrus (PRO), and estrus (ES) females, and late-pregnant (LP) (day 21) and lactating (day 5-6; LACT) females. In Exp. 2, the effects on spine density of a regimen mimicking pregnancy (and that stimulates maternal behavior) were examined, using ovariectomized, no hormone-exposed (OVX-minus) vs. sequential P&E(2)-treated (OVX + P&E2) groups. For both experiments, brains were removed, Golgi-Cox-stained and the most lateral tertiary branches of the apical dendrite of completely-stained hippocampal CA1 pyramidal neurons were traced with oil-immersion at x 1600 and dendritic spine density (# spines/10 micro dendritic segment) recorded. In Exp. 1, spine density was increased in LP and LACT females (which were not different) compared to the other virgin groups, including PRO females, who had more spines than DES and ES. In Exp. 2, OVX + P&E2 displayed significantly more dendritic spines per 10 micro than OVX-minus females (and had numbers that were similar to those of LP and LACT from Exp. 1). Pregnancy and its attendant hormonal fluctuations, therefore, may alter hippocampal neurons that regulate some non-pup-directed components of maternal behavior (e.g., nest building) or behaviors that support maternal behavior (e.g., foraging, associative memory).

  9. Changes in dendritic spine density in the nucleus accumbens do not underlie ethanol sensitization.

    PubMed

    Nona, Christina N; Bermejo, Marie Kristel; Ramsey, Amy J; Nobrega, José N

    2015-12-01

    Behavioral sensitization to various drugs of abuse has been shown to change dendritic spine density and/or morphology of nucleus accumbens (NAc) medium spiny neurons, an effect seen across drug classes. However, is it not known whether behavioral sensitization to ethanol (EtOH) is also associated with structural changes in this region. Here we compared dendritic spine density and morphology between mice showing High vs. Low levels of EtOH sensitization and found that high levels of EtOH sensitization were not associated with changes in dendritic spine density or spine type. Unexpectedly, however, a significant increase in the density of stubby-type spines was seen in mice that were resistant to sensitization. Since the presence of this spine type has been associated with long-term depression and cognitive/learning deficits this may explain why these mice fail to sensitize and why they show poor performance in conditioning tasks, as previously shown. A possible causal role for structural plasticity in behavioral sensitization to various drugs has been debated. In the case of EtOH sensitization, our results suggest that drug-induced changes in structural plasticity in the accumbens neurons may not be the cause of sensitized behavior.

  10. Stressful experience has opposite effects on dendritic spines in the hippocampus of cycling versus masculinized females

    PubMed Central

    Dalla, Christina; Whetstone, Abigail S.; Hodes, Georgia E.; Shors, Tracey J.

    2012-01-01

    Stress increases associative learning and the density of dendritic spines in the hippocampus of male rats. In contrast, exposure to the same stressor impairs associative learning and reduces spine density in females. These effects in females are most evident when they are in the proestrus phase of the estrous cycle. An injection of testosterone at the time of birth masculinizes the female brain. In adulthood, masculinized females respond like males do to stress, i.e. they learn better. Here, we hypothesized that stress would increase spine densities on pyramidal neurons in area CA1 of the hippocampus of masculinized females, because stress enhances learning ability in both males and masculinized females. To test this, we used Golgi impregnation to stain tissue from masculinized and cycling females that were exposed to the acute stressor and sacrificed one day later. There was a significant interaction between stressor exposure and testosterone treatment at birth (p<0.001). In general, cycling females that were stressed tended to possess fewer spines on apical and basal dendrites in the CA1 area of the hippocampus, whereas the masculinized females possessed significantly more spines after the stressor. These findings underscore the plastic nature of dendritic spines. They suggest that their response to stress in adulthood is organized by the presence of testosterone during very early development. Such a process may represent a mechanism for altering learning abilities after an acute traumatic experience. PMID:18952150

  11. Sleep contributes to dendritic spine formation and elimination in the developing mouse somatosensory cortex.

    PubMed

    Yang, Guang; Gan, Wen-Biao

    2012-11-01

    Sleep is maximal during early postnatal life when rapid and extensive synapse remodeling occurs. It remains unknown whether and how sleep affects synapse development and plasticity. Using transcranial two-photon microscopy, we examined the formation and elimination of fluorescently labeled dendritic spines and filopodia of Layer 5 pyramidal neurons in the barrel cortex of 3-week-old mice during wakefulness and sleep. We observed high turnover of dendritic protrusions over 2 h in both wake and sleep states. The formation rate of dendritic spines or filopodia over 2 h was comparable between the two states. The elimination rate of dendritic spines or filopodia was lower during 2-h wakefulness than during 2-h sleep. Similar results were observed on dendritic protrusion dynamics over 12-h light/dark cycle when mice spent more time asleep or awake. The substantial remodeling of dendritic protrusions during the sleep state supports the notion that sleep plays an important role in the development and plasticity of synaptic connections in the mouse cortex.

  12. 3-D confocal laser scanning microscopy used in morphometric analysis of rat Purkinje cell dendritic spines after chronic ethanol consumption.

    PubMed

    Wenisch, S; Fortmann, B; Steinmetz, T; Kriete, A; Leiser, R; Bitsch, I

    1998-12-01

    A confocal laser scanning microscope (with a 543 nm laser) was used for imaging rat Purkinje cell dendritic spines at high 3-D resolution. In a nutritionally controlled study of the rat, 5 months of ethanol consumption was demonstrated to alter the spines of Purkinje cell dendrites in rat cerebellum. Intact spines showed significant elongation after ethanol exposure, whereas this neuromorphological alteration could not be detected in controls. Spine elongation could be regarded as compensative growth of spines in search of new synaptic contacts due to alcohol induced cell loss.

  13. Cell-Autonomous Regulation of Dendritic Spine Density by PirB.

    PubMed

    Vidal, George S; Djurisic, Maja; Brown, Kiana; Sapp, Richard W; Shatz, Carla J

    2016-01-01

    Synapse density on cortical pyramidal neurons is modulated by experience. This process is highest during developmental critical periods, when mechanisms of synaptic plasticity are fully engaged. In mouse visual cortex, the critical period for ocular dominance (OD) plasticity coincides with the developmental pruning of synapses. At this time, mice lacking paired Ig-like receptor B (PirB) have excess numbers of dendritic spines on L5 neurons; these spines persist and are thought to underlie the juvenile-like OD plasticity observed in adulthood. Here we examine whether PirB is required specifically in excitatory neurons to exert its effect on dendritic spine and synapse density during the critical period. In mice with a conditional allele of PirB (PirB(fl/fl)), PirB was deleted only from L2/3 cortical pyramidal neurons in vivo by timed in utero electroporation of Cre recombinase. Sparse mosaic expression of Cre produced neurons lacking PirB in a sea of wild-type neurons and glia. These neurons had significantly elevated dendritic spine density, as well as increased frequency of miniature EPSCs, suggesting that they receive a greater number of synaptic inputs relative to Cre(-) neighbors. The effect of cell-specific PirB deletion on dendritic spine density was not accompanied by changes in dendritic branching complexity or axonal bouton density. Together, results imply a neuron-specific, cell-autonomous action of PirB on synaptic density in L2/3 pyramidal cells of visual cortex. Moreover, they are consistent with the idea that PirB functions normally to corepress spine density and synaptic plasticity, thereby maintaining headroom for cells to encode ongoing experience-dependent structural change throughout life.

  14. Cell-Autonomous Regulation of Dendritic Spine Density by PirB

    PubMed Central

    2016-01-01

    Synapse density on cortical pyramidal neurons is modulated by experience. This process is highest during developmental critical periods, when mechanisms of synaptic plasticity are fully engaged. In mouse visual cortex, the critical period for ocular dominance (OD) plasticity coincides with the developmental pruning of synapses. At this time, mice lacking paired Ig-like receptor B (PirB) have excess numbers of dendritic spines on L5 neurons; these spines persist and are thought to underlie the juvenile-like OD plasticity observed in adulthood. Here we examine whether PirB is required specifically in excitatory neurons to exert its effect on dendritic spine and synapse density during the critical period. In mice with a conditional allele of PirB (PirBfl/fl), PirB was deleted only from L2/3 cortical pyramidal neurons in vivo by timed in utero electroporation of Cre recombinase. Sparse mosaic expression of Cre produced neurons lacking PirB in a sea of wild-type neurons and glia. These neurons had significantly elevated dendritic spine density, as well as increased frequency of miniature EPSCs, suggesting that they receive a greater number of synaptic inputs relative to Cre– neighbors. The effect of cell-specific PirB deletion on dendritic spine density was not accompanied by changes in dendritic branching complexity or axonal bouton density. Together, results imply a neuron-specific, cell-autonomous action of PirB on synaptic density in L2/3 pyramidal cells of visual cortex. Moreover, they are consistent with the idea that PirB functions normally to corepress spine density and synaptic plasticity, thereby maintaining headroom for cells to encode ongoing experience-dependent structural change throughout life. PMID:27752542

  15. Perinatal undernutrition attenuates field excitatory postsynaptic potentials and influences dendritic spine density and morphology in hippocampus of male rat offspring.

    PubMed

    Zhang, Y; Wei, J; Yang, Z

    2013-08-06

    Perinatal undernutrition affects the hippocampus, a brain region crucial for learning and memory. However, far less is known about the changes of dendritic spine density and morphology related to hippocampal synaptic plasticity. As dendritic spines are dynamic structures essential for synaptic plasticity and serve as the primary post-synaptic location of the excitatory neurotransmission that underlies learning and memory, the aim of the present study was to investigate whether the perinatal undernutrition affected hippocampal synaptic plasticity accompanied by the change of dendritic spines in anesthetized rats. An input-output curve was first determined using the measurements of field excitatory postsynaptic potential (fEPSP) slope in response to a series of stimulation intensities. Long-term potentiation (LTP) induced by high-frequency stimulation was recorded in the Schaffer collateral-CA1 pathway. Post-tetanic potentiation derived from the fEPSP slope was also measured immediately after LTP induction. Quantitative data of dendritic spines from hippocampal CA1 pyramidal cells were obtained using Golgi staining. The results showed that 50% perinatal food restriction (FR50) impaired the magnitude of LTP of the fEPSP slope in the Schaffer collateral-CA1 pathway. Additionally, FR50 reduced overall spine densities in both basal dendrites and apical dendrites of hippocampal CA1 pyramidal cells. Moreover, FR50 reduced type densities of thin and mushroom spines in apical dendrites, whereas a reduction in the type of mushroom spines was only observed in the basal dendrites of hippocampal CA1 pyramidal cells. These findings suggested that perinatal undernutrition decreased excitatory synaptic input and further affected the processing of information in a given network by selectively reducing the number of special dendritic spines. Thus, these changes in the density and the types of dendritic spines in CA1 pyramidal neurons may partly explain the impaired hippocampal

  16. Seeding and transgenic overexpression of alpha-synuclein triggers dendritic spine pathology in the neocortex.

    PubMed

    Blumenstock, Sonja; Rodrigues, Eva F; Peters, Finn; Blazquez-Llorca, Lidia; Schmidt, Felix; Giese, Armin; Herms, Jochen

    2017-03-28

    Although misfolded and aggregated α-synuclein (α-syn) is recognized in the disease progression of synucleinopathies, its role in the impairment of cortical circuitries and synaptic plasticity remains incompletely understood. We investigated how α-synuclein accumulation affects synaptic plasticity in the mouse somatosensory cortex using two distinct approaches. Long-term in vivo imaging of apical dendrites was performed in mice overexpressing wild-type human α-synuclein. Additionally, intracranial injection of preformed α-synuclein fibrils was performed to induce cortical α-syn pathology. We find that α-synuclein overexpressing mice show decreased spine density and abnormalities in spine dynamics in an age-dependent manner. We also provide evidence for the detrimental effects of seeded α-synuclein aggregates on dendritic architecture. We observed spine loss as well as dystrophic deformation of dendritic shafts in layer V pyramidal neurons. Our results provide a link to the pathophysiology underlying dementia associated with synucleinopathies and may enable the evaluation of potential drug candidates on dendritic spine pathology in vivo.

  17. Stress and trauma: BDNF control of dendritic-spine formation and regression.

    PubMed

    Bennett, M R; Lagopoulos, J

    2014-01-01

    Chronic restraint stress leads to increases in brain derived neurotrophic factor (BDNF) mRNA and protein in some regions of the brain, e.g. the basal lateral amygdala (BLA) but decreases in other regions such as the CA3 region of the hippocampus and dendritic spine density increases or decreases in line with these changes in BDNF. Given the powerful influence that BDNF has on dendritic spine growth, these observations suggest that the fundamental reason for the direction and extent of changes in dendritic spine density in a particular region of the brain under stress is due to the changes in BDNF there. The most likely cause of these changes is provided by the stress initiated release of steroids, which readily enter neurons and alter gene expression, for example that of BDNF. Of particular interest is how glucocorticoids and mineralocorticoids tend to have opposite effects on BDNF gene expression offering the possibility that differences in the distribution of their receptors and of their downstream effects might provide a basis for the differential transcription of the BDNF genes. Alternatively, differences in the extent of methylation and acetylation in the epigenetic control of BDNF transcription are possible in different parts of the brain following stress. Although present evidence points to changes in BDNF transcription being the major causal agent for the changes in spine density in different parts of the brain following stress, steroids have significant effects on downstream pathways from the TrkB receptor once it is acted upon by BDNF, including those that modulate the density of dendritic spines. Finally, although glucocorticoids play a canonical role in determining BDNF modulation of dendritic spines, recent studies have shown a role for corticotrophin releasing factor (CRF) in this regard. There is considerable improvement in the extent of changes in spine size and density in rodents with forebrain specific knockout of CRF receptor 1 (CRFR1) even when

  18. Dendritic Spine Loss and Chronic White Matter Inflammation in a Mouse Model of Highly Repetitive Head Trauma

    PubMed Central

    Winston, Charisse N.; Noël, Anastasia; Neustadtl, Aidan; Parsadanian, Maia; Barton, David J.; Chellappa, Deepa; Wilkins, Tiffany E.; Alikhani, Andrew D.; Zapple, David N.; Villapol, Sonia; Planel, Emmanuel; Burns, Mark P.

    2017-01-01

    Mild traumatic brain injury (mTBI) is an emerging risk for chronic behavioral, cognitive, and neurodegenerative conditions. Athletes absorb several hundred mTBIs each year; however, rodent models of repeat mTBI (rmTBI) are often limited to impacts in the single digits. Herein, we describe the effects of 30 rmTBIs, examining structural and pathological changes in mice up to 365 days after injury. We found that single mTBI causes a brief loss of consciousness and a transient reduction in dendritic spines, reflecting a loss of excitatory synapses. Single mTBI does not cause axonal injury, neuroinflammation, or cell death in the gray or white matter. Thirty rmTBIs with a 1-day interval between each mTBI do not cause dendritic spine loss; however, when the interinjury interval is increased to 7 days, dendritic spine loss is reinstated. Thirty rmTBIs cause white matter pathology characterized by positive silver and Fluoro-Jade B staining, and microglial proliferation and activation. This pathology continues to develop through 60 days, and is still apparent at 365 days, after injury. However, rmTBIs did not increase β-amyloid levels or tau phosphorylation in the 3xTg-AD mouse model of Alzheimer disease. Our data reveal that single mTBI causes a transient loss of synapses, but that rmTBIs habituate to repetitive injury within a short time period. rmTBI causes the development of progressive white matter pathology that continues for months after the final impact. PMID:26857506

  19. Conditional self-discrimination enhances dendritic spine number and dendritic length at prefrontal cortex and hippocampal neurons of rats.

    PubMed

    Penagos-Corzo, Julio C; Bonilla, Andrea; Rodríguez-Moreno, Antonio; Flores, Gonzalo; Negrete-Díaz, José V

    2015-11-01

    We studied conditional self-discrimination (CSD) in rats and compared the neuronal cytoarchitecture of untrained animals and rats that were trained in self-discrimination. For this purpose, we used thirty 10-week-old male rats were randomized into three groups: one control group and two conditioning groups: a comparison group (associative learning) and an experimental group (self-discrimination). At the end of the conditioning process, the experimental group managed to discriminate their own state of thirst. After the conditioning process, dendritic morphological changes in the pyramidal neurons of the prefrontal cortex and CA1 region of the dorsal hippocampus were evaluated using Golgi-Cox stain method and then analyzed by the Sholl method. Differences were found in total dendritic length and spine density. Animals trained in self-discrimination showed an increase in the dendritic length and the number of dendritic spines of neurons of the prefrontal cortex and CA1 region of the dorsal hippocampus. Our data suggest that conditional self-discrimination improves the connectivity of the prefrontal cortex and dorsal CA1, which has implications for memory and learning processes.

  20. Reversible loss of dendritic spines and altered excitability after chronic epilepsy in hippocampal slice cultures.

    PubMed Central

    Müller, M; Gähwiler, B H; Rietschin, L; Thompson, S M

    1993-01-01

    The morphological and functional consequences of epileptic activity were investigated by applying the convulsants bicuculline and/or picrotoxin to mature rat hippocampal slice cultures. After 3 days, some cells in all hippocampal subfields showed signs of degeneration, including swollen somata, vacuolation, and dendritic deformities, whereas others displayed only a massive reduction in the number of their dendritic spines. Intracellular recordings from CA3 pyramidal cells revealed a decrease in the amplitude of evoked excitatory synaptic potentials. gamma-Aminobutyric acid-releasing interneurons and inhibitory synaptic potentials were unaffected. Seven days after withdrawal of convulsants, remaining cells possessed a normal number of dendritic spines, thus demonstrating a considerable capacity for recovery. The pathological changes induced by convulsants are similar to those found in the hippocampi of human epileptics, suggesting that they are a consequence, rather than a cause, of epilepsy. Images PMID:8093558

  1. Protein kinase D promotes plasticity-induced F-actin stabilization in dendritic spines and regulates memory formation

    PubMed Central

    Bencsik, Norbert; Szíber, Zsófia; Liliom, Hanna; Tárnok, Krisztián; Borbély, Sándor; Gulyás, Márton; Rátkai, Anikó; Szűcs, Attila; Hazai-Novák, Diána; Ellwanger, Kornelia; Rácz, Bence; Pfizenmaier, Klaus; Hausser, Angelika

    2015-01-01

    Actin turnover in dendritic spines influences spine development, morphology, and plasticity, with functional consequences on learning and memory formation. In nonneuronal cells, protein kinase D (PKD) has an important role in stabilizing F-actin via multiple molecular pathways. Using in vitro models of neuronal plasticity, such as glycine-induced chemical long-term potentiation (LTP), known to evoke synaptic plasticity, or long-term depolarization block by KCl, leading to homeostatic morphological changes, we show that actin stabilization needed for the enlargement of dendritic spines is dependent on PKD activity. Consequently, impaired PKD functions attenuate activity-dependent changes in hippocampal dendritic spines, including LTP formation, cause morphological alterations in vivo, and have deleterious consequences on spatial memory formation. We thus provide compelling evidence that PKD controls synaptic plasticity and learning by regulating actin stability in dendritic spines. PMID:26304723

  2. Urokinase-Type Plasminogen Activator Promotes Dendritic Spine Recovery and Improves Neurological Outcome Following Ischemic Stroke

    PubMed Central

    Wu, Fang; Catano, Marcela; Echeverry, Ramiro; Torre, Enrique; Haile, Woldeab B.; An, Jie; Chen, Changhua; Cheng, Lihong; Nicholson, Andrew; Tong, Frank C.; Park, Jaekeun

    2014-01-01

    Spines are dendritic protrusions that receive most of the excitatory input in the brain. Early after the onset of cerebral ischemia dendritic spines in the peri-infarct cortex are replaced by areas of focal swelling, and their re-emergence from these varicosities is associated with neurological recovery after acute ischemic stroke (AIS). Urokinase-type plasminogen activator (uPA) is a serine proteinase that plays a central role in tissue remodeling via binding to the urokinase plasminogen activator receptor (uPAR). We report that cerebral cortical neurons release uPA during the recovery phase from ischemic stroke in vivo or hypoxia in vitro. Although uPA does not have an effect on ischemia- or hypoxia-induced neuronal death, genetic deficiency of uPA (uPA−/−) or uPAR (uPAR−/−) abrogates functional recovery after AIS. Treatment with recombinant uPA after ischemic stroke induces neurological recovery in wild-type and uPA−/− but not in uPAR−/− mice. Diffusion tensor imaging studies indicate that uPA−/− mice have increased water diffusivity and decreased anisotropy associated with impaired dendritic spine recovery and decreased length of distal neurites in the peri-infarct cortex. We found that the excitotoxic injury induces the clustering of uPAR in dendritic varicosities, and that the binding of uPA to uPAR promotes the reorganization of the actin cytoskeleton and re-emergence of dendritic filopodia from uPAR-enriched varicosities. This effect is independent of uPA's proteolytic properties and instead is mediated by Rac-regulated profilin expression and cofilin phosphorylation. Our data indicate that binding of uPA to uPAR promotes dendritic spine recovery and improves functional outcome following AIS. PMID:25339736

  3. Abnormal intrinsic dynamics of dendritic spines in a fragile X syndrome mouse model in vivo

    PubMed Central

    Nagaoka, Akira; Takehara, Hiroaki; Hayashi-Takagi, Akiko; Noguchi, Jun; Ishii, Kazuhiko; Shirai, Fukutoshi; Yagishita, Sho; Akagi, Takanori; Ichiki, Takanori; Kasai, Haruo

    2016-01-01

    Dendritic spine generation and elimination play an important role in learning and memory, the dynamics of which have been examined within the neocortex in vivo. Spine turnover has also been detected in the absence of specific learning tasks, and is frequently exaggerated in animal models of autistic spectrum disorder (ASD). The present study aimed to examine whether the baseline rate of spine turnover was activity-dependent. This was achieved using a microfluidic brain interface and open-dura surgery, with the goal of abolishing neuronal Ca2+ signaling in the visual cortex of wild-type mice and rodent models of fragile X syndrome (Fmr1 knockout [KO]). In wild-type and Fmr1 KO mice, the majority of baseline turnover was found to be activity-independent. Accordingly, the application of matrix metalloproteinase-9 inhibitors selectively restored the abnormal spine dynamics observed in Fmr1 KO mice, without affecting the intrinsic dynamics of spine turnover in wild-type mice. Such findings indicate that the baseline turnover of dendritic spines is mediated by activity-independent intrinsic dynamics. Furthermore, these results suggest that the targeting of abnormal intrinsic dynamics might pose a novel therapy for ASD. PMID:27221801

  4. Ca2+ sensor proteins in dendritic spines: a race for Ca2+

    PubMed Central

    Raghuram, Vijeta; Sharma, Yogendra; Kreutz, Michael R.

    2012-01-01

    Dendritic spines are believed to be micro-compartments of Ca2+ regulation. In a recent study, it was suggested that the ubiquitous and evolutionarily conserved Ca2+ sensor, calmodulin (CaM), is the first to intercept Ca2+ entering the spine and might be responsible for the fast decay of Ca2+ transients in spines. Neuronal calcium sensor (NCS) and neuronal calcium-binding protein (nCaBP) families consist of Ca2+ sensors with largely unknown synaptic functions despite an increasing number of interaction partners. Particularly how these sensors operate in spines in the presence of CaM has not been discussed in detail before. The limited Ca2+ resources and the existence of common targets create a highly competitive environment where Ca2+ sensors compete with each other for Ca2+ and target binding. In this review, we take a simple numerical approach to put forth possible scenarios and their impact on signaling via Ca2+ sensors of the NCS and nCaBP families. We also discuss the ways in which spine geometry and properties of ion channels, their kinetics and distribution, alter the spatio-temporal aspects of Ca2+ transients in dendritic spines, whose interplay with Ca2+ sensors in turn influences the race for Ca2+. PMID:22586368

  5. Arg kinase regulates prefrontal dendritic spine refinement and cocaine-induced plasticity.

    PubMed

    Gourley, Shannon L; Olevska, Anastasia; Warren, M Sloan; Taylor, Jane R; Koleske, Anthony J

    2012-02-15

    Adolescence is characterized by vulnerability to the development of neuropsychiatric disorders including drug addiction, as well as prefrontal cortical refinement that culminates in structural stability in adulthood. Neuronal refinement and stabilization are hypothesized to confer resilience to poor decision making and addictive-like behaviors, although intracellular mechanisms are largely unknown. We characterized layer V prefrontal dendritic spine development and refinement in adolescent wild-type mice and mice lacking the cytoskeletal regulatory protein Abl-related gene (Arg) kinase. Relative to hippocampal CA1 pyramidal neurons, which exhibited a nearly linear increase in spine density up to postnatal day 60 (P60), wild-type prefrontal spine density peaked at P31, and then declined by 18% by P56-P60. In contrast, dendritic spines in mice lacking Arg destabilized by P31, leading to a net loss in both structures. Destabilization corresponded temporally to the emergence of exaggerated psychomotor sensitivity to cocaine. Moreover, cocaine reduced dendritic spine density in wild-type orbitofrontal cortex and enlarged remaining spine heads, but arg(-/-) spines were unresponsive. Local application of Arg or actin polymerization inhibitors exaggerated cocaine sensitization, as did reduced gene dosage of the Arg substrate, p190RhoGAP. Genetic and pharmacological Arg inhibition also retarded instrumental reversal learning and potentiated responding for reward-related cues, providing evidence that Arg regulates both psychomotor sensitization and decision-making processes implicated in addiction. These findings also indicate that structural refinement in the adolescent orbitofrontal cortex mitigates psychostimulant sensitivity and support the emerging perspective that the structural response to cocaine may, at any age, have behaviorally protective consequences.

  6. Chronic alcohol drinking alters neuronal dendritic spines in the brain reward center nucleus accumbens.

    PubMed

    Zhou, Feng C; Anthony, Bruce; Dunn, Kenneth W; Lindquist, W Brent; Xu, Zao C; Deng, Ping

    2007-02-23

    Alcohol is known to affect glutamate transmission. However, how chronic alcohol affects the synaptic structure mediating glutamate transmission is unknown. Repeated alcohol exposure in a subject with familial alcoholic history often leads to alcohol addiction. The current study adopts alcohol-preferring rats, which are known to develop high drinking. Two-photon microscopy analysis indicates that chronic alcohol of 14 weeks either, under continuous alcohol (C-Alc) or with repeated deprivation (RD-Alc), causes dysmorphology--thickened, beaded, and disoriented dendrites that are reminiscent of reactive astrocytes--in a subpopulation of medium spiny neurons. The density of dendritic spines was found differentially lower in the nucleus accumbens of RD-Alc and C-Alc groups as compared with those of Water groups. Large-sized spines and multiple-headed spines were increased in the RD-Alc group. The NMDA receptor subunit NR1 proteins, as analyzed with Western blot, were upregulated in C-Alc, but not in RD-Alc. The upregulated NMDA receptor subunits of NR1 however, are predominantly a splice variant isoform with truncated exon 21, which is required for membrane-bound trafficking or anchoring into a spine synaptic site. These maladaptations may contribute to the transformation of spines. The changes, in density and head-size of spines and the corresponding NMDA receptors, demonstrated an alteration of microcircuitry for glutamate reception. The current study demonstrates for the first time that chronic alcohol exposure causes structural alteration of dendrites and their spines in the key reward brain region in animals that have a genetic background leading to alcohol addiction.

  7. Ceramide Levels Regulated by Carnitine Palmitoyltransferase 1C Control Dendritic Spine Maturation and Cognition*

    PubMed Central

    Carrasco, Patricia; Sahún, Ignasi; McDonald, Jerome; Ramírez, Sara; Jacas, Jordi; Gratacós, Esther; Sierra, Adriana Y.; Serra, Dolors; Herrero, Laura; Acker-Palmer, Amparo; Hegardt, Fausto G.; Dierssen, Mara; Casals, Núria

    2012-01-01

    The brain-specific isoform carnitine palmitoyltransferase 1C (CPT1C) has been implicated in the hypothalamic regulation of food intake and energy homeostasis. Nevertheless, its molecular function is not completely understood, and its role in other brain areas is unknown. We demonstrate that CPT1C is expressed in pyramidal neurons of the hippocampus and is located in the endoplasmic reticulum throughout the neuron, even inside dendritic spines. We used molecular, cellular, and behavioral approaches to determine CPT1C function. First, we analyzed the implication of CPT1C in ceramide metabolism. CPT1C overexpression in primary hippocampal cultured neurons increased ceramide levels, whereas in CPT1C-deficient neurons, ceramide levels were diminished. Correspondingly, CPT1C knock-out (KO) mice showed reduced ceramide levels in the hippocampus. At the cellular level, CPT1C deficiency altered dendritic spine morphology by increasing immature filopodia and reducing mature mushroom and stubby spines. Total protrusion density and spine head area in mature spines were unaffected. Treatment of cultured neurons with exogenous ceramide reverted the KO phenotype, as did ectopic overexpression of CPT1C, indicating that CPT1C regulation of spine maturation is mediated by ceramide. To study the repercussions of the KO phenotype on cognition, we performed the hippocampus-dependent Morris water maze test on mice. Results show that CPT1C deficiency strongly impairs spatial learning. All of these results demonstrate that CPT1C regulates the levels of ceramide in the endoplasmic reticulum of hippocampal neurons, and this is a relevant mechanism for the correct maturation of dendritic spines and for proper spatial learning. PMID:22539351

  8. Estradiol reduces dendritic spine density in the ventral striatum of female Syrian hamsters.

    PubMed

    Staffend, Nancy A; Loftus, Caroline M; Meisel, Robert L

    2011-01-01

    Estradiol affects a variety of brain regions by modulating physiological and cellular functions as well as neuronal morphology. Within the striatum, estradiol is known to induce physiological and molecular changes, yet estradiol's effects on striatal dendritic morphology have not yet been evaluated. Using ballistic delivery of the lipophilic dye DiI to tissue sections, we were able to evaluate estradiol's effects on striatal morphology in female Syrian hamsters. We found that estradiol significantly decreased spine density within the nucleus accumbens core, with no effect in the nucleus accumbens shell or caudate. Interestingly, estradiol treatment caused a significant deconstruction of spines from more to less mature spine subtypes in both the nucleus accumbens core and shell regardless of changes in spine density. These results are significant in that they offer a novel mechanism for estradiol actions on a wide variety of nucleus accumbens functions such as motivation or reward as well as their pathological consequences (e.g. drug addiction).

  9. Reelin Regulates the Maturation of Dendritic Spines, Synaptogenesis and Glial Ensheathment of Newborn Granule Cells.

    PubMed

    Bosch, Carles; Masachs, Nuria; Exposito-Alonso, David; Martínez, Albert; Teixeira, Cátia M; Fernaud, Isabel; Pujadas, Lluís; Ulloa, Fausto; Comella, Joan X; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

    2016-09-13

    The Reelin pathway is essential for both neural migration and for the development and maturation of synaptic connections. However, its role in adult synaptic formation and remodeling is still being investigated. Here, we investigated the impact of the Reelin/Dab1 pathway on the synaptogenesis of newborn granule cells (GCs) in the young-adult mouse hippocampus. We show that neither Reelin overexpression nor the inactivation of its intracellular adapter, Dab1, substantially alters dendritic spine numbers in these neurons. In contrast, 3D-electron microscopy (focused ion beam milling/scanning electron microscope) revealed that dysregulation of the Reelin/Dab1 pathway leads to both transient and permanent changes in the types and morphology of dendritic spines, mainly altering mushroom, filopodial, and branched GC spines. We also found that the Reelin/Dab1 pathway controls synaptic configuration of presynaptic boutons in the dentate gyrus, with its dysregulation leading to a substantial decrease in multi-synaptic bouton innervation. Lastly, we show that the Reelin/Dab1 pathway controls astroglial ensheathment of synapses. Thus, the Reelin pathway is a key regulator of adult-generated GC integration, by controlling dendritic spine types and shapes, their synaptic innervation patterns, and glial ensheathment. These findings may help to better understanding of hippocampal circuit alterations in neurological disorders in which the Reelin pathway is implicated.

  10. The Gαo Activator Mastoparan-7 Promotes Dendritic Spine Formation in Hippocampal Neurons.

    PubMed

    Ramírez, Valerie T; Ramos-Fernández, Eva; Inestrosa, Nibaldo C

    2016-01-01

    Mastoparan-7 (Mas-7), an analogue of the peptide mastoparan, which is derived from wasp venom, is a direct activator of Pertussis toxin- (PTX-) sensitive G proteins. Mas-7 produces several biological effects in different cell types; however, little is known about how Mas-7 influences mature hippocampal neurons. We examined the specific role of Mas-7 in the development of dendritic spines, the sites of excitatory synaptic contact that are crucial for synaptic plasticity. We report here that exposure of hippocampal neurons to a low dose of Mas-7 increases dendritic spine density and spine head width in a time-dependent manner. Additionally, Mas-7 enhances postsynaptic density protein-95 (PSD-95) clustering in neurites and activates Gα(o) signaling, increasing the intracellular Ca(2+) concentration. To define the role of signaling intermediates, we measured the levels of phosphorylated protein kinase C (PKC), c-Jun N-terminal kinase (JNK), and calcium-calmodulin dependent protein kinase IIα (CaMKIIα) after Mas-7 treatment and determined that CaMKII activation is necessary for the Mas-7-dependent increase in dendritic spine density. Our results demonstrate a critical role for Gα(o) subunit signaling in the regulation of synapse formation.

  11. The Gαo Activator Mastoparan-7 Promotes Dendritic Spine Formation in Hippocampal Neurons

    PubMed Central

    Ramírez, Valerie T.; Ramos-Fernández, Eva; Inestrosa, Nibaldo C.

    2016-01-01

    Mastoparan-7 (Mas-7), an analogue of the peptide mastoparan, which is derived from wasp venom, is a direct activator of Pertussis toxin- (PTX-) sensitive G proteins. Mas-7 produces several biological effects in different cell types; however, little is known about how Mas-7 influences mature hippocampal neurons. We examined the specific role of Mas-7 in the development of dendritic spines, the sites of excitatory synaptic contact that are crucial for synaptic plasticity. We report here that exposure of hippocampal neurons to a low dose of Mas-7 increases dendritic spine density and spine head width in a time-dependent manner. Additionally, Mas-7 enhances postsynaptic density protein-95 (PSD-95) clustering in neurites and activates Gαo signaling, increasing the intracellular Ca2+ concentration. To define the role of signaling intermediates, we measured the levels of phosphorylated protein kinase C (PKC), c-Jun N-terminal kinase (JNK), and calcium-calmodulin dependent protein kinase IIα (CaMKIIα) after Mas-7 treatment and determined that CaMKII activation is necessary for the Mas-7-dependent increase in dendritic spine density. Our results demonstrate a critical role for Gαo subunit signaling in the regulation of synapse formation. PMID:26881110

  12. The pseudokinase CaMKv is required for the activity-dependent maintenance of dendritic spines

    PubMed Central

    Liang, Zhuoyi; Zhan, Yi; Shen, Yang; Wong, Catherine C. L.; Yates, John R.; Plattner, Florian; Lai, Kwok-On; Ip, Nancy Y.

    2016-01-01

    Dendritic spine stabilization depends on afferent synaptic input and requires changes in actin cytoskeleton dynamics and protein synthesis. However, the underlying molecular mechanism remains unclear. Here we report the identification of ‘calmodulin kinase-like vesicle-associated' (CaMKv), a pseudokinase of the CaMK family with unknown function, as a synaptic protein crucial for dendritic spine maintenance. CaMKv mRNA localizes at dendrites, and its protein synthesis is regulated by neuronal activity. CaMKv function is inhibited upon phosphorylation by cyclin-dependent kinase 5 (Cdk5) at Thr345. Furthermore, CaMKv knockdown in mouse hippocampal CA1 pyramidal neurons impairs synaptic transmission and plasticity in vivo, resulting in hyperactivity and spatial memory impairment. These findings collectively indicate that the precise regulation of CaMKv through activity-dependent synthesis and post-translational phosphorylation is critical for dendritic spine maintenance, revealing an unusual signalling pathway in the regulation of synaptic transmission and brain function that involves a pseudokinase. PMID:27796283

  13. An in vitro reproduction of stress-induced memory defects: Effects of corticoids on dendritic spine dynamics

    PubMed Central

    Saito, Shinichi; Kimura, Satoshi; Adachi, Naoki; Numakawa, Tadahiro; Ogura, Akihiko; Tominaga-Yoshino, Keiko

    2016-01-01

    Previously, in organotypic slice culture of rodent hippocampus we found that three repeated inductions of LTP, but not a single induction, led to a slow-developing long-lasting enhancement of synaptic strength coupled with synapse formation. Naming this structural plasticity RISE (repetitive LTP-induced synaptic enhancement) and assuming it to be a potential in vitro reproduction of repetition-dependent memory consolidation, we are analyzing its cellular mechanisms. Here, we applied a glucocorticoid to the culture to mimic acute excess stress and demonstrated its blockade of RISE. Since excess stress interferes with behavioral memory consolidation, the parallelism between RISE in vitro and memory consolidation in vivo is supported. We recently reported that RISE developed after stochastic processes. Here we found that the glucocorticoid interfered with RISE by suppressing the increment of dendritic spine fluctuation that precedes a net increase in spine density. The present study provides clues for understanding the mechanism of stress-induced memory defects. PMID:26765339

  14. An in vitro reproduction of stress-induced memory defects: Effects of corticoids on dendritic spine dynamics.

    PubMed

    Saito, Shinichi; Kimura, Satoshi; Adachi, Naoki; Numakawa, Tadahiro; Ogura, Akihiko; Tominaga-Yoshino, Keiko

    2016-01-14

    Previously, in organotypic slice culture of rodent hippocampus we found that three repeated inductions of LTP, but not a single induction, led to a slow-developing long-lasting enhancement of synaptic strength coupled with synapse formation. Naming this structural plasticity RISE (repetitive LTP-induced synaptic enhancement) and assuming it to be a potential in vitro reproduction of repetition-dependent memory consolidation, we are analyzing its cellular mechanisms. Here, we applied a glucocorticoid to the culture to mimic acute excess stress and demonstrated its blockade of RISE. Since excess stress interferes with behavioral memory consolidation, the parallelism between RISE in vitro and memory consolidation in vivo is supported. We recently reported that RISE developed after stochastic processes. Here we found that the glucocorticoid interfered with RISE by suppressing the increment of dendritic spine fluctuation that precedes a net increase in spine density. The present study provides clues for understanding the mechanism of stress-induced memory defects.

  15. Ablation of ErbB4 from excitatory neurons leads to reduced dendritic spine density in mouse prefrontal cortex

    PubMed Central

    Cooper, Margaret A.; Koleske, Anthony J.

    2014-01-01

    Dendritic spine loss is observed in many psychiatric disorders, including schizophrenia, and likely contributes to the altered sense of reality, disruption of working memory, and attention deficits that characterize these disorders. ErbB4, a member of the EGF family of receptor tyrosine kinases, is genetically associated0020with schizophrenia, suggesting that alterations in ErbB4 function contribute to the disease pathology. Additionally, ErbB4 functions in synaptic plasticity, leading us to hypothesize that disruption of ErbB4 signaling may affect dendritic spine development. We show that dendritic spine density is reduced in the dorsomedial prefrontal cortex of ErbB4 conditional whole-brain knockout mice. We find that ErbB4 localizes to dendritic spines of excitatory neurons in cortical neuronal cultures and is present in synaptic plasma membrane preparations. Finally, we demonstrate that selective ablation of ErbB4 from excitatory neurons leads to a decrease in the proportion of mature spines and an overall reduction in dendritic spine density in the prefrontal cortex of weanling (P21) mice that persists at 2 months of age. These results suggest that ErbB4 signaling in excitatory pyramidal cells is critical for the proper formation and maintenance of dendritic spines in excitatory pyramidal cells. PMID:24752666

  16. Reduced Dendritic Spine Density In Auditory Cortex Of Subjects With Schizophrenia

    PubMed Central

    Sweet, Robert A.; Henteleff, Ruth A.; Zhang, Wei; Sampson, Allan R.; Lewis, David A.

    2009-01-01

    Background We have previously identified reductions in mean pyramidal cell somal volume in deep layer 3 of BA 41 and BA 42 and reduced axon terminal density in deep layer 3 of BA 41. In other brain regions demonstrating similar deficits, reduced dendritic spine density has also been identified, leading us to hypothesize that dendritic spine density would also be reduced in BA 41 and BA 42. Because dendritic spines and their excitatory inputs are regulated in tandem, we further hypothesized that spine density would be correlated with axon terminal density. Method We used stereologic methods to quantify a marker of dendritic spines, spinophilin-immunoreactive (SP-IR) puncta, in deep layer 3 of BA 41 and 42 of 15 subjects with schizophrenia, each matched to a normal comparison subject. The effect of long-term haloperidol exposure on SP-IR puncta density was evaluated in non-human primates. Results SP-IR puncta density was significantly lower by 27.2% in deep layer 3 of BA 41 in the schizophrenia subjects, and by 22.2% in deep layer 3 of BA 42. In both BA 41 and 42, SP-IR puncta density was correlated with a marker of axon terminal density, but not with pyramidal cell somal volume. SP-IR puncta density did not differ between haloperidol-exposed and control monkeys. Conclusion Lower SP-IR puncta density in deep layer 3 of BA 41 and 42 of subjects with schizophrenia may reflect concurrent reductions in excitatory afferent input. This may contribute to impairments in auditory sensory processing which are present in subjects with schizophrenia. PMID:18463626

  17. Cofilin1 Controls Transcolumnar Plasticity in Dendritic Spines in Adult Barrel Cortex

    PubMed Central

    Tsubota, Tadashi; Okubo-Suzuki, Reiko; Ohashi, Yohei; Tamura, Keita; Ogata, Koshin; Yaguchi, Masae; Matsuyama, Makoto; Inokuchi, Kaoru; Miyashita, Yasushi

    2015-01-01

    During sensory deprivation, the barrel cortex undergoes expansion of a functional column representing spared inputs (spared column), into the neighboring deprived columns (representing deprived inputs) which are in turn shrunk. As a result, the neurons in a deprived column simultaneously increase and decrease their responses to spared and deprived inputs, respectively. Previous studies revealed that dendritic spines are remodeled during this barrel map plasticity. Because cofilin1, a predominant regulator of actin filament turnover, governs both the expansion and shrinkage of the dendritic spine structure in vitro, it hypothetically regulates both responses in barrel map plasticity. However, this hypothesis remains untested. Using lentiviral vectors, we knocked down cofilin1 locally within layer 2/3 neurons in a deprived column. Cofilin1-knocked-down neurons were optogenetically labeled using channelrhodopsin-2, and electrophysiological recordings were targeted to these knocked-down neurons. We showed that cofilin1 knockdown impaired response increases to spared inputs but preserved response decreases to deprived inputs, indicating that cofilin1 dependency is dissociated in these two types of barrel map plasticity. To explore the structural basis of this dissociation, we then analyzed spine densities on deprived column dendritic branches, which were supposed to receive dense horizontal transcolumnar projections from the spared column. We found that spine number increased in a cofilin1-dependent manner selectively in the distal part of the supragranular layer, where most of the transcolumnar projections existed. Our findings suggest that cofilin1-mediated actin dynamics regulate functional map plasticity in an input-specific manner through the dendritic spine remodeling that occurs in the horizontal transcolumnar circuits. These new mechanistic insights into transcolumnar plasticity in adult rats may have a general significance for understanding reorganization of

  18. Detection of Dendritic Spines Using Wavelet-Based Conditional Symmetric Analysis and Regularized Morphological Shared-Weight Neural Networks.

    PubMed

    Wang, Shuihua; Chen, Mengmeng; Li, Yang; Zhang, Yudong; Han, Liangxiu; Wu, Jane; Du, Sidan

    2015-01-01

    Identification and detection of dendritic spines in neuron images are of high interest in diagnosis and treatment of neurological and psychiatric disorders (e.g., Alzheimer's disease, Parkinson's diseases, and autism). In this paper, we have proposed a novel automatic approach using wavelet-based conditional symmetric analysis and regularized morphological shared-weight neural networks (RMSNN) for dendritic spine identification involving the following steps: backbone extraction, localization of dendritic spines, and classification. First, a new algorithm based on wavelet transform and conditional symmetric analysis has been developed to extract backbone and locate the dendrite boundary. Then, the RMSNN has been proposed to classify the spines into three predefined categories (mushroom, thin, and stubby). We have compared our proposed approach against the existing methods. The experimental result demonstrates that the proposed approach can accurately locate the dendrite and accurately classify the spines into three categories with the accuracy of 99.1% for "mushroom" spines, 97.6% for "stubby" spines, and 98.6% for "thin" spines.

  19. Detection of Dendritic Spines Using Wavelet-Based Conditional Symmetric Analysis and Regularized Morphological Shared-Weight Neural Networks

    PubMed Central

    Wang, Shuihua; Chen, Mengmeng; Li, Yang; Zhang, Yudong; Han, Liangxiu; Wu, Jane; Du, Sidan

    2015-01-01

    Identification and detection of dendritic spines in neuron images are of high interest in diagnosis and treatment of neurological and psychiatric disorders (e.g., Alzheimer's disease, Parkinson's diseases, and autism). In this paper, we have proposed a novel automatic approach using wavelet-based conditional symmetric analysis and regularized morphological shared-weight neural networks (RMSNN) for dendritic spine identification involving the following steps: backbone extraction, localization of dendritic spines, and classification. First, a new algorithm based on wavelet transform and conditional symmetric analysis has been developed to extract backbone and locate the dendrite boundary. Then, the RMSNN has been proposed to classify the spines into three predefined categories (mushroom, thin, and stubby). We have compared our proposed approach against the existing methods. The experimental result demonstrates that the proposed approach can accurately locate the dendrite and accurately classify the spines into three categories with the accuracy of 99.1% for “mushroom” spines, 97.6% for “stubby” spines, and 98.6% for “thin” spines. PMID:26692046

  20. Actinin-4 Governs Dendritic Spine Dynamics and Promotes Their Remodeling by Metabotropic Glutamate Receptors*

    PubMed Central

    Kalinowska, Magdalena; Chávez, Andrés E.; Lutzu, Stefano; Castillo, Pablo E.; Bukauskas, Feliksas F.; Francesconi, Anna

    2015-01-01

    Dendritic spines are dynamic, actin-rich protrusions in neurons that undergo remodeling during neuronal development and activity-dependent plasticity within the central nervous system. Although group 1 metabotropic glutamate receptors (mGluRs) are critical for spine remodeling under physiopathological conditions, the molecular components linking receptor activity to structural plasticity remain unknown. Here we identify a Ca2+-sensitive actin-binding protein, α-actinin-4, as a novel group 1 mGluR-interacting partner that orchestrates spine dynamics and morphogenesis in primary neurons. Functional silencing of α-actinin-4 abolished spine elongation and turnover stimulated by group 1 mGluRs despite intact surface receptor expression and downstream ERK1/2 signaling. This function of α-actinin-4 in spine dynamics was underscored by gain-of-function phenotypes in untreated neurons. Here α-actinin-4 induced spine head enlargement, a morphological change requiring the C-terminal domain of α-actinin-4 that binds to CaMKII, an interaction we showed to be regulated by group 1 mGluR activation. Our data provide mechanistic insights into spine remodeling by metabotropic signaling and identify α-actinin-4 as a critical effector of structural plasticity within neurons. PMID:25944910

  1. Actin Capping Protein is required for Dendritic Spine Development and Synapse Formation

    PubMed Central

    Fan, Yanjie; Tang, Xin; Vitriol, Eric; Chen, Gong; Zheng, James Q.

    2011-01-01

    Dendritic spines serve as the postsynaptic platform for most excitatory synapses in the mammalian brain and their shape and size are tightly correlated with synaptic strength. The actin cytoskeleton plays a crucial role in the spine structure and its modifications during synapse development and plasticity, but the underlying regulatory mechanisms remain to be elucidated. Here we report that actin capping protein (CP), a regulator of actin filament growth, plays an essential role for spine development and synapse formation. We found that CP expression in rat hippocampus is elevated at and after the stage of substantial synapse formation. CP knockdown in hippocampal cultures resulted in a marked decline in the spine density accompanied by increased filopodia-like protrusions. Moreover, the spines of CP knockdown neurons exhibited an altered morphology, highlighted by multiple thin filopodia-like protrusions emerging from the spine head. Finally, the number of functional synapses was reduced by CP knockdown as evidenced by a reduction in the density of paired pre- and postsynaptic markers and in the frequency of miniature excitatory postsynaptic currents. These findings indicate that capping of actin filaments by CP represents an essential step for the remodeling of the actin architecture underlying spine morphogenesis and synaptic formation during development. PMID:21752999

  2. Adolescent bisphenol-A exposure decreases dendritic spine density: role of sex and age.

    PubMed

    Bowman, Rachel E; Luine, Victoria; Khandaker, Hameda; Villafane, Joseph J; Frankfurt, Maya

    2014-11-01

    Bisphenol-A (BPA), a common environmental endocrine disruptor, modulates estrogenic, androgenic, and antiandrogenic effects throughout the lifespan. We recently showed that low dose BPA exposure during adolescence increases anxiety and impairs spatial memory independent of sex. In this study, six week old Sprague Dawley rats (n=24 males, n=24 females) received daily subcutaneous injections (40 µg/kg bodyweight) of BPA or vehicle for one week. Serum corticosterone levels in response to a 1 h restraint stress and spine density were examined at age 7 (cohort 1) and 11 (cohort 2) weeks. Adolescent BPA exposure did not alter stress dependent corticosterone responses but decreased spine density on apical and basal dendrites of pyramidal cells in the medial prefrontal cortex (mPFC) and hippocampal CA1 region (CA1). Sex differences in spine density were observed on basal dendrites of the mPFC and CA1 with females having greater spine density than males. This sex difference was further augmented by both age and treatment, with results indicating that BPA-dependent decreases in spine density were more pronounced in males than females on mPFC basal dendrites. Importantly, the robust neuronal alterations were observed in animals exposed to BPA levels below the current U.S.E.P.A. recommended safe daily limit. These results are the first demonstrating that BPA given during adolescence leads to enduring effects on neural morphology at adulthood. Given that humans are routinely exposed to low levels of BPA through a variety of sources, the decreased spine density reported in both male and female rats after BPA exposure warrants further investigation.

  3. Cerebellar dentate nuclei lesions alter prefrontal cortex dendritic spine morphology.

    PubMed

    Bauer, David J; Peterson, Todd C; Swain, Rodney A

    2014-01-28

    Anatomical tracing studies in primates have revealed neural tracts from the cerebellar dentate nuclei to prefrontal cortex, implicating a cerebellar role in nonmotor processes. Experiments in rats examining the functional role of this cerebellothalamocortical pathway have demonstrated the development of visuospatial and motivational deficits following lesions of the dentate nuclei, in the absence of motor impairment. These behavioral deficits possibly occur due to structural modifications of the cerebral cortex secondary to loss of cerebellar input. The current study characterized morphological alterations in prefrontal cortex important for visuospatial and motivational processes following bilateral cerebellar dentate nuclei lesions. Rats received either bilateral electrolytic cerebellar dentate nuclei lesions or sham surgery followed by a 30-day recovery. Randomly selected Golgi-impregnated neurons in prefrontal cortex were examined for analysis. Measures of branch length and spine density revealed no differences between lesioned and sham rats in either apical or basilar arbors; however, the proportion of immature to mature spines significantly decreased in lesioned rats as compared to sham controls, with reductions of 33% in the basilar arbor and 28% in the apical arbor. Although expected pruning of branches and spines did not occur, the results are consistent with the hypothesis that cerebellar lesions influence prefrontal morphology and support the possibility that functional deficits following cerebellar dentate nuclei lesions are related to prefrontal morphological alteration.

  4. Voltage-sensitive dye recording from axons, dendrites and dendritic spines of individual neurons in brain slices.

    PubMed

    Popovic, Marko; Gao, Xin; Zecevic, Dejan

    2012-11-29

    phototoxic effects (4, 6, 12, 13). At present, we take advantage of the superb brightness and stability of a laser light source at near-optimal wavelength to maximize the sensitivity of the V(m)-imaging technique. The current sensitivity permits multiple site optical recordings of V(m) transients from all parts of a neuron, including axons and axon collaterals, terminal dendritic branches, and individual dendritic spines. The acquired information on signal interactions can be analyzed quantitatively as well as directly visualized in the form of a movie.

  5. State-dependent diffusion of actin-depolymerizing factor/cofilin underlies the enlargement and shrinkage of dendritic spines

    PubMed Central

    Noguchi, Jun; Hayama, Tatsuya; Watanabe, Satoshi; Ucar, Hasan; Yagishita, Sho; Takahashi, Noriko; Kasai, Haruo

    2016-01-01

    Dendritic spines are the postsynaptic sites of most excitatory synapses in the brain, and spine enlargement and shrinkage give rise to long-term potentiation and depression of synapses, respectively. Because spine structural plasticity is accompanied by remodeling of actin scaffolds, we hypothesized that the filamentous actin regulatory protein cofilin plays a crucial role in this process. Here we investigated the diffusional properties of cofilin, the actin-severing and depolymerizing actions of which are activated by dephosphorylation. Cofilin diffusion was measured using fluorescently labeled cofilin fusion proteins and two-photon imaging. We show that cofilins are highly diffusible along dendrites in the resting state. However, during spine enlargement, wild-type cofilin and a phosphomimetic cofilin mutant remain confined to the stimulated spine, whereas a nonphosphorylatable mutant does not. Moreover, inhibition of cofilin phosphorylation with a competitive peptide disables spine enlargement, suggesting that phosphorylated-cofilin accumulation is a key regulator of enlargement, which is localized to individual spines. Conversely, spine shrinkage spreads to neighboring spines, even though triggered by weaker stimuli than enlargement. Diffusion of exogenous cofilin injected into a pyramidal neuron soma causes spine shrinkage and reduced PSD95 in spines, suggesting that diffusion of dephosphorylated endogenous cofilin underlies the spreading of spine shrinkage and long-term depression. PMID:27595610

  6. Effect of Ovarian Hormones on Genes Promoting Dendritic Spines In Laser Captured Serotonin Neurons From Macaques

    PubMed Central

    Bethea, Cynthia L.; Reddy, Arubala P.

    2009-01-01

    Dendritic spines are the elementary structural units of neuronal plasticity and the cascades that promote dendrite spine remodeling center on Rho GTPases and downstream effectors of actin dynamics. In a model of hormone replacement therapy (HT), we sought the effect of estradiol (E) and progesterone (P) on gene expression in these cascades in laser captured serotonin neurons from rhesus macaques with cDNA array analysis. Spayed rhesus macaques were treated with either placebo, E or E+P via Silastic implant for 1 month prior to euthanasia after which the midbrain was obtained, sectioned and immunostained for TPH. TPH-positive neurons were laser captured using an Arcturus Laser Dissection Microscope (PixCell II). RNA from laser captured serotonin neurons (n=2 animals/treatment) was hybridized to Rhesus Affymetrix GeneChips. There was a significant change in 744 probe sets (ANOVA, p < 0.05), but 10,493 probe sets exhibited a 2-fold or greater change. Pivotal changes in pathways leading to dendrite spine proliferation and transformation included 2-fold or greater increases in expression of the Rho GTPases called CDC42, Rac1 and RhoA. In addition, 2-fold or greater increases occurred in downstream effectors of actin dynamics including PAK1, ROCK, PIP5K, IRSp53, WASP, WAVE, MLC, cofilin, gelsolin, profilin and 3 subunits of ARP2/3. Finally, 2-fold or greater decreases occurred in CRIPAK, LIMK2 and MLCK. The regulation of RhoA, Rac1, CDC42, ROCK, PIP5k, IRSp53, WASP, WAVE, LIMK2, CRIPAK1, MLCK, ARP2/3 subunit 3, gelsolin, profilin and cofilin was confirmed with nested qRT-PCR on laser captured RNA (n=3 animals/treatment). The data indicate that ovarian steroids target gene expression of the Rho GTPases and pivotal downstream proteins that in turn, would promote dendritic spine proliferation and stabilization on serotonin neurons of the dorsal raphe nucleus. PMID:19687787

  7. Actin-Dependent Alterations of Dendritic Spine Morphology in Shankopathies

    PubMed Central

    Sarowar, Tasnuva

    2016-01-01

    Shank proteins (Shank1, Shank2, and Shank3) act as scaffolding molecules in the postsynaptic density of many excitatory neurons. Mutations in SHANK genes, in particular SHANK2 and SHANK3, lead to autism spectrum disorders (ASD) in both human and mouse models. Shank3 proteins are made of several domains—the Shank/ProSAP N-terminal (SPN) domain, ankyrin repeats, SH3 domain, PDZ domain, a proline-rich region, and the sterile alpha motif (SAM) domain. Via various binding partners of these domains, Shank3 is able to bind and interact with a wide range of proteins including modulators of small GTPases such as RICH2, a RhoGAP protein, and βPIX, a RhoGEF protein for Rac1 and Cdc42, actin binding proteins and actin modulators. Dysregulation of all isoforms of Shank proteins, but especially Shank3, leads to alterations in spine morphogenesis, shape, and activity of the synapse via altering actin dynamics. Therefore, here, we highlight the role of Shank proteins as modulators of small GTPases and, ultimately, actin dynamics, as found in multiple in vitro and in vivo models. The failure to mediate this regulatory role might present a shared mechanism in the pathophysiology of autism-associated mutations, which leads to dysregulation of spine morphogenesis and synaptic signaling. PMID:27795858

  8. Chronic Social Defeat Stress Modulates Dendritic Spines Structural Plasticity in Adult Mouse Frontal Association Cortex

    PubMed Central

    Shu, Yu

    2017-01-01

    Chronic stress is associated with occurrence of many mental disorders. Previous studies have shown that dendrites and spines of pyramidal neurons of the prefrontal cortex undergo drastic reorganization following chronic stress experience. So the prefrontal cortex is believed to play a key role in response of neural system to chronic stress. However, how stress induces dynamic structural changes in neural circuit of prefrontal cortex remains unknown. In the present study, we examined the effects of chronic social defeat stress on dendritic spine structural plasticity in the mouse frontal association (FrA) cortex in vivo using two-photon microscopy. We found that chronic stress altered spine dynamics in FrA and increased the connectivity in FrA neural circuits. We also found that the changes in spine dynamics in FrA are correlated with the deficit of sucrose preference in defeated mice. Our findings suggest that chronic stress experience leads to adaptive change in neural circuits that may be important for encoding stress experience related memory and anhedonia. PMID:28197343

  9. Distribution of NMDA and AMPA receptor subunits at thalamo-amygdaloid dendritic spines.

    PubMed

    Radley, Jason J; Farb, Claudia R; He, Yong; Janssen, William G M; Rodrigues, Sarina M; Johnson, Luke R; Hof, Patrick R; LeDoux, Joseph E; Morrison, John H

    2007-02-23

    Synapses onto dendritic spines in the lateral amygdala formed by afferents from the auditory thalamus represent a site of plasticity in Pavlovian fear conditioning. Previous work has demonstrated that thalamic afferents synapse onto LA spines expressing glutamate receptor (GluR) subunits, but the GluR subunit distribution at the synapse and within the cytoplasm has not been characterized. Therefore, we performed a quantitative analysis for alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor subunits GluR2 and GluR3 and N-methyl-D-aspartate (NMDA) receptor subunits NR1 and NR2B by combining anterograde labeling of thalamo-amygdaloid afferents with postembedding immunoelectron microscopy for the GluRs in adult rats. A high percentage of thalamo-amygdaloid spines was immunoreactive for GluR2 (80%), GluR3 (83%), and NR1 (83%), while a smaller proportion of spines expressed NR2B (59%). To compare across the various subunits, the cytoplasmic to synaptic ratios of GluRs were measured within thalamo-amygdaloid spines. Analyses revealed that the cytoplasmic pool of GluR2 receptors was twice as large compared to the GluR3, NR1, and NR2B subunits. Our data also show that in the adult brain, the NR2B subunit is expressed in the majority of in thalamo-amygdaloid spines and that within these spines, the various GluRs are differentially distributed between synaptic and non-synaptic sites. The prevalence of the NR2B subunit in thalamo-amygdaloid spines provides morphological evidence supporting its role in the fear conditioning circuit while the differential distribution of the GluR subtypes may reflect distinct roles for their involvement in this circuitry and synaptic plasticity.

  10. The influence of phospho-tau on dendritic spines of cortical pyramidal neurons in patients with Alzheimer’s disease

    PubMed Central

    Merino-Serrais, Paula; Benavides-Piccione, Ruth; Blazquez-Llorca, Lidia; Kastanauskaite, Asta; Rábano, Alberto; Avila, Jesús

    2013-01-01

    The dendritic spines on pyramidal cells represent the main postsynaptic elements of cortical excitatory synapses and they are fundamental structures in memory, learning and cognition. In the present study, we used intracellular injections of Lucifer yellow in fixed tissue to analyse over 19 500 dendritic spines that were completely reconstructed in three dimensions along the length of the basal dendrites of pyramidal neurons in the parahippocampal cortex and CA1 of patients with Alzheimer’s disease. Following intracellular injection, sections were immunostained for anti-Lucifer yellow and with tau monoclonal antibodies AT8 and PHF-1, which recognize tau phosphorylated at Ser202/Thr205 and at Ser396/404, respectively. We observed that the diffuse accumulation of phospho-tau in a putative pre-tangle state did not induce changes in the dendrites of pyramidal neurons, whereas the presence of tau aggregates forming intraneuronal neurofibrillary tangles was associated with progressive alteration of dendritic spines (loss of dendritic spines and changes in their morphology) and dendrite atrophy, depending on the degree of tangle development. Thus, the presence of phospho-tau in neurons does not necessarily mean that they suffer severe and irreversible effects as thought previously but rather, the characteristic cognitive impairment in Alzheimer’s disease is likely to depend on the relative number of neurons that have well developed tangles. PMID:23715095

  11. The influence of phospho-τ on dendritic spines of cortical pyramidal neurons in patients with Alzheimer's disease.

    PubMed

    Merino-Serrais, Paula; Benavides-Piccione, Ruth; Blazquez-Llorca, Lidia; Kastanauskaite, Asta; Rábano, Alberto; Avila, Jesús; DeFelipe, Javier

    2013-06-01

    The dendritic spines on pyramidal cells represent the main postsynaptic elements of cortical excitatory synapses and they are fundamental structures in memory, learning and cognition. In the present study, we used intracellular injections of Lucifer yellow in fixed tissue to analyse over 19 500 dendritic spines that were completely reconstructed in three dimensions along the length of the basal dendrites of pyramidal neurons in the parahippocampal cortex and CA1 of patients with Alzheimer's disease. Following intracellular injection, sections were immunostained for anti-Lucifer yellow and with tau monoclonal antibodies AT8 and PHF-1, which recognize tau phosphorylated at Ser202/Thr205 and at Ser396/404, respectively. We observed that the diffuse accumulation of phospho-tau in a putative pre-tangle state did not induce changes in the dendrites of pyramidal neurons, whereas the presence of tau aggregates forming intraneuronal neurofibrillary tangles was associated with progressive alteration of dendritic spines (loss of dendritic spines and changes in their morphology) and dendrite atrophy, depending on the degree of tangle development. Thus, the presence of phospho-tau in neurons does not necessarily mean that they suffer severe and irreversible effects as thought previously but rather, the characteristic cognitive impairment in Alzheimer's disease is likely to depend on the relative number of neurons that have well developed tangles.

  12. Ankyrin Repeat-rich Membrane Spanning/Kidins220 protein regulates dendritic branching and spine stability in vivo.

    PubMed

    Wu, Synphen H; Arévalo, Juan Carlos; Sarti, Federica; Tessarollo, Lino; Gan, Wen-Biao; Chao, Moses V

    2009-08-01

    The development of nervous system connectivity depends upon the arborization of dendritic fields and the stabilization of dendritic spine synapses. It is well established that neuronal activity and the neurotrophin BDNF modulate these correlated processes. However, the downstream mechanisms by which these extrinsic signals regulate dendritic development and spine stabilization are less well known. Here we report that a substrate of BDNF signaling, the Ankyrin Repeat-rich Membrane Spanning (ARMS) protein or Kidins220, plays a critical role in the branching of cortical and hippocampal dendrites and in the turnover of cortical spines. In the barrel somatosensory cortex and the dentate gyrus, regions where ARMS/Kidins220 is highly expressed, no difference in the complexity of dendritic arbors was observed in 1-month-old adolescent ARMS/Kidins220(+/-) mice compared to wild-type littermates. However, at 3 months of age, young adult ARMS/Kidins220(+/-) mice exhibited decreased dendritic complexity. This suggests that ARMS/Kidins220 does not play a significant role in the initial formation of dendrites but, rather, is involved in the refinement or stabilization of the arbors later in development. In addition, at 1 month of age, the rate of spine elimination was higher in ARMS/Kidins220(+/-) mice than in wild-type mice, suggesting that ARMS/Kidins220(+/-) levels regulate spine stability. Taken together, these data suggest that ARMS/Kidins220 is important for the growth of dendritic arbors and spine stability during an activity- and BDNF-dependent period of development.

  13. Dopamine depletion of the prefrontal cortex induces dendritic spine loss: reversal by atypical antipsychotic drug treatment.

    PubMed

    Wang, Hui-Dong; Deutch, Ariel Y

    2008-05-01

    Dystrophic changes in dendrites of cortical neurons are present in several neuro-psychiatric disorders, including schizophrenia. The mechanisms that account for dendritic changes in the prefrontal cortex (PFC) in schizophrenia are unclear. Cognitive deficits in schizophrenia have been linked to compromised cortical dopamine function, and the density of the PFC dopamine innervation is decreased in schizophrenia. We determined if 6-hydroxydopamine lesions of the ventral tegmental area that disrupt the PFC dopamine innervation cause dystrophic changes in cortical neurons. Three weeks post-operatively we observed a marked decrease in basal dendritic length and spine density of layer V pyramidal cells in the prelimbic cortex; no change was seen in neurons of the motor cortex. We then examined rats in which the PFC dopamine innervation was lesioned and 3 weeks later were started on chronic treatment with an atypical (olanzapine) or typical (haloperidol) antipsychotic drug. Olanzapine but not haloperidol reversed lesion-induced changes in PFC pyramidal cell dendrites. These data suggest that dopamine regulates dendritic structure in PFC neurons. Moreover, the findings are consistent with a decrease in cortical dopaminergic tone contributing to the pathological changes in the cortex of schizophrenia, and suggest that the progressive cortical loss in schizophrenia may be slowed or reversed by treatment with atypical antipsychotic drugs.

  14. The internal architecture of dendritic spines revealed by super-resolution imaging: What did we learn so far?

    SciTech Connect

    MacGillavry, Harold D. Hoogenraad, Casper C.

    2015-07-15

    The molecular architecture of dendritic spines defines the efficiency of signal transmission across excitatory synapses. It is therefore critical to understand the mechanisms that control the dynamic localization of the molecular constituents within spines. However, because of the small scale at which most processes within spines take place, conventional light microscopy techniques are not adequate to provide the necessary level of resolution. Recently, super-resolution imaging techniques have overcome the classical barrier imposed by the diffraction of light, and can now resolve the localization and dynamic behavior of proteins within small compartments with nanometer precision, revolutionizing the study of dendritic spine architecture. Here, we highlight exciting new findings from recent super-resolution studies on neuronal spines, and discuss how these studies revealed important new insights into how protein complexes are assembled and how their dynamic behavior shapes the efficiency of synaptic transmission.

  15. The short-time structural plasticity of dendritic spines is altered in a model of Rett syndrome.

    PubMed

    Landi, Silvia; Putignano, Elena; Boggio, Elena Maria; Giustetto, Maurizio; Pizzorusso, Tommaso; Ratto, Gian Michele

    2011-01-01

    The maturation of excitatory transmission comes about through a developmental period in which dendritic spines are highly motile and their number, form and size are rapidly changing. Surprisingly, although these processes are crucial for the formation of cortical circuitry, little is known about possible alterations of these processes in brain disease. By means of acute in vivo 2-photon imaging we show that the dynamic properties of dendritic spines of layer V cortical neurons are deeply affected in a mouse model of Rett syndrome (RTT) at a time around P25 when the neuronal phenotype of the disease is still mild. Then, we show that 24h after a subcutaneous injection of IGF-1 spine dynamics is restored. Our study demonstrates that spine dynamics in RTT mice is severely impaired early during development and suggest that treatments for RTT should be started very early in order to reestablish a normal period of spine plasticity.

  16. Reelin Regulates the Maturation of Dendritic Spines, Synaptogenesis and Glial Ensheathment of Newborn Granule Cells

    PubMed Central

    Bosch, Carles; Masachs, Nuria; Exposito-Alonso, David; Martínez, Albert; Teixeira, Cátia M.; Fernaud, Isabel; Pujadas, Lluís; Ulloa, Fausto; Comella, Joan X.; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

    2016-01-01

    The Reelin pathway is essential for both neural migration and for the development and maturation of synaptic connections. However, its role in adult synaptic formation and remodeling is still being investigated. Here, we investigated the impact of the Reelin/Dab1 pathway on the synaptogenesis of newborn granule cells (GCs) in the young-adult mouse hippocampus. We show that neither Reelin overexpression nor the inactivation of its intracellular adapter, Dab1, substantially alters dendritic spine numbers in these neurons. In contrast, 3D-electron microscopy (focused ion beam milling/scanning electron microscope) revealed that dysregulation of the Reelin/Dab1 pathway leads to both transient and permanent changes in the types and morphology of dendritic spines, mainly altering mushroom, filopodial, and branched GC spines. We also found that the Reelin/Dab1 pathway controls synaptic configuration of presynaptic boutons in the dentate gyrus, with its dysregulation leading to a substantial decrease in multi-synaptic bouton innervation. Lastly, we show that the Reelin/Dab1 pathway controls astroglial ensheathment of synapses. Thus, the Reelin pathway is a key regulator of adult-generated GC integration, by controlling dendritic spine types and shapes, their synaptic innervation patterns, and glial ensheathment. These findings may help to better understanding of hippocampal circuit alterations in neurological disorders in which the Reelin pathway is implicated. Significance Statement The extracellular protein Reelin has an important role in neurological diseases, including epilepsy, Alzheimer's disease and psychiatric diseases, targeting hippocampal circuits. Here we address the role of Reelin in the development of synaptic contacts in adult-generated granule cells (GCs), a neuronal population that is crucial for learning and memory and implicated in neurological and psychiatric diseases. We found that the Reelin pathway controls the shapes, sizes, and types of dendritic

  17. KCC2 regulates actin dynamics in dendritic spines via interaction with β-PIX

    PubMed Central

    Llano, Olaya; Smirnov, Sergey; Soni, Shetal; Golubtsov, Andrey; Guillemin, Isabelle; Hotulainen, Pirta; Medina, Igor; Nothwang, Hans Gerd

    2015-01-01

    Chloride extrusion in mature neurons is largely mediated by the neuron-specific potassium-chloride cotransporter KCC2. In addition, independently of its chloride transport function, KCC2 regulates the development and morphology of dendritic spines through structural interactions with the actin cytoskeleton. The mechanism of this effect remains largely unknown. In this paper, we show a novel pathway for KCC2-mediated regulation of the actin cytoskeleton in neurons. We found that KCC2, through interaction with the b isoform of Rac/Cdc42 guanine nucleotide exchange factor β-PIX, regulates the activity of Rac1 GTPase and the phosphorylation of one of the major actin-regulating proteins, cofilin-1. KCC2-deficient neurons had abnormally high levels of phosphorylated cofilin-1. Consistently, dendritic spines of these neurons exhibited a large pool of stable actin, resulting in reduced spine motility and diminished density of functional synapses. In conclusion, we describe a novel signaling pathway that couples KCC2 to the cytoskeleton and regulates the formation of glutamatergic synapses. PMID:26056138

  18. Neuronal Actin Dynamics, Spine Density and Neuronal Dendritic Complexity Are Regulated by CAP2.

    PubMed

    Kumar, Atul; Paeger, Lars; Kosmas, Kosmas; Kloppenburg, Peter; Noegel, Angelika A; Peche, Vivek S

    2016-01-01

    Actin remodeling is crucial for dendritic spine development, morphology and density. CAP2 is a regulator of actin dynamics through sequestering G-actin and severing F-actin. In a mouse model, ablation of CAP2 leads to cardiovascular defects and delayed wound healing. This report investigates the role of CAP2 in the brain using Cap2(gt/gt) mice. Dendritic complexity, the number and morphology of dendritic spines were altered in Cap2(gt/gt) with increased number of excitatory synapses. This was accompanied by increased F-actin content and F-actin accumulation in cultured Cap2(gt/gt) neurons. Moreover, reduced surface GluA1 was observed in mutant neurons under basal condition and after induction of chemical LTP. Additionally, we show an interaction between CAP2 and n-cofilin, presumably mediated through the C-terminal domain of CAP2 and dependent on cofilin Ser3 phosphorylation. In vivo, the consequences of this interaction were altered phosphorylated cofilin levels and formation of cofilin aggregates in the neurons. Thus, our studies identify a novel role of CAP2 in neuronal development and neuronal actin dynamics.

  19. Neuronal Actin Dynamics, Spine Density and Neuronal Dendritic Complexity Are Regulated by CAP2

    PubMed Central

    Kumar, Atul; Paeger, Lars; Kosmas, Kosmas; Kloppenburg, Peter; Noegel, Angelika A.; Peche, Vivek S.

    2016-01-01

    Actin remodeling is crucial for dendritic spine development, morphology and density. CAP2 is a regulator of actin dynamics through sequestering G-actin and severing F-actin. In a mouse model, ablation of CAP2 leads to cardiovascular defects and delayed wound healing. This report investigates the role of CAP2 in the brain using Cap2gt/gt mice. Dendritic complexity, the number and morphology of dendritic spines were altered in Cap2gt/gt with increased number of excitatory synapses. This was accompanied by increased F-actin content and F-actin accumulation in cultured Cap2gt/gt neurons. Moreover, reduced surface GluA1 was observed in mutant neurons under basal condition and after induction of chemical LTP. Additionally, we show an interaction between CAP2 and n-cofilin, presumably mediated through the C-terminal domain of CAP2 and dependent on cofilin Ser3 phosphorylation. In vivo, the consequences of this interaction were altered phosphorylated cofilin levels and formation of cofilin aggregates in the neurons. Thus, our studies identify a novel role of CAP2 in neuronal development and neuronal actin dynamics. PMID:27507934

  20. The Role of Posttraumatic Hypothermia in Preventing Dendrite Degeneration and Spine Loss after Severe Traumatic Brain Injury

    PubMed Central

    Wang, Chuan-fang; Zhao, Cheng-cheng; Jiang, Gan; Gu, Xiao; Feng, Jun-feng; Jiang, Ji-yao

    2016-01-01

    Posttraumatic hypothermia prevents cell death and promotes functional outcomes after traumatic brain injury (TBI). However, little is known regarding the effect of hypothermia on dendrite degeneration and spine loss after severe TBI. In the present study, we used thy1-GFP transgenic mice to investigate the effect of hypothermia on the dendrites and spines in layer V/VI of the ipsilateral cortex after severe TBI. We found that hypothermia (33 °C) dramatically prevented dendrite degeneration and spine loss 1 and 7 days after CCI. The Morris water maze test revealed that hypothermia preserved the learning and memory functions of mice after CCI. Hypothermia significantly increased the expression of the synaptic proteins GluR1 and PSD-95 at 1 and 7 days after CCI in the ipsilateral cortex and hippocampus compared with that of the normothermia TBI group. Hypothermia also increased cortical and hippocampal BDNF levels. These results suggest that posttraumatic hypothermia is an effective method to prevent dendrite degeneration and spine loss and preserve learning and memory function after severe TBI. Increasing cortical and hippocampal BDNF levels might be the mechanism through which hypothermia prevents dendrite degeneration and spine loss and preserves learning and memory function. PMID:27833158

  1. Reduced density of dendritic spines in pyramidal neurons of rats exposed to alcohol during early postnatal life.

    PubMed

    De Giorgio, Andrea; Granato, Alberto

    2015-04-01

    Dendritic spines are the main postsynaptic sites of excitatory connections of neocortical pyramidal neurons. Alterations of spine shape, number, and density can be observed in different mental diseases, including those caused by developmental alcohol exposure. Pyramidal neurons of layer 2/3 are the most abundant cells of the neocortex and represent the main source of associative cortico-cortical connections. These neurons are essential for higher functions mediated by the cortex such as feature selection and perceptual grouping. Furthermore, their connections have been shown to be altered in experimental models of fetal alcohol spectrum disorders. Here, we used a Golgi-like tracing method to study the spine density of layer 2/3 associative pyramidal neurons in the somatosensory cortex of adult rats exposed to alcohol during the first postnatal week. The main result of the present study is represented by the decreased spine density in the apical dendrite of alcohol-treated rats, as compared to controls. As to the basal dendritic tree, there were no significant differences between the experimental and the control group. A decreased density of dendritic spines in the apical dendrite may impair the excitatory input onto pyramidal neurons, thus resulting in a widespread alteration of the cortical information flow.

  2. Fragile X-like behaviors and abnormal cortical dendritic spines in cytoplasmic FMR1-interacting protein 2-mutant mice.

    PubMed

    Han, Kihoon; Chen, Hogmei; Gennarino, Vincenzo A; Richman, Ronald; Lu, Hui-Chen; Zoghbi, Huda Y

    2015-04-01

    Silencing of fragile X mental retardation 1 (FMR1) gene and loss of fragile X mental retardation protein (FMRP) cause fragile X syndrome (FXS), a genetic disorder characterized by intellectual disability and autistic behaviors. FMRP is an mRNA-binding protein regulating neuronal translation of target mRNAs. Abnormalities in actin-rich dendritic spines are major neuronal features in FXS, but the molecular mechanism and identity of FMRP targets mediating this phenotype remain largely unknown. Cytoplasmic FMR1-interacting protein 2 (Cyfip2) was identified as an interactor of FMRP, and its mRNA is a highly ranked FMRP target in mouse brain. Importantly, Cyfip2 is a component of WAVE regulatory complex, a key regulator of actin cytoskeleton, suggesting that Cyfip2 could be implicated in the dendritic spine phenotype of FXS. Here, we generated and characterized Cyfip2-mutant (Cyfip2(+/-)) mice. We found that Cyfip2(+/-) mice exhibited behavioral phenotypes similar to Fmr1-null (Fmr1(-/y)) mice, an animal model of FXS. Synaptic plasticity and dendritic spines were normal in Cyfip2(+/-) hippocampus. However, dendritic spines were altered in Cyfip2(+/-) cortex, and the dendritic spine phenotype of Fmr1(-/y) cortex was aggravated in Fmr1(-/y); Cyfip2(+/-) double-mutant mice. In addition to the spine changes at basal state, metabotropic glutamate receptor (mGluR)-induced dendritic spine regulation was impaired in both Fmr1(-/y) and Cyfip2(+/-) cortical neurons. Mechanistically, mGluR activation induced mRNA translation-dependent increase of Cyfip2 in wild-type cortical neurons, but not in Fmr1(-/y) or Cyfip2(+/-) neurons. These results suggest that misregulation of Cyfip2 function and its mGluR-induced expression contribute to the neurobehavioral phenotypes of FXS.

  3. Neuropeptide VGF Promotes Maturation of Hippocampal Dendrites That Is Reduced by Single Nucleotide Polymorphisms

    PubMed Central

    Behnke, Joseph; Cheedalla, Aneesha; Bhatt, Vatsal; Bhat, Maysa; Teng, Shavonne; Palmieri, Alicia; Windon, Charles Christian; Thakker-Varia, Smita; Alder, Janet

    2017-01-01

    The neuropeptide VGF (non-acronymic) is induced by brain-derived neurotrophic factor and promotes hippocampal neurogenesis, as well as synaptic activity. However, morphological changes induced by VGF have not been elucidated. Developing hippocampal neurons were exposed to VGF through bath application or virus-mediated expression in vitro. VGF-derived peptide, TLQP-62, enhanced dendritic branching, and outgrowth. Furthermore, VGF increased dendritic spine density and the proportion of immature spines. Spine formation was associated with increased synaptic protein expression and co-localization of pre- and postsynaptic markers. Three non-synonymous single nucleotide polymorphisms (SNPs) were selected in human VGF gene. Transfection of N2a cells with plasmids containing these SNPs revealed no relative change in protein expression levels and normal protein size, except for a truncated protein from the premature stop codon, E525X. All three SNPs resulted in a lower proportion of N2a cells bearing neurites relative to wild-type VGF. Furthermore, all three mutations reduced the total length of dendrites in developing hippocampal neurons. Taken together, our results suggest VGF enhances dendritic maturation and that these effects can be altered by common mutations in the VGF gene. The findings may have implications for people suffering from psychiatric disease or other conditions who may have altered VGF levels. PMID:28287464

  4. Centella asiatica attenuates Aβ-induced neurodegenerative spine loss and dendritic simplification.

    PubMed

    Gray, Nora E; Zweig, Jonathan A; Murchison, Charles; Caruso, Maya; Matthews, Donald G; Kawamoto, Colleen; Harris, Christopher J; Quinn, Joseph F; Soumyanath, Amala

    2017-04-12

    The medicinal plant Centella asiatica has long been used to improve memory and cognitive function. We have previously shown that a water extract from the plant (CAW) is neuroprotective against the deleterious cognitive effects of amyloid-β (Aβ) exposure in a mouse model of Alzheimer's disease, and improves learning and memory in healthy aged mice as well. This study explores the physiological underpinnings of those effects by examining how CAW, as well as chemical compounds found within the extract, modulate synaptic health in Aβ-exposed neurons. Hippocampal neurons from amyloid precursor protein over-expressing Tg2576 mice and their wild-type (WT) littermates were used to investigate the effect of CAW and various compounds found within the extract on Aβ-induced dendritic simplification and synaptic loss. CAW enhanced arborization and spine densities in WT neurons and prevented the diminished outgrowth of dendrites and loss of spines caused by Aβ exposure in Tg2576 neurons. Triterpene compounds present in CAW were found to similarly improve arborization although they did not affect spine density. In contrast caffeoylquinic acid (CQA) compounds from CAW were able to modulate both of these endpoints, although there was specificity as to which CQAs mediated which effect. These data suggest that CAW, and several of the compounds found therein, can improve dendritic arborization and synaptic differentiation in the context of Aβ exposure which may underlie the cognitive improvement observed in response to the extract in vivo. Additionally, since CAW, and its constituent compounds, also improved these endpoints in WT neurons, these results may point to a broader therapeutic utility of the extract beyond Alzheimer's disease.

  5. A Postsynaptic Role for Short-Term Neuronal Facilitation in Dendritic Spines

    PubMed Central

    Yang, Sunggu; Santos, Mariton D.; Tang, Cha-Min; Kim, Jae Geun; Yang, Sungchil

    2016-01-01

    Synaptic plasticity is a fundamental component of information processing in the brain. Presynaptic facilitation in response to repetitive stimuli, often referred to as paired-pulse facilitation (PPF), is a dominant form of short-term synaptic plasticity. Recently, an additional cellular mechanism for short-term facilitation, short-term postsynaptic plasticity (STPP), has been proposed. While a dendritic mechanism was described in hippocampus, its expression has not yet been demonstrated at the levels of the spine. Furthermore, it is unknown whether the mechanism can be expressed in other brain regions, such as sensory cortex. Here, we demonstrated that a postsynaptic response can be facilitated by prior spine excitation in both hippocampal and cortical neurons, using 3D digital holography and two-photon calcium imaging. The coordinated action of pre- and post-synaptic plasticity may provide a more thorough account of information processing in the brain. PMID:27746721

  6. Voluntary exercise and caloric restriction enhance hippocampal dendritic spine density and BDNF levels in diabetic mice.

    PubMed

    Stranahan, Alexis M; Lee, Kim; Martin, Bronwen; Maudsley, Stuart; Golden, Erin; Cutler, Roy G; Mattson, Mark P

    2009-10-01

    Diabetes may adversely affect cognitive function, but the underlying mechanisms are unknown. To investigate whether manipulations that enhance neurotrophin levels will also restore neuronal structure and function in diabetes, we examined the effects of wheel running and dietary energy restriction on hippocampal neuron morphology and brain-derived neurotrophic factor (BDNF) levels in db/db mice, a model of insulin resistant diabetes. Running wheel activity, caloric restriction, or the combination of the two treatments increased levels of BDNF in the hippocampus of db/db mice. Enhancement of hippocampal BDNF was accompanied by increases in dendritic spine density on the secondary and tertiary dendrites of dentate granule neurons. These studies suggest that diabetes exerts detrimental effects on hippocampal structure, and that this state can be attenuated by increasing energy expenditure and decreasing energy intake.

  7. Voluntary exercise and caloric restriction enhance hippocampal dendritic spine density and BDNF levels in diabetic mice

    PubMed Central

    Stranahan, Alexis M.; Lee, Kim; Martin, Bronwen; Maudsley, Stuart; Golden, Erin; Cutler, Roy G.; Mattson, Mark P.

    2009-01-01

    Diabetes may adversely affect cognitive function, but the underlying mechanisms are unknown. To investigate whether manipulations that enhance neurotrophin levels will also restore neuronal structure and function in diabetes, we examined the effects of wheel running and dietary energy restriction on hippocampal neuron morphology and BDNF levels in db/db mice, a model of insulin resistant diabetes. Running wheel activity, caloric restriction, or the combination of the two treatments increased levels of BDNF in the hippocampus of db/db mice. Enhancement of hippocampal BDNF was accompanied by increases in dendritic spine density on the secondary and tertiary dendrites of dentate granule neurons. These studies suggest that diabetes exerts detrimental effects on hippocampal structure, and that this state can be attenuated by increasing energy expenditure and decreasing energy intake. PMID:19280661

  8. A deconvolution method to improve automated 3D-analysis of dendritic spines: application to a mouse model of Huntington's disease.

    PubMed

    Heck, Nicolas; Betuing, Sandrine; Vanhoutte, Peter; Caboche, Jocelyne

    2012-04-01

    Dendritic spines are postsynaptic structures the morphology of which correlates with the strength of synaptic efficacy. Measurements of spine density and spine morphology are achievable using recent imaging and bioinformatics tools. The three-dimensional automated analysis requires optimization of image acquisition and treatment. Here, we studied the critical steps for optimal confocal microscopy imaging of dendritic spines. We characterize the deconvolution process and show that it improves spine morphology analysis. With this method, images of dendritic spines from medium spiny neurons are automatically detected by the software Neuronstudio, which retrieves spine density as well as spine diameter and volume. This approach is illustrated with three-dimensional analysis of dendritic spines in a mouse model of Huntington's disease: the transgenic R6/2 mice. In symptomatic mutant mice, we confirm the decrease in spine density, and the method brings further information and show a decrease in spine volume and dendrite diameter. Moreover, we show a significant decrease in spine density at presymptomatic age which so far has gone unnoticed.

  9. Alterations to dendritic spine morphology, but not dendrite patterning, of cortical projection neurons in Tc1 and Ts1Rhr mouse models of Down syndrome.

    PubMed

    Haas, Matilda A; Bell, Donald; Slender, Amy; Lana-Elola, Eva; Watson-Scales, Sheona; Fisher, Elizabeth M C; Tybulewicz, Victor L J; Guillemot, François

    2013-01-01

    Down Syndrome (DS) is a highly prevalent developmental disorder, affecting 1/700 births. Intellectual disability, which affects learning and memory, is present in all cases and is reflected by below average IQ. We sought to determine whether defective morphology and connectivity in neurons of the cerebral cortex may underlie the cognitive deficits that have been described in two mouse models of DS, the Tc1 and Ts1Rhr mouse lines. We utilised in utero electroporation to label a cohort of future upper layer projection neurons in the cerebral cortex of developing mouse embryos with GFP, and then examined neuronal positioning and morphology in early adulthood, which revealed no alterations in cortical layer position or morphology in either Tc1 or Ts1Rhr mouse cortex. The number of dendrites, as well as dendrite length and branching was normal in both DS models, compared with wildtype controls. The sites of projection neuron synaptic inputs, dendritic spines, were analysed in Tc1 and Ts1Rhr cortex at three weeks and three months after birth, and significant changes in spine morphology were observed in both mouse lines. Ts1Rhr mice had significantly fewer thin spines at three weeks of age. At three months of age Tc1 mice had significantly fewer mushroom spines--the morphology associated with established synaptic inputs and learning and memory. The decrease in mushroom spines was accompanied by a significant increase in the number of stubby spines. This data suggests that dendritic spine abnormalities may be a more important contributor to cognitive deficits in DS models, rather than overall neuronal architecture defects.

  10. Alterations to Dendritic Spine Morphology, but Not Dendrite Patterning, of Cortical Projection Neurons in Tc1 and Ts1Rhr Mouse Models of Down Syndrome

    PubMed Central

    Haas, Matilda A.; Bell, Donald; Slender, Amy; Lana-Elola, Eva; Watson-Scales, Sheona; Fisher, Elizabeth M. C.; Tybulewicz, Victor L. J.; Guillemot, François

    2013-01-01

    Down Syndrome (DS) is a highly prevalent developmental disorder, affecting 1/700 births. Intellectual disability, which affects learning and memory, is present in all cases and is reflected by below average IQ. We sought to determine whether defective morphology and connectivity in neurons of the cerebral cortex may underlie the cognitive deficits that have been described in two mouse models of DS, the Tc1 and Ts1Rhr mouse lines. We utilised in utero electroporation to label a cohort of future upper layer projection neurons in the cerebral cortex of developing mouse embryos with GFP, and then examined neuronal positioning and morphology in early adulthood, which revealed no alterations in cortical layer position or morphology in either Tc1 or Ts1Rhr mouse cortex. The number of dendrites, as well as dendrite length and branching was normal in both DS models, compared with wildtype controls. The sites of projection neuron synaptic inputs, dendritic spines, were analysed in Tc1 and Ts1Rhr cortex at three weeks and three months after birth, and significant changes in spine morphology were observed in both mouse lines. Ts1Rhr mice had significantly fewer thin spines at three weeks of age. At three months of age Tc1 mice had significantly fewer mushroom spines - the morphology associated with established synaptic inputs and learning and memory. The decrease in mushroom spines was accompanied by a significant increase in the number of stubby spines. This data suggests that dendritic spine abnormalities may be a more important contributor to cognitive deficits in DS models, rather than overall neuronal architecture defects. PMID:24205261

  11. Splice variants of the CaV1.3 L-type calcium channel regulate dendritic spine morphology

    PubMed Central

    Stanika, Ruslan; Campiglio, Marta; Pinggera, Alexandra; Lee, Amy; Striessnig, Jörg; Flucher, Bernhard E.; Obermair, Gerald J.

    2016-01-01

    Dendritic spines are the postsynaptic compartments of glutamatergic synapses in the brain. Their number and shape are subject to change in synaptic plasticity and neurological disorders including autism spectrum disorders and Parkinson’s disease. The L-type calcium channel CaV1.3 constitutes an important calcium entry pathway implicated in the regulation of spine morphology. Here we investigated the importance of full-length CaV1.3L and two C-terminally truncated splice variants (CaV1.342A and CaV1.343S) and their modulation by densin-180 and shank1b for the morphology of dendritic spines of cultured hippocampal neurons. Live-cell immunofluorescence and super-resolution microscopy of epitope-tagged CaV1.3L revealed its localization at the base-, neck-, and head-region of dendritic spines. Expression of the short splice variants or deletion of the C-terminal PDZ-binding motif in CaV1.3L induced aberrant dendritic spine elongation. Similar morphological alterations were induced by co-expression of densin-180 or shank1b with CaV1.3L and correlated with increased CaV1.3 currents and dendritic calcium signals in transfected neurons. Together, our findings suggest a key role of CaV1.3 in regulating dendritic spine structure. Under physiological conditions it may contribute to the structural plasticity of glutamatergic synapses. Conversely, altered regulation of CaV1.3 channels may provide an important mechanism in the development of postsynaptic aberrations associated with neurodegenerative disorders. PMID:27708393

  12. Visualization and genetic manipulation of dendrites and spines in the mouse cerebral cortex and hippocampus using in utero electroporation.

    PubMed

    Pacary, Emilie; Haas, Matilda A; Wildner, Hendrik; Azzarelli, Roberta; Bell, Donald M; Abrous, Djoher Nora; Guillemot, François

    2012-07-26

    In utero electroporation (IUE) has become a powerful technique to study the development of different regions of the embryonic nervous system (1-5). To date this tool has been widely used to study the regulation of cellular proliferation, differentiation and neuronal migration especially in the developing cerebral cortex (6-8). Here we detail our protocol to electroporate in utero the cerebral cortex and the hippocampus and provide evidence that this approach can be used to study dendrites and spines in these two cerebral regions. Visualization and manipulation of neurons in primary cultures have contributed to a better understanding of the processes involved in dendrite, spine and synapse development. However neurons growing in vitro are not exposed to all the physiological cues that can affect dendrite and/or spine formation and maintenance during normal development. Our knowledge of dendrite and spine structures in vivo in wild-type or mutant mice comes mostly from observations using the Golgi-Cox method( 9). However, Golgi staining is considered to be unpredictable. Indeed, groups of nerve cells and fiber tracts are labeled randomly, with particular areas often appearing completely stained while adjacent areas are devoid of staining. Recent studies have shown that IUE of fluorescent constructs represents an attractive alternative method to study dendrites, spines as well as synapses in mutant / wild-type mice (10-11) (Figure 1A). Moreover in comparison to the generation of mouse knockouts, IUE represents a rapid approach to perform gain and loss of function studies in specific population of cells during a specific time window. In addition, IUE has been successfully used with inducible gene expression or inducible RNAi approaches to refine the temporal control over the expression of a gene or shRNA (12). These advantages of IUE have thus opened new dimensions to study the effect of gene expression/suppression on dendrites and spines not only in specific cerebral

  13. Reproductive experience modified dendritic spines on cortical pyramidal neurons to enhance sensory perception and spatial learning in rats

    PubMed Central

    Chen, Jeng-Rung; Lim, Seh Hong; Chung, Sin-Cun; Lee, Yee-Fun; Wang, Yueh-Jan; Tseng, Guo-Fang; Wang, Tsyr-Jiuan

    2016-01-01

    Behavioral adaptations during motherhood are aimed at increasing reproductive success. Alterations of hormones during motherhood could trigger brain morphological changes to underlie behavioral alterations. Here we investigated whether motherhood changes a rat’s sensory perception and spatial memory in conjunction with cortical neuronal structural changes. Female rats of different statuses, including virgin, pregnant, lactating, and primiparous rats were studied. Behavioral test showed that the lactating rats were most sensitive to heat, while rats with motherhood and reproduction experience outperformed virgin rats in a water maze task. By intracellular dye injection and computer-assisted 3-dimensional reconstruction, the dendritic arbors and spines of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons were revealed for closer analysis. The results showed that motherhood and reproductive experience increased dendritic spines but not arbors or the lengths of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons. In addition, lactating rats had a higher incidence of spines than pregnant or primiparous rats. The increase of dendritic spines was coupled with increased expression of the glutamatergic postsynaptic marker protein (PSD-95), especially in lactating rats. On the basis of the present results, it is concluded that motherhood enhanced rat sensory perception and spatial memory and was accompanied by increases in dendritic spines on output neurons of the somatosensory cortex and CA1 hippocampus. The effect was sustained for at least 6 weeks after the weaning of the pups. PMID:27784858

  14. Matrix Metalloproteinases Regulate the Formation of Dendritic Spine Head Protrusions during Chemically Induced Long-Term Potentiation

    PubMed Central

    Szepesi, Zsuzsanna; Bijata, Monika; Ruszczycki, Blazej; Kaczmarek, Leszek; Wlodarczyk, Jakub

    2013-01-01

    Dendritic spines are are small membranous protrusions that extend from neuronal dendrites and harbor the majority of excitatory synapses. Increasing evidence has shown that matrix metalloproteinases (MMPs), a family of extracellularly acting and Zn2+-dependent endopeptidases, are able to rapidly modulate dendritic spine morphology. Spine head protrusions (SHPs) are filopodia-like processes that extend from the dendritic spine head, representing a form of postsynaptic structural remodeling in response to altered neuronal activity. Herein, we show that chemically induced long-term potentiation (cLTP) in dissociated hippocampal cultures upregulates MMP-9 activity that controls the formation of SHPs. Blocking of MMPs activity or microtubule dynamics abolishes the emergence of SHPs. In addition, autoactive recombinant MMP-9, promotes the formation of SHPs in organotypic hippocampal slices. Furthermore, spines with SHPs gained postsynaptic α-amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA) receptors upon cLTP and the synaptic delivery of AMPA receptors was controlled by MMPs. The present results strongly imply that MMP-9 is functionally involved in the formation of SHPs and the control of postsynaptic receptor distribution upon cLTP. PMID:23696812

  15. Reproductive experience modified dendritic spines on cortical pyramidal neurons to enhance sensory perception and spatial learning in rats.

    PubMed

    Chen, Jeng-Rung; Lim, Seh Hong; Chung, Sin-Cun; Lee, Yee-Fun; Wang, Yueh-Jan; Tseng, Guo-Fang; Wang, Tsyr-Jiuan

    2017-01-27

    Behavioral adaptations during motherhood are aimed at increasing reproductive success. Alterations of hormones during motherhood could trigger brain morphological changes to underlie behavioral alterations. Here we investigated whether motherhood changes a rat's sensory perception and spatial memory in conjunction with cortical neuronal structural changes. Female rats of different statuses, including virgin, pregnant, lactating, and primiparous rats were studied. Behavioral test showed that the lactating rats were most sensitive to heat, while rats with motherhood and reproduction experience outperformed virgin rats in a water maze task. By intracellular dye injection and computer-assisted 3-dimensional reconstruction, the dendritic arbors and spines of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons were revealed for closer analysis. The results showed that motherhood and reproductive experience increased dendritic spines but not arbors or the lengths of the layer III and V pyramidal neurons of the somatosensory cortex and CA1 hippocampal pyramidal neurons. In addition, lactating rats had a higher incidence of spines than pregnant or primiparous rats. The increase of dendritic spines was coupled with increased expression of the glutamatergic postsynaptic marker protein (PSD-95), especially in lactating rats. On the basis of the present results, it is concluded that motherhood enhanced rat sensory perception and spatial memory and was accompanied by increases in dendritic spines on output neurons of the somatosensory cortex and CA1 hippocampus. The effect was sustained for at least 6 weeks after the weaning of the pups.

  16. Cux1 and Cux2 regulate dendritic branching, spine morphology and synapses of the upper layer neurons of the cortex

    PubMed Central

    Cubelos, Beatriz; Sebastián-Serrano, Alvaro; Beccari, Leonardo; Calcagnotto, Maria Elisa; Cisneros, Elsa; Kim, Seonhee; Dopazo, Ana; Alvarez-Dolado, Manuel; Redondo, Juan Miguel; Bovolenta, Paola; Walsh, Christopher A.; Nieto, Marta

    2010-01-01

    Summary Dendrite branching and spine formation determines the function of morphologically distinct and specialized neuronal subclasses. However, little is known about the programs instructing specific branching patterns in vertebrate neurons and whether such programs influence dendritic spines and synapses. Using knockout and knockdown studies combined with morphological, molecular and electrophysiological analysis we show that the homeobox Cux1 and Cux2 are intrinsic and complementary regulators of dendrite branching, spine development and synapse formation in layer II–III neurons of the cerebral cortex. Cux genes control the number and maturation of dendritic spines partly through direct regulation of the expression of Xlr3b and Xlr4b, chromatin remodeling genes previously implicated in cognitive defects. Accordingly, abnormal dendrites and synapses in Cux2−/− mice correlate with reduced synaptic function and defects in working memory. These demonstrate critical roles of Cux in dendritogenesis and highlight novel subclass-specific mechanisms of synapse regulation that contribute to the establishment of cognitive circuits. PMID:20510857

  17. Dendritic spine plasticity in gonadatropin-releasing hormone (GnRH) neurons activated at the time of the preovulatory surge.

    PubMed

    Chan, Heidi; Prescott, Melanie; Ong, ZhiYi; Herde, Michel K; Herbison, Allan E; Campbell, Rebecca E

    2011-12-01

    GnRH neuron activity is dependent on gonadal steroid hormone feedback. Altered synaptic input may be one mechanism by which steroids modify GnRH neuron activity. In other neuronal populations, steroid hormones have been shown to elicit profound effects on dendritic spine density, a measure of excitatory synaptic input. The present study examined gonadal steroid feedback effects on GnRH neuron spine density in female GnRH-green fluorescent protein (GFP) mice. Immunocytochemical labeling of GFP in this model reveals fine morphological details of GnRH neurons. Spine density and other features were quantified by confocal analysis. Ovariectomy resulted in a significant reduction in somatic spine density (27%, P < 0.05) compared with sham-operated diestrous females. However, dendritic spine density was unaltered. Positive feedback effects of estradiol on spine density were investigated using a protocol to mimic the GnRH/LH surge. Ten GnRH-GFP mice underwent an established protocol, receiving either estradiol benzoate (1 μg per 20 g body weight) or vehicle (n = 5/group) 32 h prior to being killed during the expected surge. Double-label immunofluorescence showed that all estradiol-treated females expressed cFos in a subpopulation of GnRH neurons. Spine density was determined by confocal analysis of activated (cFos-positive, n = 10 neurons/animal) and nonactivated (cFos-negative, n = 10 neurons/animal) GnRH neurons from estradiol-treated animals and for GnRH neurons (n = 20 neurons/animal) from nonsurged controls (all cFos negative). Activated GnRH neurons (cFos positive) showed a dramatic 60% increase in total spine density (0.78 ± 0.06 spines/μm) compared with nonactivated GnRH neurons (0.50 ± 0.01 spines/μm) in estradiol-treated animals (P < 0.001). Both somatic and dendritic spine density was significantly increased. Spine density was not different between nonactivated GnRH neurons from surged animals (0.50 ± 0.01 spines/μm) and GnRH neurons from nonsurged

  18. Layer 4 pyramidal neurons exhibit robust dendritic spine plasticity in vivo after input deprivation.

    PubMed

    Miquelajauregui, Amaya; Kribakaran, Sahana; Mostany, Ricardo; Badaloni, Aurora; Consalez, G Giacomo; Portera-Cailliau, Carlos

    2015-05-06

    Pyramidal neurons in layers 2/3 and 5 of primary somatosensory cortex (S1) exhibit somewhat modest synaptic plasticity after whisker input deprivation. Whether neurons involved at earlier steps of sensory processing show more or less plasticity has not yet been examined. Here, we used longitudinal in vivo two-photon microscopy to investigate dendritic spine dynamics in apical tufts of GFP-expressing layer 4 (L4) pyramidal neurons of the vibrissal (barrel) S1 after unilateral whisker trimming. First, we characterize the molecular, anatomical, and electrophysiological properties of identified L4 neurons in Ebf2-Cre transgenic mice. Next, we show that input deprivation results in a substantial (∼50%) increase in the rate of dendritic spine loss, acutely (4-8 d) after whisker trimming. This robust synaptic plasticity in L4 suggests that primary thalamic recipient pyramidal neurons in S1 may be particularly sensitive to changes in sensory experience. Ebf2-Cre mice thus provide a useful tool for future assessment of initial steps of sensory processing in S1.

  19. Super resolution microscopy is poised to reveal new insights into the formation and maturation of dendritic spines

    PubMed Central

    Robinson, Cristina M.; Patel, Mikin R.; Webb, Donna J.

    2016-01-01

    Dendritic spines and synapses are critical for neuronal communication, and they are perturbed in many neurological disorders; however, the study of these structures in living cells has been hindered by their small size. Super resolution microscopy, unlike conventional light microscopy, is diffraction unlimited and thus is well suited for imaging small structures, such as dendritic spines and synapses. Super resolution microscopy has already revealed important new information about spine and synapse morphology, actin remodeling, and nanodomain composition in both healthy cells and diseased states. In this review, we highlight the advancements in probes that make super resolution more amenable to live-cell imaging of spines and synapses. We also discuss recent data obtained by super resolution microscopy that has advanced our knowledge of dendritic spine and synapse structure, organization, and dynamics in both healthy and diseased contexts. Finally, we propose a series of critical questions for understanding spine and synapse formation and maturation that super resolution microscopy is poised to answer. PMID:27408691

  20. SUSTAINED EXPRESSION OF BDNF IS REQUIRED FOR MAINTENANCE OF DENDRITIC SPINES AND NORMAL BEHAVIOR

    PubMed Central

    VIGERS, ALISON J.; AMIN, DIPESH S.; TALLEY-FARNHAM, TIFFANY; GORSKI, JESSICA A.; XU, BAOJI; JONES, KEVIN R.

    2012-01-01

    Brain-derived neurotrophic factor (BDNF) plays important roles in the development, maintenance, and plasticity of the mammalian forebrain. These functions include regulation of neuronal maturation and survival, axonal and dendritic arborization, synaptic efficacy, and modulation of complex behaviors including depression and spatial learning. Although analysis of mutant mice has helped establish essential developmental functions for BDNF, its requirement in the adult is less well documented. We have studied late-onset forebrain-specific BDNF knockout (CaMK-BDNFKO) mice, in which BDNF is lost primarily from the cortex and hippocampus in early adulthood, well after BDNF expression has begun in these structures. We found that although CaMK-BDNFKO mice grew at a normal rate and can survive more than a year, they had smaller brains than wild type siblings. The CaMK-BDNFKO mice had generally normal behavior in tests for ataxia and anxiety, but displayed reduced spatial learning ability in the Morris water task and increased depression in the Porsolt swim test. These behavioral deficits were very similar to those we previously described in an early-onset forebrain-specific BDNF knockout. To identify an anatomical correlate of the abnormal behavior, we quantified dendritic spines in cortical neurons. The spine density of CaMK-BDNFKO mice was normal at P35, but by P84, there was a 30% reduction in spine density. The strong similarities we find between early- and late-onset BDNF knockouts suggests that BDNF signaling is required continuously in the CNS for the maintenance of some forebrain circuitry also affected by developmental BDNF depletion. PMID:22542678

  1. Glutamatergic regulation prevents hippocampal-dependent age-related cognitive decline through dendritic spine clustering

    PubMed Central

    Pereira, Ana C.; Lambert, Hilary K.; Grossman, Yael S.; Dumitriu, Dani; Waldman, Rachel; Jannetty, Sophia K.; Calakos, Katina; Janssen, William G.; McEwen, Bruce S.; Morrison, John H.

    2014-01-01

    The dementia of Alzheimer’s disease (AD) results primarily from degeneration of neurons that furnish glutamatergic corticocortical connections that subserve cognition. Although neuron death is minimal in the absence of AD, age-related cognitive decline does occur in animals as well as humans, and it decreases quality of life for elderly people. Age-related cognitive decline has been linked to synapse loss and/or alterations of synaptic proteins that impair function in regions such as the hippocampus and prefrontal cortex. These synaptic alterations are likely reversible, such that maintenance of synaptic health in the face of aging is a critically important therapeutic goal. Here, we show that riluzole can protect against some of the synaptic alterations in hippocampus that are linked to age-related memory loss in rats. Riluzole increases glutamate uptake through glial transporters and is thought to decrease glutamate spillover to extrasynaptic NMDA receptors while increasing synaptic glutamatergic activity. Treated aged rats were protected against age-related cognitive decline displayed in nontreated aged animals. Memory performance correlated with density of thin spines on apical dendrites in CA1, although not with mushroom spines. Furthermore, riluzole-treated rats had an increase in clustering of thin spines that correlated with memory performance and was specific to the apical, but not the basilar, dendrites of CA1. Clustering of synaptic inputs is thought to allow nonlinear summation of synaptic strength. These findings further elucidate neuroplastic changes in glutamatergic circuits with aging and advance therapeutic development to prevent and treat age-related cognitive decline. PMID:25512503

  2. Cortical regulation of striatal medium spiny neuron dendritic remodeling in parkinsonism: modulation of glutamate release reverses dopamine depletion-induced dendritic spine loss.

    PubMed

    Garcia, Bonnie G; Neely, M Diana; Deutch, Ariel Y

    2010-10-01

    Striatal medium spiny neurons (MSNs) receive glutamatergic afferents from the cerebral cortex and dopaminergic inputs from the substantia nigra (SN). Striatal dopamine loss decreases the number of MSN dendritic spines. This loss of spines has been suggested to reflect the removal of tonic dopamine inhibitory control over corticostriatal glutamatergic drive, with increased glutamate release culminating in MSN spine loss. We tested this hypothesis in two ways. We first determined in vivo if decortication reverses or prevents dopamine depletion-induced spine loss by placing motor cortex lesions 4 weeks after, or at the time of, 6-hydroxydopamine lesions of the SN. Animals were sacrificed 4 weeks after cortical lesions. Motor cortex lesions significantly reversed the loss of MSN spines elicited by dopamine denervation; a similar effect was observed in the prevention experiment. We then determined if modulating glutamate release in organotypic cocultures prevented spine loss. Treatment of the cultures with the mGluR2/3 agonist LY379268 to suppress corticostriatal glutamate release completely blocked spine loss in dopamine-denervated cultures. These studies provide the first evidence to show that MSN spine loss associated with parkinsonism can be reversed and point to suppression of corticostriatal glutamate release as a means of slowing progression in Parkinson's disease.

  3. Remodeling the Dendritic Spines in the Hindlimb Representation of the Sensory Cortex after Spinal Cord Hemisection in Mice.

    PubMed

    Zhang, Kexue; Zhang, Jinhui; Zhou, Yanmei; Chen, Chao; Li, Wei; Ma, Lei; Zhang, Licheng; Zhao, Jingxin; Gan, Wenbiao; Zhang, Lihai; Tang, Peifu

    2015-01-01

    Spinal cord injury (SCI) can induce remodeling of multiple levels of the cerebral cortex system especially in the sensory cortex. The aim of this study was to assess, in vivo and bilaterally, the remodeling of dendritic spines in the hindlimb representation of the sensory cortex after spinal cord hemisection. Thy1-YFP transgenic mice were randomly divided into the control group and the SCI group, and the spinal vertebral plates (T11-T12) of all mice were excised. Next, the left hemisphere of the spinal cord (T12) was hemisected in the SCI group. The hindlimb representations of the sensory cortex in both groups were imaged bilaterally on the day before (0d), and three days (3d), two weeks (2w), and one month (1m) after the SCI. The rates of stable, newly formed, and eliminated spines were calculated by comparing images of individual dendritic spine in the same areas at different time points. In comparison to the control group, the rate of newly formed spines in the contralateral sensory cortex of the SCI group increased at three days and two weeks after injury. The rates of eliminated spines in the bilateral sensory cortices increased and the rate of stable spines in the bilateral cortices declined at two weeks and one month. From three days to two weeks, the stable rates of bilaterally stable spines in the SCI group decreased. In comparison to the control group and contralateral cortex in the SCI group, the re-emerging rate of eliminated spines in ipsilateral cortex of the SCI group decreased significantly. The stable rates of newly formed spines in bilateral cortices of the SCI group decreased from two weeks to one month. We found that the remodeling in the hindlimb representation of the sensory cortex after spinal cord hemisection occurred bilaterally. This remodeling included eliminating spines and forming new spines, as well as changing the reorganized regions of the brain cortex after the SCI over time. Soon after the SCI, the cortex was remodeled by

  4. Withdrawal from chronic intermittent alcohol exposure increases dendritic spine density in the lateral orbitofrontal cortex of mice.

    PubMed

    McGuier, Natalie S; Padula, Audrey E; Lopez, Marcelo F; Woodward, John J; Mulholland, Patrick J

    2015-02-01

    Alcohol use disorders (AUDs) are associated with functional and morphological changes in subfields of the prefrontal cortex. Clinical and preclinical evidence indicates that the orbitofrontal cortex (OFC) is critical for controlling impulsive behaviors, representing the value of a predicted outcome, and reversing learned associations. Individuals with AUDs often demonstrate deficits in OFC-dependent tasks, and rodent models of alcohol exposure show that OFC-dependent behaviors are impaired by chronic alcohol exposure. To explore the mechanisms that underlie these impairments, we examined dendritic spine density and morphology, and NMDA-type glutamate receptor expression in the lateral OFC of C57BL/6J mice following chronic intermittent ethanol (CIE) exposure. Western blot analysis demonstrated that NMDA receptors were not altered immediately following CIE exposure or after 7 days of withdrawal. Morphological analysis of basal dendrites of layer II/III pyramidal neurons revealed that dendritic spine density was also not affected immediately after CIE exposure. However, the total density of dendritic spines was significantly increased after a 7-day withdrawal from CIE exposure. The effect of withdrawal on spine density was mediated by an increase in the density of long, thin spines with no change in either stubby or mushroom spines. These data suggest that morphological neuroadaptations in lateral OFC neurons develop during alcohol withdrawal and occur in the absence of changes in the expression of NMDA-type glutamate receptors. The enhanced spine density that follows alcohol withdrawal may contribute to the impairments in OFC-dependent behaviors observed in CIE-treated mice.

  5. ERK1/2 Activation Is Necessary for BDNF to Increase Dendritic Spine Density in Hippocampal CA1 Pyramidal Neurons

    ERIC Educational Resources Information Center

    Alonso, Mariana; Medina, Jorge H.; Pozzo-Miller, Lucas

    2004-01-01

    Brain-derived neurotrophic factor (BDNF) is a potent modulator of synaptic transmission and plasticity in the CNS, acting both pre- and postsynaptically. We demonstrated recently that BDNF/TrkB signaling increases dendritic spine density in hippocampal CA1 pyramidal neurons. Here, we tested whether activation of the prominent ERK (MAPK) signaling…

  6. Wnt-5a/Frizzled9 Receptor Signaling through the Gαo-Gβγ Complex Regulates Dendritic Spine Formation.

    PubMed

    Ramírez, Valerie T; Ramos-Fernández, Eva; Henríquez, Juan Pablo; Lorenzo, Alfredo; Inestrosa, Nibaldo C

    2016-09-02

    Wnt ligands play crucial roles in the development and regulation of synapse structure and function. Specifically, Wnt-5a acts as a secreted growth factor that regulates dendritic spine formation in rodent hippocampal neurons, resulting in postsynaptic development that promotes the clustering of the PSD-95 (postsynaptic density protein 95). Here, we focused on the early events occurring after the interaction between Wnt-5a and its Frizzled receptor at the neuronal cell surface. Additionally, we studied the role of heterotrimeric G proteins in Wnt-5a-dependent synaptic development. We report that FZD9 (Frizzled9), a Wnt receptor related to Williams syndrome, is localized in the postsynaptic region, where it interacts with Wnt-5a. Functionally, FZD9 is required for the Wnt-5a-mediated increase in dendritic spine density. FZD9 forms a precoupled complex with Gαo under basal conditions that dissociates after Wnt-5a stimulation. Accordingly, we found that G protein inhibition abrogates the Wnt-5a-dependent pathway in hippocampal neurons. In particular, the activation of Gαo appears to be a key factor controlling the Wnt-5a-induced dendritic spine density. In addition, we found that Gβγ is required for the Wnt-5a-mediated increase in cytosolic calcium levels and spinogenesis. Our findings reveal that FZD9 and heterotrimeric G proteins regulate Wnt-5a signaling and dendritic spines in cultured hippocampal neurons.

  7. The effects of cocaine self-administration on dendritic spine density in the rat hippocampus are dependent on genetic background.

    PubMed

    Miguéns, Miguel; Kastanauskaite, Asta; Coria, Santiago M; Selvas, Abraham; Ballesteros-Yañez, Inmaculada; DeFelipe, Javier; Ambrosio, Emilio

    2015-01-01

    Chronic exposure to cocaine induces modifications to neurons in the brain regions involved in addiction. Hence, we evaluated cocaine-induced changes in the hippocampal CA1 field in Fischer 344 (F344) and Lewis (LEW) rats, 2 strains that have been widely used to study genetic predisposition to drug addiction, by combining intracellular Lucifer yellow injection with confocal microscopy reconstruction of labeled neurons. Specifically, we examined the effects of cocaine self-administration on the structure, size, and branching complexity of the apical dendrites of CA1 pyramidal neurons. In addition, we quantified spine density in the collaterals of the apical dendritic arbors of these neurons. We found differences between these strains in several morphological parameters. For example, CA1 apical dendrites were more branched and complex in LEW than in F344 rats, while the spine density in the collateral dendrites of the apical dendritic arbors was greater in F344 rats. Interestingly, cocaine self-administration in LEW rats augmented the spine density, an effect that was not observed in the F344 strain. These results reveal significant structural differences in CA1 pyramidal cells between these strains and indicate that cocaine self-administration has a distinct effect on neuron morphology in the hippocampus of rats with different genetic backgrounds.

  8. The role of heparan sulfate deficiency in autistic phenotype: potential involvement of Slit/Robo/srGAPs-mediated dendritic spine formation.

    PubMed

    Pérez, Christine; Sawmiller, Darrell; Tan, Jun

    2016-04-18

    Autism Spectrum Disorders (ASD) are the second most common developmental cause of disability in the United States. ASDs are accompanied with substantial economic and emotional cost. The brains of ASD patients have marked structural abnormalities, in the form of increased dendritic spines and decreased long distance connections. These structural differences may be due to deficiencies in Heparin Sulfate (HS), a proteoglycan involved in a variety of neurodevelopmental processes. Of particular interest is its role in the Slit/Robo pathway. The Slit/Robo pathway is known to be involved in the regulation of axonal guidance and dendritic spine formation. HS mediates the Slit/Robo interaction; without its presence Slit's repulsive activity is abrogated. Slit/Robo regulates dendritic spine formation through its interaction with srGAPs (slit-robo GTPase Activating Proteins), which leads to downstream signaling, actin cytoskeleton depolymerization and dendritic spine collapse. Through interference with this pathway, HS deficiency can lead to excess spine formation.

  9. Expansion of mossy fibers and CA3 apical dendritic length accompanies the fall in dendritic spine density after gonadectomy in male, but not female, rats

    PubMed Central

    Mendell, Ari L.; Atwi, Sarah; Bailey, Craig D. C.; McCloskey, Dan; Scharfman, Helen E.

    2017-01-01

    Androgen loss is an important clinical concern because of its cognitive and behavioral effects. Changes in androgen levels are also suspected to contribute to neurological disease. However, the available data on the effects of androgen deprivation in areas of the brain that are central to cognition, like the hippocampus, are mixed. In this study, morphological analysis of pyramidal cells was used to investigate if structural changes could potentially contribute to the mixed cognitive effects that have been observed after androgen loss in males. Male Sprague–Dawley rats were orchidectomized or sham-operated. Two months later, their brains were Golgi-impregnated for morphological analysis. Morphological endpoints were studied in areas CA3 and CA1, with comparisons to females either intact or 2 months after ovariectomy. CA3 pyramidal neurons of orchidectomized rats exhibited marked increases in apical dendritic arborization. There were increases in mossy fiber afferent density in area CA3, as well as robust enhancements to dendritic structure in area CA3 of orchidectomized males, but not in CA1. Remarkably, apical dendritic length of CA3 pyramidal cells increased, while spine density declined. By contrast, in females overall dendritic structure was minimally affected by ovariectomy, while dendritic spine density was greatly reduced. Sex differences and subfield-specific effects of gonadal hormone deprivation on the hippocampal circuitry may help explain the different behavioral effects reported in males and females after gonadectomy, or other conditions associated with declining gonadal hormone secretion. PMID:27283589

  10. Intraneuronal APP and extracellular Aβ independently cause dendritic spine pathology in transgenic mouse models of Alzheimer's disease.

    PubMed

    Zou, Chengyu; Montagna, Elena; Shi, Yuan; Peters, Finn; Blazquez-Llorca, Lidia; Shi, Song; Filser, Severin; Dorostkar, Mario M; Herms, Jochen

    2015-06-01

    Alzheimer's disease (AD) is thought to be caused by accumulation of amyloid-β protein (Aβ), which is a cleavage product of amyloid precursor protein (APP). Transgenic mice overexpressing APP have been used to recapitulate amyloid-β pathology. Among them, APP23 and APPswe/PS1deltaE9 (deltaE9) mice are extensively studied. APP23 mice express APP with Swedish mutation and develop amyloid plaques late in their life, while cognitive deficits are observed in young age. In contrast, deltaE9 mice with mutant APP and mutant presenilin-1 develop amyloid plaques early but show typical cognitive deficits in old age. To unveil the reasons for different progressions of cognitive decline in these commonly used mouse models, we analyzed the number and turnover of dendritic spines as important structural correlates for learning and memory. Chronic in vivo two-photon imaging in apical tufts of layer V pyramidal neurons revealed a decreased spine density in 4-5-month-old APP23 mice. In age-matched deltaE9 mice, in contrast, spine loss was only observed on cortical dendrites that were in close proximity to amyloid plaques. In both cases, the reduced spine density was caused by decreased spine formation. Interestingly, the patterns of alterations in spine morphology differed between these two transgenic mouse models. Moreover, in APP23 mice, APP was found to accumulate intracellularly and its content was inversely correlated with the absolute spine density and the relative number of mushroom spines. Collectively, our results suggest that different pathological mechanisms, namely an intracellular accumulation of APP or extracellular amyloid plaques, may lead to spine abnormalities in young adult APP23 and deltaE9 mice, respectively. These distinct features, which may represent very different mechanisms of synaptic failure in AD, have to be taken into consideration when translating results from animal studies to the human disease.

  11. Hippocampal Neuro-Networks and Dendritic Spine Perturbations in Epileptogenesis Are Attenuated by Neuroprotectin D1

    PubMed Central

    Musto, Alberto E.; Walker, Chelsey P.; Petasis, Nicos A.; Bazan, Nicolas G.

    2015-01-01

    Purpose Limbic epileptogenesis triggers molecular and cellular events that foster the establishment of aberrant neuronal networks that, in turn, contribute to temporal lobe epilepsy (TLE). Here we have examined hippocampal neuronal network activities in the pilocarpine post-status epilepticus model of limbic epileptogenesis and asked whether or not the docosahexaenoic acid (DHA)-derived lipid mediator, neuroprotectin D1 (NPD1), modulates epileptogenesis. Methods Status epilepticus (SE) was induced by intraperitoneal administration of pilocarpine in adult male C57BL/6 mice. To evaluate simultaneous hippocampal neuronal networks, local field potentials were recorded from multi-microelectrode arrays (silicon probe) chronically implanted in the dorsal hippocampus. NPD1 (570 μg/kg) or vehicle was administered intraperitoneally daily for five consecutive days 24 hours after termination of SE. Seizures and epileptiform activity were analyzed in freely-moving control and treated mice during epileptogenesis and epileptic periods. Then hippocampal dendritic spines were evaluated using Golgi-staining. Results We found brief spontaneous microepileptiform activity with high amplitudes in the CA1 pyramidal and stratum radiatum in epileptogenesis. These aberrant activities were attenuated following systemic NPD1 administration, with concomitant hippocampal dendritic spine protection. Moreover, NPD1 treatment led to a reduction in spontaneous recurrent seizures. Conclusions Our results indicate that NPD1 displays neuroprotective bioactivity on the hippocampal neuronal network ensemble that mediates aberrant circuit activity during epileptogenesis. Insight into the molecular signaling mediated by neuroprotective bioactivity of NPD1 on neuronal network dysfunction may contribute to the development of anti-epileptogenic therapeutic strategies. PMID:25617763

  12. Altered sensory experience exacerbates stable dendritic spine and synapse loss in a mouse model of Huntington's disease.

    PubMed

    Murmu, Reena Prity; Li, Wen; Szepesi, Zsuzsanna; Li, Jia-Yi

    2015-01-07

    A key question in Huntington's disease (HD) is what underlies the early cognitive deficits that precede the motor symptoms and the characteristic neuronal death observed in HD. The mechanisms underlying cognitive symptoms in HD remain unknown. Postmortem HD brain and animal model studies demonstrate pathologies in dendritic spines and abnormal synaptic plasticity before motor symptoms and neurodegeneration. Experience-dependent synaptic plasticity caused by mechanisms such as LTP or novel sensory experience potentiates synaptic strength, enhances new dendritic spine formation and stabilization, and may contribute to normal cognitive processes, such as learning and memory. We have previously reported that under baseline conditions (without any sensory manipulation) neuronal circuitry in HD (R6/2 mouse model) was highly unstable, which led to a progressive loss of persistent spines in these mice, and that mutant huntingtin was directly involved in the process. Here, we investigated whether pathological processes of HD interfere with the normal experience-dependent plasticity of dendritic spines in the R6/2 model. Six weeks of two-photon in vivo imaging before and after whisker trimming revealed that sensory deprivation exacerbates loss of persistent-type, stable spines in R6/2 mice compared with wild-type littermates. In addition, sensory deprivation leads to impaired transformation of newly generated spines into persistent spines in R6/2 mice. As a consequence, reduced synaptic density and decreased PSD-95 protein levels are evident in their barrel cortical neurons. These data suggest that mutant huntingtin is implicated in maladaptive synaptic plasticity, which could be one of the plausible mechanisms underlying early cognitive deficits in HD.

  13. High throughput, detailed, cell-specific neuroanatomy of dendritic spines using microinjection and confocal microscopy

    PubMed Central

    Dumitriu, Dani; Rodriguez, Alfredo; Morrison, John H.

    2012-01-01

    Morphological features such as size, shape and density of dendritic spines have been shown to reflect important synaptic functional attributes and potential for plasticity. Here we describe in detail a protocol for obtaining detailed morphometric analysis of spines using microinjection of fluorescent dyes, high resolution confocal microscopy, deconvolution and image analysis using NeuronStudio. Recent technical advancements include better preservation of tissue resulting in prolonged ability to microinject, and algorithmic improvements that compensate for the residual Z-smear inherent in all optical imaging. Confocal imaging parameters were probed systematically for the identification of both optimal resolution as well as highest efficiency. When combined, our methods yield size and density measurements comparable to serial section transmission electron microscopy in a fraction of the time. An experiment containing 3 experimental groups with 8 subjects in each can take as little as one month if optimized for speed, or approximately 4 to 5 months if the highest resolution and morphometric detail is sought. PMID:21886104

  14. The Endosome Localized Arf-GAP AGAP1 Modulates Dendritic Spine Morphology Downstream of the Neurodevelopmental Disorder Factor Dysbindin

    PubMed Central

    Arnold, Miranda; Cross, Rebecca; Singleton, Kaela S.; Zlatic, Stephanie; Chapleau, Christopher; Mullin, Ariana P.; Rolle, Isaiah; Moore, Carlene C.; Theibert, Anne; Pozzo-Miller, Lucas; Faundez, Victor; Larimore, Jennifer

    2016-01-01

    AGAP1 is an Arf1 GTPase activating protein that interacts with the vesicle-associated protein complexes adaptor protein 3 (AP-3) and Biogenesis of Lysosome Related Organelles Complex-1 (BLOC-1). Overexpression of AGAP1 in non-neuronal cells results in an accumulation of endosomal cargoes, which suggests a role in endosome-dependent traffic. In addition, AGAP1 is a candidate susceptibility gene for two neurodevelopmental disorders, autism spectrum disorder (ASD) and schizophrenia (SZ); yet its localization and function in neurons have not been described. Here, we describe that AGAP1 localizes to axons, dendrites, dendritic spines and synapses, colocalizing preferentially with markers of early and recycling endosomes. Functional studies reveal overexpression and down-regulation of AGAP1 affects both neuronal endosomal trafficking and dendritic spine morphology, supporting a role for AGAP1 in the recycling endosomal trafficking involved in their morphogenesis. Finally, we determined the sensitivity of AGAP1 expression to mutations in the DTNBP1 gene, which is associated with neurodevelopmental disorder, and found that AGAP1 mRNA and protein levels are selectively reduced in the null allele of the mouse ortholog of DTNBP1. We postulate that endosomal trafficking contributes to the pathogenesis of neurodevelopmental disorders affecting dendritic spine morphology, and thus excitatory synapse structure and function. PMID:27713690

  15. Chronic intermittent ethanol exposure and withdrawal leads to adaptations in nucleus accumbens core postsynaptic density proteome and dendritic spines.

    PubMed

    Uys, Joachim D; McGuier, Natalie S; Gass, Justin T; Griffin, William C; Ball, Lauren E; Mulholland, Patrick J

    2016-05-01

    Alcohol use disorder is a chronic relapsing brain disease characterized by the loss of ability to control alcohol (ethanol) intake despite knowledge of detrimental health or personal consequences. Clinical and pre-clinical models provide strong evidence for chronic ethanol-associated alterations in glutamatergic signaling and impaired synaptic plasticity in the nucleus accumbens (NAc). However, the neural mechanisms that contribute to aberrant glutamatergic signaling in ethanol-dependent individuals in this critical brain structure remain unknown. Using an unbiased proteomic approach, we investigated the effects of chronic intermittent ethanol (CIE) exposure on neuroadaptations in postsynaptic density (PSD)-enriched proteins in the NAc of ethanol-dependent mice. Compared with controls, CIE exposure significantly changed expression levels of 50 proteins in the PSD-enriched fraction. Systems biology and functional annotation analyses demonstrated that the dysregulated proteins are expressed at tetrapartite synapses and critically regulate cellular morphology. To confirm this latter finding, the density and morphology of dendritic spines were examined in the NAc core of ethanol-dependent mice. We found that CIE exposure and withdrawal differentially altered dendrite diameter and dendritic spine density and morphology. Through the use of quantitative proteomics and functional annotation, these series of experiments demonstrate that ethanol dependence produces neuroadaptations in proteins that modify dendritic spine morphology. In addition, these studies identified novel PSD-related proteins that contribute to the neurobiological mechanisms of ethanol dependence that drive maladaptive structural plasticity of NAc neurons.

  16. Constellation of HCN channels and cAMP regulating proteins in dendritic spines of the primate prefrontal cortex: potential substrate for working memory deficits in schizophrenia.

    PubMed

    Paspalas, Constantinos D; Wang, Min; Arnsten, Amy F T

    2013-07-01

    Schizophrenia associates with impaired prefrontal cortical (PFC) function and alterations in cyclic AMP (cAMP) signaling pathways. These include genetic insults to disrupted-in-schizophrenia (DISC1) and phosphodiesterases (PDE4s) regulating cAMP hydrolysis, and increased dopamine D1 receptor (D1R) expression that elevates cAMP. We used immunoelectron microscopy to localize DISC1, PDE4A, PDE4B, and D1R in monkey PFC and to view spatial interactions with hyperpolarization-activated cyclic nucleotide-gated (HCN) channels that gate network inputs when opened by cAMP. Physiological interactions between PDE4s and HCN channels were tested in recordings of PFC neurons in monkeys performing a spatial working memory task. The study reveals a constellation of cAMP-related proteins (DISC1, PDE4A, and D1R) and HCN channels next to excitatory synapses and the spine neck in thin spines of superficial PFC, where working memory microcircuits interconnect and spine loss is most evident in schizophrenia. In contrast, channels in dendrites were distant from synapses and cAMP-related proteins, and were associated with endosomal trafficking. The data suggest that a cAMP signalplex is selectively positioned in the spines to gate PFC pyramidal cell microcircuits. Single-unit recordings confirmed physiological interactions between cAMP and HCN channels, consistent with gating actions. These data may explain why PFC networks are especially vulnerable to genetic insults that dysregulate cAMP signaling.

  17. Dysfunctional epileptic neuronal circuits and dysmorphic dendritic spines are mitigated by platelet-activating factor receptor antagonism

    PubMed Central

    Musto, Alberto E.; Rosencrans, Robert F.; Walker, Chelsey P.; Bhattacharjee, Surjyadipta; Raulji, Chittalsinh M.; Belayev, Ludmila; Fang, Zhide; Gordon, William C.; Bazan, Nicolas G.

    2016-01-01

    Temporal lobe epilepsy or limbic epilepsy lacks effective therapies due to a void in understanding the cellular and molecular mechanisms that set in motion aberrant neuronal network formations during the course of limbic epileptogenesis (LE). Here we show in in vivo rodent models of LE that the phospholipid mediator platelet-activating factor (PAF) increases in LE and that PAF receptor (PAF-r) ablation mitigates its progression. Synthetic PAF-r antagonists, when administered intraperitoneally in LE, re-establish hippocampal dendritic spine density and prevent formation of dysmorphic dendritic spines. Concomitantly, hippocampal interictal spikes, aberrant oscillations, and neuronal hyper-excitability, evaluated 15–16 weeks after LE using multi-array silicon probe electrodes implanted in the dorsal hippocampus, are reduced in PAF-r antagonist-treated mice. We suggest that over-activation of PAF-r signaling induces aberrant neuronal plasticity in LE and leads to chronic dysfunctional neuronal circuitry that mediates epilepsy. PMID:27444269

  18. Estrogen-induced dendritic spine elimination on female rat ventromedial hypothalamic neurons that project to the periaqueductal gray.

    PubMed

    Calizo, Lyngine H; Flanagan-Cato, Loretta M

    2002-06-03

    Neurons of the ventromedial hypothalamic nucleus (VMH) that project to the periaqueductal gray (PAG) form a crucial segment of the motor pathway that produces the lordosis posture, the hallmark of female rat sexual behavior. One suggested mechanism through which estrogen facilitates lordosis is by remodeling synaptic connectivity within the VMH. For instance, estrogen alters VMH dendritic spine density. Little is known, however, about the local VMH microcircuitry governing lordosis nor how estrogen alters synaptic connectivity within this local circuit to facilitate sexual behavior. The goal of this study was to define better the neuron types within the VMH microcircuitry and to examine whether estrogen alters synaptic connectivity, as measured by dendritic spine density, on VMH projection neurons. A retrograde tracer was injected into the PAG of ovariectomized rats treated with vehicle or estradiol. Retrogradely labeled VMH neurons were filled with Lucifer yellow, then immunostained for estrogen receptor-alpha (ER alpha). VMH neurons that project to the PAG had more dendrites than functionally unidentified neurons. Additionally, VMH projection neurons could be subdivided into those located within the cluster of ER alpha-containing neurons and those medial to the cluster. Estrogen decreased spine density by 57% on the long primary dendrites of VMH projection neurons located within the ER alpha cluster but not on projection neurons medial to the cluster. Only 4% of the VMH projection neurons expressed ER alpha. These results suggest that estrogen may facilitate sexual behavior by decreasing spines selectively, via an indirect mechanism, on a subset of VMH neurons that project to the PAG.

  19. GSK-3β Overexpression Alters the Dendritic Spines of Developmentally Generated Granule Neurons in the Mouse Hippocampal Dentate Gyrus

    PubMed Central

    Pallas-Bazarra, Noemí; Kastanauskaite, Asta; Avila, Jesús; DeFelipe, Javier; Llorens-Martín, María

    2017-01-01

    The dentate gyrus (DG) plays a crucial role in hippocampal-related memory. The most abundant cellular type in the DG, namely granule neurons, are developmentally generated around postnatal day P6 in mice. Moreover, a unique feature of the DG is the occurrence of adult hippocampal neurogenesis, a process that gives rise to newborn granule neurons throughout life. Adult-born and developmentally generated granule neurons share some maturational aspects but differ in others, such as in their positioning within the granule cell layer. Adult hippocampal neurogenesis encompasses a series of plastic changes that modify the function of the hippocampal trisynaptic network. In this regard, it is known that glycogen synthase kinase 3β (GSK-3β) regulates both synaptic plasticity and memory. By using a transgenic mouse overexpressing GSK-3β in hippocampal neurons, we previously demonstrated that the overexpression of this kinase has deleterious effects on the maturation of newborn granule neurons. In the present study, we addressed the effects of GSK-3β overexpression on the morphology and number of dendritic spines of developmentally generated granule neurons. To this end, we performed intracellular injections of Lucifer Yellow in developmentally generated granule neurons of wild-type and GSK-3β-overexpressing mice and analyzed the number and morphologies of dendritic spines (namely, stubby, thin and mushroom). GSK-3β overexpression led to a general reduction in the number of dendritic spines. In addition, it caused a slight reduction in the percentage, head diameter and length of thin spines, whereas the head diameter of mushroom spines was increased. PMID:28344548

  20. Prolonged ampakine exposure prunes dendritic spines and increases presynaptic release probability for enhanced long-term potentiation in the hippocampus.

    PubMed

    Chang, Philip K-Y; Prenosil, George A; Verbich, David; Gill, Raminder; McKinney, R Anne

    2014-09-01

    CX 546, an allosteric positive modulator of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type ionotropic glutamate receptors (AMPARs), belongs to a drug class called ampakines. These compounds have been shown to enhance long-term potentiation (LTP), a cellular model of learning and memory, and improve animal learning task performance, and have augmented cognition in neurodegenerative patients. However, the chronic effect of CX546 on synaptic structures has not been examined. The structure and integrity of dendritic spines are thought to play a role in learning and memory, and their abnormalities have been implicated in cognitive disorders. In addition, their structural plasticity has been shown to be important for cognitive function, such that dendritic spine remodeling has been proposed as the morphological correlate for LTP. Here, we tested the effect of CX546 on dendritic spine remodeling following long-term treatment. We found that, with prolonged CX546 treatment, organotypic hippocampal slice cultures showed a significant reduction in CA3-CA1 excitatory synapse and spine density. Electrophysiological approaches revealed that the CA3-CA1 circuitry compensates for this synapse loss by increasing synaptic efficacy through enhancement of presynaptic release probability. CX546-treated slices showed prolonged and enhanced potentiation upon LTP induction. Furthermore, structural plasticity, namely spine head enlargement, was also more pronounced after CX546 treatment. Our results suggest a concordance of functional and structural changes that is enhanced with prolonged CX546 exposure. Thus, the improved cognitive ability of patients receiving ampakine treatment may result from the priming of synapses through increases in the structural plasticity and functional reliability of hippocampal synapses.

  1. miR-132 Regulates Dendritic Spine Structure by Direct Targeting of Matrix Metalloproteinase 9 mRNA.

    PubMed

    Jasińska, Magdalena; Miłek, Jacek; Cymerman, Iwona A; Łęski, Szymon; Kaczmarek, Leszek; Dziembowska, Magdalena

    2016-09-01

    Mir-132 is a neuronal activity-regulated microRNA that controls the morphology of dendritic spines and neuronal transmission. Similar activities have recently been attributed to matrix metalloproteinase-9 (MMP-9), an extrasynaptic protease. In the present study, we provide evidence that miR-132 directly regulates MMP-9 mRNA in neurons to modulate synaptic plasticity. With the use of luciferase reporter system, we show that miR-132 binds to the 3'UTR of MMP-9 mRNA to regulate its expression in neurons. The overexpression of miR-132 in neurons reduces the level of endogenous MMP-9 protein secretion. In synaptoneurosomes, metabotropic glutamate receptor (mGluR)-induced signaling stimulates the dissociation of miR-132 from polyribosomal fractions and shifts it towards the messenger ribonucleoprotein (mRNP)-containing fraction. Furthermore, we demonstrate that the overexpression of miR-132 in the cultured hippocampal neurons from Fmr1 KO mice that have increased synaptic MMP-9 level provokes enlargement of the dendritic spine heads, a process previously implicated in enhanced synaptic plasticity. We propose that activity-dependent miR-132 regulates structural plasticity of dendritic spines through matrix metalloproteinase 9.

  2. MDL constrained 3-D grayscale skeletonization algorithm for automated extraction of dendrites and spines from fluorescence confocal images.

    PubMed

    Yuan, Xiaosong; Trachtenberg, Joshua T; Potter, Steve M; Roysam, Badrinath

    2009-12-01

    This paper presents a method for improved automatic delineation of dendrites and spines from three-dimensional (3-D) images of neurons acquired by confocal or multi-photon fluorescence microscopy. The core advance presented here is a direct grayscale skeletonization algorithm that is constrained by a structural complexity penalty using the minimum description length (MDL) principle, and additional neuroanatomy-specific constraints. The 3-D skeleton is extracted directly from the grayscale image data, avoiding errors introduced by image binarization. The MDL method achieves a practical tradeoff between the complexity of the skeleton and its coverage of the fluorescence signal. Additional advances include the use of 3-D spline smoothing of dendrites to improve spine detection, and graph-theoretic algorithms to explore and extract the dendritic structure from the grayscale skeleton using an intensity-weighted minimum spanning tree (IW-MST) algorithm. This algorithm was evaluated on 30 datasets organized in 8 groups from multiple laboratories. Spines were detected with false negative rates less than 10% on most datasets (the average is 7.1%), and the average false positive rate was 11.8%. The software is available in open source form.

  3. Cortical synaptic and dendritic spine abnormalities in a presymptomatic TDP-43 model of amyotrophic lateral sclerosis

    PubMed Central

    Fogarty, Matthew J.; Klenowski, Paul M.; Lee, John D.; Drieberg-Thompson, Joy R.; Bartlett, Selena E.; Ngo, Shyuan T.; Hilliard, Massimo A.; Bellingham, Mark C.; Noakes, Peter G.

    2016-01-01

    Layer V pyramidal neurons (LVPNs) within the motor cortex integrate sensory cues and co-ordinate voluntary control of motor output. In amyotrophic lateral sclerosis (ALS) LVPNs and spinal motor neurons degenerate. The pathogenesis of neural degeneration is unknown in ALS; 10% of cases have a genetic cause, whereas 90% are sporadic, with most of the latter showing TDP-43 inclusions. Clinical and experimental evidence implicate excitotoxicity as a prime aetiological candidate. Using patch clamp and dye-filling techniques in brain slices, combined with high-resolution confocal microscopy, we report increased excitatory synaptic inputs and dendritic spine densities in early presymptomatic mice carrying a TDP-43Q331K mutation. These findings demonstrate substantive alterations in the motor cortex neural network, long before an overt degenerative phenotype has been reported. We conclude that increased excitatory neurotransmission is a common pathophysiology amongst differing genetic cases of ALS and may be of relevance to the 95% of sporadic ALS cases that exhibit TDP-43 inclusions. PMID:27897242

  4. Dendritic spine density, morphology, and fibrillar actin content surrounding amyloid-β plaques in a mouse model of amyloid-β deposition.

    PubMed

    Kirkwood, Caitlin M; Ciuchta, Jennifer; Ikonomovic, Milos D; Fish, Kenneth N; Abrahamson, Eric E; Murray, Patrick S; Klunk, William E; Sweet, Robert A

    2013-08-01

    Dendritic spines are the site of most excitatory synapses, the loss of which correlates with cognitive impairment in patients with Alzheimer disease. Substantial evidence indicates that amyloid-β (Aβ) peptide, either insoluble fibrillar Aβ deposited into plaques or soluble nonfibrillar Aβ species, can cause spine loss but the concurrent contributions of fibrillar Aβ and nonfibrillar Aβ to spine loss has not been previously assessed. We used multiple-label immunohistochemistry to measure spine density, size, and F-actin content surrounding plaques in the cerebral cortex in the PSAPP mouse model of Aβ deposition. Our approach allowed us to measure fibrillar Aβ plaque content and an index of nonfibrillar Aβ species concurrently. We found that spine density was reduced within 6 μm of the plaque perimeter, remaining spines were more compact, and F-actin content per spine was increased. Measures of fibrillar Aβ plaque content were associated with reduced spine density near plaques, whereas measures of nonfibrillar Aβ species were associated with reduced spine density and size but not altered F-actin content. These findings suggest that strategies to preserve dendritic spines in AD patients may need to address both nonfibrillar and fibrillar forms of Aβ and that nonfibrillar Aβ may exert spine toxicity through pathways not mediated by depolymerization of F-actin.

  5. Cell class-specific regulation of neocortical dendrite and spine growth by AMPA receptor splice and editing variants.

    PubMed

    Hamad, Mohammad I K; Ma-Högemeier, Zhan-Lu; Riedel, Christian; Conrads, Claudius; Veitinger, Thomas; Habijan, Tim; Schulz, Jan-Niklas; Krause, Martin; Wirth, Marcus J; Hollmann, Michael; Wahle, Petra

    2011-10-01

    Glutamatergic transmission converging on calcium signaling plays a key role in dendritic differentiation. In early development, AMPA receptor (AMPAR) transcripts are extensively spliced and edited to generate subunits that differ in their biophysical properties. Whether these subunits have specific roles in the context of structural differentiation is unclear. We have investigated the role of nine GluA variants and revealed a correlation between the expression of flip variants and the period of major dendritic growth. In interneurons, only GluA1(Q)-flip increased dendritic length and branching. In pyramidal cells, GluA2(Q)-flop, GluA2(Q)-flip, GluA3(Q)-flip and calcium-impermeable GluA2(R)-flip promoted dendritic growth, suggesting that flip variants with slower desensitization kinetics are more important than receptors with elevated calcium permeability. Imaging revealed significantly higher calcium signals in pyramidal cells transfected with GluA2(R)-flip as compared with GluA2(R)-flop, suggesting a contribution of voltage-activated calcium channels. Indeed, dendritic growth induced by GluA2(R)-flip in pyramidal cells was prevented by blocking NMDA receptors (NMDARs) or voltage-gated calcium channels (VGCCs), suggesting that they act downstream of AMPARs. Intriguingly, the action of GluA1(Q)-flip in interneurons was also dependent on NMDARs and VGCCs. Cell class-specific effects were not observed for spine formation, as GluA2(Q)-flip and GluA2(Q)-flop increased spine density in pyramidal cells as well as in interneurons. The results suggest that AMPAR variants expressed early in development are important determinants for activity-dependent dendritic growth in a cell type-specific and cell compartment-specific manner.

  6. Opposite Effects of mGluR1a and mGluR5 Activation on Nucleus Accumbens Medium Spiny Neuron Dendritic Spine Density

    PubMed Central

    Gross, Kellie S.; Brandner, Dieter D.; Martinez, Luis A.; Olive, M. Foster; Meisel, Robert L.

    2016-01-01

    The group I metabotropic glutamate receptors (mGluR1a and mGluR5) are important modulators of neuronal structure and function. Although these receptors share common signaling pathways, they are capable of having distinct effects on cellular plasticity. We investigated the individual effects of mGluR1a or mGluR5 activation on dendritic spine density in medium spiny neurons in the nucleus accumbens (NAc), which has become relevant with the potential use of group I mGluR based therapeutics in the treatment of drug addiction. We found that systemic administration of mGluR subtype-specific positive allosteric modulators had opposite effects on dendritic spine densities. Specifically, mGluR5 positive modulation decreased dendritic spine densities in the NAc shell and core, but was without effect in the dorsal striatum, whereas increased spine densities in the NAc were observed with mGluR1a positive modulation. Additionally, direct activation of mGluR5 via CHPG administration into the NAc also decreased the density of dendritic spines. These data provide insight on the ability of group I mGluRs to induce structural plasticity in the NAc and demonstrate that the group I mGluRs are capable of producing not just distinct, but opposing, effects on dendritic spine density. PMID:27618534

  7. Postpartum corticosterone administration reduces dendritic complexity and increases the density of mushroom spines of hippocampal CA3 arbours in dams.

    PubMed

    Workman, J L; Brummelte, S; Galea, L A M

    2013-02-01

    Postpartum depression (PPD) affects approximately 15% of mothers after giving birth. A complete understanding of depression during the postpartum period has yet to be established, although disruptions in the hypothalamic-pituitary-adrenal axis and stress during the postpartum may be involved. To model these components in rats, we administered high corticosterone (CORT) postpartum, which increases immobility in the forced swim test (FST), and reduces maternal care, body weight and hippocampal cell proliferation in dams. The hippocampus is altered in response to chronic stress, exposure to high glucocorticoids and in major depression in humans. In the present study, we examined whether high CORT reduced dendritic complexity and spines in the CA3 region of the hippocampus. Additionally, housing complexity was manipulated so that dams and litters were housed either with tubes (complex) or without tubes (impoverished) to investigate the consequences of new animal care regulations. Dams received 40 mg/kg/day of CORT or oil starting on day 2 postpartum for 23 days. Maternal behaviours were assessed on postpartum days 2-8 and dams were tested using the FST on days 21 and 22. Dams were killed on day 24 and brains were processed for Golgi impregnation. Pyramidal cells in the CA3 subfield were traced using a camera lucida and analysed for branch points and dendritic complexity, as well as spine density and type on both basal and apical arbours. As previously established, high CORT postpartum reduced maternal care and increased immobility in the FST, which is a measure of depressive-like behaviour. High CORT postpartum reduced the complexity of basal arbours and increased mushroom spines on both apical and basal dendrites. Housing complexity had no effect on spines of CA3 pyramidal cells but modest effects on cell morphology. These data show that chronic high CORT in postpartum females alters hippocampal morphology and may provide insight regarding the neurobiological

  8. KIS, a kinase associated with microtubule regulators, enhances translation of AMPA receptors and stimulates dendritic spine remodeling.

    PubMed

    Pedraza, Neus; Ortiz, Raúl; Cornadó, Alba; Llobet, Artur; Aldea, Martí; Gallego, Carme

    2014-10-15

    Local regulation of protein synthesis allows a neuron to rapidly alter the proteome in response to synaptic signals, an essential mechanism in synaptic plasticity that is altered in many neurological diseases. Synthesis of many synaptic proteins is under local control and much of this regulation occurs through structures termed RNA granules. KIS is a protein kinase that associates with stathmin, a modulator of the tubulin cytoskeleton. Furthermore, KIS is found in RNA granules and stimulates translation driven by the β-actin 3'UTR in neurites. Here we explore the physiological and molecular mechanisms underlying the action of KIS on hippocampal synaptic plasticity in mice. KIS downregulation compromises spine development, alters actin dynamics, and reduces postsynaptic responsiveness. The absence of KIS results in a significant decrease of protein levels of PSD-95, a postsynaptic scaffolding protein, and the AMPAR subunits GluR1 and GluR2 in a CPEB3-dependent manner. Underlying its role in spine maturation, KIS is able to suppress the spine developmental defects caused by CPEB3 overexpression. Moreover, either by direct or indirect mechanisms, KIS counteracts the inhibitory activity of CPEB3 on the GluR2 3'UTR at both mRNA translation and polyadenylation levels. Our study provides insights into the mechanisms that mediate dendritic spine morphogenesis and functional synaptic maturation, and suggests KIS as a link regulating spine cytoskeleton and postsynaptic activity in memory formation.

  9. Loss of neuronal GSK3β reduces dendritic spine stability and attenuates excitatory synaptic transmission via β-catenin

    PubMed Central

    Ochs, S M; Dorostkar, M M; Aramuni, G; Schön, C; Filser, S; Pöschl, J; Kremer, A; Van Leuven, F; Ovsepian, S V; Herms, J

    2015-01-01

    Central nervous glycogen synthase kinase 3β (GSK3β) is implicated in a number of neuropsychiatric diseases, such as bipolar disorder, depression, schizophrenia, fragile X syndrome or anxiety disorder. Many drugs employed to treat these conditions inhibit GSK3β either directly or indirectly. We studied how conditional knockout of GSK3β affected structural synaptic plasticity. Deletion of the GSK3β gene in a subset of cortical and hippocampal neurons in adult mice led to reduced spine density. In vivo imaging revealed that this was caused by a loss of persistent spines, whereas stabilization of newly formed spines was reduced. In electrophysiological recordings, these structural alterations correlated with a considerable drop in the frequency and amplitude of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-dependent miniature excitatory postsynaptic currents. Expression of constitutively active β-catenin caused reduction in spine density and electrophysiological alterations similar to GSK3β knockout, suggesting that the effects of GSK3β knockout were mediated by the accumulation of β-catenin. In summary, changes of dendritic spines, both in quantity and in morphology, are correlates of experience-dependent synaptic plasticity; thus, these results may help explain the mechanism of action of psychotropic drugs inhibiting GSK3β. PMID:24912492

  10. Pharmacological reversion of sphingomyelin-induced dendritic spine anomalies in a Niemann Pick disease type A mouse model

    PubMed Central

    Arroyo, Ana I; Camoletto, Paola G; Morando, Laura; Sassoe-Pognetto, Marco; Giustetto, Maurizio; Van Veldhoven, Paul P; Schuchman, Edward H; Ledesma, Maria D

    2014-01-01

    Understanding the role of lipids in synapses and the aberrant molecular mechanisms causing the cognitive deficits that characterize most lipidosis is necessary to develop therapies for these diseases. Here we describe sphingomyelin (SM) as a key modulator of the dendritic spine actin cytoskeleton. We show that increased SM levels in neurons of acid sphingomyelinase knock out mice (ASMko), which mimic Niemann Pick disease type A (NPA), result in reduced spine number and size and low levels of filamentous actin. Mechanistically, SM accumulation decreases the levels of metabotropic glutamate receptors type I (mGluR1/5) at the synaptic membrane impairing membrane attachment and activity of RhoA and its effectors ROCK and ProfilinIIa. Pharmacological enhancement of the neutral sphingomyelinase rescues the aberrant molecular and morphological phenotypes in vitro and in vivo and improves motor and memory deficits in ASMko mice. Altogether, these data demonstrate the influence of SM and its catabolic enzymes in dendritic spine physiology and contribute to our understanding of the cognitive deficits of NPA patients, opening new perspectives for therapeutic interventions. Subject Categories Genetics, Gene Therapy & Genetic Disease; Neuroscience PMID:24448491

  11. Distinct Ca2+ sources in dendritic spines of hippocampal CA1 neurons couple to SK and Kv4 channels

    PubMed Central

    Wang, Kang; Lin, Mike T.; Adelman, John P.; Maylie, James

    2013-01-01

    SUMMARY Ca2+-activated SK channels and voltage-gated A-type Kv4 channels shape dendritic excitatory postsynaptic potentials (EPSPs) in hippocampal CA1 pyramidal neurons. Synaptically evoked Ca2+ influx through N-methyl-D-aspartate receptors (NMDARs) activates spine SK channels, reducing EPSPs and the associated spine head Ca2+ transient. However, results using glutamate uncaging implicated Ca2+ influx through SNX-482 (SNX) sensitive Cav2.3 (R-type) Ca2+ channels as the Ca2+ source for SK channel activation. The present findings show that using Schaffer collateral stimulation the effects of SNX and apamin are not mutually exclusive and SNX increases EPSPs independent of SK channel activity. Dialysis with 1,2-bis(o-aminophenoxy)ethane-N’N’N’-tetraacetic acid (BAPTA), application of 4-Aminopyridine (4-AP), expression of a Kv4.2 dominant negative subunit, and dialysis with a KChIPs antibody occluded the SNX-induced increase of EPSPs. The results suggest two distinct Ca2+ signaling pathways within dendritic spines, that links Ca2+ influx through NMDARs to SK channels and Ca2+ influx through R-type Ca2+ channels to Kv4.2-containing channels. PMID:24462100

  12. Fatigue reversibly reduced cortical and hippocampal dendritic spines concurrent with compromise of motor endurance and spatial memory.

    PubMed

    Chen, J-R; Wang, T-J; Huang, H-Y; Chen, L-J; Huang, Y-S; Wang, Y-J; Tseng, G-F

    2009-07-21

    Fatigue could be induced following forced exercise, sickness, heat stroke or sleep disturbance and impaired brain-related functions such as concentration, attention and memory. Here we investigated whether fatigue altered the dendrites of central neurons. Central fatigue was induced by housing rats in cage with 1.5-cm deep water for 1-5 days. Three days of sleep deprivation seriously compromised rats' performance in weight-loaded forced swimming and spatial learning tests, and 5 days of treatment worsened it further. Combinations of intracellular dye injection and three-dimensional analysis revealed that dendritic spines on retrograde tracer-identified corticospinal neurons and Cornu Ammonis (CA)1 and CA3 pyramidal neurons were significantly reduced while the shape or length of the dendritic arbors was not altered. Three days of rest restored the spine loss and the degraded spatial learning and weight-loaded forced swimming performances to control levels. In conclusion, although we could not rule out additional non-hypothalamic-pituitary-adrenal stress, the apparent fatigue induced following a few days of sleep deprivation could change brain structurally and functionally and the effects were reversible with a few days of rest.

  13. FIB/SEM technology and high-throughput 3D reconstruction of dendritic spines and synapses in GFP-labeled adult-generated neurons.

    PubMed

    Bosch, Carles; Martínez, Albert; Masachs, Nuria; Teixeira, Cátia M; Fernaud, Isabel; Ulloa, Fausto; Pérez-Martínez, Esther; Lois, Carlos; Comella, Joan X; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

    2015-01-01

    The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM) and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM) allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs) in mice. 3D reconstruction of dendritic spines in GCs aged 3-4 and 8-9 weeks revealed two different stages of dendritic spine development and unexpected features of synapse formation, including vacant and branched dendritic spines and presynaptic terminals establishing synapses with up to 10 dendritic spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner.

  14. FIB/SEM technology and high-throughput 3D reconstruction of dendritic spines and synapses in GFP-labeled adult-generated neurons

    PubMed Central

    Bosch, Carles; Martínez, Albert; Masachs, Nuria; Teixeira, Cátia M.; Fernaud, Isabel; Ulloa, Fausto; Pérez-Martínez, Esther; Lois, Carlos; Comella, Joan X.; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

    2015-01-01

    The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM) and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM) allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs) in mice. 3D reconstruction of dendritic spines in GCs aged 3–4 and 8–9 weeks revealed two different stages of dendritic spine development and unexpected features of synapse formation, including vacant and branched dendritic spines and presynaptic terminals establishing synapses with up to 10 dendritic spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner. PMID:26052271

  15. Essential role for vav Guanine nucleotide exchange factors in brain-derived neurotrophic factor-induced dendritic spine growth and synapse plasticity.

    PubMed

    Hale, Carly F; Dietz, Karen C; Varela, Juan A; Wood, Cody B; Zirlin, Benjamin C; Leverich, Leah S; Greene, Robert W; Cowan, Christopher W

    2011-08-31

    Brain-derived neurotrophic factor (BDNF) and its cognate receptor, TrkB, regulate a wide range of cellular processes, including dendritic spine formation and functional synapse plasticity. However, the signaling mechanisms that link BDNF-activated TrkB to F-actin remodeling enzymes and dendritic spine morphological plasticity remain poorly understood. We report here that BDNF/TrkB signaling in neurons activates the Vav family of Rac/RhoA guanine nucleotide exchange factors through a novel TrkB-dependent mechanism. We find that Vav is required for BDNF-stimulated Rac-GTP production in cortical and hippocampal neurons. Vav is partially enriched at excitatory synapses in the postnatal hippocampus but does not appear to be required for normal dendritic spine density. Rather, we observe significant reductions in both BDNF-induced, rapid, dendritic spine head growth and in CA3-CA1 theta burst-stimulated long-term potentiation in Vav-deficient mouse hippocampal slices, suggesting that Vav-dependent regulation of dendritic spine morphological plasticity facilitates normal functional synapse plasticity.

  16. Deletion of KIBRA, protein expressed in kidney and brain, increases filopodial-like long dendritic spines in neocortical and hippocampal neurons in vivo and in vitro

    PubMed Central

    Blanque, Anja; Repetto, Daniele; Rohlmann, Astrid; Brockhaus, Johannes; Duning, Kerstin; Pavenstädt, Hermann; Wolff, Ilka; Missler, Markus

    2015-01-01

    Spines are small protrusions arising from dendrites that receive most excitatory synaptic input in the brain. Dendritic spines represent dynamic structures that undergo activity-dependent adaptations, for example, during synaptic plasticity. Alterations of spine morphology, changes of spine type ratios or density have consequently been found in paradigms of learning and memory, and accompany many neuropsychiatric disorders. Polymorphisms in the gene encoding KIBRA, a protein present in kidney and brain, are linked to memory performance and cognition in humans and mouse models. Deletion of KIBRA impairs long-term synaptic plasticity and postsynaptic receptor recycling but no information is available on the morphology of dendritic spines in null-mutant mice. Here, we directly examine the role of KIBRA in spinous synapses using knockout mice. Since KIBRA is normally highly expressed in neocortex and hippocampus at juvenile age, we analyze synapse morphology in intact tissue and in neuronal cultures from these brain regions. Quantification of different dendritic spine types in Golgi-impregnated sections and in transfected neurons coherently reveal a robust increase of filopodial-like long protrusions in the absence of KIBRA. While distribution of pre- and postsynaptic marker proteins, overall synapse ultrastructure and density of asymmetric contacts were remarkably normal, electron microscopy additionally uncovered less perforated synapses and spinules in knockout neurons. Thus, our results indicate that KIBRA is involved in the maintenance of normal ratios of spinous synapses, and may thus provide a structural correlate of altered cognitive functions when this memory-associated molecule is mutated. PMID:25750616

  17. Myosin II ATPase activity mediates the long-term potentiation-induced exodus of stable F-actin bound by drebrin A from dendritic spines.

    PubMed

    Mizui, Toshiyuki; Sekino, Yuko; Yamazaki, Hiroyuki; Ishizuka, Yuta; Takahashi, Hideto; Kojima, Nobuhiko; Kojima, Masami; Shirao, Tomoaki

    2014-01-01

    The neuronal actin-binding protein drebrin A forms a stable structure with F-actin in dendritic spines. NMDA receptor activation causes an exodus of F-actin bound by drebrin A (DA-actin) from dendritic spines, suggesting a pivotal role for DA-actin exodus in synaptic plasticity. We quantitatively assessed the extent of DA-actin localization to spines using the spine-dendrite ratio of drebrin A in cultured hippocampal neurons, and found that (1) chemical long-term potentiation (LTP) stimulation induces rapid DA-actin exodus and subsequent DA-actin re-entry in dendritic spines, (2) Ca(2+) influx through NMDA receptors regulates the exodus and the basal accumulation of DA-actin, and (3) the DA-actin exodus is blocked by myosin II ATPase inhibitor, but is not blocked by myosin light chain kinase (MLCK) or Rho-associated kinase (ROCK) inhibitors. These results indicate that myosin II mediates the interaction between NMDA receptor activation and DA-actin exodus in LTP induction. Furthermore, myosin II seems to be activated by a rapid actin-linked mechanism rather than slow MLC phosphorylation. Thus the myosin-II mediated DA-actin exodus might be an initial event in LTP induction, triggering actin polymerization and spine enlargement.

  18. Association of Anxiety and Depression With Microtubule-Associated Protein 2– and Synaptopodin-Immunolabeled Dendrite and Spine Densities in Hippocampal CA3 of Older Humans

    PubMed Central

    Soetanto, Ainie; Wilson, Robert S.; Talbot, Konrad; Un, Ashley; Schneider, Julie A.; Sobiesk, Mark; Kelly, Jeremiah; Leurgans, Sue; Bennett, David A.; Arnold, Steven E.

    2010-01-01

    Context Chronic psychological distress has deleterious effects on many of the body’s physiological systems. In experimental animal models, chronic stress leads to neuroanatomic changes in the hippocampus, in particular a decrease in the length and branching of dendrites as well as a decrease in the number of dendritic spines. Objectives To examine whether analogous distress-related neuroanatomic changes occur in humans and whether such changes might also be related to cognitive dysfunction observed in older people who report greater psychological distress. Design Postmortem study of brain tissues from participants of the Religious Orders Study, an ongoing population-based clinicopathological study of aging and cognition. Setting The Rush University Religious Orders Study and the University of Pennsylvania Cellular and Molecular Neuropathology Program. Participants Seventy-two deceased participants of the Religious Orders Study. Main Outcome Measures Densities of microtubule-associated protein 2–immunolabeled dendrites and synaptopodin-immunolabeled dendritic spines in the CA3 subfield of the hippocampus, quantified using semiautomated image acquisition and analysis. Results Higher levels of trait anxiety and longitudinal depression scores were associated with decreased densities of dendrites and spines in CA3. Dendrite and spine densities did not correlate with an index of global cognition or with densities of common age-related pathological changes. Conclusions Regressive neuronal changes occur in humans who experience greater psychological distress. These changes are analogous to neuronal changes in animal models of chronic stress. PMID:20439826

  19. Effects of ethanol exposure and withdrawal on dendritic morphology and spine density in the nucleus accumbens core and shell.

    PubMed

    Peterson, Veronica L; McCool, Brian A; Hamilton, Derek A

    2015-01-12

    Exposure to drugs of abuse can result in profound structural modifications on neurons in circuits involved in addiction that may contribute to drug dependence, withdrawal and related processes. Structural alterations on medium spiny neurons (MSNs) of the nucleus accumbens (NAc) have been observed following exposure to and withdrawal from a variety of drugs; however, relatively little is known about the effects of alcohol exposure and withdrawal on structural alterations of NAc MSNs. In the present study male rats were chronically exposed to vaporized ethanol for 10 days and underwent 1 or 7 days of withdrawal after which the brains were processed for Golgi-Cox staining and analysis of dendritic length, branching and spine density. MSNs of the NAc shell and core underwent different patterns of changes following ethanol exposure and withdrawal. At 1 day of withdrawal there were modest reductions in the dendritic length and branching of MSNs in both the core and the shell compared to control animals exposed only to air. At 7 days of withdrawal the length and branching of shell MSNs was reduced, whereas the length and branching of core MSNs were increased relative to the shell. The density of mature spines was increased in the core at 1 day of withdrawal, whereas the density of less mature spines was increased in both regions at 7 days of withdrawal. Collectively, these observations indicate that MSNs of the NAc core and shell undergo distinct patterns of structural modifications following ethanol exposure and withdrawal suggesting that modifications in dendritic structure in these regions may contribute differentially to ethanol withdrawal.

  20. Serotonin 5-HT7 receptor increases the density of dendritic spines and facilitates synaptogenesis in forebrain neurons.

    PubMed

    Speranza, Luisa; Labus, Josephine; Volpicelli, Floriana; Guseva, Daria; Lacivita, Enza; Leopoldo, Marcello; Bellenchi, Gian Carlo; di Porzio, Umberto; Bijata, Monika; Perrone-Capano, Carla; Ponimaskin, Evgeni

    2017-01-25

    Precise control of dendritic spine density and synapse formation is critical for normal and pathological brain functions. Therefore, signaling pathways influencing dendrite outgrowth and remodeling remain a subject of extensive investigations. Here we report that prolonged activation of the serotonin 5-HT7 receptor (5-HT7R) with selective agonist LP-211 promotes formation of dendritic spines and facilitates synaptogenesis in postnatal cortical and striatal neurons. Critical role of 5-HT7R in neuronal morphogenesis was confirmed by analysis of neurons isolated from 5-HT7R-deficient mice and by pharmacological inactivation of the receptor. Acute activation of 5-HT7R results in pronounced neurite elongation in postnatal striatal and cortical neurons, thus extending previous data on the morphogenic role of 5-HT7R in embryonic and hippocampal neurons. We also observed decreased number of spines in neurons with either genetically (i.e. 5-HT7R-KO) or pharmacologically (i.e. antagonist treatment) blocked 5-HT7R, suggesting that constitutive 5-HT7R activity is critically involved in the spinogenesis. Moreover, cyclin-dependent kinase 5 (Cdk5) and small GTPase Cdc42 were identified as important downstream effectors mediating morphogenic effects of 5-HT7R in neurons. Altogether, our data suggest that the 5-HT7R-mediated structural reorganization during the postnatal development might have a crucial role for the development and plasticity of forebrain areas such as cortex and striatum, and thereby can be implicated in regulation of the higher cognitive functions. This article is protected by copyright. All rights reserved.

  1. Actin/alpha-actinin-dependent transport of AMPA receptors in dendritic spines: role of the PDZ-LIM protein RIL.

    PubMed

    Schulz, Torsten W; Nakagawa, Terunaga; Licznerski, Pawel; Pawlak, Verena; Kolleker, Alexander; Rozov, Andrei; Kim, Jinhyun; Dittgen, Tanjew; Köhr, Georg; Sheng, Morgan; Seeburg, Peter H; Osten, Pavel

    2004-09-29

    The efficacy of excitatory transmission in the brain depends to a large extent on synaptic AMPA receptors, hence the importance of understanding the delivery and recycling of the receptors at the synaptic sites. Here we report a novel regulation of the AMPA receptor transport by a PDZ (postsynaptic density-95/Drosophila disc large tumor suppressor zona occludens 1) and LIM (Lin11/rat Isl-1/Mec3) domain-containing protein, RIL (reversion-induced LIM protein). We show that RIL binds to the AMPA glutamate receptor subunit GluR-A C-terminal peptide via its LIM domain and to alpha-actinin via its PDZ domain. RIL is enriched in the postsynaptic density fraction isolated from rat forebrain, strongly localizes to dendritic spines in cultured neurons, and coprecipitates, together with alpha-actinin, in a protein complex isolated by immunoprecipitation of AMPA receptors from forebrain synaptosomes. Functionally, in heterologous cells, RIL links AMPA receptors to the alpha-actinin/actin cytoskeleton, an effect that appears to apply selectively to the endosomal surface-internalized population of the receptors. In cultured neurons, an overexpression of recombinant RIL increases the accumulation of AMPA receptors in dendritic spines, both at the total level, as assessed by immunodetection of endogenous GluR-A-containing receptors, and at the synaptic surface, as assessed by recording of miniature EPSCs. Our results thus indicate that RIL directs the transport of GluR-A-containing AMPA receptors to and/or within dendritic spines, in an alpha-actinin/actin-dependent manner, and that such trafficking function promotes the synaptic accumulation of the receptors.

  2. Modulation of dendritic spine development and plasticity by BDNF and vesicular trafficking: fundamental roles in neurodevelopmental disorders associated with mental retardation and autism.

    PubMed

    Chapleau, Christopher A; Larimore, Jennifer L; Theibert, Anne; Pozzo-Miller, Lucas

    2009-09-01

    The process of axonal and dendritic development establishes the synaptic circuitry of the central nervous system (CNS) and is the result of interactions between intrinsic molecular factors and the external environment. One growth factor that has a compelling function in neuronal development is the neurotrophin brain-derived neurotrophic factor (BDNF). BDNF participates in axonal and dendritic differentiation during embryonic stages of neuronal development, as well as in the formation and maturation of dendritic spines during postnatal development. Recent studies have also implicated vesicular trafficking of BDNF via secretory vesicles, and both secretory and endosomal trafficking of vesicles containing synaptic proteins, such as neurotransmitter and neurotrophin receptors, in the regulation of axonal and dendritic differentiation, and in dendritic spine morphogenesis. Several genes that are either mutated or deregulated in neurodevelopmental disorders associated with mental retardation have now been identified, and several mouse models of these disorders have been generated and characterized. Interestingly, abnormalities in dendritic and synaptic structure are consistently observed in human neurodevelopmental disorders associated with mental retardation, and in mouse models of these disorders as well. Abnormalities in dendritic and synaptic differentiation are thought to underlie altered synaptic function and network connectivity, thus contributing to the clinical outcome. Here, we review the roles of BDNF and vesicular trafficking in axonal and dendritic differentiation in the context of dendritic and axonal morphological impairments commonly observed in neurodevelopmental disorders associated with mental retardation.

  3. GALLIUM ARSENIDE DENDRITE SINGLE CRYSTAL PROGRAM

    DTIC Science & Technology

    ARSENIDES, *GALLIUM COMPOUNDS, *LABORATORY FURNACES, * SOLAR CELLS , CRUCIBLES, DESIGN, DIFFUSION, EXPLOSIONS, INTERMETALLIC COMPOUNDS, MATERIALS, PHOSPHORUS, SINGLE CRYSTALS, TEMPERATURE CONTROL, ZINC

  4. Early Postnatal Lesion of the Medial Dorsal Nucleus Leads to Loss of Dendrites and Spines in Adult Prefrontal Cortex

    PubMed Central

    Marmolejo, Naydu; Paez, Jesse; Levitt, Jonathan B.; Jones, Liesl B.

    2013-01-01

    Research suggests that the medial dorsal nucleus (MD) of the thalamus influences pyramidal cell development in the prefrontal cortex (PFC) in an activity-dependent manner. The MD is reciprocally connected to the PFC. Many psychiatric disorders, such as schizophrenia, affect the PFC, and one of the most consistent findings in schizophrenia is a decrease in volume and neuronal number in the MD. Therefore, understanding the role the MD plays in the development of the PFC is important and may help in understanding the progression of psychiatric disorders that have their root in development. Focusing on the interplay between the MD and the PFC, this study examined the hypothesis that the MD plays a role in the dendritic development of pyramidal cells in the PFC. Unilateral electrolytic lesions of the MD in Long-Evans rat pups were made on postnatal day 4 (P4), and the animals developed to P60. We then examined dendritic morphology by examining MAP2 immunostaining and by using Golgi techniques to determine basilar dendrite number and spine density. Additionally, we examined pyramidal cell density in cingulate area 1 (Cg1), prelimbic region, and dorsolateral anterior cortex, which receive afferents from the MD. Thalamic lesions caused a mean MD volume decrease of 12.4% which led to a significant decrease in MAP2 staining in both superficial and deep layers in all 3 cortical areas. The lesions also caused a significant decrease in spine density and in the number of primary and secondary basilar dendrites on superficial and deep layer pyramidal neurons in all 3 regions. No significant difference was observed in pyramidal cell density in any of the regions or layers, but a nonsignificant increase in cell density was observed in 2 regions. Our data are thus consistent with the hypothesis that the MD plays a role in the development of the PFC and, therefore, may be a good model to begin to examine neurodevelopmental disorders such as autism and schizophrenia. PMID:23406908

  5. Transactivation of TrkB by Sigma-1 receptor mediates cocaine-induced changes in dendritic spine density and morphology in hippocampal and cortical neurons

    PubMed Central

    Ka, Minhan; Kook, Yeon-Hee; Liao, Ke; Buch, Shilpa; Kim, Woo-Yang

    2016-01-01

    Cocaine is a highly addictive narcotic associated with dendritic spine plasticity in the striatum. However, it remains elusive whether cocaine modifies spines in a cell type-specific or region-specific manner or whether it alters different types of synapses in the brain. In addition, there is a paucity of data on the regulatory mechanism(s) involved in cocaine-induced modification of spine density. In the current study, we report that cocaine exposure differentially alters spine density, spine morphology, and the types of synapses in hippocampal and cortical neurons. Cocaine exposure in the hippocampus resulted in increased spine density, but had no significant effect on cortical neurons. Although cocaine exposure altered spine morphology in both cell types, the patterns of spine morphology were distinct for each cell type. Furthermore, we observed that cocaine selectively affects the density of excitatory synapses. Intriguingly, in hippocampal neurons cocaine-mediated effects on spine density and morphology involved sigma-1 receptor (Sig-1 R) and its downstream TrkB signaling, which were not the case in cortical neurons. Furthermore, pharmacological inhibition of Sig-1 R prevented cocaine-induced TrkB activation in hippocampal neurons. Our findings reveal a novel mechanism by which cocaine induces selective changes in spine morphology, spine density, and synapse formation, and could provide insights into the cellular basis for the cognitive impairment observed in cocaine addicts. PMID:27735948

  6. Dendritic Spines and Development: Towards a Unifying Model of Spinogenesis—A Present Day Review of Cajal's Histological Slides and Drawings

    PubMed Central

    García-López, Pablo; García-Marín, Virginia; Freire, Miguel

    2010-01-01

    Dendritic spines receive the majority of excitatory connections in the central nervous system, and, thus, they are key structures in the regulation of neural activity. Hence, the cellular and molecular mechanisms underlying their generation and plasticity, both during development and in adulthood, are a matter of fundamental and practical interest. Indeed, a better understanding of these mechanisms should provide clues to the development of novel clinical therapies. Here, we present original results obtained from high-quality images of Cajal's histological preparations, stored at the Cajal Museum (Instituto Cajal, CSIC), obtained using extended focus imaging, three-dimensional reconstruction, and rendering. Based on the data available in the literature regarding the formation of dendritic spines during development and our results, we propose a unifying model for dendritic spine development. PMID:21584262

  7. Single-Molecule Imaging of PSD-95 mRNA Translation in Dendrites and Its Dysregulation in a Mouse Model of Fragile X Syndrome.

    PubMed

    Ifrim, Marius F; Williams, Kathryn R; Bassell, Gary J

    2015-05-06

    Fragile X syndrome (FXS) is caused by the loss of the fragile X mental retardation protein (FMRP), an RNA binding protein that regulates translation of numerous target mRNAs, some of which are dendritically localized. Our previous biochemical studies using synaptoneurosomes demonstrate a role for FMRP and miR-125a in regulating the translation of PSD-95 mRNA. However, the local translation of PSD-95 mRNA within dendrites and spines, as well as the roles of FMRP or miR-125a, have not been directly studied. Herein, local synthesis of a Venus-PSD-95 fusion protein was directly visualized in dendrites and spines using single-molecule imaging of a diffusion-restricted Venus-PSD-95 reporter under control of the PSD-95 3'UTR. The basal translation rates of Venus-PSD-95 mRNA was increased in cultured hippocampal neurons from Fmr1 KO mice compared with WT neurons, which correlated with a transient elevation of endogenous PSD-95 within dendrites. Following mGluR stimulation with (S)-3,5-dihydroxyphenylglycine, the rate of Venus-PSD-95 mRNA translation increased rapidly in dendrites of WT hippocampal neurons, but not in those of Fmr1 KO neurons or when the binding site of miR125a, previously shown to bind PSD-95 3'UTR, was mutated. This study provides direct support for the hypothesis that local translation within dendrites and spines is dysregulated in FXS. Impairments in the regulated local synthesis of PSD-95, a critical regulator of synaptic structure and function, may affect the spatiotemporal control of PSD-95 levels and affect dendritic spine development and synaptic plasticity in FXS.

  8. FGF-2 deficiency causes dysregulation of Arhgef6 and downstream targets in the cerebral cortex accompanied by altered neurite outgrowth and dendritic spine morphology.

    PubMed

    Baum, Philip; Vogt, Miriam A; Gass, Peter; Unsicker, Klaus; von Bohlen und Halbach, Oliver

    2016-05-01

    Fibroblast growth factor 2 (FGF-2) is an abundant growth factor in the brain and exerts multiple functions on neural cells ranging from cell division, cell fate determination to differentiation. However, many details of the molecular mechanisms underlying the diverse functions of FGF-2 are poorly understood. In a comparative microarray analysis of motor sensory cortex (MSC) tissue of adult knockout (FGF-2(-/-)) and control (FGF-2(+/+)) mice, we found a substantial number of regulated genes, which are implicated in cytoskeletal machinery dynamics. Specifically, we found a prominent downregulation of Arhgef6. Arhgef6 mRNA was significantly reduced in the FGF-2(-/-) cortex, and Arhgef6 protein virtually absent, while RhoA protein levels were massively increased and Cdc42 protein levels were reduced. Since Arhgef6 is localized to dendritic spines, we next analyzed dendritic spines of adult FGF2(-/-) and control mouse cortices. Spine densities were significantly increased, whereas mean length of spines on dendrites of layer V of MSC neurons in adult FGF-2(-/-) mice was significantly decreased as compared to respective controls. Furthermore, neurite length in dissociated cortical cultures from E18 FGF-2(-/-) mice was significantly reduced at DIV7 as compared to wildtype neurons. Despite the fact that altered neuronal morphology and alterations in dendritic spines were observed, FGF-2(-/-) mice behave relatively unsuspicious in several behavioral tasks. However, FGF-2(-/-) mice exhibited decreased thermal pain sensitivity in the hotplate-test.

  9. Hdac Activity is Required for Bdnf to Increase Quantal Neurotransmitter Release and Dendritic Spine Density in CA1 Pyramidal Neurons

    PubMed Central

    Calfa, Gaston; Chapleau, Christopher A.; Campbell, Susan; Inoue, Takafumi; Morse, Sarah J.; Lubin, Farah D.; Pozzo-Miller, Lucas

    2012-01-01

    Molecular mechanisms involved in the strengthening and formation of synapses include the activation and repression of specific genes or subsets of genes by epigenetic modifications that do not alter the genetic code itself. Chromatin modifications mediated by histone acetylation have been shown to be critical for synaptic plasticity at hippocampal excitatory synapses and hippocampal-dependent memory formation. Considering that brain-derived neurotrophic factor (BDNF) plays an important role in synaptic plasticity and behavioral adaptations, it is not surprising that regulation of this gene is subject to histone acetylation changes during synaptic plasticity and hippocampal-dependent memory formation. Whether the effects of BDNF on dendritic spines and quantal transmitter release require histone modifications remains less known. By using two different inhibitors of histone deacetylases (HDAC), we describe here that their activity is required for BDNF to increase dendritic spine density and excitatory quantal transmitter release onto CA1 pyramidal neurons in hippocampal slice cultures. These results suggest that histone acetylation/deacetylation is a critical step in the modulation of hippocampal synapses by BDNF. Thus, mechanisms of epigenetic modulation of synapse formation and function are novel targets to consider for the amelioration of symptoms of intellectual disabilities and neurodegenerative disorders associated with cognitive and memory deficits. PMID:22161912

  10. Extracerebellar role for Cerebellin1: modulation of dendritic spine density and synapses in striatal medium spiny neurons.

    PubMed

    Kusnoor, S V; Parris, J; Muly, E C; Morgan, J I; Deutch, A Y

    2010-07-01

    Cerebellin1 (Cbln1) is a secreted glycoprotein that was originally isolated from the cerebellum and subsequently found to regulate synaptic development and stability. Cbln1 has a heterogeneous distribution in brain, but the only site in which it has been shown to have central effects is the cerebellar cortex, where loss of Cbln1 causes a reduction in granule cell-Purkinje cell synapses. Neurons of the thalamic parafascicular nucleus (PF), which provide glutamatergic projections to the striatum, also express high levels of Cbln1. We first examined Cbln1 in thalamostriatal neurons and then determined if cbln1 knockout mice exhibit structural deficits in striatal neurons. Virtually all PF neurons express Cbln1-immunoreactivity (-ir). In contrast, only rare Cbln1-ir neurons are present in the central medial complex, the other thalamic region that projects heavily to the dorsal striatum. In the striatum Cbln1-ir processes are apposed to medium spiny neuron (MSN) dendrites; ultrastructural studies revealed that Cbln1-ir axon terminals form axodendritic synapses with MSNs. Tract-tracing studies found that all PF cells retrogradely labeled from the striatum express Cbln1-ir. We then examined the dendritic structure of Golgi-impregnated MSNs in adult cbln1 knockout mice. MSN dendritic spine density was markedly increased in cbln1(-/-) mice relative to wildtype littermates, but total dendritic length was unchanged. Ultrastructural examination revealed an increase in the density of MSN axospinous synapses in cbln1(-/-) mice, with no change in postsynaptic density length. Thus, Cbln1 determines the dendritic structure of striatal MSNs, with effects distinct from those seen in the cerebellum.

  11. Enhanced dendritic spine number of neurons of the prefrontal cortex, hippocampus and nucleus accumbens in old rats after chronic donepezil administration

    PubMed Central

    Alcantara-Gonzalez, Faviola; Juarez, Ismael; Solis, Oscar; Martinez-Tellez, Isaura; Camacho-Abrego, Israel; Masliah, Eliezer; Mena, Raul; Flores, Gonzalo

    2010-01-01

    In Alzheimer's disease brains morphological changes in the dendrites of pyramidal neurons of the prefrontal cortex (PFC) and hippocampus have been observed. These changes are particularly reflected in the decrement of both the dendritic tree and spine number. Donepezil is a potent and selective acetylcholinesterase inhibitor used in the treatment of Alzheimer's disease. We have studied the effect of oral administration of this drug on the morphology of neuronal cells from the brain of aged rats. We examined dendrites of pyramidal neurons of the PFC, dorsal or ventral hippocampus and medium spiny neurons of the nucleus accumbens (NAcc). Donepezil (1 mg/Kg, vo) was administrated every day for 60 days to rats aged 10 and 18 months. Dendritic morphology was studied by the Golgi-Cox stain procedure followed by Sholl analysis at 12 and 20 months ages, respectively. In all Donepezil treated-rats a significant increment of the dendritic spines number in pyramidal neurons of the PFC, dorsal hippocampus was observed. However, pyramidal neurons of the ventral hippocampus and medium spiny cells of the NAcc only showed an increase in the number of their spines in 12 months old-rats. Our results suggest that Donepezil prevents the alterations of the neuronal dendrite morphology caused by aging. PMID:20336627

  12. Sustained expression of brain-derived neurotrophic factor is required for maintenance of dendritic spines and normal behavior.

    PubMed

    Vigers, A J; Amin, D S; Talley-Farnham, T; Gorski, J A; Xu, B; Jones, K R

    2012-06-14

    Brain-derived neurotrophic factor (BDNF) plays important roles in the development, maintenance, and plasticity of the mammalian forebrain. These functions include regulation of neuronal maturation and survival, axonal and dendritic arborization, synaptic efficacy, and modulation of complex behaviors including depression and spatial learning. Although analysis of mutant mice has helped establish essential developmental functions for BDNF, its requirement in the adult is less well documented. We have studied late-onset forebrain-specific BDNF knockout (CaMK-BDNF(KO)) mice, in which BDNF is lost primarily from the cortex and hippocampus in early adulthood, well after BDNF expression has begun in these structures. We found that although CaMK-BDNF(KO) mice grew at a normal rate and can survive more than a year, they had smaller brains than wild-type siblings. The CaMK-BDNF(KO) mice had generally normal behavior in tests for ataxia and anxiety, but displayed reduced spatial learning ability in the Morris water task and increased depression in the Porsolt swim test. These behavioral deficits were very similar to those we previously described in an early-onset forebrain-specific BDNF knockout. To identify an anatomical correlate of the abnormal behavior, we quantified dendritic spines in cortical neurons. The spine density of CaMK-BDNF(KO) mice was normal at P35, but by P84, there was a 30% reduction in spine density. The strong similarities we find between early- and late-onset BDNF knockouts suggest that BDNF signaling is required continuously in the CNS for the maintenance of some forebrain circuitry also affected by developmental BDNF depletion.

  13. Increased dendritic spine density and tau expression are associated with individual differences in steroidal regulation of male sexual behavior.

    PubMed

    Bharadwaj, Pranay; McInnis, Christine; Madden, Amanda M K; Bonthuis, Paul J; Zup, Susan; Rissman, Emilie F; Park, Jin Ho

    2013-01-01

    Male sexual behavior (MSB) is modulated by gonadal steroids, yet this relationship is highly variable across species and between individuals. A significant percentage (~30%) of B6D2F1 hybrid male mice demonstrate MSB after long-term orchidectomy (herein after referred to as "maters"), providing an opportunity to examine the mechanisms that underlie individual differences in steroidal regulation of MSB. Use of gene expression arrays comparing maters and non-maters has provided a first pass look at the genetic underpinnings of steroid-independent MSB. Surprisingly, of the ~500 genes in the medial preoptic area (MPOA) that differed between maters and non-maters, no steroid hormone or receptor genes were differentially expressed between the two groups. Interestingly, best known for their association with Alzheimer's disease, amyloid precursor protein (APP) and the microtubule-associated protein tau (MAPT) were elevated in maters. Increased levels of their protein products (APP and tau) in their non-pathological states have been implicated in cell survival, neuroprotection, and supporting synaptic integrity. Here we tested transgenic mice that overexpress tau and found facilitated mounting and intromission behavior after long-term orchidectomy relative to littermate controls. In addition, levels of synaptophysin and spinophilin, proteins generally enriched in synapses and dendritic spines respectively, were elevated in the MPOA of maters. Dendritic morphology was also assessed in Golgi-impregnated brains of orchidectomized B6D2F1 males, and hybrid maters exhibited greater dendritic spine density in MPOA neurons. In sum, we show for the first time that retention of MSB in the absence of steroids is correlated with morphological differences in neurons.

  14. Synaptic pruning in the female hippocampus is triggered at puberty by extrasynaptic GABAA receptors on dendritic spines

    PubMed Central

    Afroz, Sonia; Parato, Julie; Shen, Hui; Smith, Sheryl Sue

    2016-01-01

    Adolescent synaptic pruning is thought to enable optimal cognition because it is disrupted in certain neuropathologies, yet the initiator of this process is unknown. One factor not yet considered is the α4βδ GABAA receptor (GABAR), an extrasynaptic inhibitory receptor which first emerges on dendritic spines at puberty in female mice. Here we show that α4βδ GABARs trigger adolescent pruning. Spine density of CA1 hippocampal pyramidal cells decreased by half post-pubertally in female wild-type but not α4 KO mice. This effect was associated with decreased expression of kalirin-7 (Kal7), a spine protein which controls actin cytoskeleton remodeling. Kal7 decreased at puberty as a result of reduced NMDAR activation due to α4βδ-mediated inhibition. In the absence of this inhibition, Kal7 expression was unchanged at puberty. In the unpruned condition, spatial re-learning was impaired. These data suggest that pubertal pruning requires α4βδ GABARs. In their absence, pruning is prevented and cognition is not optimal. DOI: http://dx.doi.org/10.7554/eLife.15106.001 PMID:27136678

  15. An Automated Pipeline for Dendrite Spine Detection and Tracking of 3D Optical Microscopy Neuron Images of In Vivo Mouse Models

    PubMed Central

    Fan, Jing; Zhou, Xiaobo; Dy, Jennifer G.; Zhang, Yong; Wong, Stephen T. C.

    2009-01-01

    The variations in dendritic branch morphology and spine density provide insightful information about the brain function and possible treatment to neurodegenerative disease, for example investigating structural plasticity during the course of Alzheimer's disease. Most automated image processing methods aiming at analyzing these problems are developed for in vitro data. However, in vivo neuron images provide real time information and direct observation of the dynamics of a disease process in a live animal model. This paper presents an automated approach for detecting spines and tracking spine evolution over time with in vivo image data in an animal model of Alzheimer's disease. We propose an automated pipeline starting with curvilinear structure detection to determine the medial axis of the dendritic backbone and spines connected to the backbone. We, then, propose the adaptive local binary fitting (aLBF) energy level set model to accurately locate the boundary of dendritic structures using the central line of curvilinear structure as initialization. To track the growth or loss of spines, we present a maximum likelihood based technique to find the graph homomorphism between two image graph structures at different time points. We employ dynamic programming to search for the optimum solution. The pipeline enables us to extract dynamically changing information from real time in vivo data. We validate our proposed approach by comparing with manual results generated by neurologists. In addition, we discuss the performance of 3D based segmentation and conclude that our method is more accurate in identifying weak spines. Experiments show that our approach can quickly and accurately detect and quantify spines of in vivo neuron images and is able to identify spine elimination and formation. PMID:19434521

  16. Long-term study of dendritic spines from hippocampal CA1 pyramidal cells, after neuroprotective melatonin treatment following global cerebral ischemia in rats.

    PubMed

    González-Burgos, Ignacio; Letechipía-Vallejo, Graciela; López-Loeza, Elisa; Moralí, Gabriela; Cervantes, Miguel

    2007-08-16

    Melatonin reduces pyramidal neuronal death in the hippocampus and prevents the impairment of place learning and memory in the Morris water maze, otherwise occurring following global cerebral ischemia. The cytoarchitectonic characteristics of the hippocampal CA1 remaining pyramidal neurons in brains of rats submitted 120 days earlier to acute global cerebral ischemia (15-min four vessel occlusion, and melatonin 10mg/(kg h 6h), i.v. or vehicle administration) were compared to those of intact control rats in order to gain information concerning the neural substrate underlying preservation of hippocampal functioning. Hippocampi were processed according to a modification of the Golgi method. Dendritic bifurcations from pyramidal neurons in both the oriens-alveus and the striatum radiatum; as well as spine density and proportions of thin, stubby, mushroom-shaped, wide, ramified, and double spines in a 50 microm length segment of an oblique dendrite branching from the apical dendrite of the hippocampal CA1 remaining pyramidal neurons were evaluated. No impregnated CA1 pyramidal neurons were found in the ischemic-vehicle-treated rats. CA1 pyramidal neurons from ischemic-melatonin-treated rats showed stick-like and less ramified dendrites than those seen in intact control neurons. In addition, lesser density of spines, lower proportional density of thin spines, and higher proportional density of mushroom spines were counted in ischemic-melatonin-treated animals than those in the sinuously branched dendrites of the intact control group. These cytoarchitectural arrangements seem to be compatible with place learning and memory functions long after ischemia and melatonin neuroprotection.

  17. Reversible reduction in dendritic spines in CA1 of rat and ground squirrel subjected to hypothermia-normothermia in vivo: A three-dimensional electron microscope study.

    PubMed

    Popov, V I; Medvedev, N I; Patrushev, I V; Ignat'ev, D A; Morenkov, E D; Stewart, M G

    2007-11-09

    A study was made at electron microscope level of changes in the three-dimensional (3-D) morphology of dendritic spines and postsynaptic densities (PSDs) in CA1 of the hippocampus in ground squirrels, taken either at low temperature during hibernation (brain temperature 2-4 degrees C), or after warming and recovery to the normothermic state (34 degrees C). In addition, the morphology of PSDs and spines was measured in a non-hibernating mammal, rat, subjected to cooling at 2 degrees C at which time core rectal temperature was 15 degrees C, and then after warming to normothermic conditions. Significant differences were found in the proportion of thin and stubby spines, and shaft synapses in CA1 for rats and ground squirrels for normothermia compared with cooling or hibernation. Hypothermia induced a decrease in the proportion of thin spines, and an increase in stubby and shaft spines, but no change in the proportion of mushroom spines. The changes in redistribution of these three categories of spines in ground squirrel are more prominent than in rat. There were no significant differences in synapse density determined for ground squirrels or rats at normal compared with low temperature. Measurement of spine and PSD volume (for mushroom and thin spines) also showed no significant differences between the two functional states in either rats or ground squirrels, nor were there any differences in distances between neighboring synapses. Spinules on dendritic shafts were notable qualitatively during hibernation, but absent in normothermia. These data show that hypothermia results in morphological changes which are essentially similar in both a hibernating and a non-hibernating animal.

  18. Fluoxetine induces input-specific hippocampal dendritic spine remodeling along the septo-temporal axis in adulthood and middle age

    PubMed Central

    McAvoy, Kathleen; Russo, Craig; Kim, Shannen; Rankin, Genelle; Sahay, Amar

    2015-01-01

    Fluoxetine, a selective serotonin-reuptake inhibitor (SSRI), is known to induce structural rearrangements and changes in synaptic transmission in hippocampal circuitry. In the adult hippocampus, structural changes include neurogenesis, dendritic and axonal plasticity of pyramidal and dentate granule neurons, and dedifferentiation of dentate granule neurons. However, much less is known about how chronic fluoxetine affects these processes along the septo-temporal axis and during the aging process. Importantly, studies documenting the effects of fluoxetine on density and distribution of spines along different dendritic segments of dentate granule neurons and CA1 pyramidal neurons along the septo-temporal axis of hippocampus in adulthood and during aging are conspicuously absent. Here, we use a transgenic mouse line in which mature dentate granule neurons and CA1 pyramidal neurons are genetically labeled with green fluorescent protein (GFP) to investigate the effects of chronic fluoxetine treatment (18mg/kg/day) on input-specific spine remodeling and mossy fiber structural plasticity in the dorsal and ventral hippocampus in adulthood and middle age. In addition, we examine levels of adult hippocampal neurogenesis, maturation state of dentate granule neurons, neuronal activity and glutamic acid decarboxylase-67 expression in response to chronic fluoxetine in adulthood and middle age. Our studies reveal that while chronic fluoxetine fails to augment adult hippocampal neurogenesis in middle age, the middle-aged hippocampus retains high sensitivity to changes in the dentate gyrus (DG) such as dematuration, hypoactivation, and increased glutamic acid decarboxylase 67 (GAD67) expression. Interestingly, the middle-aged hippocampus shows greater sensitivity to fluoxetine-induced input-specific synaptic remodeling than the hippocampus in adulthood with the stratum-oriens of CA1 exhibiting heightened structural plasticity. The input-specific changes and circuit

  19. Fluoxetine induces input-specific hippocampal dendritic spine remodeling along the septotemporal axis in adulthood and middle age.

    PubMed

    McAvoy, Kathleen; Russo, Craig; Kim, Shannen; Rankin, Genelle; Sahay, Amar

    2015-11-01

    Fluoxetine, a selective serotonin-reuptake inhibitor (SSRI), is known to induce structural rearrangements and changes in synaptic transmission in hippocampal circuitry. In the adult hippocampus, structural changes include neurogenesis, dendritic, and axonal plasticity of pyramidal and dentate granule neurons, and dedifferentiation of dentate granule neurons. However, much less is known about how chronic fluoxetine affects these processes along the septotemporal axis and during the aging process. Importantly, studies documenting the effects of fluoxetine on density and distribution of spines along different dendritic segments of dentate granule neurons and CA1 pyramidal neurons along the septotemporal axis of hippocampus in adulthood and during aging are conspicuously absent. Here, we use a transgenic mouse line in which mature dentate granule neurons and CA1 pyramidal neurons are genetically labeled with green fluorescent protein (GFP) to investigate the effects of chronic fluoxetine treatment (18 mg/kg/day) on input-specific spine remodeling and mossy fiber structural plasticity in the dorsal and ventral hippocampus in adulthood and middle age. In addition, we examine levels of adult hippocampal neurogenesis, maturation state of dentate granule neurons, neuronal activity, and glutamic acid decarboxylase-67 expression in response to chronic fluoxetine in adulthood and middle age. Our studies reveal that while chronic fluoxetine fails to augment adult hippocampal neurogenesis in middle age, the middle-aged hippocampus retains high sensitivity to changes in the dentate gyrus (DG) such as dematuration, hypoactivation, and increased glutamic acid decarboxylase 67 (GAD67) expression. Interestingly, the middle-aged hippocampus shows greater sensitivity to fluoxetine-induced input-specific synaptic remodeling than the hippocampus in adulthood with the stratum-oriens of CA1 exhibiting heightened structural plasticity. The input-specific changes and circuit

  20. Chemical genetic identification of NDR1/2 kinase substrates AAK1 and Rabin8 uncovers their roles in controlling dendrite arborization and spine development

    PubMed Central

    Ultanir, Sila K.; Hertz, Nicholas T.; Li, Guangnan; Ge, Woo-Ping; Burlingame, Alma L.; Pleasure, Samuel J.; Shokat, Kevan M.; Jan, Lily Yeh; Jan, Yuh-Nung

    2012-01-01

    Summary Dendrite arborization and synapse formation are essential for wiring the neural circuitry. The evolutionarily conserved NDR1/2 kinase pathway, important for polarized growth from yeast to mammals, controls dendrite growth and morphology in worm and fly. Whether NDR1/2 kinases regulate dendrite and synapse development in mammals was not known. Nor have their phosphorylation targets been identified. Here we show that expression of dominant negative (kinase dead) NDR1/2 mutants or siRNA increase dendrite length and proximal branching of mammalian pyramidal neurons in cultures and in vivo, whereas expression of constitutively active NDR1/2 has the opposite effects. Moreover, NDR1/2 contributes to dendritic spine development and excitatory synaptic function. We further employed chemical genetics and identified NDR1/2 substrates in the brain, including two proteins involved in intracellular vesicle trafficking: AAK1 (AP-2 associated kinase) and Rabin8, a GDP/GTP exchange factor (GEF) of Rab8 GTPase. We finally show that AAK1 contributes to dendrite growth regulation and Rabin8 regulates spine development. PMID:22445341

  1. Unilateral injection of Aβ25-35 in the hippocampus reduces the number of dendritic spines in hyperglycemic rats.

    PubMed

    Lazcano, Zayda; Solis, Oscar; Bringas, María Elena; Limón, Daniel; Diaz, Alfonso; Espinosa, Blanca; García-Peláez, Isabel; Flores, Gonzalo; Guevara, Jorge

    2014-07-22

    Alzheimer's disease (AD) is a neurodegenerative process exacerbated by several risk factors including impaired glucose metabolism in the brain that could cause molecular and neurochemical alterations in cognitive regions such as the hippocampus (Hp). Consequently, this process could cause neuronal morphological changes; however, the mechanism remains elusive. We induced chronic hyperglycemia after streptozotocin (STZ) administration. Then, we examined spatial learning and memory using the Morris water maze test and evaluated neuronal morphological changes using the Golgi-Cox stain procedure in hyperglycemic rats that received a Aβ25-35 unilateral injection into the Hp. Our results demonstrate that STZ combined with Aβ25-35 induced significant deficits in the spatial memory. In addition, we observed a significant reduction in the number of dendritic spines of pyramidal neurons in the dorsal Hp of rats with STZ plus Aβ25-35 . In conclusion, the reduced spine density of pyramidal neurons in the CA1 dorsal Hp could produce the spatial memory deficit observed in these animals. These results suggest that hyperglycemia can trigger Aβ-induced neurodegeneration and thus the appearance of AD symptoms would be accelerated. Synapse, 2014. © 2014 Wiley Periodicals, Inc.

  2. The NAP motif of activity-dependent neuroprotective protein (ADNP) regulates dendritic spines through microtubule end binding proteins.

    PubMed

    Oz, S; Kapitansky, O; Ivashco-Pachima, Y; Malishkevich, A; Giladi, E; Skalka, N; Rosin-Arbesfeld, R; Mittelman, L; Segev, O; Hirsch, J A; Gozes, I

    2014-10-01

    The NAP motif of activity-dependent neuroprotective protein (ADNP) enhanced memory scores in patients suffering from mild cognitive impairment and protected activities of daily living in schizophrenia patients, while fortifying microtubule (MT)-dependent axonal transport, in mice and flies. The question is how does NAP fortify MTs? Our sequence analysis identified the MT end-binding protein (EB1)-interacting motif SxIP (SIP, Ser-Ile-Pro) in ADNP/NAP and showed specific SxIP binding sites in all members of the EB protein family (EB1-3). Others found that EB1 enhancement of neurite outgrowth is attenuated by EB2, while EB3 interacts with postsynaptic density protein 95 (PSD-95) to modulate dendritic plasticity. Here, NAP increased PSD-95 expression in dendritic spines, which was inhibited by EB3 silencing. EB1 or EB3, but not EB2 silencing inhibited NAP-mediated cell protection, which reflected NAP binding specificity. NAPVSKIPQ (SxIP=SKIP), but not NAPVAAAAQ mimicked NAP activity. ADNP, essential for neuronal differentiation and brain formation in mouse, a member of the SWI/SNF chromatin remodeling complex and a major protein mutated in autism and deregulated in schizophrenia in men, showed similar EB interactions, which were enhanced by NAP treatment. The newly identified shared MT target of NAP/ADNP is directly implicated in synaptic plasticity, explaining the breadth and efficiency of neuroprotective/neurotrophic capacities.

  3. Reelin Supplementation Enhances Cognitive Ability, Synaptic Plasticity, and Dendritic Spine Density

    ERIC Educational Resources Information Center

    Rogers, Justin T.; Rusiana, Ian; Trotter, Justin; Zhao, Lisa; Donaldson, Erika; Pak, Daniel T.S.; Babus, Lenard W.; Peters, Melinda; Banko, Jessica L.; Chavis, Pascale; Rebeck, G. William; Hoe, Hyang-Sook; Weeber, Edwin J.

    2011-01-01

    Apolipoprotein receptors belong to an evolutionarily conserved surface receptor family that has intimate roles in the modulation of synaptic plasticity and is necessary for proper hippocampal-dependent memory formation. The known lipoprotein receptor ligand Reelin is important for normal synaptic plasticity, dendritic morphology, and cognitive…

  4. Association of N-cadherin levels and downstream effectors of Rho GTPases with dendritic spine loss induced by chronic stress in rat hippocampal neurons.

    PubMed

    Castañeda, Patricia; Muñoz, Mauricio; García-Rojo, Gonzalo; Ulloa, José L; Bravo, Javier A; Márquez, Ruth; García-Pérez, M Alexandra; Arancibia, Damaris; Araneda, Karina; Rojas, Paulina S; Mondaca-Ruff, David; Díaz-Véliz, Gabriela; Mora, Sergio; Aliaga, Esteban; Fiedler, Jenny L

    2015-10-01

    Chronic stress promotes cognitive impairment and dendritic spine loss in hippocampal neurons. In this animal model of depression, spine loss probably involves a weakening of the interaction between pre- and postsynaptic cell adhesion molecules, such as N-cadherin, followed by disruption of the cytoskeleton. N-cadherin, in concert with catenin, stabilizes the cytoskeleton through Rho-family GTPases. Via their effector LIM kinase (LIMK), RhoA and ras-related C3 botulinum toxin substrate 1 (RAC) GTPases phosphorylate and inhibit cofilin, an actin-depolymerizing molecule, favoring spine growth. Additionally, RhoA, through Rho kinase (ROCK), inactivates myosin phosphatase through phosphorylation of the myosin-binding subunit (MYPT1), producing actomyosin contraction and probable spine loss. Some micro-RNAs negatively control the translation of specific mRNAs involved in Rho GTPase signaling. For example, miR-138 indirectly activates RhoA, and miR-134 reduces LIMK1 levels, resulting in spine shrinkage; in contrast, miR-132 activates RAC1, promoting spine formation. We evaluated whether N-cadherin/β-catenin and Rho signaling is sensitive to chronic restraint stress. Stressed rats exhibit anhedonia, impaired associative learning, and immobility in the forced swim test and reduction in N-cadherin levels but not β-catenin in the hippocampus. We observed a reduction in spine number in the apical dendrites of CA1 pyramidal neurons, with no effect on the levels of miR-132 or miR-134. Although the stress did not modify the RAC-LIMK-cofilin signaling pathway, we observed increased phospho-MYPT1 levels, probably mediated by RhoA-ROCK activation. Furthermore, chronic stress raises the levels of miR-138 in accordance with the observed activation of the RhoA-ROCK pathway. Our findings suggest that a dysregulation of RhoA-ROCK activity by chronic stress could potentially underlie spine loss in hippocampal neurons.

  5. Chronic stimulation of alpha-2A-adrenoceptors with guanfacine protects rodent prefrontal cortex dendritic spines and cognition from the effects of chronic stress

    PubMed Central

    Hains, Avis Brennan; Yabe, Yoko; Arnsten, Amy F.T.

    2015-01-01

    The prefrontal cortex (PFC) provides top-down regulation of behavior, cognition, and emotion, including spatial working memory. However, these PFC abilities are greatly impaired by exposure to acute or chronic stress. Chronic stress exposure in rats induces atrophy of PFC dendrites and spines that correlates with working memory impairment. As similar PFC grey matter loss appears to occur in mental illness, the mechanisms underlying these changes need to be better understood. Acute stress exposure impairs PFC cognition by activating feedforward cAMP-calcium- K+ channel signaling, which weakens synaptic inputs and reduces PFC neuronal firing. Spine loss with chronic stress has been shown to involve calcium-protein kinase C signaling, but it is not known if inhibiting cAMP signaling would similarly prevent the atrophy induced by repeated stress. The current study examined whether inhibiting cAMP signaling through alpha-2A-adrenoceptor stimulation with chronic guanfacine treatment would protect PFC spines and working memory performance during chronic stress exposure. Guanfacine was selected due to 1) its established effects on cAMP signaling at post-synaptic alpha-2A receptors on spines in PFC, and 2) its increasing clinical use for the treatment of pediatric stress disorders. Daily guanfacine treatment compared to vehicle control was found to prevent dendritic spine loss in layer II/III pyramidal neurons of prelimbic PFC in rats exposed to chronic restraint stress. Guanfacine also protected working memory performance; cognitive performance correlated with dendritic spine density. These findings suggest that chronic guanfacine use may have clinical utility by protecting PFC gray matter from the detrimental effects of stress. PMID:25664335

  6. Beyond counts and shapes: studying pathology of dendritic spines in the context of the surrounding neuropil through serial section electron microscopy.

    PubMed

    Kuwajima, M; Spacek, J; Harris, K M

    2013-10-22

    Because dendritic spines are the sites of excitatory synapses, pathological changes in spine morphology should be considered as part of pathological changes in neuronal circuitry in the forms of synaptic connections and connectivity strength. In the past, spine pathology has usually been measured by changes in their number or shape. A more complete understanding of spine pathology requires visualization at the nanometer level to analyze how the changes in number and size affect their presynaptic partners and associated astrocytic processes, as well as organelles and other intracellular structures. Currently, serial section electron microscopy (ssEM) offers the best approach to address this issue because of its ability to image the volume of brain tissue at the nanometer resolution. Renewed interest in ssEM has led to recent technological advances in imaging techniques and improvements in computational tools indispensable for three-dimensional analyses of brain tissue volumes. Here we consider the small but growing literature that has used ssEM analysis to unravel ultrastructural changes in neuropil including dendritic spines. These findings have implications in altered synaptic connectivity and cell biological processes involved in neuropathology, and serve as anatomical substrates for understanding changes in network activity that may underlie clinical symptoms.

  7. Chemical genetic identification of NDR1/2 kinase substrates AAK1 and Rabin8 Uncovers their roles in dendrite arborization and spine development.

    PubMed

    Ultanir, Sila K; Hertz, Nicholas T; Li, Guangnan; Ge, Woo-Ping; Burlingame, Alma L; Pleasure, Samuel J; Shokat, Kevan M; Jan, Lily Yeh; Jan, Yuh-Nung

    2012-03-22

    Dendrite arborization and synapse formation are essential for wiring the neural circuitry. The evolutionarily conserved NDR1/2 kinase pathway, important for polarized growth from yeast to mammals, controls dendrite growth and morphology in the worm and fly. The function of NDR1/2 in mammalian neurons and their downstream effectors were not known. Here we show that the expression of dominant negative (kinase-dead) NDR1/2 mutants or siRNA increase dendrite length and proximal branching of mammalian pyramidal neurons in cultures and in vivo, whereas the expression of constitutively active NDR1/2 has the opposite effect. Moreover, NDR1/2 contributes to dendritic spine development and excitatory synaptic function. We further employed chemical genetics and identified NDR1/2 substrates in the brain, including two proteins involved in intracellular vesicle trafficking: AAK1 (AP-2 associated kinase) and Rabin8, a GDP/GTP exchange factor (GEF) of Rab8 GTPase. We finally show that AAK1 contributes to dendrite growth regulation, and Rabin8 regulates spine development.

  8. Reduced Hippocampal Dendritic Spine Density and BDNF Expression following Acute Postnatal Exposure to Di(2-Ethylhexyl) Phthalate in Male Long Evans Rats

    PubMed Central

    Smith, Catherine A.; Holahan, Matthew R.

    2014-01-01

    Early developmental exposure to di(2-ethylhexyl) phthalate (DEHP) has been linked to a variety of neurodevelopmental changes, particularly in rodents. The primary goal of this work was to establish whether acute postnatal exposure to a low dose of DEHP would alter hippocampal dendritic morphology and BDNF and caspase-3 mRNA expression in male and female Long Evans rats. Treatment with DEHP in male rats led to a reduction in spine density on basal and apical dendrites of neurons in the CA3 dorsal hippocampal region compared to vehicle-treated male controls. Dorsal hippocampal BDNF mRNA expression was also down-regulated in male rats exposed to DEHP. No differences in hippocampal spine density or BDNF mRNA expression were observed in female rats treated with DEHP compared to controls. DEHP treatment did not affect hippocampal caspase-3 mRNA expression in male or female rats. These results suggest a gender-specific vulnerability to early developmental DEHP exposure in male rats whereby postnatal DEHP exposure may interfere with normal synaptogenesis and connectivity in the hippocampus. Decreased expression of BDNF mRNA may represent a molecular mechanism underlying the reduction in dendritic spine density observed in hippocampal CA3 neurons. These findings provide initial evidence for a link between developmental exposure to DEHP, reduced levels of BDNF and hippocampal atrophy in male rats. PMID:25295592

  9. Late-Postnatal Cannabinoid Exposure Persistently Elevates Dendritic Spine Densities in Area X and HVC Song Regions of Zebra Finch Telencephalon

    PubMed Central

    Gilbert, Marcoita T.; Soderstrom, Ken

    2011-01-01

    Centrally acting cannabinoids are well known for their ability to impair functions associated with both learning and memory but appreciation of the physiological mechanisms underlying these actions, particularly those that persist, remains incomplete. Our earlier studies have shown that song stereotypy is persistently reduced in male zebra finches that have been developmentally exposed to cannabinoids. In the present work, we examined the extent to which changes in neuronal morphology (dendritic spine densities and soma size) within brain regions associated with zebra finch vocal learning are affected by late-postnatal cannabinoid agonist exposure. We found that daily treatment with the cannabinoid agonist WIN55212-2 (WIN, 1 mg/kg IM) is associated with 27 % and 31 % elevations in dendritic spine densities in the song regions Area X and HVC, respectively. We also found an overall increase in cell diameter within HVC. Changes in dendritic spine densities were only produced following developmental exposure; treatments given to adults that had completed vocal learning were not effective. These findings have important implications for understanding how repeated cannabinoid exposure can produce significant, lasting alteration of brain morphology, which may contribute to altered development and behavior. PMID:21737064

  10. Chronic treatment with valproic acid or sodium butyrate attenuates novel object recognition deficits and hippocampal dendritic spine loss in a mouse model of autism.

    PubMed

    Takuma, Kazuhiro; Hara, Yuta; Kataoka, Shunsuke; Kawanai, Takuya; Maeda, Yuko; Watanabe, Ryo; Takano, Erika; Hayata-Takano, Atsuko; Hashimoto, Hitoshi; Ago, Yukio; Matsuda, Toshio

    2014-11-01

    We recently showed that prenatal exposure to valproic acid (VPA) in mice causes autism-like behavioral abnormalities, including social interaction deficits, anxiety-like behavior and spatial learning disability, in male offspring. In the present study, we examined the effect of prenatal VPA on cognitive function and whether the effect is improved by chronic treatment with VPA and sodium butyrate, histone deacetylase inhibitors. In addition, we examined whether the cognitive dysfunction is associated with hippocampal dendritic morphological changes. Mice given prenatal exposure to VPA exhibited novel object recognition deficits at 9 weeks of age, and that the impairment was blocked by chronic (5-week) treatment with VPA (30 mg/kg/d, i.p.) or sodium butyrate (1.2g/kg/d, i.p.) starting at 4 weeks of age. In agreement with the behavioral findings, the mice prenatally exposed to VPA showed a decrease in dendritic spine density in the hippocampal CA1 region, and the spine loss was attenuated by chronic treatment with sodium butyrate or VPA. Furthermore, acute treatment with sodium butyrate, but not VPA, significantly increased acetylation of histone H3 in the hippocampus at 30 min, suggesting the difference in the mechanism for the effects of chronic VPA and sodium butyrate. These findings suggest that prenatal VPA-induced cognitive dysfunction is associated with changes in hippocampal dendritic spine morphology.

  11. Reduced hippocampal dendritic spine density and BDNF expression following acute postnatal exposure to di(2-ethylhexyl) phthalate in male Long Evans rats.

    PubMed

    Smith, Catherine A; Holahan, Matthew R

    2014-01-01

    Early developmental exposure to di(2-ethylhexyl) phthalate (DEHP) has been linked to a variety of neurodevelopmental changes, particularly in rodents. The primary goal of this work was to establish whether acute postnatal exposure to a low dose of DEHP would alter hippocampal dendritic morphology and BDNF and caspase-3 mRNA expression in male and female Long Evans rats. Treatment with DEHP in male rats led to a reduction in spine density on basal and apical dendrites of neurons in the CA3 dorsal hippocampal region compared to vehicle-treated male controls. Dorsal hippocampal BDNF mRNA expression was also down-regulated in male rats exposed to DEHP. No differences in hippocampal spine density or BDNF mRNA expression were observed in female rats treated with DEHP compared to controls. DEHP treatment did not affect hippocampal caspase-3 mRNA expression in male or female rats. These results suggest a gender-specific vulnerability to early developmental DEHP exposure in male rats whereby postnatal DEHP exposure may interfere with normal synaptogenesis and connectivity in the hippocampus. Decreased expression of BDNF mRNA may represent a molecular mechanism underlying the reduction in dendritic spine density observed in hippocampal CA3 neurons. These findings provide initial evidence for a link between developmental exposure to DEHP, reduced levels of BDNF and hippocampal atrophy in male rats.

  12. CaMKII-dependent dendrite ramification and spine generation promote spatial training-induced memory improvement in a rat model of sporadic Alzheimer's disease.

    PubMed

    Jiang, Xia; Chai, Gao-Shang; Wang, Zhi-Hao; Hu, Yu; Li, Xiao-Guang; Ma, Zhi-Wei; Wang, Qun; Wang, Jian-Zhi; Liu, Gong-Ping

    2015-02-01

    Participation in cognitively stimulating activities can preserve memory capacities in patients with Alzheimer's disease (AD), but the mechanism is not fully understood. Here, we used a rat model with hyperhomocysteinemia, an independent risk factor of AD, to study whether spatial training could remodel the synaptic and/or dendritic plasticity and the key molecular target(s) involved. We found that spatial training in water maze remarkably improved the subsequent short-term and long-term memory performance in contextual fear conditioning and Barnes maze. The trained rats showed an enhanced dendrite ramification, spine generation and plasticity in dentate gyrus (DG) neurons, and stimulation of long-term potentiation between perforant path and DG circuit. Spatial training also increased the levels of postsynaptic GluA1, GluN2A, GluN2B, and PSD93 with selective activation of calcium/calmodulin-dependent protein kinase II (CaMKII), although inhibition of CaMKII by stereotaxic injection of KN93 into hippocampal DG, abolished the training-induced cognitive improvement, dendrite ramification, and spine generation. We conclude that spatial training can preserve the cognitive function by CaMKII-dependent remodeling of dendritic plasticity in hyperhomocysteinemia-induced sporadic AD-like rats.

  13. Hyperforin modulates dendritic spine morphology in hippocampal pyramidal neurons by activating Ca(2+) -permeable TRPC6 channels.

    PubMed

    Leuner, Kristina; Li, Wei; Amaral, Michelle D; Rudolph, Stephanie; Calfa, Gaston; Schuwald, Anita M; Harteneck, Christian; Inoue, Takafumi; Pozzo-Miller, Lucas

    2013-01-01

    The standardized extract of the St. John's wort plant (Hypericum perforatum) is commonly used to treat mild to moderate depression. Its active constituent is hyperforin, a phloroglucinol derivative that reduces the reuptake of serotonin and norepinephrine by increasing intracellular Na(+) concentration through the activation of nonselective cationic TRPC6 channels. TRPC6 channels are also Ca(2+) -permeable, resulting in intracellular Ca(2+) elevations. Indeed, hyperforin activates TRPC6-mediated currents and Ca(2+) transients in rat PC12 cells, which induce their differentiation, mimicking the neurotrophic effect of nerve growth factor. Here, we show that hyperforin modulates dendritic spine morphology in CA1 and CA3 pyramidal neurons of hippocampal slice cultures through the activation of TRPC6 channels. Hyperforin also evoked intracellular Ca(2+) transients and depolarizing inward currents sensitive to the TRPC channel blocker La(3+) , thus resembling the actions of the neurotrophin brain-derived neurotrophic factor (BDNF) in hippocampal pyramidal neurons. These results suggest that the antidepressant actions of St. John's wort are mediated by a mechanism similar to that engaged by BDNF.

  14. HYPERFORIN MODULATES DENDRITIC SPINE MORPHOLOGY IN HIPPOCAMPAL PYRAMIDAL NEURONS BY ACTIVATING Ca2+-PERMEABLE TRPC6 CHANNELS

    PubMed Central

    Leuner, Kristina; Li, Wei; Amaral, Michelle D.; Rudolph, Stephanie; Calfa, Gaston; Schuwald, Anita M.; Harteneck, Christian; Inoue, Takafumi; Pozzo-Miller, Lucas

    2012-01-01

    The standardized extract of the St. John’s wort plant (Hypericum perforatum) is commonly used to treat mild to moderate depression. Its active constituent is hyperforin, a phloroglucinol derivative that reduces the reuptake of serotonin and norepinephrine by increasing intracellular Na+ concentration through the activation of non-selective cationic TRPC6 channels. TRPC6 channels are also Ca2+-permeable, resulting in intracellular Ca2+ elevations. Indeed, hyperforin activates TRPC6-mediated currents and Ca2+ transients in rat PC12 cells, which induce their differentiation, mimicking the neurotrophic effect of NGF. Here, we show that hyperforin modulates dendritic spine morphology in CA1 and CA3 pyramidal neurons of hippocampal slice cultures through the activation of TRPC6 channels. Hyperforin also evoked intracellular Ca2+ transients and depolarizing inward currents sensitive to the TRPC channel blocker La3+, thus resembling the actions of the neurotrophin BDNF in hippocampal pyramidal neurons. These results suggest that the antidepressant actions of St. John’s wort are mediated by a mechanism similar to that engaged by BDNF. PMID:22815087

  15. Chronic oestradiol reduces the dendritic spine density of KNDy (kisspeptin/neurokinin B/dynorphin) neurones in the arcuate nucleus of ovariectomised Tac2-enhanced green fluorescent protein transgenic mice.

    PubMed

    Cholanian, M; Krajewski-Hall, S J; McMullen, N T; Rance, N E

    2015-04-01

    Neurones in the arcuate nucleus that express neurokinin B (NKB), kisspeptin and dynorphin (KNDy) play an important role in the reproductive axis. Oestradiol modulates the gene expression and somatic size of these neurones, although there is limited information available about whether their dendritic structure, a correlate of cellular plasticity, is altered by oestrogens. In the present study, we investigated the morphology of KNDy neurones by filling fluorescent neurones in the arcuate nucleus of Tac2-enhanced green fluorescent protein (EGFP) transgenic mice with biocytin. Filled neurones from ovariectomised (OVX) or OVX plus 17β-oestradiol (E2)-treated mice were visualised with anti-biotin immunohistochemistry and reconstructed in three dimensions with computer-assisted microscopy. KNDy neurones exhibited two primary dendrites, each with a few branches confined to the arcuate nucleus. Quantitative analysis revealed that E2 treatment of OVX mice decreased the cell size and dendritic spine density of KNDy neurones. The axons of KNDy neurones originated from the cell body or proximal dendrite and gave rise to local branches that appeared to terminate within the arcuate nucleus. Numerous terminal boutons were also visualised within the ependymal layer of the third ventricle adjacent to the arcuate nucleus. Axonal branches also projected to the adjacent median eminence and exited the arcuate nucleus. Confocal microscopy revealed close apposition of EGFP and gonadotrophin-releasing hormone-immunoreactive fibres within the median eminence and confirmed the presence of KNDy axon terminals in the ependymal layer of the third ventricle. The axonal branching pattern of KNDy neurones suggests that a single KNDy neurone could influence multiple arcuate neurones, tanycytes in the wall of the third ventricle, axon terminals in the median eminence and numerous areas outside of the arcuate nucleus. In parallel with its inhibitory effects on electrical excitability, E2 treatment

  16. Chronic oestradiol reduces the dendritic spine density of KNDy (kisspeptin/neurokinin B/dynorphin) neurones in the arcuate nucleus of ovariectomised Tac2-enhanced green fluorescent protein transgenic mice

    PubMed Central

    Cholanian, Marina; Krajewski-Hall, Sally J.; McMullen, Nathaniel T.; Rance, Naomi E.

    2016-01-01

    Neurones in the arcuate nucleus that express neurokinin B (NKB), kisspeptin and dynorphin (KNDy) play an important role in the reproductive axis. Oestradiol modulates the gene expression and somatic size of these neurones but there is limited information whether their dendritic structure, a correlate of cellular plasticity, is altered by oestrogens. Here we study the morphology of KNDy neurones by filling fluorescent neurones in the arcuate nucleus of Tac2-EGFP transgenic mice with biocytin. Filled neurones from ovariectomized (OVX) or OVX plus 17β-oestradiol (E2)-treated mice were visualized with anti-biotin immunohistochemistry and reconstructed in three dimensions with computer-assisted microscopy. KNDy neurones exhibited two primary dendrites, each with a few branches confined to the arcuate nucleus. Quantitative analysis revealed that E2 treatment of OVX mice decreased the cell size and dendritic spine density of KNDy neurones. The axons of KNDy neurones originated from the cell body or proximal dendrite and gave rise to local branches that appeared to terminate within the arcuate nucleus. Numerous terminal boutons were also visualized within the ependymal layer of the third ventricle adjacent to the arcuate nucleus. Axonal branches also projected to the adjacent median eminence and exited the arcuate nucleus. Confocal microscopy revealed close apposition of EGFP and GnRH-immunoreactive fibers within the median eminence and confirmed the presence of KNDy axon terminals in the ependymal layer of the third ventricle. The axonal branching pattern of KNDy neurones suggests that a single KNDy neurone could influence multiple arcuate neurones, tanycytes in the wall of the third ventricle, axon terminals in the median eminence and numerous areas outside of the arcuate nucleus. In parallel with its inhibitory effects on electrical excitability, E2 treatment of OVX Tac2-EGFP mice induces structural changes in the somata and dendrites of KNDy neurones. PMID:25659412

  17. hamlet, a binary genetic switch between single- and multiple- dendrite neuron morphology.

    PubMed

    Moore, Adrian W; Jan, Lily Yeh; Jan, Yuh Nung

    2002-08-23

    The dendritic morphology of neurons determines the number and type of inputs they receive. In the Drosophila peripheral nervous system (PNS), the external sensory (ES) neurons have a single nonbranched dendrite, whereas the lineally related multidendritic (MD) neurons have extensively branched dendritic arbors. We report that hamlet is a binary genetic switch between these contrasting morphological types. In hamlet mutants, ES neurons are converted to an MD fate, whereas ectopic hamlet expression in MD precursors results in transformation of MD neurons into ES neurons. Moreover, hamlet expression induced in MD neurons undergoing dendrite outgrowth drastically reduces arbor branching.

  18. The Stress-Induced Atf3-Gelsolin Cascade Underlies Dendritic Spine Deficits in Neuronal Models of Tuberous Sclerosis Complex

    PubMed Central

    Nie, Duyu; Chen, Zehua; Ebrahimi-Fakhari, Darius; Di Nardo, Alessia; Julich, Kristina; Robson, Victoria K.; Cheng, Yung-Chih; Woolf, Clifford J.; Heiman, Myriam

    2015-01-01

    Hyperactivation of the mechanistic target of rapamycin (mTOR) kinase, as a result of loss-of-function mutations in tuberous sclerosis complex 1 (TSC1) or TSC2 genes, causes protein synthesis dysregulation, increased cell size, and aberrant neuronal connectivity. Dysregulated synthesis of synaptic proteins has been implicated in the pathophysiology of autism spectrum disorder (ASD) associated with TSC and fragile X syndrome. However, cell type-specific translational profiles in these disease models remain to be investigated. Here, we used high-fidelity and unbiased Translating Ribosome Affinity Purification (TRAP) methodology to purify ribosome-associated mRNAs and identified translational alterations in a rat neuronal culture model of TSC. We find that expression of many stress and/or activity-dependent proteins is highly induced while some synaptic proteins are repressed. Importantly, transcripts for the activating transcription factor-3 (Atf3) and mitochondrial uncoupling protein-2 (Ucp2) are highly induced in Tsc2-deficient neurons, as well as in a neuron-specific Tsc1 conditional knock-out mouse model, and show differential responses to the mTOR inhibitor rapamycin. Gelsolin, a known target of Atf3 transcriptional activity, is also upregulated. shRNA-mediated block of Atf3 induction suppresses expression of gelsolin, an actin-severing protein, and rescues spine deficits found in Tsc2-deficient neurons. Together, our data demonstrate that a cell-autonomous program consisting of a stress-induced Atf3-gelsolin cascade affects the change in dendritic spine morphology following mTOR hyperactivation. This previously unidentified molecular cascade could be a therapeutic target for treating mTORopathies. SIGNIFICANCE STATEMENT Tuberous sclerosis complex (TSC) is a genetic disease associated with epilepsy and autism. Dysregulated protein synthesis has been implicated as a cause of this disease. However, cell type-specific translational profiles that are aberrant in this

  19. A Comparison between Growth Morphology of "Eutectic" Cells/Dendrites and Single-Phase Cells/Dendrites

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Raj, S. V.; Locci, I. E.

    2003-01-01

    Directionally solidified (DS) intermetallic and ceramic-based eutectic alloys with an in-situ composite microstructure containing finely distributed, long aspect ratio, fiber, or plate reinforcements are being seriously examined for several advanced aero-propulsion applications. In designing these alloys, additional solutes need to be added to the base eutectic composition in order to improve heir high-temperature strength, and provide for adequate toughness and resistance to environmental degradation. Solute addition, however, promotes instability at the planar liquid-solid interface resulting in the formation of two-phase eutectic "colonies." Because morphology of eutectic colonies is very similar to the single-phase cells and dendrites, the stability analysis of Mullins and Sekerka has been extended to describe their formation. Onset of their formation shows a good agreement with this approach; however, unlike the single-phase cells and dendrites, there is limited examination of their growth speed dependence of spacing, morphology, and spatial distribution. The purpose of this study is to compare the growth speed dependence of the morphology, spacing, and spatial distribution of eutectic cells and dendrites with that for the single-phase cells and dendrites.

  20. Sequential Elution Interactome Analysis of the Mind Bomb 1 Ubiquitin Ligase Reveals a Novel Role in Dendritic Spine Outgrowth*

    PubMed Central

    Mertz, Joseph; Tan, Haiyan; Pagala, Vishwajeeth; Bai, Bing; Chen, Ping-Chung; Li, Yuxin; Cho, Ji-Hoon; Shaw, Timothy; Wang, Xusheng; Peng, Junmin

    2015-01-01

    The mind bomb 1 (Mib1) ubiquitin ligase is essential for controlling metazoan development by Notch signaling and possibly the Wnt pathway. It is also expressed in postmitotic neurons and regulates neuronal morphogenesis and synaptic activity by mechanisms that are largely unknown. We sought to comprehensively characterize the Mib1 interactome and study its potential function in neuron development utilizing a novel sequential elution strategy for affinity purification, in which Mib1 binding proteins were eluted under different stringency and then quantified by the isobaric labeling method. The strategy identified the Mib1 interactome with both deep coverage and the ability to distinguish high-affinity partners from low-affinity partners. A total of 817 proteins were identified during the Mib1 affinity purification, including 56 high-affinity partners and 335 low-affinity partners, whereas the remaining 426 proteins are likely copurified contaminants or extremely weak binding proteins. The analysis detected all previously known Mib1-interacting proteins and revealed a large number of novel components involved in Notch and Wnt pathways, endocytosis and vesicle transport, the ubiquitin-proteasome system, cellular morphogenesis, and synaptic activities. Immunofluorescence studies further showed colocalization of Mib1 with five selected proteins: the Usp9x (FAM) deubiquitinating enzyme, alpha-, beta-, and delta-catenins, and CDKL5. Mutations of CDKL5 are associated with early infantile epileptic encephalopathy-2 (EIEE2), a severe form of mental retardation. We found that the expression of Mib1 down-regulated the protein level of CDKL5 by ubiquitination, and antagonized CDKL5 function during the formation of dendritic spines. Thus, the sequential elution strategy enables biochemical characterization of protein interactomes; and Mib1 analysis provides a comprehensive interactome for investigating its role in signaling networks and neuronal development. PMID:25931508

  1. A Mouse Model of Visual Perceptual Learning Reveals Alterations in Neuronal Coding and Dendritic Spine Density in the Visual Cortex

    PubMed Central

    Wang, Yan; Wu, Wei; Zhang, Xian; Hu, Xu; Li, Yue; Lou, Shihao; Ma, Xiao; An, Xu; Liu, Hui; Peng, Jing; Ma, Danyi; Zhou, Yifeng; Yang, Yupeng

    2016-01-01

    Visual perceptual learning (VPL) can improve spatial vision in normally sighted and visually impaired individuals. Although previous studies of humans and large animals have explored the neural basis of VPL, elucidation of the underlying cellular and molecular mechanisms remains a challenge. Owing to the advantages of molecular genetic and optogenetic manipulations, the mouse is a promising model for providing a mechanistic understanding of VPL. Here, we thoroughly evaluated the effects and properties of VPL on spatial vision in C57BL/6J mice using a two-alternative, forced-choice visual water task. Briefly, the mice underwent prolonged training at near the individual threshold of contrast or spatial frequency (SF) for pattern discrimination or visual detection for 35 consecutive days. Following training, the contrast-threshold trained mice showed an 87% improvement in contrast sensitivity (CS) and a 55% gain in visual acuity (VA). Similarly, the SF-threshold trained mice exhibited comparable and long-lasting improvements in VA and significant gains in CS over a wide range of SFs. Furthermore, learning largely transferred across eyes and stimulus orientations. Interestingly, learning could transfer from a pattern discrimination task to a visual detection task, but not vice versa. We validated that this VPL fully restored VA in adult amblyopic mice and old mice. Taken together, these data indicate that mice, as a species, exhibit reliable VPL. Intrinsic signal optical imaging revealed that mice with perceptual training had higher cut-off SFs in primary visual cortex (V1) than those without perceptual training. Moreover, perceptual training induced an increase in the dendritic spine density in layer 2/3 pyramidal neurons of V1. These results indicated functional and structural alterations in V1 during VPL. Overall, our VPL mouse model will provide a platform for investigating the neurobiological basis of VPL. PMID:27014004

  2. Suppression of spreading depolarization and stabilization of dendritic spines by GLYX-13, an NMDA receptor glycine-site functional partial agonist.

    PubMed

    Zhang, Xiao-Lei; Shuttleworth, C William; Moskal, Joseph R; Stanton, Patric K

    2015-11-01

    Cortical spreading depolarization (SD) is a slow self-propagating wave of mass cellular depolarization in brain tissue, thought to be the underlying cause of migraine scintillating scotoma and aura, and associated with stroke, traumatic brain injury, and termination of status epilepticus. The N-methyl-d-aspartate subtype of glutamate receptor (NMDAR), which gates influx of calcium and is an important trigger of long-term synaptic plasticity, is also a contributor to the initiation and propagation of SD. The current study tested the potential of pharmacological modulation of NMDAR activity through the obligatory co-agonist binding site, to suppress the initiation of SD, and modulate the effects of SD on dendritic spine morphology, in in vitro hippocampal slices. A novel NMDAR functional glycine site partial agonist, GLYX-13, sometimes completely prevented the induction of SD and consistently slowed its rate of propagation. The passage of SD through the hippocampal CA1 region produced a rapid retraction of dendritic spines which reversed after neuronal depolarization had recovered. GLYX-13 improved the rate and extent of return of dendritic spines to their original sizes and locations following SD, suggesting that NMDAR modulators can protect synaptic connections in the brain from structural alterations elicited by SD. These data indicate that NMDAR modulation to renormalize activity may be an effective new treatment strategy for suppression or amelioration of the contribution of SD to short and long-term symptoms of migraine attacks, as well as the effects of SD on tissue damaged by stroke or traumatic brain injury.

  3. Bisphenol-A exposure during adolescence leads to enduring alterations in cognition and dendritic spine density in adult male and female rats.

    PubMed

    Bowman, Rachel E; Luine, Victoria; Diaz Weinstein, Samantha; Khandaker, Hameda; DeWolf, Sarah; Frankfurt, Maya

    2015-03-01

    We have previously demonstrated that adolescent exposure of rats to bisphenol-A (BPA), an environmental endocrine disrupter, increases anxiety, impairs spatial memory, and decreases dendritic spine density in the CA1 region of the hippocampus (CA1) and medial prefrontal cortex (mPFC) when measured in adolescents in both sexes. The present study examined whether the behavioral and morphological alterations following BPA exposure during adolescent development are maintained into adulthood. Male and female, adolescent rats received BPA, 40μg/kg/bodyweight, or control treatments for one week. In adulthood, subjects were tested for anxiety and locomotor activity, spatial memory, non-spatial visual memory, and sucrose preference. Additionally, stress-induced serum corticosterone levels and dendritic spine density in the mPFC and CA1 were measured. BPA-treated males, but not females, had decreased arm visits on the elevated plus maze, but there was no effect on anxiety. Non-spatial memory, object recognition, was also decreased in BPA treated males, but not in females. BPA exposure did not alter spatial memory, object placement, but decreased exploration during the tasks in both sexes. No significant group differences in sucrose preference or serum corticosterone levels in response to a stress challenge were found. However, BPA exposure, regardless of sex, significantly decreased spine density of both apical and basal dendrites on pyramidal cells in CA1 but had no effect in the mPFC. Current data are discussed in relation to BPA dependent changes, which were present during adolescence and did, or did not, endure into adulthood. Overall, adolescent BPA exposure, below the current reference safe daily limit set by the U.S.E.P.A., leads to alterations in some behaviors and neuronal morphology that endure into adulthood.

  4. The Shank3 Interaction Partner ProSAPiP1 Regulates Postsynaptic SPAR Levels and the Maturation of Dendritic Spines in Hippocampal Neurons

    PubMed Central

    Reim, Dominik; Weis, Tobias M.; Halbedl, Sonja; Delling, Jan Philipp; Grabrucker, Andreas M.; Boeckers, Tobias M.; Schmeisser, Michael J.

    2016-01-01

    The postsynaptic density or PSD is a submembranous compartment containing a wide array of proteins that contribute to both morphology and function of excitatory glutamatergic synapses. In this study, we have analyzed functional aspects of the Fezzin ProSAP-interacting protein 1 (ProSAPiP1), an interaction partner of the well-known PSD proteins Shank3 and SPAR. Using lentiviral-mediated overexpression and knockdown of ProSAPiP1, we found that this protein is dispensable for the formation of both pre- and postsynaptic specializations per se. We further show that ProSAPiP1 regulates SPAR levels at the PSD and the maturation of dendritic spines. In line with previous findings on the ProSAPiP1 homolog PSD-Zip70, we conclude that Fezzins essentially contribute to the maturation of excitatory spine synapses. PMID:27252646

  5. Uncoupling Dendrite Growth and Patterning: Single Cell Knockout Analysis of NMDA Receptor 2B

    PubMed Central

    Espinosa, J. Sebastian; Wheeler, Damian G.; Tsien, Richard W.; Luo, Liqun

    2009-01-01

    SUMMARY N-Methyl-D-aspartate receptors (NMDARs) play important functions in neural development. NR2B is the predominant NR2 subunit of NMDAR in the developing brain. Here we use MADM (Mosaic Analysis with Double Markers) to knock out NR2B in isolated single cells and analyze its cell-autonomous function in dendrite development. NR2B mutant dentate gyrus granule cells (dGCs) and barrel cortex layer 4 spiny stellate cells (bSCs) have similar dendritic growth rates, total length and branch number as control cells. However, mutant dGCs maintain supernumerary primary dendrites resulting from a pruning defect. Furthermore, while control bSCs restrict dendritic growth to a single barrel, mutant bSCs maintain dendritic growth in multiple barrels. Thus, NR2B functions cell-autonomously to regulate dendrite patterning to ensure that sensory information is properly represented in the cortex. Our study also indicates that molecular mechanisms that regulate activity-dependent dendrite patterning can be separated from those that control general dendrite growth and branching. PMID:19409266

  6. Uncoupling dendrite growth and patterning: single-cell knockout analysis of NMDA receptor 2B.

    PubMed

    Espinosa, J Sebastian; Wheeler, Damian G; Tsien, Richard W; Luo, Liqun

    2009-04-30

    N-methyl-D-aspartate receptors (NMDARs) play important functions in neural development. NR2B is the predominant NR2 subunit of NMDAR in the developing brain. Here we use mosaic analysis with double markers (MADM) to knock out NR2B in isolated single cells and analyze its cell-autonomous function in dendrite development. NR2B mutant dentate gyrus granule cells (dGCs) and barrel cortex layer 4 spiny stellate cells (bSCs) have similar dendritic growth rates, total length, and branch number as control cells. However, mutant dGCs maintain supernumerary primary dendrites resulting from a pruning defect. Furthermore, while control bSCs restrict dendritic growth to a single barrel, mutant bSCs maintain dendritic growth in multiple barrels. Thus, NR2B functions cell autonomously to regulate dendrite patterning to ensure that sensory information is properly represented in the cortex. Our study also indicates that molecular mechanisms that regulate activity-dependent dendrite patterning can be separated from those that control general dendrite growth and branching.

  7. Single-image hard-copy display of the spine utilizing digital radiography

    NASA Astrophysics Data System (ADS)

    Artz, Dorothy S.; Janchar, Timothy; Milzman, David; Freedman, Matthew T.; Mun, Seong K.

    1997-04-01

    Regions of the entire spine contain a wide latitude of tissue densities within the imaged field of view presenting a problem for adequate radiological evaluation. With screen/film technology, the optimal technique for one area of the radiograph is sub-optimal for another area. Computed radiography (CR) with its inherent wide dynamic range, has been shown to be better than screen/film for lateral cervical spine imaging, but limitations are still present with standard image processing. By utilizing a dynamic range control (DRC) algorithm based on unsharp masking and signal transformation prior to gradation and frequency processing within the CR system, more vertebral bodies can be seen on a single hard copy display of the lateral cervical, thoracic, and thoracolumbar examinations. Examinations of the trauma cross-table lateral cervical spine, lateral thoracic spine, and lateral thoracolumbar spine were collected on live patient using photostimulable storage phosphor plates, the Fuji FCR 9000 reader, and the Fuji AC-3 computed radiography reader. Two images were produced from a single exposure; one with standard image processing and the second image with the standard process and the additional DRC algorithm. Both sets were printed from a Fuji LP 414 laser printer. Two different DRC algorithms were applied depending on which portion of the spine was not well visualized. One algorithm increased optical density and the second algorithm decreased optical density. The resultant image pairs were then reviewed by a panel of radiologists. Images produced with the additional DRC algorithm demonstrated improved visualization of previously 'under exposed' and 'over exposed' regions within the same image. Where lung field had previously obscured bony detail of the lateral thoracolumbar spine due to 'over exposure,' the image with the DRC applied to decrease the optical density allowed for easy visualization of the entire area of interest. For areas of the lateral cervical spine

  8. Local and global subaxial cervical spine biomechanics after single-level fusion or cervical arthroplasty.

    PubMed

    Finn, Michael A; Brodke, Darrel S; Daubs, Michael; Patel, Alpesh; Bachus, Kent N

    2009-10-01

    An experimental in vitro biomechanical study was conducted on human cadaveric spines to evaluate the motion segment (C4-C5) and global subaxial cervical spine motion after placement of a cervical arthroplasty device (Altia TDI,Amedica, Salt Lake City, UT) as compared to both the intact spine and a single-level fusion. Six specimens (C2-C7) were tested in flexion/extension, lateral bending, and axial rotation under a +/- 1.5 Nm moment with a 100 N axial follower load. Following the intact spine was tested; the cervical arthroplasty device was implanted at C4-C5 and tested. Then, a fusion using lateral mass fixation and an anterior plate was simulated and tested. Stiffness and range of motion (ROM) data were calculated. The ROM of the C4-C5 motion segment with the arthroplasty device was similar to that of the intact spine in flexion/extension and slightly less in lateral bending and rotation, while the fusion construct allowed significantly less motion in all directions. The fusion construct caused broader effects of increasing motion in the remaining segments of the subaxial cervical spine, whereas the TDI did not alter the adjacent and remote motion segments. The fusion construct was also far stiffer in all motion planes than the intact motion segment and the TDI, while the artificial disc treated level was slightly stiffer than the intact segment. The Altia TDI allows for a magnitude of motion similar to that of the intact spine at the treated and adjacent levels in the in vitro setting.

  9. Dendrite

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Researchers have found that as melted metals and alloys (combinations of metals) solidify, they can form with different arrangements of atoms, called microstructures. These microstructures depend on the shape of the interface (boundary) between the melted metal and the solid crystal it is forming. There are generally three shapes that the interface can take: planar, or flat; cellular, which looks like the cells of a beehive; and dendritic, which resembles tiny fir trees. Convection at this interface can affect the interface shape and hide the other phenomena (physical events). To reduce the effects of convection, researchers conduct experiments that examine and control conditions at the interface in microgravity. Microgravity also helps in the study of alloys composed of two metals that do not mix. On Earth, the liquid mixtures of these alloys settle into different layers due to gravity. In microgravity, the liquid metals do not settle, and a solid more uniform mixture of both metals can be formed.

  10. Rapid effects of the G-protein coupled oestrogen receptor (GPER) on learning and dorsal hippocampus dendritic spines in female mice.

    PubMed

    Gabor, Christopher; Lymer, Jennifer; Phan, Anna; Choleris, Elena

    2015-10-01

    Recently, oestrogen receptors (ERs) have been implicated in rapid learning processes. We have previously shown that 17β-estradiol, ERα and ERβ agonists can improve learning within 40 min of drug administration in mice. However, oestrogen action at the classical receptors may only in part explain these rapid learning effects. Chronic treatment of a G-protein coupled oestrogen receptor (GPER) agonist has been shown to affect learning and memory in ovariectomized rats, yet little is known about its rapid learning effects. Therefore we investigated whether the GPER agonist G-1 at 1 μg/kg, 6 μg/kg, 10 μg/kg, and 30 μg/kg could affect social recognition, object recognition, and object placement learning in ovariectomized CD1 mice within 40 min of drug administration. We also examined rapid effects of G-1 on CA1 hippocampal dendritic spine density and length within 40 min of drug administration, but in the absence of any learning tests. Results suggest a rapid enhancing effect of GPER activation on social recognition, object recognition and object placement learning. G-1 treatment also resulted in increased dendritic spine density in the stratum radiatum of the CA1 hippocampus. Hence GPER, along with the classical ERs, may mediate the rapid effects of oestrogen on learning and neuronal plasticity. To our knowledge, this is the first report of GPER effects occurring within a 40 min time frame.

  11. Probing synaptic function in dendrites with calcium imaging.

    PubMed

    Siegel, Friederike; Lohmann, Christian

    2013-04-01

    Calcium imaging has become a widely used technique to probe neuronal activity on the cellular and subcellular levels. In contrast to standard electrophysiological methods, calcium imaging resolves sub- and suprathreshold activation patterns in structures as small as fine dendritic branches and spines. This review highlights recent findings gained on the subcellular level using calcium imaging, with special emphasis on synaptic transmission and plasticity in individual spines. Since imaging allows monitoring activity across populations of synapses, it has recently been adopted to investigate how dendrites integrate information from many synapses. Future experiments, ideally carried out in vivo, will reveal how the dendritic tree integrates and computes afferent signals. For example, it is now possible to directly test the concept that dendritic inputs are clustered and that single dendrites or dendritic stretches act as independent computational units.

  12. Differential emotional experience induces elevated spine densities on basal dendrites of pyramidal neurons in the anterior cingulate cortex of Octodon degus.

    PubMed

    Helmeke, C; Poeggel, G; Braun, K

    2001-01-01

    It appears likely that, in analogy to the synaptic development of sensory and motor cortices, which critically depends on sensory or motor stimulation (Rosenzweig and Bennett, 1996), the synaptic development of limbic cortical regions are modulated by early postnatal cognitive and emotional experiences. The very first postnatal experience, which takes place in a confined and stable familial environment, is the interaction of the newborn individual with the parents and siblings (Gray, 1958). The aim of this quantitative morphological study was to analyze the impact of different degrees of juvenile emotional experience on the synaptic development in a limbic cortical area, the dorsal anterior cingulate cortex, a region which is involved in the perception and regulation of emotions. We study the precocious trumpet-tailed rat (Octodon degus) as the animal model, because, like human babies, this species is born with functional visual and acoustic systems and the pups are therefore capable of detecting even subtle environmental changes immediately after birth (Reynolds and Wright, 1979; Poeggel and Braun, 1996; Braun et al., 2000; Ovtscharoff and Braun, 2001). The results demonstrate that already a subtle disturbance of the familial environment such as handling induced significantly elevated spine densities on the basal dendrites of layer III cortical pyramidal neurons. More severe disturbances of the emotional environment, such as periodic parental deprivation with or without subsequent chronic social isolation, resulted in an elevation of spine densities of similar magnitude as seen after handling and in addition, altered spine densities confined to specific dendritic segments were observed in these groups. These observations unveil the remarkable sensitivity of the dorsal anterior cingulate cortex towards environmental influences and behavioral experiences during phases of postnatal development. The behavioral consequences of these experience-induced synaptic changes

  13. Longitudinal Effects of Ketamine on Dendritic Architecture In Vivo in the Mouse Medial Frontal Cortex123

    PubMed Central

    Phoumthipphavong, Victoria; Barthas, Florent; Hassett, Samantha

    2016-01-01

    Abstract A single subanesthetic dose of ketamine, an NMDA receptor antagonist, leads to fast-acting antidepressant effects. In rodent models, systemic ketamine is associated with higher dendritic spine density in the prefrontal cortex, reflecting structural remodeling that may underlie the behavioral changes. However, turnover of dendritic spines is a dynamic process in vivo, and the longitudinal effects of ketamine on structural plasticity remain unclear. The purpose of the current study is to use subcellular resolution optical imaging to determine the time course of dendritic alterations in vivo following systemic ketamine administration in mice. We used two-photon microscopy to visualize repeatedly the same set of dendritic branches in the mouse medial frontal cortex (MFC) before and after a single injection of ketamine or saline. Compared to controls, ketamine-injected mice had higher dendritic spine density in MFC for up to 2 weeks. This prolonged increase in spine density was driven by an elevated spine formation rate, and not by changes in the spine elimination rate. A fraction of the new spines following ketamine injection was persistent, which is indicative of functional synapses. In a few cases, we also observed retraction of distal apical tuft branches on the day immediately after ketamine administration. These results indicate that following systemic ketamine administration, certain dendritic inputs in MFC are removed immediately, while others are added gradually. These dynamic structural modifications are consistent with a model of ketamine action in which the net effect is a rebalancing of synaptic inputs received by frontal cortical neurons. PMID:27066532

  14. The role of amygdaloid brain-derived neurotrophic factor, activity-regulated cytoskeleton-associated protein and dendritic spines in anxiety and alcoholism.

    PubMed

    Moonat, Sachin; Sakharkar, Amul J; Zhang, Huaibo; Pandey, Subhash C

    2011-04-01

    Innate anxiety appears to be a robust factor in the promotion of alcohol intake, possibly due to the anxiolytic effects of self-medication with alcohol. Brain-derived neurotrophic factor (BDNF) and its downstream target, activity-regulated cytoskeleton-associated (Arc) protein, play a role in the regulation of synaptic function and structure. In order to examine the role of the BDNF-Arc system and associated dendritic spines in the anxiolytic effects of ethanol, we investigated the effects of acute ethanol exposure on anxiety-like behaviors of alcohol-preferring (P) and -nonpreferring (NP) rats. We also examined changes in the expression of BDNF and Arc, and dendritic spine density (DSD), in amygdaloid brain regions of P and NP rats with or without ethanol exposure. It was found that in comparison with NP rats, P rats displayed innate anxiety-like behaviors, and had lower mRNA and protein levels of both BDNF and Arc, and also had lower DSD in the central amygdala (CeA) and medial amygdala (MeA), but not in the basolateral amygdala (BLA). Acute ethanol treatment had an anxiolytic effect in P, but not in NP rats, and was associated with an increase in mRNA and protein levels of BDNF and Arc, and in DSD in the CeA and MeA, but not BLA. These results suggest that innate deficits in BDNF-Arc levels, and DSD, in the CeA and MeA may be involved in the anxiety-like and excessive alcohol-drinking behaviors of P rats, as ethanol increased these amygdaloid synaptic markers and produced anxiolytic effects in P rats, but not NP rats.

  15. Vitamin B1-deficient mice show impairment of hippocampus-dependent memory formation and loss of hippocampal neurons and dendritic spines: potential microendophenotypes of Wernicke-Korsakoff syndrome.

    PubMed

    Inaba, Hiroyoshi; Kishimoto, Takuya; Oishi, Satoru; Nagata, Kan; Hasegawa, Shunsuke; Watanabe, Tamae; Kida, Satoshi

    2016-12-01

    Patients with severe Wernicke-Korsakoff syndrome (WKS) associated with vitamin B1 (thiamine) deficiency (TD) show enduring impairment of memory formation. The mechanisms of memory impairment induced by TD remain unknown. Here, we show that hippocampal degeneration is a potential microendophenotype (an endophenotype of brain disease at the cellular and synaptic levels) of WKS in pyrithiamine-induced thiamine deficiency (PTD) mice, a rodent model of WKS. PTD mice show deficits in the hippocampus-dependent memory formation, although they show normal hippocampus-independent memory. Similarly with WKS, impairments in memory formation did not recover even at 6 months after treatment with PTD. Importantly, PTD mice exhibit a decrease in neurons in the CA1, CA3, and dentate gyrus (DG) regions of the hippocampus and reduced density of wide dendritic spines in the DG. Our findings suggest that TD induces hippocampal degeneration, including the loss of neurons and spines, thereby leading to enduring impairment of hippocampus-dependent memory formation.

  16. Vitamin B1-deficient mice show impairment of hippocampus-dependent memory formation and loss of hippocampal neurons and dendritic spines: potential microendophenotypes of Wernicke–Korsakoff syndrome

    PubMed Central

    Inaba, Hiroyoshi; Kishimoto, Takuya; Oishi, Satoru; Nagata, Kan; Hasegawa, Shunsuke; Watanabe, Tamae; Kida, Satoshi

    2016-01-01

    Patients with severe Wernicke–Korsakoff syndrome (WKS) associated with vitamin B1 (thiamine) deficiency (TD) show enduring impairment of memory formation. The mechanisms of memory impairment induced by TD remain unknown. Here, we show that hippocampal degeneration is a potential microendophenotype (an endophenotype of brain disease at the cellular and synaptic levels) of WKS in pyrithiamine-induced thiamine deficiency (PTD) mice, a rodent model of WKS. PTD mice show deficits in the hippocampus-dependent memory formation, although they show normal hippocampus-independent memory. Similarly with WKS, impairments in memory formation did not recover even at 6 months after treatment with PTD. Importantly, PTD mice exhibit a decrease in neurons in the CA1, CA3, and dentate gyrus (DG) regions of the hippocampus and reduced density of wide dendritic spines in the DG. Our findings suggest that TD induces hippocampal degeneration, including the loss of neurons and spines, thereby leading to enduring impairment of hippocampus-dependent memory formation. PMID:27576603

  17. Brilliant Blue G improves cognition in an animal model of Alzheimer's disease and inhibits amyloid-β-induced loss of filopodia and dendrite spines in hippocampal neurons.

    PubMed

    Chen, X; Hu, J; Jiang, L; Xu, S; Zheng, B; Wang, C; Zhang, J; Wei, X; Chang, L; Wang, Q

    2014-10-24

    Deposits of amyloid-β (Aβ) protein are one of the hallmarks of Alzheimer's disease (AD). Numerous studies report that the Aβ peptide, especially in the oligomeric form, causes memory decline and other cognitive deficits. However, there have been very few effective interventions for termination or even delay of AD progression. Brilliant Blue G (BBG), a safe triphenylmethane dye and P2X7 antagonist, has been reported to have protective effects on neuroinflammation, ischemia, spinal injury and neurodegenerative disorders. Here we report that systematic administration of BBG diminishes spatial memory impairment and cognitive deficits in a mouse AD model produced by injecting soluble Aβ peptide into the hippocampal CA1 region. In addition, we show that Aβ-induced loss of filopodia and spine density in cultured hippocampal neurons was prevented by administration of BBG. We conclude that BBG prevents the learning and memory impairment and cognitive deficits induced by the toxicity of soluble Aβ, and improves the development of dendritic spines in hippocampal neurons in an AD model mouse. Considering the safety and blood-brain-barrier (BBB)-permeability of BBG, our data suggest a potential for BBG as a new therapy for AD.

  18. Amyloid Beta (Aβ) Induces the Morphological Neurodegenerative Triad of Spine Loss, Dendritic Simplification, and Neuritic Dystrophies through Calcineurin (CaN) Activation

    PubMed Central

    Wu, Hai-Yan; Hudry, Eloise; Hashimoto, Tadafumi; Kuchibhotla, Kishore; Rozkalne, Anete; Fan, Zhanyun; Spires-Jones, Tara; Xie, Hong; Arbel-Ornath, Michal; Grosskreutz, Cynthia L.; Bacskai, Brian J.; Hyman, Bradley T

    2010-01-01

    Amyloid beta containing plaques are surrounded by dystrophic neurites in the Alzheimer disease (AD) brain, but whether and how plaques induce these neuritic abnormalities remain unknown. We tested the hypothesis that soluble oligomeric assemblies of Aβ, which surround plaques, induce calcium mediated secondary cascades that lead to dystrophic changes in local neurites. We show that soluble Aβ oligomers lead to activation of the calcium-dependent phosphatase CaN (PP2B) which in turn activates the transcriptional factor nuclear factor of activated T cells (NFAT). Activation of these signaling pathways, even in the absence of Aβ, is sufficient to produce a virtual phenocopy of Aβ induced dystrophic neurites, dendritic simplification, and dendritic spine loss in both neurons in culture and in the adult mouse brain. Importantly, the morphological deficits in the vicinity of Aβ deposits in a mouse model of AD are ameliorated by CaN inhibition, supporting the hypothesis that CaN/NFAT are aberrantly activated by Aβ, and that CaN/NFAT activation is responsible for disruption of neuronal structure near plaques. In accord with this, we also detect increased levels of an active form of CaN and NFATc4 in the nuclear fraction from the cortex of patients with AD. Thus, Aβ appears to mediate the neurodegeneration of AD, at least in part, by activation of CaN and subsequent NFAT-mediated downstream cascades. PMID:20164348

  19. Continuous single cell imaging reveals sequential steps of plasmacytoid dendritic cell development from common dendritic cell progenitors

    PubMed Central

    Dursun, Ezgi; Endele, Max; Musumeci, Andrea; Failmezger, Henrik; Wang, Shu-Hung; Tresch, Achim; Schroeder, Timm; Krug, Anne B.

    2016-01-01

    Functionally distinct plasmacytoid and conventional dendritic cells (pDC and cDC) shape innate and adaptive immunity. They are derived from common dendritic cell progenitors (CDPs) in the murine bone marrow, which give rise to CD11c+ MHCII− precursors with early commitment to DC subpopulations. In this study, we dissect pDC development from CDP into an ordered sequence of differentiation events by monitoring the expression of CD11c, MHC class II, Siglec H and CCR9 in CDP cultures by continuous single cell imaging and tracking. Analysis of CDP genealogies revealed a stepwise differentiation of CDPs into pDCs in a part of the CDP colonies. This developmental pathway involved an early CD11c+ SiglecH− pre-DC stage and a Siglec H+ CCR9low precursor stage, which was followed rapidly by upregulation of CCR9 indicating final pDC differentiation. In the majority of the remaining CDP pedigrees however the Siglec H+ CCR9low precursor state was maintained for several generations. Thus, although a fraction of CDPs transits through precursor stages rapidly to give rise to a first wave of pDCs, the majority of CDP progeny differentiate more slowly and give rise to longer lived precursor cells which are poised to differentiate on demand. PMID:27892478

  20. In vivo micro-lesion of single dendrite with femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Sacconi, L.; Masi, A.; Diana, G.; Buffelli, M.; Pavone, F. S.

    2007-07-01

    Recently, two-photon microscopy has been used for high spatial resolution imaging of the intact neocortex in living rodents. In this work we used near-IR femtosecond laser pulses for a combination of two-photon microscopy and microdissection on fluorescently-labeled neuronal structures in living mice. Three-dimensional reconstructions of dendrites expressing the green fluorescence protein were made in the cortex of GFP-M and YFP-H transgenic mice. Afterwards, single dendrites were laser-dissected irradiating the structure with a high femtosecond laser energy dose. We report that laser dissection can be performed with micrometric precision and without any visible collateral damage of the surrounding neuronal structures. After laser irradiation, one part of the severed dendrite underwent degeneration and disappeared within 5 hours. Using a chronically implanted glass window, we performed long-term imaging in the area of the dissected dendrite. Images of the long-term morphological changes in the neuronal network after dendritic lesioning will be provided. Laser microdissection of selected structures of the neuronal branching in vivo represents a promising tool for neurobiological research.

  1. Axonal and dendritic density field estimation from incomplete single-slice neuronal reconstructions

    PubMed Central

    van Pelt, Jaap; van Ooyen, Arjen; Uylings, Harry B. M.

    2014-01-01

    Neuronal information processing in cortical networks critically depends on the organization of synaptic connectivity. Synaptic connections can form when axons and dendrites come in close proximity of each other. The spatial innervation of neuronal arborizations can be described by their axonal and dendritic density fields. Recently we showed that potential locations of synapses between neurons can be estimated from their overlapping axonal and dendritic density fields. However, deriving density fields from single-slice neuronal reconstructions is hampered by incompleteness because of cut branches. Here, we describe a method for recovering the lost axonal and dendritic mass. This so-called completion method is based on an estimation of the mass inside the slice and an extrapolation to the space outside the slice, assuming axial symmetry in the mass distribution. We validated the method using a set of neurons generated with our NETMORPH simulator. The model-generated neurons were artificially sliced and subsequently recovered by the completion method. Depending on slice thickness and arbor extent, branches that have lost their outside parents (orphan branches) may occur inside the slice. Not connected anymore to the contiguous structure of the sliced neuron, orphan branches result in an underestimation of neurite mass. For 300 μm thick slices, however, the validation showed a full recovery of dendritic and an almost full recovery of axonal mass. The completion method was applied to three experimental data sets of reconstructed rat cortical L2/3 pyramidal neurons. The results showed that in 300 μm thick slices intracortical axons lost about 50% and dendrites about 16% of their mass. The completion method can be applied to single-slice reconstructions as long as axial symmetry can be assumed in the mass distribution. This opens up the possibility of using incomplete neuronal reconstructions from open-access data bases to determine population mean mass density fields

  2. The "addicted" spine.

    PubMed

    Spiga, Saturnino; Mulas, Giovanna; Piras, Francesca; Diana, Marco

    2014-01-01

    Units of dendritic branches called dendritic spines represent more than simply decorative appendages of the neuron and actively participate in integrative functions of "spinous" nerve cells thereby contributing to the general phenomenon of synaptic plasticity. In animal models of drug addiction, spines are profoundly affected by treatments with drugs of abuse and represent important sub cellular markers which interfere deeply into the physiology of the neuron thereby providing an example of the burgeoning and rapidly increasing interest in "structural plasticity". Medium Spiny Neurons (MSNs) of the Nucleus Accumbens (Nacc) show a reduced number of dendritic spines and a decrease in TH-positive terminals upon withdrawal from opiates, cannabinoids and alcohol. The reduction is localized "strictly" to second order dendritic branches where dopamine (DA)-containing terminals, impinging upon spines, make synaptic contacts. In addition, long-thin spines seems preferentially affected raising the possibility that cellular learning of these neurons may be selectively hampered. These findings suggest that dendritic spines are affected by drugs widely abused by humans and provide yet another example of drug-induced aberrant neural plasticity with marked reflections on the physiology of synapses, system structural organization, and neuronal circuitry remodeling.

  3. In-vivo administration of clozapine affects behaviour but does not reverse dendritic spine deficits in the 14-3-3ζ KO mouse model of schizophrenia-like disorders.

    PubMed

    Jaehne, Emily J; Ramshaw, Hayley; Xu, Xiangjun; Saleh, Eiman; Clark, Scott R; Schubert, Klaus Oliver; Lopez, Angel; Schwarz, Quenten; Baune, Bernhard T

    2015-11-01

    Clozapine is an atypical antipsychotic drug used in the treatment of schizophrenia, which has been shown to reverse behavioural and dendritic spine deficits in mice. It has recently been shown that deficiency of 14-3-3ζ has an association with schizophrenia, and that a mouse model lacking this protein displays several schizophrenia-like behavioural deficits. To test the effect of clozapine in this mouse model, 14-3-3ζ KO mice were administered clozapine (5mg/kg) for two weeks prior to being analysed in a test battery of cognition, anxiety, and despair (depression-like) behaviours. Following behavioural testing brain samples were collected for analysis of specific anatomical defects and dendritic spine formation. We found that clozapine reduced despair behaviour of 14-3-3ζ KO mice in the forced swim test (FST) and altered the behaviour of wild types and 14-3-3ζ KO mice in the Y-maze task. In contrast, clozapine had no effects on hippocampal laminar defects or decreased dendritic spine density observed in 14-3-3ζ KO mice. Our results suggest that clozapine may have beneficial effects on clinical behaviours associated with deficiencies in the 14-3-3ζ molecular pathway, despite having no effects on morphological defects. These findings may provide mechanistic insight to the action of this drug.

  4. Controlled reversible debundling of single-walled carbon nanotubes by photo-switchable dendritic surfactants

    NASA Astrophysics Data System (ADS)

    Kördel, Christian; Setaro, Antonio; Bluemmel, Pascal; Popeney, Chris S.; Reich, Stephanie; Haag, Rainer

    2012-05-01

    Stimulus responsive surfactants based on dendritic glycerol azobenzene conjugates were used to solubilize and debundle single-walled carbon nanotubes in aqueous media. Their debundling property as well as their reaggregation behavior upon irradiation with light was examined and light triggered reversible bundling and precipitation are shown.Stimulus responsive surfactants based on dendritic glycerol azobenzene conjugates were used to solubilize and debundle single-walled carbon nanotubes in aqueous media. Their debundling property as well as their reaggregation behavior upon irradiation with light was examined and light triggered reversible bundling and precipitation are shown. Electronic supplementary information (ESI) available: Experimental methods and more details about the switching process. See DOI: 10.1039/c2nr30305a

  5. Defects in dendrite and spine maturation and synaptogenesis associated with an anxious-depressive-like phenotype of GABAA receptor-deficient mice.

    PubMed

    Ren, Zhen; Sahir, Nadia; Murakami, Shoko; Luellen, Beth A; Earnheart, John C; Lal, Rachnanjali; Kim, Ju Young; Song, Hongjun; Luscher, Bernhard

    2015-01-01

    Mice that were rendered heterozygous for the γ2 subunit of GABAA receptors (γ2(+/-) mice) have been characterized extensively as a model for major depressive disorder. The phenotype of these mice includes behavior indicative of heightened anxiety, despair, and anhedonia, as well as defects in hippocampus-dependent pattern separation, HPA axis hyperactivity and increased responsiveness to antidepressant drugs. The γ2(+/-) model thereby provides strong support for the GABAergic deficit hypothesis of major depressive disorder. Here we show that γ2(+/-) mice additionally exhibit specific defects in late stage survival of adult-born hippocampal granule cells, including reduced complexity of dendritic arbors and impaired maturation of synaptic spines. Moreover, cortical γ2(+/-) neurons cultured in vitro show marked deficits in GABAergic innervation selectively when grown under competitive conditions that may mimic the environment of adult-born hippocampal granule cells. Finally, brain extracts of γ2(+/-) mice show a numerical but insignificant trend (p = 0.06) for transiently reduced expression of brain derived neurotrophic factor (BDNF) at three weeks of age, which might contribute to the previously reported developmental origin of the behavioral phenotype of γ2(+/-) mice. The data indicate increasing congruence of the GABAergic, glutamatergic, stress-based and neurotrophic deficit hypotheses of major depressive disorder.

  6. Increased expression of AT-1/SLC33A1 causes an autistic-like phenotype in mice by affecting dendritic branching and spine formation

    PubMed Central

    Hullinger, Rikki; Li, Mi; Wang, Jingxin; Peng, Yajing; Dowell, James A.; Bomba-Warczak, Ewa; Mitchell, Heather A.; Burger, Corinna; Chapman, Edwin R.; Denu, John M.; Li, Lingjun

    2016-01-01

    The import of acetyl-CoA into the lumen of the endoplasmic reticulum (ER) by AT-1/SLC33A1 regulates Nε-lysine acetylation of ER-resident and -transiting proteins. Specifically, lysine acetylation within the ER appears to influence the efficiency of the secretory pathway by affecting ER-mediated quality control. Mutations or duplications in AT-1/SLC33A1 have been linked to diseases such as familial spastic paraplegia, developmental delay with premature death, and autism spectrum disorder with intellectual disability. In this study, we generated an AT-1 Tg mouse model that selectively overexpresses human AT-1 in neurons. These animals demonstrate cognitive deficits, autistic-like social behavior, aberrations in synaptic plasticity, an increased number of dendritic spines and branches, and widespread proteomic changes. We also found that AT-1 activity regulates acetyl-CoA flux, causing epigenetic modulation of the histone epitope H3K27 and mitochondrial adaptation. In conclusion, our results indicate that increased expression of AT-1 can cause an autistic-like phenotype by affecting key neuronal metabolic pathways. PMID:27242167

  7. Effects of Chronic Dopamine D2R Agonist Treatment and Polysialic Acid Depletion on Dendritic Spine Density and Excitatory Neurotransmission in the mPFC of Adult Rats

    PubMed Central

    Castillo-Gómez, Esther; Varea, Emilio; Blasco-Ibáñez, José Miguel; Crespo, Carlos; Nacher, Juan

    2016-01-01

    Dopamine D2 receptors (D2R) in the medial prefrontal cortex (mPFC) are key players in the etiology and therapeutics of schizophrenia. The overactivation of these receptors contributes to mPFC dysfunction. Chronic treatment with D2R agonists modifies the expression of molecules implicated in neuronal structural plasticity, synaptic function, and inhibitory neurotransmission, which are also altered in schizophrenia. These changes are dependent on the expression of the polysialylated form of the neural cell adhesion molecule (PSA-NCAM), a plasticity-related molecule, but nothing is known about the effects of D2R and PSA-NCAM on excitatory neurotransmission and the structure of mPFC pyramidal neurons, two additional features affected in schizophrenia. To evaluate these parameters, we have chronically treated adult rats with PPHT (a D2R agonist) after enzymatic removal of PSA with Endo-N. Both treatments decreased spine density in apical dendrites of pyramidal neurons without affecting their inhibitory innervation. Endo-N also reduced the expression of vesicular glutamate transporter-1. These results indicate that D2R and PSA-NCAM are important players in the regulation of the structural plasticity of mPFC excitatory neurons. This is relevant to our understanding of the neurobiological basis of schizophrenia, in which structural alterations of pyramidal neurons and altered expression of D2R and PSA-NCAM have been found. PMID:27110404

  8. α4βδ GABAA receptors reduce dendritic spine density in CA1 hippocampus and impair relearning ability of adolescent female mice: Effects of a GABA agonist and a stress steroid.

    PubMed

    Afroz, Sonia; Shen, Hui; Smith, Sheryl S

    2017-04-07

    Synaptic pruning underlies the transition from an immature to an adult CNS through refinements of neuronal circuits. Our recent study indicates that pubertal synaptic pruning is triggered by the inhibition generated by extrasynaptic α4βδ GABAA receptors (GABARs) which are increased for 10 d on dendritic spines of CA1 pyramidal cells at the onset of puberty (PND 35-44) in the female mouse, suggesting α4βδ GABARs as a novel target for the regulation of adolescent synaptic pruning. In the present study we used a pharmacological approach to further examine the role of these receptors in altering spine density during puberty of female mice and the impact of these changes on spatial learning, assessed in adulthood. Two drugs were chronically administered during the pubertal period (PND 35-44): the GABA agonist gaboxadol (GBX, 0.1mg/kg, i.p.), to enhance current gated by α4βδ GABARs and the neurosteroid/stress steroid THP (3α-OH-5β-pregnan-20-one, 10mg/kg, i.p.) to decrease expression of α4βδ. Spine density was determined on PND 56 with Golgi staining. Spatial learning and relearning were assessed using the multiple object relocation task and an active place avoidance task on PND 56. Pubertal GBX decreased spine density post-pubertally by 70% (P<0.05), while decreasing α4βδ expression with THP increased spine density by twofold (P<0.05), in both cases, with greatest effects on the mushroom spines. Adult relearning ability was compromised in both hippocampus-dependent tasks after pubertal administration of either drug. These findings suggest that an optimal spine density produced by α4βδ GABARs is necessary for optimal cognition in adults.

  9. Construction of cuprous oxide electrodes composed of 2D single-crystalline dendritic nanosheets.

    PubMed

    Jang, Ho Seong; Kim, Suk Jun; Choi, Kyoung-Shin

    2010-10-04

    An unusual anisotropic growth of Cu(2)O is stabilized via the electrochemical synthesis of Cu(2)O in the presence of Ag(+) ions, which results in the formation of Cu(2)O electrodes composed of 2D sheetlike crystals containing complex dendritic patterns. It is quite unusual for Cu(2)O to form a 2D morphology since it has a 3D isotropic cubic crystal structure where the a, b, and c axes are equivalent. Each Cu(2)O sheet is single-crystalline in nature and is grown parallel to the {110} plane, which is rarely observed in Cu(2)O crystal shapes. A various set of experiments are performed to understand the role of Ag(+) ions on the 2D growth of Cu(2)O. The results show that Ag(+) ions are deposited as silver islands on already growing Cu(2)O crystals and serve as nucleation sites for the new growth of Cu(2)O crystals. As a result, the growth direction of the newly forming Cu(2)O crystals is governed by the diffusion layer structure created by the pre-existing Cu(2)O crystals, which results in the formation of 2D dendritic patterns. The thin 2D crystal morphology can significantly increase the surface-to-volume ratio of Cu(2)O crystals, which is beneficial for enhancing various electrochemical and photoelectrochemical properties of the electrodes. The photoelectrochemical properties of the Cu(2)O electrodes composed of 2D dendritic crystals are investigated and compared to those of 3D dendritic crystals. This study provides a unique and effective route to maximize the {110} area per unit volume of Cu(2)O, which will be beneficial for any catalytic/sensing abilities that can be anisotropically enhanced by the {110} planes of Cu(2)O.

  10. Pathological characteristics of spine metastases treated with high-dose single-fraction stereotactic radiosurgery.

    PubMed

    Katsoulakis, Evangelia; Laufer, Ilya; Bilsky, Mark; Agaram, Narasimhan P; Lovelock, Michael; Yamada, Yoshiya

    2017-01-01

    OBJECTIVE Spine radiosurgery is increasingly being used to treat spinal metastases. As patients are living longer because of the increasing efficacy of systemic agents, appropriate follow-up and posttreatment management for these patients is critical. Tumor progression after spine radiosurgery is rare; however, vertebral compression fractures are recognized as a more common posttreatment effect. The use of radiographic imaging alone posttreatment may makeit difficult to distinguish tumor progression from postradiation changes such as fibrosis. This is the largest series from a prospective database in which the authors examine histopathology of samples obtained from patients who underwent surgical intervention for presumed tumor progression or mechanical pain secondary to compression fracture. The majority of patients had tumor ablation and resulting fibrosis rather than tumor progression. The aim of this study was to evaluate tumor histopathology and characteristics of patients who underwent pathological sampling because of radiographic tumor progression, fibrosis, or collapsed vertebrae after receiving high-dose single-fraction stereotactic radiosurgery. METHODS Between January 2005 and January 2014, a total of 582 patients were treated with linear accelerator-based single-fraction (18-24 Gy) stereotactic radiosurgery. The authors retrospectively identified 30 patients (5.1%) who underwent surgical intervention for 32 lesions with vertebral cement augmentation for either mechanical pain or instability secondary to vertebral compression fracture (n = 17) or instrumentation (n = 15) for radiographic tumor progression. Radiation and surgical treatment, histopathology, and long-term outcomes were reviewed. Survival and time to recurrence were calculated using the Kaplan-Meier method. RESULTS The mean age at the time of radiosurgery was 59 years (range 36-80 years). The initial pathological diagnoses were obtained for all patients and primarily included radioresistant

  11. Inhibition of the Ras/Raf/ERK1/2 Signaling Pathway Restores Cultured Spinal Cord-Injured Neuronal Migration, Adhesion, and Dendritic Spine Development.

    PubMed

    Xu, Dongdong; Cao, Fujiang; Sun, Shiwei; Liu, Tao; Feng, Shiqing

    2016-08-01

    The Ras/Raf/ERK1/2 signaling pathway plays an important role in central and peripheral neurons in functions such as dendritic arborization, neuronal polarity, and axon assembly. However, emerging evidence also shows that up-regulation of this signaling pathway may lead to the development of spinal cord injury. The present study aimed to determine the effects of Ras/Raf/ERK1/2 signaling pathway inhibition on properties of spinal cord-injured neurons. First, neurons from spinal cord-injured C57BL/6 J mouse pups and sham-operated C57BL/6 J mouse pups were harvested. Then, immunofluorescence, western blotting, cell adhesion and cell migration assays, and DiI labeling were employed to investigate the effect of Ras/Raf/ERK1/2 signaling pathway inhibition on spinal cord-injured neurons. Immunofluorescence results of synapse formation indicated that the experimental spinal cord injury model was successfully established. Western blot results identified upregulated Erk phosphorylation in the spinal cord-injured neurons, and also showed that U0126 inhibited phosphorylation of Erk, which is a downstream kinase in the Ras/Raf signaling pathway. Additionally, cell migration and adhesion was significantly increased in the spinal cord-injured neurons. DiI labeling results also showed an increased formation of mature spines after inhibition of Ras/Raf/ERK1/2 signaling. Taken together, these results suggested that the Ras/Raf/ERK1/2 signaling pathway could serve as an effective treatment target for spinal cord injury.

  12. Peripheral nervous system injury after high-dose single-fraction image-guided stereotactic radiosurgery for spine tumors.

    PubMed

    Stubblefield, Michael D; Ibanez, Katarzyna; Riedel, Elyn R; Barzilai, Ori; Laufer, Ilya; Lis, Eric; Yamada, Yoshiya; Bilsky, Mark H

    2017-03-01

    OBJECTIVE The object of this study was to determine the percentage of high-dose (1800-2600 cGy) single-fraction stereotactic radiosurgery (SF-SRS) treatments to the spine that result in peripheral nervous system (PNS) injury. METHODS All patients treated with SF-SRS for primary or metastatic spine tumors between January 2004 and May 2013 and referred to the Rehabilitation Medicine Service for evaluation and treatment of neuromuscular, musculoskeletal, or functional impairments or pain were retrospectively identified. RESULTS Five hundred fifty-seven SF-SRS treatments in 447 patients resulted in 14 PNS injuries in 13 patients. All injures resulted from SF-SRS delivered to the cervical or lumbosacral spine at 2400 cGy. The overall percentage of SF-SRS treatments resulting in PNS injury was 2.5%, increasing to 4.5% when the thoracic spine was excluded from analysis. The median time to symptom onset following SF-SRS was 10 months (range 4-32 months). The plexus (cervical, brachial, and/or lumbosacral) was affected clinically and/or electrophysiologically in 12 (86%) of 14 cases, the nerve root in 2 (14%) of 14, and both in 6 (43%) of 14 cases. All patients experienced pain and most (93%) developed weakness. Peripheral nervous system injuries were CTCAE Grade 1 in 14% of cases, 2 in 64%, and 3 in 21%. No dose relationship between SF-SRS dose and PNS injury was detected. CONCLUSIONS Single-fraction SRS to the spine can result in PNS injury with major implications for function and quality of life.

  13. Rpph1 Upregulates CDC42 Expression and Promotes Hippocampal Neuron Dendritic Spine Formation by Competing with miR-330-5p

    PubMed Central

    Cai, Yifei; Sun, Ziling; Jia, Huizhen; Luo, Hongxue; Ye, Xiaoyang; Wu, Qi; Xiong, Yi; Zhang, Wei; Wan, Jun

    2017-01-01

    Alzheimer’s disease (AD) is a heterogeneous neurodegenerative disease. Recent studies employing microRNA-seq and genome-wide sequencing have identified some non-coding RNAs that are influentially involved in AD pathogenesis. Non-coding RNAs can compete with other endogenous RNAs by microRNA response elements (MREs) and manipulate biological processes, such as tumorigenesis. However, only a few non-coding RNAs have been reported in the pathogenesis of AD. In this study, we constructed the first competing endogenous RNA (ceRNA) network leveraging whole transcriptome sequencing and a previously studied microRNA-seq of APPswe/PS1ΔE9 transgenic mice. The underlying mechanisms for the involvement of ceRNA in AD were validated using the Dual Luciferase Reporter Assay, detection of transcription levels by quantitative RT-PCR and translation levels by Western blotting, and morphological examination in primary cultured neurons. In the ceRNA network, four lncRNAs (C030034L19Rik, Rpph1, A830012C17Rik, and Gm15477) and five miRNAs (miR-182-5p, miR-330-5p, miR-326-3p, miR-132-3p, and miR-484) are enriched in nine pathways and an AD-related gene pool. Among them, Ribonuclease P RNA component H1 (Rpph1) is upregulated in the cortex of APPswe/PS1ΔE9 mice compared to wild type controls. Rpph1 binds to miR326-3p/miR-330-5p and causes the release of their downstream target Cdc42, which leads to CDC42 upregulation. This effect was disrupted upon mutation of the MRE on Rpph1. Moreover, overexpression of Rpph1 increased dendritic spine density in primary cultured hippocampal pyramidal neurons, whereas knocking down of Rpph1 had the reverse effect. In conclusion, Rpph1 modulates CDC42 expression level in a ceRNA-dependent manner, which may represent a compensatory mechanism in the early stage of the AD pathogenesis. PMID:28223918

  14. Chronic caffeine consumption prevents cognitive decline from young to middle age in rats, and is associated with increased length, branching, and spine density of basal dendrites in CA1 hippocampal neurons.

    PubMed

    Vila-Luna, S; Cabrera-Isidoro, S; Vila-Luna, L; Juárez-Díaz, I; Bata-García, J L; Alvarez-Cervera, F J; Zapata-Vázquez, R E; Arankowsky-Sandoval, G; Heredia-López, F; Flores, G; Góngora-Alfaro, J L

    2012-01-27

    Chronic caffeine consumption has been inversely associated with the risk of developing dementia and Alzheimer's disease. Here we assessed whether chronic caffeine treatment prevents the behavioral and cognitive decline that male Wistar rats experience from young (≈3 months) to middle age (≈10 months). When animals were young they were evaluated at weekly intervals in three tests: motor activity habituation in the open field (30-min sessions at the same time on consecutive days), continuous spontaneous alternation in the Y-maze (8 min), and elevated plus-maze (5 min). Afterward, rats from the same litter were randomly assigned either to a caffeine-treated group (n=13) or a control group (n=11), which received only tap water. Caffeine treatment (5 mg/kg/day) began when animals were ≈4 months old, and lasted for 6 months. Behavioral tests were repeated from day 14 to day 28 after caffeine withdrawal, a time period that is far in excess for the full excretion of a caffeine dose in this species. Thirty days after caffeine discontinuation brains were processed for Golgi-Cox staining. Compared with controls, we found that middle-aged rats that had chronically consumed low doses of caffeine (1) maintained their locomotor habituation during the second consecutive day exposure to the open field (an index of non-associative learning), (2) maintained their exploratory drive to complete the conventional minimum of nine arm visits required to calculate the alternation performance in the Y-maze in a greater proportion, (3) maintained their alternation percentage above chance level (an index of working memory), and (4) did not increase the anxiety indexes assessed by measuring the time spent in the open arms of the elevated plus maze. In addition, morphometric analysis of hippocampal neurons revealed that dendritic branching (90-140 μm from the soma), length of 4th and 5th order branches, total dendritic length, and spine density in distal dendritic branches were greater in

  15. Effects of exposure to moderate levels of ethanol during prenatal brain development on dendritic length, branching, and spine density in the nucleus accumbens and dorsal striatum of adult rats.

    PubMed

    Rice, James P; Suggs, Lisa E; Lusk, Alexandra V; Parker, Matthew O; Candelaria-Cook, Felicha T; Akers, Katherine G; Savage, Daniel D; Hamilton, Derek A

    2012-09-01

    Reductions in measures of dendritic morphology in the agranular insular cortex have been identified as consequences of prenatal exposure to moderate levels of ethanol in the rat. Motivated by the strong connectivity between this region of frontal cortex and the striatum and a growing body of data linking specific components of the mesocortical/limbic system to effects of ethanol and ethanol self-administration, the current study investigated the effects of moderate fetal ethanol exposure on the dendritic morphology of medium spiny neurons (MSNs) in several regions of the striatum. Throughout gestation, pregnant rat dams either consumed a saccharin solution (control) or achieved average daily blood ethanol concentrations of 84 mg% via voluntary consumption of a 5% ethanol solution. The brains of adult male offspring were extracted and processed for Golgi-Cox staining. MSNs from the dorsomedial striatum, dorsolateral striatum and the nucleus accumbens core and shell were sampled for analysis. Relative to saccharin controls, robust reductions in dendritic length and branching, but not spine density, were observed in the shell of the nucleus accumbens in fetal-ethanol-exposed rats. No significant prenatal ethanol effects were found in the other regions of the striatum. These findings suggest that exposure to moderate levels of ethanol in utero can have profound effects on brain regions related to reward processing and provide possible clues relevant to understanding increased self-administration of drugs of abuse in animals exposed to ethanol during brain development.

  16. Properties of single voltage-dependent K+ channels in dendrites of CA1 pyramidal neurones of rat hippocampus

    PubMed Central

    Chen, Xixi; Johnston, Daniel

    2004-01-01

    Voltage-dependent K+ channels in the apical dendrites of CA1 pyramidal neurones play important roles in regulating dendritic excitability, synaptic integration, and synaptic plasticity. Using cell-attached, voltage-clamp recordings, we found a large variability in the waveforms of macroscopic K+ currents in the dendrites. With single-channel analysis, however, we were able to identify four types of voltage-dependent K+ channels and we categorized them as belonging to delayed-rectifier, M-, D-, or A-type K+ channels previously described from whole-cell recordings. Delayed-rectifier-type K+ channels had a single-channel conductance of 19 ± 0.5 pS, and made up the majority of the sustained K+ current uniformly distributed along the apical dendrites. The M-type K+ channels had a single-channel conductance of 11 ± 0.8 pS, did not inactivate with prolonged membrane depolarization, deactivated with slow kinetics (time constant 100 ± 6 ms at −40 mV), and were inhibited by bath-applied muscarinic agonist carbachol (10 μm). The D-type K+ channels had a single-channel conductance of around 18 pS, and inactivated with a time constant of 98 ± 4 ms at +54 mV. The A-type K+ channels had a single-channel conductance of 6 ± 0.6 pS, inactivated with a time constant of 23 ± 2 ms at +54 mV, and contributed to the majority of the transient K+ current previously described. These results suggest both functional and molecular complexity for K+ channels in dendrites of CA1 pyramidal neurones. PMID:15218076

  17. Quantitation and morphological characterization of rapid axon and dendritic growth from single cerebral hemispheric neurons in hydrated collagen lattice culture.

    PubMed

    Coates, P W

    1986-02-01

    Quantitative and qualitative data are reported for single cerebral hemispheric neurons in a 3-dimensional hydrated collagen lattice (HCL) culture system. Individual neurons not in contact with other cells or cell processes, including synapses, rapidly displayed two morphologically distinct classes of processes that could be traced from origin to termination: long thin processes interpreted as being axons, and shorter tapering and sometimes branched processes interpreted as being dendrites. Axons and dendrites of single neurons that had at least one process longer than the cell body were measured on each of 3 days after plating using an image analysis system coupled to a phase-contrast microscope and a microcomputer. Mean lengths of axons and dendrites alone or combined as total new growth per neuron, increased 3- to 5-fold and were as high as 745, 694 and 1226 microns respectively after 3 days in HCL, although some individual axons measured over 1500 microns. Other indices of neuron growth and differentiation increased 1- to 5-fold including the number of primary processes, branch points, segments and growth cones. Phase-contrast microscopy, staining with Nissl and silver, and scanning and transmission electron microscopy demonstrated many single multipolar and other neurons with axons, dendrites and well-differentiated properties. The data show that individual central nervous system neurons have an inherent capacity to quickly express characteristic differentiated features and also to grow rapidly in HCL.

  18. Spatial and Working Memory Is Linked to Spine Density and Mushroom Spines

    PubMed Central

    Aher, Yogesh D.; Sase, Ajinkya; Gröger, Marion; Mokhtar, Maher; Höger, Harald; Lubec, Gert

    2015-01-01

    Background Changes in synaptic structure and efficacy including dendritic spine number and morphology have been shown to underlie neuronal activity and size. Moreover, the shapes of individual dendritic spines were proposed to correlate with their capacity for structural change. Spine numbers and morphology were reported to parallel memory formation in the rat using a water maze but, so far, there is no information on spine counts or shape in the radial arm maze (RAM), a frequently used paradigm for the evaluation of complex memory formation in the rodent. Methods 24 male Sprague-Dawley rats were divided into three groups, 8 were trained, 8 remained untrained in the RAM and 8 rats served as cage controls. Dendritic spine numbers and individual spine forms were counted in CA1, CA3 areas and dentate gyrus of hippocampus using a DIL dye method with subsequent quantification by the Neuronstudio software and the image J program. Results Working memory errors (WME) and latency in the RAM were decreased along the training period indicating that animals performed the task. Total spine density was significantly increased following training in the RAM as compared to untrained rats and cage controls. The number of mushroom spines was significantly increased in the trained as compared to untrained and cage controls. Negative significant correlations between spine density and WME were observed in CA1 basal dendrites and in CA3 apical and basal dendrites. In addition, there was a significant negative correlation between spine density and latency in CA3 basal dendrites. Conclusion The study shows that spine numbers are significantly increased in the trained group, an observation that may suggest the use of this method representing a morphological parameter for memory formation studies in the RAM. Herein, correlations between WME and latency in the RAM and spine density revealed a link between spine numbers and performance in the RAM. PMID:26469788

  19. Comparison between basal and apical dendritic spines in estrogen-induced rapid spinogenesis of CA1 principal neurons in the adult hippocampus

    SciTech Connect

    Murakami, Gen; Mukai, Hideo; Hojo, Yasushi; Kawato, Suguru ||; Tsurugizawa, Tomokazu; Hatanaka, Yusuke; Tanabe, Nobuaki; Komatsuzaki, Yoshimasa |; Kominami, Shiro; Yamazaki, Takeshi; Kimoto, Tetsuya |; Kawato, Suguru ||. E-mail: kawato@phys.c.u-tokyo.ac.jp

    2006-12-15

    Modulation of hippocampal synaptic plasticity by estrogen has been attracting much attention. Here, we demonstrated the rapid effect of 17{beta}-estradiol on the density and morphology of spines in the stratum oriens (s.o., basal side) and in the stratum lacunosum-moleculare (s.l.m., apical side) by imaging Lucifer Yellow-injected CA1 neurons in adult male rat hippocampal slices, because spines in s.o. and s.l.m. have been poorly understood as compared with spines in the stratum radiatum. The application of 1 nM estradiol-induced a rapid increase in the density of spines of pyramidal neurons within 2 h. This increase by estradiol was blocked by Erk MAP kinase inhibitor and estrogen receptor inhibitor in both regions. Effect of blockade by agonists of AMPA receptors and NMDA receptors was different between s.o. and s.l.m. In both regions, ER{alpha} agonist PPT induced the same enhancing effect of spinogenesis as that induced by estradiol.

  20. Single-Session Combined Anterior-Posterior Approach for Treatment of Ankylosing Spondylitis with Obvious Displaced Lower Cervical Spine Fractures and Dislocations

    PubMed Central

    Yang, Baohui; Lu, Teng

    2017-01-01

    For patients with AS and lower cervical spine fractures, surgical methods have mainly included the single anterior approach, single posterior approach, and combined anterior-posterior approach. However, various surgical procedures were utilized because the fractures have not been clearly classified according to presence of displacement in these previous studies. Consequently, controversies have been raised regarding the selection of the surgical procedure. This study retrospective analysis was conducted in 12 patients with AS and lower cervical spine fractures and dislocations and explored single-session combined anterior-posterior approach for the treatment of AS with obvious displaced lower cervical spine fractures and dislocations which has demonstrated advantages such as good stabilization, satisfied fracture healing, and easy postoperative cares. However, to some extent, the difficulty and risk of this approach should be considered. Attention should be paid to the prevention of perioperative complications. PMID:28133616

  1. Single-Session Combined Anterior-Posterior Approach for Treatment of Ankylosing Spondylitis with Obvious Displaced Lower Cervical Spine Fractures and Dislocations.

    PubMed

    Yang, Baohui; Lu, Teng; Li, Haopeng

    2017-01-01

    For patients with AS and lower cervical spine fractures, surgical methods have mainly included the single anterior approach, single posterior approach, and combined anterior-posterior approach. However, various surgical procedures were utilized because the fractures have not been clearly classified according to presence of displacement in these previous studies. Consequently, controversies have been raised regarding the selection of the surgical procedure. This study retrospective analysis was conducted in 12 patients with AS and lower cervical spine fractures and dislocations and explored single-session combined anterior-posterior approach for the treatment of AS with obvious displaced lower cervical spine fractures and dislocations which has demonstrated advantages such as good stabilization, satisfied fracture healing, and easy postoperative cares. However, to some extent, the difficulty and risk of this approach should be considered. Attention should be paid to the prevention of perioperative complications.

  2. Ryanodine Receptor Activation Induces Long-Term Plasticity of Spine Calcium Dynamics

    PubMed Central

    Pannasch, Ulrike; Rückl, Martin; Rüdiger, Sten; Schmitz, Dietmar

    2015-01-01

    A key feature of signalling in dendritic spines is the synapse-specific transduction of short electrical signals into biochemical responses. Ca2+ is a major upstream effector in this transduction cascade, serving both as a depolarising electrical charge carrier at the membrane and an intracellular second messenger. Upon action potential firing, the majority of spines are subject to global back-propagating action potential (bAP) Ca2+ transients. These transients translate neuronal suprathreshold activation into intracellular biochemical events. Using a combination of electrophysiology, two-photon Ca2+ imaging, and modelling, we demonstrate that bAPs are electrochemically coupled to Ca2+ release from intracellular stores via ryanodine receptors (RyRs). We describe a new function mediated by spine RyRs: the activity-dependent long-term enhancement of the bAP-Ca2+ transient. Spines regulate bAP Ca2+ influx independent of each other, as bAP-Ca2+ transient enhancement is compartmentalized and independent of the dendritic Ca2+ transient. Furthermore, this functional state change depends exclusively on bAPs travelling antidromically into dendrites and spines. Induction, but not expression, of bAP-Ca2+ transient enhancement is a spine-specific function of the RyR. We demonstrate that RyRs can form specific Ca2+ signalling nanodomains within single spines. Functionally, RyR mediated Ca2+ release in these nanodomains induces a new form of Ca2+ transient plasticity that constitutes a spine specific storage mechanism of neuronal suprathreshold activity patterns. PMID:26098891

  3. Radiation dose reduction using a neck detection algorithm for single spiral brain and cervical spine CT acquisition in the trauma setting.

    PubMed

    Ardley, Nicholas D; Lau, Ken K; Buchan, Kevin

    2013-12-01

    Cervical spine injuries occur in 4-8 % of adults with head trauma. Dual acquisition technique has been traditionally used for the CT scanning of brain and cervical spine. The purpose of this study was to determine the efficacy of radiation dose reduction by using a single acquisition technique that incorporated both anatomical regions with a dedicated neck detection algorithm. Thirty trauma patients for brain and cervical spine CT were included and were scanned with the single acquisition technique. The radiation doses from the single CT acquisition technique with the neck detection algorithm, which allowed appropriate independent dose administration relevant to brain and cervical spine regions, were recorded. Comparison was made both to the doses calculated from the simulation of the traditional dual acquisitions with matching parameters, and to the doses of retrospective dual acquisition legacy technique with the same sample size. The mean simulated dose for the traditional dual acquisition technique was 3.99 mSv, comparable to the average dose of 4.2 mSv from 30 previous patients who had CT of brain and cervical spine as dual acquisitions. The mean dose from the single acquisition technique was 3.35 mSv, resulting in a 16 % overall dose reduction. The images from the single acquisition technique were of excellent diagnostic quality. The new single acquisition CT technique incorporating the neck detection algorithm for brain and cervical spine significantly reduces the overall radiation dose by eliminating the unavoidable overlapping range between 2 anatomical regions which occurs with the traditional dual acquisition technique.

  4. Calcium Transients in Dendrites of Neocortical Neurons Evoked by Single Subthreshold Excitatory Postsynaptic Potentials via Low-Voltage-Activated Calcium Channels

    NASA Astrophysics Data System (ADS)

    Markram, Henry; Sakmann, Bert

    1994-05-01

    Simultaneous recordings of membrane voltage and concentration of intracellular Ca2+ ([Ca2+]_i) were made in apical dendrites of layer 5 pyramidal cells of rat neocortex after filling dendrites with the fluorescent Ca2+ indicator Calcium Green-1. Subthreshold excitatory postsynaptic potentials (EPSPs), mediated by the activation of glutamate receptor channels, caused a brief increase in dendritic [Ca2+]_i. This rise in dendritic [Ca2+]_i was mediated by the opening of low-voltage-activated Ca2+ channels in the dendritic membrane. The results provide direct evidence that dendrites do not function as passive cables even at low-frequency synaptic activity; rather, a single subthreshold EPSP changes the dendritic membrane conductance by opening Ca2+ channels and generating a [Ca2+]_i transient that may propagate towards the soma. The activation of these Ca2+ channels at a low-voltage threshold is likely to influence the way in which dendritic EPSPs contribute to the electrical activity of the neuron.

  5. Outcomes and Toxicity for Hypofractionated and Single-Fraction Image-Guided Stereotactic Radiosurgery for Sarcomas Metastasizing to the Spine

    SciTech Connect

    Folkert, Michael R.; Bilsky, Mark H.; Tom, Ashlyn K.; Oh, Jung Hun; Alektiar, Kaled M.; Laufer, Ilya; Tap, William D.; Yamada, Yoshiya

    2014-04-01

    Purpose: Conventional radiation treatment (20-40 Gy in 5-20 fractions, 2-5 Gy per fraction) for sarcoma metastatic to the spine provides subtherapeutic doses, resulting in poor durable local control (LC) (50%-77% at 1 year). Hypofractionated (HF) and/or single-fraction (SF) image-guided stereotactic radiosurgery (IG-SRS) may provide a more effective means of managing these lesions. Methods and Materials: Patients with pathologically proven high-grade sarcoma metastatic to the spine treated with HF and SF IG-SRS were included. LC and overall survival (OS) were analyzed by the use of Kaplan-Meier statistics. Univariate and multivariate analyses were performed by the use of Cox regression with competing-risks analysis; all confidence intervals are 95%. Toxicities were assessed according to Common Terminology Criteria for Adverse Events, version 4.0. Results: From May 2005 to November 11, 2012, 88 patients with 120 discrete metastases received HF (3-6 fractions; median dose, 28.5 Gy; n=52, 43.3%) or SF IG-SRS (median dose, 24 Gy; n=68, 56.7%). The median follow-up time was 12.3 months. At 12 months, LC was 87.9% (confidence interval [CI], 81.3%-94.5%), OS was 60.6% (CI, 49.6%-71.6%), and median survival was 16.9 months. SF IG-SRS demonstrated superior LC to HF IG-SRS (12-month LC of 90.8% [CI, 83%-98.6%] vs 84.1% [CI, 72.9%-95.3%] P=.007) and retained significance on multivariate analysis (P=.030, hazard ratio 0.345; CI, 0.132-0.901]. Treatment was well tolerated, with 1% acute grade 3 toxicity, 4.5% chronic grade 3 toxicity, and no grade >3 toxicities. Conclusions: In the largest series of metastatic sarcoma to the spine to date, IG-SRS provides excellent LC in the setting of an aggressive disease with low radiation sensitivity and poor prognosis. Single-fraction IG-SRS is associated with the highest rates of LC with minimal toxicity.

  6. Fractional Cable Models for Spiny Neuronal Dendrites

    NASA Astrophysics Data System (ADS)

    Henry, B. I.; Langlands, T. A. M.; Wearne, S. L.

    2008-03-01

    Cable equations with fractional order temporal operators are introduced to model electrotonic properties of spiny neuronal dendrites. These equations are derived from Nernst-Planck equations with fractional order operators to model the anomalous subdiffusion that arises from trapping properties of dendritic spines. The fractional cable models predict that postsynaptic potentials propagating along dendrites with larger spine densities can arrive at the soma faster and be sustained at higher levels over longer times. Calibration and validation of the models should provide new insight into the functional implications of altered neuronal spine densities, a hallmark of normal aging and many neurodegenerative disorders.

  7. Adverse Outcomes After Palliative Radiation Therapy for Uncomplicated Spine Metastases: Role of Spinal Instability and Single-Fraction Radiation Therapy

    SciTech Connect

    Lam, Tai-Chung; Krishnan, Monica; Groff, Michael; Cheney, Matthew; Balboni, Tracy

    2015-10-01

    Purpose: Level I evidence demonstrates equivalent pain response after single-fraction (SF) or multifraction (MF) radiation therapy (RT) for bone metastases. The purpose of this study is to provide additional data to inform the incidence and predictors of adverse outcomes after RT for spine metastases. Methods and Materials: At a single institution, 299 uncomplicated spine metastases (without cord compression, prior RT, or surgery) treated with RT from 2008 to 2013 were retrospectively reviewed. The spinal instability neoplastic score (SINS) was used to assess spinal instability. The primary outcome was time to first spinal adverse event (SAE) at the site, including symptomatic vertebral fracture, hospitalization for site-related pain, salvage surgery, interventional procedure, new neurologic symptoms, or cord compression. Fine and Gray's multivariable model assessed associations of the primary outcome with SINS, SF RT, and other significant baseline factors. Propensity score matched analysis further assessed the relationship of SF RT to first SAEs. Results: The cumulative incidence of first SAE after SF RT (n=66) was 6.8% at 30 days, 16.9% at 90 days, and 23.6% at 180 days. For MF RT (n=233), the incidence was 3.5%, 6.4%, and 9.2%, respectively. In multivariable analysis, SF RT (hazard ratio [HR] = 2.8, 95% confidence interval [CI] 1.5-5.2, P=.001) and SINS ≥11 (HR=2.5 , 95% CI 1.3-4.9, P=.007) were predictors of the incidence of first SAE. In propensity score matched analysis, first SAEs had developed in 22% of patients with SF RT versus 6% of those with MF RT cases (HR=3.9, 95% CI 1.6-9.6, P=.003) at 90 days after RT. Conclusion: In uncomplicated spinal metastases treated with RT alone, spinal instability with SINS ≥11 and SF RT were associated with a higher rate of SAEs.

  8. A Single Subset of Dendritic Cells Controls the Cytokine Bias of Natural Killer T Cell Responses to Diverse Glycolipid Antigens

    PubMed Central

    Arora, Pooja; Baena, Andres; Yu, Karl O.A.; Saini, Neeraj K.; Kharkwal, Shalu S.; Goldberg, Michael F.; Kunnath-Velayudhan, Shajo; Carreño, Leandro J.; Venkataswamy, Manjunatha M.; Kim, John; Lazar-Molnar, Eszter; Lauvau, Gregoire; Chang, Young-tae; Liu, Zheng; Bittman, Robert; Al-Shamkhani, Aymen; Cox, Liam R.; Jervis, Peter J.; Veerapen, Natacha; Besra, Gurdyal S.; Porcelli, Steven A.

    2014-01-01

    Summary Many hematopoietic cell types express CD1d and are capable of presenting glycolipid antigens to invariant natural killer T cells (iNKT cells). However, the question of which cells are the principal presenters of glycolipid antigens in vivo remains controversial, and it has been suggested that this might vary depending on the structure of a particular glycolipid antigen. Here we have shown that a single type of cell, the CD8α+ DEC-205+ dendritic cell, was mainly responsible for capturing and presenting a variety of different glycolipid antigens, including multiple forms of α-galactosylceramide that stimulate widely divergent cytokine responses. After glycolipid presentation, these dendritic cells rapidly altered their expression of various costimulatory and coinhibitory molecules in a manner that was dependent on the structure of the antigen. These findings show flexibility in the outcome of two-way communication between CD8α+ dendritic cells and iNKT cells, providing a mechanism for biasing toward either proinflammatory or anti-inflammatory responses. PMID:24412610

  9. A single subset of dendritic cells controls the cytokine bias of natural killer T cell responses to diverse glycolipid antigens.

    PubMed

    Arora, Pooja; Baena, Andres; Yu, Karl O A; Saini, Neeraj K; Kharkwal, Shalu S; Goldberg, Michael F; Kunnath-Velayudhan, Shajo; Carreño, Leandro J; Venkataswamy, Manjunatha M; Kim, John; Lazar-Molnar, Eszter; Lauvau, Gregoire; Chang, Young-tae; Liu, Zheng; Bittman, Robert; Al-Shamkhani, Aymen; Cox, Liam R; Jervis, Peter J; Veerapen, Natacha; Besra, Gurdyal S; Porcelli, Steven A

    2014-01-16

    Many hematopoietic cell types express CD1d and are capable of presenting glycolipid antigens to invariant natural killer T cells (iNKT cells). However, the question of which cells are the principal presenters of glycolipid antigens in vivo remains controversial, and it has been suggested that this might vary depending on the structure of a particular glycolipid antigen. Here we have shown that a single type of cell, the CD8α(+) DEC-205(+) dendritic cell, was mainly responsible for capturing and presenting a variety of different glycolipid antigens, including multiple forms of α-galactosylceramide that stimulate widely divergent cytokine responses. After glycolipid presentation, these dendritic cells rapidly altered their expression of various costimulatory and coinhibitory molecules in a manner that was dependent on the structure of the antigen. These findings show flexibility in the outcome of two-way communication between CD8α(+) dendritic cells and iNKT cells, providing a mechanism for biasing toward either proinflammatory or anti-inflammatory responses.

  10. Ear manipulations reveal a critical period for survival and dendritic development at the single-cell level in Mauthner neurons.

    PubMed

    Elliott, Karen L; Houston, Douglas W; DeCook, Rhonda; Fritzsch, Bernd

    2015-12-01

    Second-order sensory neurons are dependent on afferents from the sense organs during a critical period in development for their survival and differentiation. Past research has mostly focused on whole populations of neurons, hampering progress in understanding the mechanisms underlying these critical phases. To move toward a better understanding of the molecular and cellular basis of afferent-dependent neuronal development, we developed a new model to study the effects of ear removal on a single identifiable cell in the hindbrain of a frog, the Mauthner cell. Ear extirpation at various stages of Xenopus laevis development defines a critical period of progressively-reduced dependency of Mauthner cell survival/differentiation on the ear afferents. Furthermore, ear removal results in a progressively decreased reduction in the number of dendritic branches. Conversely, addition of an ear results in an increase in the number of dendritic branches. These results suggest that the duration of innervation and the number of inner ear afferents play a quantitative role in Mauthner cell survival/differentiation, including dendritic development.

  11. Tuberculosis of spine

    PubMed Central

    Agrawal, Vinod; Patgaonkar, P. R.; Nagariya, S. P.

    2010-01-01

    Tuberculosis of the spine is one of the most common spine pathology in India. Over last 4 decades a lot has changed in the diagnosis, medical treatment and surgical procedures to treat this disorder. Further developments in diagnosis using molecular genetic techniques, more effective antibiotics and more aggressive surgical protocols have become essential with emergence of multidrug resistant TB. Surgical procedures such as single stage anterior and posterior stabilization, extrapleral dorsal spine anterior stabilization and endoscopic thoracoscopic surgeries have reduced the mortality and morbidity of the surgical procedures. is rapidly progressing. It is a challenge to treat MDR-TB Spine with late onset paraplegia and progressive deformity. Physicians must treat tuberculosis of spine on the basis of Culture and sensitivity. PMID:21572628

  12. Modification of dendritic development.

    PubMed

    Feria-Velasco, Alfredo; del Angel, Alma Rosa; Gonzalez-Burgos, Ignacio

    2002-01-01

    Since 1890 Ramón y Cajal strongly defended the theory that dendrites and their processes and spines had a function of not just nutrient transport to the cell body, but they had an important conductive role in neural impulse transmission. He extensively discussed and supported this theory in the Volume 1 of his extraordinary book Textura del Sistema Nervioso del Hombre y de los Vertebrados. Also, Don Santiago significantly contributed to a detailed description of the various neural components of the hippocampus and cerebral cortex during development. Extensive investigation has been done in the last Century related to the functional role of these complex brain regions, and their association with learning, memory and some limbic functions. Likewise, the organization and expression of neuropsychological qualities such as memory, exploratory behavior and spatial orientation, among others, depend on the integrity and adequate functional activity of the cerebral cortex and hippocampus. It is known that brain serotonin synthesis and release depend directly and proportionally on the availability of its precursor, tryptophan (TRY). By using a chronic TRY restriction model in rats, we studied their place learning ability in correlation with the dendritic spine density of pyramidal neurons in field CA1 of the hippocampus during postnatal development. We have also reported alterations in the maturation pattern of the ability for spontaneous alternation and task performance evaluating short-term memory, as well as adverse effects on the density of dendritic spines of hippocampal CA1 field pyramidal neurons and on the dendritic arborization and the number of dendritic spines of pyramidal neurons from the third layer of the prefrontal cortex using the same model of TRY restriction. The findings obtained in these studies employing a modified Golgi method, can be interpreted as a trans-synaptic plastic response due to understimulation of serotoninergic receptors located in the

  13. Integration of the olfactory code across dendritic claws of single mushroom body neurons

    PubMed Central

    Gruntman, Eyal; Turner, Glenn C.

    2013-01-01

    In the olfactory system, sensory inputs are arranged in different glomerular channels, which respond in combinatorial ensembles to the various chemical features of an odor. Here we investigate where and how this combinatorial code is read out deeper in the brain. We exploit the unique morphology of neurons in the mushroom body (MB), which receive input on large dendritic claws. Imaging odor responses of these dendritic claws shows that input channels with distinct odor tuning converge on individual MB neurons. We determined how these inputs interact to drive the cell to spike threshold using intracellular recordings to examine MB responses to optogenetically controlled input. Our results provide an elegant explanation for the characteristic selectivity of MB neurons: these cells receive different types of input, and require those inputs to be coactive in order to spike. These results establish the MB as an important site of integration in the fly olfactory system. PMID:24141312

  14. Cervical artificial disc replacement versus fusion in the cervical spine: a systematic review comparing multilevel versus single-level surgery

    PubMed Central

    Kepler, Christopher K.; Brodt, Erika D.; Dettori, Joseph R.; Albert, Todd J.

    2012-01-01

    Study design: Systematic review. Clinical questions: What is the effectiveness of multilevel cervical artificial disc replacement (C-ADR) compared with multilevel fusion with respect to pain and functional outcomes, and are the two procedures comparable in terms of safety? What is the effectiveness of multilevel C-ADR compared with single-level C-ADR with respect to pain and functional outcomes, and are the two procedures comparable in terms of safety? Methods: A systematic review was undertaken for articles published up to October 2011. Electronic databases and reference lists of key articles were searched to identify studies comparing multilevel C-ADR with multilevel anterior cervical discectomy and fusion (ACDF) or comparing multilevel C-ADR with single-level C-ADR. Studies which compared these procedures in the lumbar or thoracic spine or that reported alignment outcomes only were excluded. Two independent reviewers assessed the strength of evidence using the GRADE criteria and disagreements were resolved by consensus. Results: Two studies compared multilevel C-ADR with multilevel ACDF. While both reported improved Neck Disability Index (NDI) and Short-Form 36 (SF-36) scores after C-ADR compared with ACDF, only one study reported statistically significant results. Seven studies compared single-level C-ADR with multilevel C-ADR. Results were similar in terms of overall success, NDI and SF-36 scores, and patient satisfaction. There is discrepant information regarding rates of heterotopic ossification; dysphagia rate may be higher in multilevel C-ADR. Conclusions: The literature suggests that outcomes are at least similar for multilevel C-ADR and ACDF and may favor C-ADR. Future studies are necessary before firm recommendations can be made favoring one treatment strategy. Multilevel C-ADR seems to have similar results to single-level C-ADR but may have higher rates of heterotopic ossification and dysphagia. PMID:23236310

  15. Melatonin synergizes with low doses of L-DOPA to improve dendritic spine density in the mouse striatum in experimental Parkinsonism.

    PubMed

    Naskar, Amit; Manivasagam, Thamilarasan; Chakraborty, Joy; Singh, Raghavendra; Thomas, Bobby; Dhanasekaran, Muralikrishnan; Mohanakumar, Kochupurackal P

    2013-10-01

    The dopamine precursor, L-3,4-dihydroxyphenylalanine (L-DOPA), is the preferred drug for Parkinson's disease, but long-term treatment results in the drug-induced dyskinesias and other side effects. This study was undertaken to examine whether melatonin could potentiate low dose L-DOPA effects in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced experimental parkinsonism. Mice were treated with the parkinsonian neurotoxin, MPTP, and different doses of melatonin and low doses of L-DOPA. Behavior, striatal histology, and dopamine metabolism were evaluated on the 7th day. MPTP-induced striatal dopamine loss was not modified by melatonin administration (10-30 mg/kg; i.p. at 10-hr intervals, 6 times; or at 2-hr intervals, by day). However, low doses of L-DOPA (5 mg/kg, by oral gavage) administered alone or along with melatonin (10 mg/kg, i.p.) twice everyday for 2 days, 10 hr apart, after two doses of MPTP significantly attenuated striatal dopamine loss and provided improvements in both catalepsy and akinesia. Additionally, Golgi-impregnated striatal sections showed preservation of the medium spiny neurons, which have been damaged in MPTP-treated mouse. The results demonstrated that melatonin, but not L-DOPA, restored spine density and spine morphology of medium spiny neurons in the striatum and suggest that melatonin could be an ideal adjuvant to L-DOPA therapy in Parkinson's disease, and by the use of this neurohormone, it is possible to bring down the therapeutic doses of L-DOPA.

  16. Essential role of GluD1 in dendritic spine development and GluN2B to GluN2A NMDAR subunit switch in the cortex and hippocampus reveals ability of GluN2B inhibition in correcting hyperconnectivity

    PubMed Central

    Gupta, Subhash C.; Yadav, Roopali; Pavuluri, Ratnamala; Morley, Barbara J.; Stairs, Dustin J.; Dravid, Shashank M.

    2015-01-01

    The glutamate delta-1 (GluD1) receptor is highly expressed in the forebrain. We have previously shown that loss of GluD1 leads to social and cognitive deficits in mice, however, its role in synaptic development and neurotransmission remains poorly understood. Here we report that GluD1 is enriched in the medial prefrontal cortex (mPFC) and GluD1 knockout mice exhibit a higher dendritic spine number, greater excitatory neurotransmission as well as higher number of synapses in mPFC. In addition abnormalities in the LIMK1-cofilin signaling, which regulates spine dynamics, and a lower ratio of GluN2A/GluN2B expression was observed in the mPFC in GluD1 knockout mice. Analysis of the GluD1 knockout CA1 hippocampus similarly indicated the presence of higher spine number and synapses and altered LIMK1-cofilin signaling. We found that systemic administration of an N-methyl-d-aspartate (NMDA) receptor partial agonist d-cycloserine (DCS) at a high-dose, but not at a low-dose, and a GluN2B-selective inhibitor Ro-25-6981 partially normalized the abnormalities in LIMK1-cofilin signaling and reduced excess spine number in mPFC. The molecular effects of high-dose DCS and GluN2B inhibitor correlated with their ability to reduce the higher stereotyped behavior and depression-like behavior in GluD1 knockout mice. Together these findings demonstrate a critical requirement for GluD1 in normal spine development in the cortex and hippocampus. Moreover, these results identify inhibition of GluN2Bcontaining receptors as a mechanism for reducing excess dendritic spines and stereotyped behavior which may have therapeutic value in certain neurodevelopmental disorders. PMID:25721396

  17. Single Posterior Approach for En-Bloc Resection and Stabilization for Locally Advanced Pancoast Tumors Involving the Spine: Single Centre Experience

    PubMed Central

    Sunna, Tarek; Liberman, Moishe; Boubez, Ghassan; Wang, Zhi; Shedid, Daniel

    2016-01-01

    Study Design Monocentric prospective study. Purpose To assess the safety and effectiveness of the posterior approach for resection of advanced Pancoast tumors. Overview of Literature In patients with advanced Pancoast tumors invading the spine, most surgical teams consider the combined approach to be necessary for “en-bloc” resection to control visceral, vascular, and neurological structures. We report our preliminary experience with a single-stage posterior approach. Methods We included all patients who underwent posterior en-bloc resection of advanced Pancoast tumors invading the spine in our institution between January 2014 and May 2015. All patients had locally advanced tumors without N2 nodes or distant metastases. All patients, except 1, benefited from induction treatment consisting of a combination of concomitant chemotherapy (cisplatin-VP16) and radiation. Results Five patients were included in this study. There were 2 men and 3 women with a mean age of 55 years (range, 46–61 years). The tumor involved 2 adjacent levels in 1 patient, 3 levels in 1 patient, and 4 levels in 3 patients. There were no intraoperative complications. The mean operative time was 9 hours (range, 8–12 hours), and the mean estimated blood loss was 3.2 L (range, 1.5–7 L). No patient had a worsened neurological condition at discharge. Four complications occurred in 4 patients. Three complications required reoperation and none was lethal. The mean follow-up was 15.5 months (range, 9–24 months). Four patients harbored microscopically negative margins (R0 resection) and remained disease free. One patient harbored a microscopically positive margin (R1 resection) and exhibited local recurrence at 8 months following radiation treatment. Conclusions The posterior approach was a valuable option that avoided the need for a second-stage operation. Induction chemoradiation is highly suitable for limiting the risk of local recurrence. PMID:27994780

  18. Incidence of Deep Vein Thrombosis in Patients Undergoing Degenerative Spine Surgery onProphylactic Dalteparin; A Single Center Report

    PubMed Central

    Moayer, AlirezaFarid; Mohebali, Navideh; Razmkon, Ali

    2016-01-01

    Objective: To determine the incidence of deep vein thrombosis (DVT)in patients undergoing spinal surgeries receiving prophylactic doses of Deltaparin in a single center in central Iran. Method: This cross-sectional study was conducted in Shariatee hospital of Isfahan during a 12-month period. We included all the patients undergoing elective spinal surgeries in our center during the study period who received prophylactic dosages of subcutaneous Dalteparin (5000unit daily) thefirst postoperative day. Those with absolute contraindications of anticoagulation therapy were not included in the study. Patients were followed for 3 months clinically and the incidence of DVT was recorded. DVT was suspected clinically and was confirmed by color Doppler sonography. Results: Overall we included 120 patients with mean age of 44.8 ± 12.6years among whom there were 54 (45%) men and 66 (55%) women. Lumbar discectomy (32.9%)and laminectomy (20.2%)were the most common performed procedures. DVT was detected in 1 (0.83%) patient in postoperative period. None of the patients developed pulmonary embolism and none hemorrhagic adverse event was recorded. The patient was treated with therapeutic unfractionated heparin and was discharged with warfarin.  Conclusion: Our results shows the efficacy of LMWH (Dalteparin) in reducing the incidence of DVT to 0.83%. These results also show the safety of Dalteparin in spine surgery because of lack of bleeding complication. PMID:27162925

  19. Web-dendritic growth. [single crystal silicon ribbons for solar cells

    NASA Technical Reports Server (NTRS)

    Hilborn, R. B.; Faust, J. W., Jr.; Rhodes, C.

    1977-01-01

    The effects of various machine design parameters on the growth of web dendritic silicon ribbon were investigated. Ribbons were grown up to lengths of one meter, with widths increasing linearly up to one cm at the point of termination of growth. Thermal data were collected and evaluated for actual seeding and growth with variations in parameters affecting heat loss. It was found that for suitable growth, the mechanical system should be very rigid and stable, and the tolerances and specifications of the quartz crucibles must be far tighter than normal quartz tolerances. The widening rates of the ribbons were found to be a function of the temperature gradient rather than the temperature differences alone. A twin spacing in the seed of 3 microns to 2 microns was found to be unfavorable for growth; whereas spacing of 0.9 microns to 2 microns and 8 microns to 2 microns were favorable. Thermal modeling studies of the effects of furnace design parameters on the temperature distributions in melt and the growth of the dendritic web ribbon showed that the pull rate of the ribbon is strongly dependent on the temperature of the top thermal shield, the spacing between this shield and the melt, and the thickness of the growing web.

  20. Characterization of single voltage-gated Na+ and Ca2+ channels in apical dendrites of rat CA1 pyramidal neurons.

    PubMed

    Magee, J C; Johnston, D

    1995-08-15

    1. We have used dendrite-attached patch-clamp techniques to record single Na+ and Ca2+ channel activity from the apical dendrites (up to 350 microns away from soma) of CA1 pyramidal neurons in rat hippocampal slices (ages: 2-8 weeks). 2. Na+ channels were found in every patch examined (range: 2 to > 20 channels per patch). Channel openings, which had a slope conductance of 15 +/- 0.3 pS (mean +/- S.E.M.), began with test commands to around -50 mV and consisted of both early transient channel activity and also later occurring prolonged openings of 5-15 ms. All Na+ channel activity was suppressed by inclusion of TTX (1 microM) in the recording pipette. 3. Ca2+ channel activity was recorded in about 80% of the patches examined (range: 1 to > 10 channels per patch). Several types of channel behaviour were observed in these patches. Single channel recordings in 110 mM BaCl2, revealed an approximately 10 pS channel of small unitary current amplitude (-0.5 pA at -20 mV). These channels began activating at relatively hyperpolarized potentials (-50 mV) and ensemble averages of this low voltage-activated (LVA) channel activity showed rapid inactivation. 4. A somewhat heterogeneous population of high voltage-activated, moderate conductance (HVAm; approximately 17 pS), Ca2+ channel activity was also encountered. These channels exhibited a relatively large unitary amplitude (-0.8 pA at 0 mV) and ensemble averages demonstrated moderate inactivation. The HVAm population of channels could be tentatively subdivided into two separate groups based upon mean channel open times. 5. Less frequently, HVA, large conductance (27 pS) Ca2+ channel activity (HVA1) was also observed. This large unitary amplitude (-1.5 pA at 0 mV) channel activity began with steps to approximately 0 mV and ensemble averages did not show any time-dependent inactivation. The dihydropyridine Ca2+ channel agonist Bay K 8644 (0.5 or 1 microM) was found to characteristically prolong these channel openings. 6. omega

  1. Characterization of single voltage-gated Na+ and Ca2+ channels in apical dendrites of rat CA1 pyramidal neurons.

    PubMed Central

    Magee, J C; Johnston, D

    1995-01-01

    1. We have used dendrite-attached patch-clamp techniques to record single Na+ and Ca2+ channel activity from the apical dendrites (up to 350 microns away from soma) of CA1 pyramidal neurons in rat hippocampal slices (ages: 2-8 weeks). 2. Na+ channels were found in every patch examined (range: 2 to > 20 channels per patch). Channel openings, which had a slope conductance of 15 +/- 0.3 pS (mean +/- S.E.M.), began with test commands to around -50 mV and consisted of both early transient channel activity and also later occurring prolonged openings of 5-15 ms. All Na+ channel activity was suppressed by inclusion of TTX (1 microM) in the recording pipette. 3. Ca2+ channel activity was recorded in about 80% of the patches examined (range: 1 to > 10 channels per patch). Several types of channel behaviour were observed in these patches. Single channel recordings in 110 mM BaCl2, revealed an approximately 10 pS channel of small unitary current amplitude (-0.5 pA at -20 mV). These channels began activating at relatively hyperpolarized potentials (-50 mV) and ensemble averages of this low voltage-activated (LVA) channel activity showed rapid inactivation. 4. A somewhat heterogeneous population of high voltage-activated, moderate conductance (HVAm; approximately 17 pS), Ca2+ channel activity was also encountered. These channels exhibited a relatively large unitary amplitude (-0.8 pA at 0 mV) and ensemble averages demonstrated moderate inactivation. The HVAm population of channels could be tentatively subdivided into two separate groups based upon mean channel open times. 5. Less frequently, HVA, large conductance (27 pS) Ca2+ channel activity (HVA1) was also observed. This large unitary amplitude (-1.5 pA at 0 mV) channel activity began with steps to approximately 0 mV and ensemble averages did not show any time-dependent inactivation. The dihydropyridine Ca2+ channel agonist Bay K 8644 (0.5 or 1 microM) was found to characteristically prolong these channel openings. 6. omega

  2. RORα Regulates Multiple Aspects of Dendrite Development in Cerebellar Purkinje Cells In Vivo.

    PubMed

    Takeo, Yukari H; Kakegawa, Wataru; Miura, Eriko; Yuzaki, Michisuke

    2015-09-09

    The establishment of cell-type-specific dendritic arbors is fundamental for proper neural circuit formation. Here, using temporal- and cell-specific knock-down, knock-out, and overexpression approaches, we show that multiple aspects of the dendritic organization of cerebellar Purkinje cells (PCs) are controlled by a single transcriptional factor, retinoic acid-related orphan receptor-alpha (RORα), a gene defective in staggerer mutant mice. As reported earlier, RORα was required for regression of primitive dendrites before postnatal day 4 (P4). RORα was also necessary for PCs to form a single Purkinje layer from P0 to P4. The knock-down of RORα from P4 impaired the elimination of perisomatic dendrites and maturation of single stem dendrites in PCs at P8. Filopodia and spines were also absent in these PCs. The knock-down of RORα from P8 impaired the formation and maintenance of terminal dendritic branches of PCs at P14. Finally, even after dendrite formation was completed at P21, RORα was required for PCs to maintain dendritic complexity and functional synapses, but their mature innervation pattern by single climbing fibers was unaffected. Interestingly, overexpression of RORα in PCs at various developmental stages did not facilitate dendrite development, but had specific detrimental effects on PCs. Because RORα deficiency during development is closely related to the severity of spinocerebellar ataxia type 1, delineating the specific roles of RORα in PCs in vivo at different time windows during development and throughout adulthood would facilitate our understanding of the pathogenesis of cerebellar disorders. Significance statement: The genetic programs by which each neuron subtype develops and maintains dendritic arbors have remained largely unclear. This is partly because dendrite development is modulated dynamically by neuronal activities and interactions with local environmental cues in vivo. In addition, dendrites are formed and maintained by the

  3. Vortioxetine promotes early changes in dendritic morphology compared to fluoxetine in rat hippocampus.

    PubMed

    Chen, Fenghua; du Jardin, Kristian Gaarn; Waller, Jessica A; Sanchez, Connie; Nyengaard, Jens R; Wegener, Gregers

    2016-02-01

    Preclinical studies reveal that the multimodal antidepressant vortioxetine enhances long-term potentiation and dendritic branching compared to a selective serotonin reuptake inhibitor (SSRI). In the present study, we investigated vortioxetine׳s effects on spines and dendritic morphology in rat hippocampus at two time points compared to the SSRI, fluoxetine. Rats were dosed for 1 and 4 weeks with vortioxetine and fluoxetine at doses relevant for antidepressant activity. Dendritic morphology of pyramidal neurons (i.e., dendritic length, dendritic branch, spine number and density, and Sholl analysis) was examined in Golgi-stained sections from hippocampal CA1. After 1 week of treatment, vortioxetine significantly increased spine number (apical and basal dendrites), spine density (only basal), dendritic length (only apical), and dendritic branch number (apical and basal), whereas fluoxetine had no effect. After 4 weeks of treatment, vortioxetine significantly increased all measures of dendritic spine morphology as did fluoxetine except for spine density of basal dendrites. The number of intersections in the apical and basal dendrites was also significantly increased for both treatments after 4 weeks compared to control. In addition, 4 weeks of vortioxetine treatment, but not fluoxetine, promoted a decrease in spine neck length. In conclusion, 1-week vortioxetine treatment induced changes in spine number and density and dendritic morphology, whereas an equivalent dose of fluoxetine had no effects. Decreased spine neck length following 4-week vortioxetine treatment suggests a transition to mature spine morphology. This implies that vortioxetine׳s effects on spine and dendritic morphology are mediated by mechanisms that go beyond serotonin reuptake inhibition.

  4. The transfection of BDNF to dopamine neurons potentiates the effect of dopamine D3 receptor agonist recovering the striatal innervation, dendritic spines and motor behavior in an aged rat model of Parkinson's disease.

    PubMed

    Razgado-Hernandez, Luis F; Espadas-Alvarez, Armando J; Reyna-Velazquez, Patricia; Sierra-Sanchez, Arturo; Anaya-Martinez, Veronica; Jimenez-Estrada, Ismael; Bannon, Michael J; Martinez-Fong, Daniel; Aceves-Ruiz, Jorge

    2015-01-01

    The progressive degeneration of the dopamine neurons of the pars compacta of substantia nigra and the consequent loss of the dopamine innervation of the striatum leads to the impairment of motor behavior in Parkinson's disease. Accordingly, an efficient therapy of the disease should protect and regenerate the dopamine neurons of the substantia nigra and the dopamine innervation of the striatum. Nigral neurons express Brain Derived Neurotropic Factor (BDNF) and dopamine D3 receptors, both of which protect the dopamine neurons. The chronic activation of dopamine D3 receptors by their agonists, in addition, restores, in part, the dopamine innervation of the striatum. Here we explored whether the over-expression of BDNF by dopamine neurons potentiates the effect of the activation of D3 receptors restoring nigrostriatal innervation. Twelve-month old Wistar rats were unilaterally injected with 6-hydroxydopamine into the striatum. Five months later, rats were treated with the D3 agonist 7-hydroxy-N,N-di-n-propy1-2-aminotetralin (7-OH-DPAT) administered i.p. during 4½ months via osmotic pumps and the BDNF gene transfection into nigral cells using the neurotensin-polyplex nanovector (a non-viral transfection) that selectively transfect the dopamine neurons via the high-affinity neurotensin receptor expressed by these neurons. Two months after the withdrawal of 7-OH-DPAT when rats were aged (24 months old), immunohistochemistry assays were made. The over-expression of BDNF in rats receiving the D3 agonist normalized gait and motor coordination; in addition, it eliminated the muscle rigidity produced by the loss of dopamine. The recovery of motor behavior was associated with the recovery of the nigral neurons, the dopamine innervation of the striatum and of the number of dendritic spines of the striatal neurons. Thus, the over-expression of BDNF in dopamine neurons associated with the chronic activation of the D3 receptors appears to be a promising strategy for restoring

  5. Spine Buddy® Supportive Pad Impact on Single-Leg Static Balance and a Jogging Gait of Individuals Wearing a Military Backpack

    PubMed Central

    Ward, John; Coats, Jesse; Pourmoghaddam, Amir

    2014-01-01

    The Spine Buddy® supportive pad was developed to be inserted underneath military backpacks to help disperse the heavy load of the backpack. The purpose of this study was to determine the impact the additional supportive pad had on static balance and a running gait while wearing a military backpack. Forty healthy subjects (age= 27.5 + 5.6 yrs, body height= 1.78 + 0.06 m, body mass= 86.5 + 14.0 kg: mean + SD) participated in a static single-leg balance test on a force plate with each lower limb while wearing a 15.9 kg military backpack for 30 s. Following this, participants were randomized to one of two interventions: 1) Intervention, which wore the Spine Buddy® supportive pad underneath their backpack or 2) Control, with no additional supportive pad. Post-intervention measurements of static single-leg balance were then recorded. Afterwards, a similar pre vs post testing schedule and randomization scheme was used to test the impact of the supportive pad on a 5 mph jogging gait using Vicon® cameras. Within-group data were analyzed with a 2-way repeated measures ANOVA. Statistically significant differences were not seen between the control and experimental group for balance and gait variables. Preliminarily, this suggests that the Spine Buddy® supportive pad causes no deleterious effect on static balance and a jogging gait in 18–45 year-old asymptomatic individuals. PMID:25713665

  6. Osteoporosis and Your Spine

    MedlinePlus

    ... Movement › Osteoporosis and Your Spine Osteoporosis and Your Spine Your spine is made up of small bones ... called kyphosis. Kyphosis and Bone Breaks in the Spine The bones in the spine are called vertebrae. ...

  7. The 40-year history of modeling active dendrites in cerebellar Purkinje cells: emergence of the first single cell “community model”

    PubMed Central

    Bower, James M.

    2015-01-01

    The subject of the effects of the active properties of the Purkinje cell dendrite on neuronal function has been an active subject of study for more than 40 years. Somewhat unusually, some of these investigations, from the outset have involved an interacting combination of experimental and model-based techniques. This article recounts that 40-year history, and the view of the functional significance of the active properties of the Purkinje cell dendrite that has emerged. It specifically considers the emergence from these efforts of what is arguably the first single cell “community” model in neuroscience. The article also considers the implications of the development of this model for future studies of the complex properties of neuronal dendrites. PMID:26539104

  8. Micromechanics of Sea Urchin spines.

    PubMed

    Tsafnat, Naomi; Fitz Gerald, John D; Le, Hai N; Stachurski, Zbigniew H

    2012-01-01

    The endoskeletal structure of the Sea Urchin, Centrostephanus rodgersii, has numerous long spines whose known functions include locomotion, sensing, and protection against predators. These spines have a remarkable internal microstructure and are made of single-crystal calcite. A finite-element model of the spine's unique porous structure, based on micro-computed tomography (microCT) and incorporating anisotropic material properties, was developed to study its response to mechanical loading. Simulations show that high stress concentrations occur at certain points in the spine's architecture; brittle cracking would likely initiate in these regions. These analyses demonstrate that the organization of single-crystal calcite in the unique, intricate morphology of the sea urchin spine results in a strong, stiff and lightweight structure that enhances its strength despite the brittleness of its constituent material.

  9. A dendritic single-molecule fluorescent probe that is monovalent, photostable and minimally blinking

    NASA Astrophysics Data System (ADS)

    Yang, Si Kyung; Shi, Xinghua; Park, Seongjin; Ha, Taekjip; Zimmerman, Steven C.

    2013-08-01

    Single-molecule fluorescence techniques have emerged as a powerful approach to understanding complex biological systems. However, a challenge researchers still face is the limited photostability of nearly all organic fluorophores, including the cyanine and Alexa dyes. We report a new, monovalent probe that emits in the far-red region of the visible spectrum with properties desirable for single-molecule optical imaging. This probe is based on a ring-fused boron-dipyrromethene (BODIPY) core that is conjugated to a polyglycerol dendrimer (PGD). The dendrimer makes the hydrophobic fluorophore water-soluble. This probe exhibits excellent brightness, with an emission maximum of 705 nm. We have observed strikingly long and stable emission from individual PGD-BODIPY probes, even in the absence of anti-fading agents such as Trolox, a combined oxidizing-reducing agent often used in single-molecule studies for improving the photostability of common imaging probes. These interesting properties greatly simplify use of the fluorophore.

  10. The Transfection of BDNF to Dopamine Neurons Potentiates the Effect of Dopamine D3 Receptor Agonist Recovering the Striatal Innervation, Dendritic Spines and Motor Behavior in an Aged Rat Model of Parkinson’s Disease

    PubMed Central

    Razgado-Hernandez, Luis F.; Espadas-Alvarez, Armando J.; Reyna-Velazquez, Patricia; Sierra-Sanchez, Arturo; Anaya-Martinez, Veronica; Jimenez-Estrada, Ismael; Bannon, Michael J.; Martinez-Fong, Daniel; Aceves-Ruiz, Jorge

    2015-01-01

    The progressive degeneration of the dopamine neurons of the pars compacta of substantia nigra and the consequent loss of the dopamine innervation of the striatum leads to the impairment of motor behavior in Parkinson’s disease. Accordingly, an efficient therapy of the disease should protect and regenerate the dopamine neurons of the substantia nigra and the dopamine innervation of the striatum. Nigral neurons express Brain Derived Neurotropic Factor (BDNF) and dopamine D3 receptors, both of which protect the dopamine neurons. The chronic activation of dopamine D3 receptors by their agonists, in addition, restores, in part, the dopamine innervation of the striatum. Here we explored whether the over-expression of BDNF by dopamine neurons potentiates the effect of the activation of D3 receptors restoring nigrostriatal innervation. Twelve-month old Wistar rats were unilaterally injected with 6-hydroxydopamine into the striatum. Five months later, rats were treated with the D3 agonist 7-hydroxy-N,N-di-n-propy1-2-aminotetralin (7-OH-DPAT) administered i.p. during 4½ months via osmotic pumps and the BDNF gene transfection into nigral cells using the neurotensin-polyplex nanovector (a non-viral transfection) that selectively transfect the dopamine neurons via the high-affinity neurotensin receptor expressed by these neurons. Two months after the withdrawal of 7-OH-DPAT when rats were aged (24 months old), immunohistochemistry assays were made. The over-expression of BDNF in rats receiving the D3 agonist normalized gait and motor coordination; in addition, it eliminated the muscle rigidity produced by the loss of dopamine. The recovery of motor behavior was associated with the recovery of the nigral neurons, the dopamine innervation of the striatum and of the number of dendritic spines of the striatal neurons. Thus, the over-expression of BDNF in dopamine neurons associated with the chronic activation of the D3 receptors appears to be a promising strategy for restoring

  11. Rapid formation and remodeling of postsynaptic densities in developing dendrites.

    PubMed

    Marrs, G S; Green, S H; Dailey, M E

    2001-10-01

    The dynamics of postsynaptic density (PSD) formation and remodeling were investigated in live developing hippocampal tissue slices. Time lapse imaging of transfected neurons expressing GFP-tagged PSD95, a prominent PSD protein, revealed that up to 40% of PSDs in developing dendrites are structurally dynamic; they rapidly (<15 min) appear or disappear, but also grow, shrink and move within shafts and spines. New spines containing PSDs were formed by conversion of dynamic filopodia-like spine precursors in which PSDs appeared de novo, or by direct extension of spines or spine precursors carrying preformed PSDs from the shaft. PSDs are therefore highly dynamic structures that can undergo rapid structural alteration within dendrite shafts, spines and spine precursors, permitting rapid formation and remodeling of synaptic connections in developing CNS tissues.

  12. Cysteine proteinase-1 and cut protein isoform control dendritic innervation of two distinct sensory fields by a single neuron.

    PubMed

    Lyons, Gray R; Andersen, Ryan O; Abdi, Khadar; Song, Won-Seok; Kuo, Chay T

    2014-03-13

    Dendrites often exhibit structural changes in response to local inputs. Although mechanisms that pattern and maintain dendritic arbors are becoming clearer, processes regulating regrowth, during context-dependent plasticity or after injury, remain poorly understood. We found that a class of Drosophila sensory neurons, through complete pruning and regeneration, can elaborate two distinct dendritic trees, innervating independent sensory fields. An expression screen identified Cysteine proteinase-1 (Cp1) as a critical regulator of this process. Unlike known ecdysone effectors, Cp1-mutant ddaC neurons pruned larval dendrites normally but failed to regrow adult dendrites. Cp1 expression was upregulated/concentrated in the nucleus during metamorphosis, controlling production of a truncated Cut homeodomain transcription factor. This truncated Cut, but not the full-length protein, allowed Cp1-mutant ddaC neurons to regenerate higher-order adult dendrites. These results identify a molecular pathway needed for dendrite regrowth after pruning, which allows the same neuron to innervate distinct sensory fields.

  13. Effects of Applied Electric Current on the Tip Radius and the Universal Amplitude Coefficient of a Single Growing Dendrite

    NASA Astrophysics Data System (ADS)

    Nasresfahani, Mohammad Reza; Niroumand, Behzad; Kermanpur, Ahmad; Raeissi, Mehdi

    2016-09-01

    Modification of solidification structures by applying electric current has been the subject of interest in recent years. However, the exact relationships between the dendrite growth parameters and the current density are not yet clear. The dendrite tip geometry is an important growth parameter which can be characterized using the dendrite tip radius and the universal amplitude coefficient. In this paper, the dendrite tip shape was investigated in the absence and presence of an electric field using a transparent model material, i.e. the succinonitrile-acetone alloy. The results showed that both dendrite tip radius and universal amplitude coefficient increased by increasing the applied current density. The increase in the tip radius was attributed to the Joule heat produced at the solid-liquid interface which reduced the interface undercooling. The increase in the universal amplitude coefficient was postulated to be due to the changes in the distribution coefficient of the alloy system which would result in higher solute concentration in front of the solid-liquid interface. Owing to the increased universal amplitude coefficient, more prominent dendritic fins were observed at dendrites tips under electric current.

  14. Advanced dendritic web growth development and development of single-crystal silicon dendritic ribbon and high-efficiency solar cell program

    NASA Technical Reports Server (NTRS)

    Duncan, C. S.; Seidensticker, R. G.; Mchugh, J. P.; Hopkins, R. H.

    1986-01-01

    Efforts to demonstrate that the dendritic web technology is ready for commercial use by the end of 1986 continues. A commercial readiness goal involves improvements to crystal growth furnace throughput to demonstrate an area growth rate of greater than 15 sq cm/min while simultaneously growing 10 meters or more of ribbon under conditions of continuous melt replenishment. Continuous means that the silicon melt is being replenished at the same rate that it is being consumed by ribbon growth so that the melt level remains constant. Efforts continue on computer thermal modeling required to define high speed, low stress, continuous growth configurations; the study of convective effects in the molten silicon and growth furnace cover gas; on furnace component modifications; on web quality assessments; and on experimental growth activities.

  15. Lumbar spine CT scan

    MedlinePlus

    CAT scan - lumbar spine; Computed axial tomography scan - lumbar spine; Computed tomography scan - lumbar spine; CT - lower back ... stopping.) A computer creates separate images of the spine area, called slices. These images can be stored, ...

  16. Spine osteoarthritis.

    PubMed

    Laplante, Ben L; DePalma, Michael J

    2012-05-01

    Osteoarthritis of the spine develops as a consequence of the natural aging process and is associated with significant morbidity and health care expenditures. Effective diagnosis and treatment of the resultant pathologic conditions can be clinically challenging. Recent evidence has emerged to aid the investigating clinician in formulating an accurate diagnosis and in implementing a successful treatment algorithm. This article details the degenerative cascade that results in the osteoarthritic spine, reviews prevalence data for common painful spinal disorders, and discusses evidence-based treatment options for management of zygapophysial and sacroiliac joint arthrosis.

  17. Scanning Ultrasound (SUS) Causes No Changes to Neuronal Excitability and Prevents Age-Related Reductions in Hippocampal CA1 Dendritic Structure in Wild-Type Mice

    PubMed Central

    Hatch, Robert John; Leinenga, Gerhard

    2016-01-01

    Scanning ultrasound (SUS) is a noninvasive approach that has recently been shown to ameliorate histopathological changes and restore memory functions in an Alzheimer's disease mouse model. Although no overt neuronal damage was reported, the short- and long-term effects of SUS on neuronal excitability and dendritic tree morphology had not been investigated. To address this, we performed patch-clamp recordings from hippocampal CA1 pyramidal neurons in wild-type mice 2 and 24 hours after a single SUS treatment, and one week and 3 months after six weekly SUS treatments, including sham treatments as controls. In both treatment regimes, no changes in CA1 neuronal excitability were observed in SUS-treated neurons when compared to sham-treated neurons at any time-point. For the multiple treatment groups, we also determined the dendritic morphology and spine densities of the neurons from which we had recorded. The apical trees of sham-treated neurons were reduced at the 3 month time-point when compared to one week; however, surprisingly, no longitudinal change was detected in the apical dendritic trees of SUS-treated neurons. In contrast, the length and complexity of the basal dendritic trees were not affected by SUS treatment at either time-point. The apical dendritic spine densities were reduced, independent of the treatment group, at 3 months compared to one week. Collectively, these data suggest that ultrasound can be employed to prevent an age-associated loss of dendritic structure without impairing neuronal excitability. PMID:27727310

  18. A single-step route for large-scale synthesis of core-shell palladium@platinum dendritic nanocrystals/reduced graphene oxide with enhanced electrocatalytic properties

    NASA Astrophysics Data System (ADS)

    Liu, Qi; Xu, Yan-Ru; Wang, Ai-Jun; Feng, Jiu-Ju

    2016-01-01

    In this report, a facile, seed-less and single-step method is developed for large-scale synthesis of core-shell Pd@Pt dendritic nanocrystals anchored on reduced graphene oxide (Pd@Pt DNC/rGO) under mild conditions. Poly(ethylene oxide) is employed as a structure-directing and stabilizing agent. Compared with commercial Pt/C (20 wt%) and Pd/C (20 wt%) catalysts, the as-obtained nanocomposite has large electrochemically active surface area (114.15 m2 gmetal-1), and shows superior catalytic activity and stability with the mass activities of 1210.0 and 1128.5 mAmgmetal-1 for methanol and ethanol oxidation, respectively. The improved catalytic activity is mainly the consequence of the synergistic effects between Pd and Pt of the dendritic structures, as well as rGO as a support.

  19. Differential distribution of NCX1 contributes to spine–dendrite compartmentalization in CA1 pyramidal cells

    PubMed Central

    Lőrincz, Andrea; Rózsa, Balázs; Katona, Gergely; Vizi, E. Sylvester; Tamás, Gábor

    2007-01-01

    Compartmentalization of Ca2+ between dendritic spines and shafts is governed by diffusion barriers and a range of Ca2+ extrusion mechanisms. The distinct contribution of different Ca2+ clearance systems to Ca2+ compartmentalization in dendritic spines versus shafts remains elusive. We applied a combination of ultrastructural and functional imaging methods to assess the subcellular distribution and role of NCX1 in rat CA1 pyramidal cells. Quantitative electron microscopic analysis of preembedding immunogold reactions revealed uniform densities of NCX1 along the shafts of apical and basal dendrites, but densities in dendritic shafts were approximately seven times higher than in dendritic spines. In line with these results, two-photon imaging of synaptically activated Ca2+ transients during NCX blockade showed preferential action localized to the dendritic shafts for NCXs in regulating spine–dendrite coupling. PMID:17215351

  20. Complications and Outcomes of Complex Spine Reconstructions in Poliomyelitis-Associated Spinal Deformities: A Single Institution Experience

    PubMed Central

    Godzik, Jakub; Lenke, Lawrence G.; Holekamp, Terrence; Sides, Brenda; Kelly, Michael P.

    2014-01-01

    Study Design Retrospective case-series Objective Share our institutional experience with spinal reconstruction for deformity correction in patients with a history of poliomyelitis. Background Data Polio and post-polio syndrome are not uncommonly related to a paralytic spinal deformity. Limited modern data exists regarding outcomes and complications following spinal reconstruction in this population. Methods A clinical database was reviewed for patients undergoing spinal reconstruction for polio-associated spinal deformity at our institution from 1985 to 2012. Relevant demographic, medical, surgical and postoperative information were collected from medical records and analyzed. Preoperative and last follow-up SRS-22 scores were recorded. Results A total of 22 patients with polio who underwent surgical deformity correction were identified. Mean age was 49 years (Range, 12–74), and 15 patients (68%) were female. Preoperative motor deficit was present in 14/22 (64%). All patients underwent instrumented spinal fusion (Mean 13 vertebral levels, Range, 3–18). Ten (10/22, 45%) patients developed major complications, and four patients (4/22, 18%) developed new postoperative neurological deficits. Neurological monitoring yielded a 13% false negative rate. At 2-year follow-up (20/22), patients maintained an average coronal correction of 25 degrees (33%, p = 0.001) and sagittal correction of 25 degrees (34%, p = 0.003). Minimum 2-year follow-up data were available for 11/22 (50%) of patients. At an average of 72 months of follow-up (Range, 28 – 134 months), the mean SRS22 pain subscore improved from a mean of 2.75 to 3.6 (p = 0.012); self-image from 2.8 to 3.7 (p = 0.041); function from 3.1 to 3.8 (p = 0.036); satisfaction from 2.1 to 3.9 (p = 0.08); mental health from 3.7 to 4.5 (p = 0.115). Conclusion Spine reconstruction for poliomyelitis-associated deformity was associated with high complication rates (54%) and sometimes unreliable neurologic monitoring data. Despite

  1. Loss of PSD-95 Enrichment is not a Prerequisite for Spine Retraction

    PubMed Central

    Woods, Georgia F.; Oh, Won Chan; Boudewyn, Lauren C.; Mikula, Sarah K.; Zito, Karen

    2011-01-01

    Changes in neuronal structure are thought to underlie long-term behavioral modifications associated with learning and memory. In particular, considerable evidence implicates the destabilization and retraction of dendritic spines along with the loss of spine synapses as an important cellular mechanism for refining brain circuits, yet the molecular mechanisms regulating spine elimination remain ill-defined. The postsynaptic density protein, PSD-95, is highly enriched in dendritic spines and has been associated with spine stability. Because spines with low levels of PSD-95 are more dynamic, and the recruitment of PSD-95 to nascent spines has been associated with spine stabilization, we hypothesized that loss of PSD-95 enrichment would be a prerequisite for spine retraction. To test this hypothesis, we used dual-color time-lapse two-photon microscopy to monitor rat hippocampal pyramidal neurons co-transfected with PSD-95-GFP and DsRed-Express, and we analyzed the relationship between PSD-95-GFP enrichment and spine morphological changes. Consistent with our hypothesis, we found that the majority of spines that retracted were relatively unenriched for PSD-95-GFP. However, in the subset of PSD-95-GFP-enriched spines that retracted, spine shrinkage and loss of PSD-95-GFP were tightly coupled, suggesting that loss of PSD-95-GFP enrichment did not precede spine retraction. Moreover, we found that in some instances spine retraction resulted in a significant enrichment of PSD-95-GFP on the dendritic shaft. Our data support a model of spine retraction in which loss of PSD-95 enrichment is not required prior to the destabilization of spines. PMID:21865455

  2. Dendritic planarity of Purkinje cells is independent of Reelin signaling.

    PubMed

    Kim, Jinkyung; Park, Tae-Ju; Kwon, Namseop; Lee, Dongmyeong; Kim, Seunghwan; Kohmura, Yoshiki; Ishikawa, Tetsuya; Kim, Kyong-Tai; Curran, Tom; Je, Jung Ho

    2015-07-01

    The dendritic planarity of Purkinje cells is critical for cerebellar circuit formation. In the absence of Crk and CrkL, the Reelin pathway does not function resulting in partial Purkinje cell migration and defective dendritogenesis. However, the relationships among Purkinje cell migration, dendritic development and Reelin signaling have not been clearly delineated. Here, we use synchrotron X-ray microscopy to obtain 3-D images of Golgi-stained Purkinje cell dendrites. Purkinje cells that failed to migrate completely exhibited conical dendrites with abnormal 3-D arborization and reduced dendritic complexity. Furthermore, their spines were fewer in number with a distorted morphology. In contrast, Purkinje cells that migrated successfully displayed planar dendritic and spine morphologies similar to normal cells, despite reduced dendritic complexity. These results indicate that, during cerebellar formation, Purkinje cells migrate into an environment that supports development of dendritic planarity and spine formation. While Reelin signaling is important for the migration process, it does not make a direct major contribution to dendrite formation.

  3. Laparoscopic Spine Surgery

    MedlinePlus

    ... Opportunities Exhibit Opportunities Sponsorship Opportunities Log In Laparoscopic Spine Surgery Patient Information from SAGES Download PDF Find a SAGES Surgeon Laparoscopic Spine Surgery Your spine surgeon has determined that you ...

  4. Global deprivation of brain-derived neurotrophic factor in the CNS reveals an area-specific requirement for dendritic growth.

    PubMed

    Rauskolb, Stefanie; Zagrebelsky, Marta; Dreznjak, Anita; Deogracias, Rubén; Matsumoto, Tomoya; Wiese, Stefan; Erne, Beat; Sendtner, Michael; Schaeren-Wiemers, Nicole; Korte, Martin; Barde, Yves-Alain

    2010-02-03

    Although brain-derived neurotrophic factor (BDNF) is linked with an increasing number of conditions causing brain dysfunction, its role in the postnatal CNS has remained difficult to assess. This is because the bdnf-null mutation causes the death of the animals before BDNF levels have reached adult levels. In addition, the anterograde axonal transport of BDNF complicates the interpretation of area-specific gene deletion. The present study describes the generation of a new conditional mouse mutant essentially lacking BDNF throughout the CNS. It shows that BDNF is not essential for prolonged postnatal survival, but that the behavior of such mutant animals is markedly altered. It also reveals that BDNF is not a major survival factor for most CNS neurons and for myelination of their axons. However, it is required for the postnatal growth of the striatum, and single-cell analyses revealed a marked decreased in dendritic complexity and spine density. In contrast, BDNF is dispensable for the growth of the hippocampus and only minimal changes were observed in the dendrites of CA1 pyramidal neurons in mutant animals. Spine density remained unchanged, whereas the proportion of the mushroom-type spine was moderately decreased. In line with these in vivo observations, we found that BDNF markedly promotes the growth of cultured striatal neurons and of their dendrites, but not of those of hippocampal neurons, suggesting that the differential responsiveness to BDNF is part of a neuron-intrinsic program.

  5. Analysis of Spine Motility of Newborn Granule Cells in Acute Brain Slices.

    PubMed

    Tashiro, Ayumu; Zhao, Chunmei; Suh, Hoonkyo; Gage, Fred H

    2015-10-01

    In this protocol, acute brain slices are prepared from mice in which newborn granule cells have been labeled using retroviral vector technology. Using a live-cell imaging stage and confocal microscopy coupled to imaging software, dendritic spines are analyzed.

  6. Regulation of spine morphology and spine density by NMDA receptor signaling in vivo

    PubMed Central

    Ultanir, Sila K.; Kim, Ji-Eun; Hall, Benjamin J.; Deerinck, Thomas; Ellisman, Mark; Ghosh, Anirvan

    2007-01-01

    Dendritic spines are the major sites of excitatory synaptic transmission in the CNS, and their size and density influence the functioning of neuronal circuits. Here we report that NMDA receptor signaling plays a critical role in regulating spine size and density in the developing cortex. Genetic deletion of the NR1 subunit of the NMDA receptor in the cortex leads to a decrease in spine density and an increase in spine head size in cortical layer 2/3 pyramidal neurons. This process is accompanied by an increase in the presynaptic axon bouton volume and the postsynaptic density area, as well as an increase in the miniature excitatory postsynaptic current amplitude and frequency. These observations indicate that NMDA receptors regulate synapse structure and function in the developing cortex. PMID:18048342

  7. Regulation of spine morphology and spine density by NMDA receptor signaling in vivo.

    PubMed

    Ultanir, Sila K; Kim, Ji-Eun; Hall, Benjamin J; Deerinck, Thomas; Ellisman, Mark; Ghosh, Anirvan

    2007-12-04

    Dendritic spines are the major sites of excitatory synaptic transmission in the CNS, and their size and density influence the functioning of neuronal circuits. Here we report that NMDA receptor signaling plays a critical role in regulating spine size and density in the developing cortex. Genetic deletion of the NR1 subunit of the NMDA receptor in the cortex leads to a decrease in spine density and an increase in spine head size in cortical layer 2/3 pyramidal neurons. This process is accompanied by an increase in the presynaptic axon bouton volume and the postsynaptic density area, as well as an increase in the miniature excitatory postsynaptic current amplitude and frequency. These observations indicate that NMDA receptors regulate synapse structure and function in the developing cortex.

  8. Age-related dendritic hypertrophy and sexual dimorphism in rat basolateral amygdala

    PubMed Central

    Rubinow, Marisa J.; Drogos, Lauren L.; Juraska, Janice M.

    2008-01-01

    Little research has examined the influence of aging or sex on anatomical measures in the basolateral amygdala. We quantified spine density and dendritic material in Golgi-Cox stained tissue of the basolateral nucleus in young adult (3–5 months) and aged (20–24 months) male and female Long-Evans rats. Dendritic branching and spine density were measured in principal neurons. Age, but not sex, influenced the dendritic tree, with aged animals displaying significantly more dendritic material. Previous findings from our laboratory in the same set of subjects indicate an opposite effect of aging on dendritic material in the medial prefrontal cortex and hippocampus. We also report here a sex difference across ages in dendritic spine density, favoring males. PMID:17570563

  9. Homophilic Dscam interactions control complex dendrite morphogenesis

    PubMed Central

    Hughes, Michael E.; Bortnick, Rachel; Tsubouchi, Asako; Bäumer, Philipp; Kondo, Masahiro; Uemura, Tadashi; Schmucker, Dietmar

    2007-01-01

    Summary The morphogenesis of complex dendritic fields requires highly specific patterning and dendrite-dendrite recognition mechanisms. Alternative splicing of the Drosophila cell surface receptor Dscam results in up to 38,016 different receptor isoforms and in vitro binding studies suggested that sequence variability in immunoglobulin-like ecto-domains determines the specificity of strictly homophilic interactions. We report that diverse Dscam receptors play an important role in controlling cell-intrinsic aspects of dendrite guidance. We examined the function of Dscam during morphogenesis of dendrite arborization neurons (“da” neurons) and found that loss of Dscam in single neurons causes abnormal dendritic fasciculation and a strong increase in self-crossing of dendritic branches of da neurons. Restriction of dendritic fields of neighboring class III neurons appeared intact in Dscam deficient neurons suggesting that dendritic self-avoidance but not hetero-neuronal tiling may depend on Dscam function. Over-expression of the same Dscam isoforms in two da neurons with normally overlapping dendritic fields forced a spatial segregation of the two dendritic fields. Taken together, our results suggest that dendritic branches of all four classes of da neurons use isoform-specific homophilic interactions of Dscam to ensure minimal overlap of dendrites. The large pool of Dscam’s extracellular recognition domains may allow the same ‘core’ repulsion mechanism to be used in every da neuron without interfering with hetero-neuronal interactions. PMID:17481395

  10. CREB Regulates Experience-Dependent Spine Formation and Enlargement in Mouse Barrel Cortex

    PubMed Central

    Pignataro, Annabella; Borreca, Antonella; Ammassari-Teule, Martine; Middei, Silvia

    2015-01-01

    Experience modifies synaptic connectivity through processes that involve dendritic spine rearrangements in neuronal circuits. Although cAMP response element binding protein (CREB) has a key function in spines changes, its role in activity-dependent rearrangements in brain regions of rodents interacting with the surrounding environment has received little attention so far. Here we studied the effects of vibrissae trimming, a widely used model of sensory deprivation-induced cortical plasticity, on processes associated with dendritic spine rearrangements in the barrel cortex of a transgenic mouse model of CREB downregulation (mCREB mice). We found that sensory deprivation through prolonged whisker trimming leads to an increased number of thin spines in the layer V of related barrel cortex (Contra) in wild type but not mCREB mice. In the barrel field controlling spared whiskers (Ipsi), the same trimming protocol results in a CREB-dependent enlargement of dendritic spines. Last, we demonstrated that CREB regulates structural rearrangements of synapses that associate with dynamic changes of dendritic spines. Our findings suggest that CREB plays a key role in dendritic spine dynamics and synaptic circuits rearrangements that account for new brain connectivity in response to changes in the environment. PMID:26075101

  11. Single-Molecule Tracking Photoactivated Localization Microscopy to Map Nano-Scale Structure and Dynamics in Living Spines

    PubMed Central

    MacGillavry, Harold D.; Blanpied, Thomas A.

    2013-01-01

    Super-resolution microscopy has rapidly become an indispensable tool in cell biology and neuroscience by enabling measurement in live cells of structures smaller than the classical limit imposed by diffraction. The most widely applied super-resolution method currently is localization microscopy, which takes advantage of the ability to determine the position of individual fluorescent molecules with nanometer accuracy even in cells. By iteratively measuring sparse subsets of photoactivatable fluorescent proteins, protein distribution in macromolecular structures can be accurately reconstructed. Moreover, the motion trajectories of individual molecules within cells can be measured, providing unique ability to measure transport kinetics, exchange rates, and binding affinities of even small subsets of molecules with high temporal resolution and great spatial specificity. This unit describes protocols to measure and quantify the distribution of scaffold proteins within single synapses of cultured hippocampal neurons, and to track and measure the diffusion of intracellular constituents of the neuronal plasma membrane. PMID:25429311

  12. Peculiarities and Patterns of Cervical Spine Injuries in Children and Adolescents: A Retrospective Series of 84 Patients from a Single Institute.

    PubMed

    Babu, R Arun; Arivazhagan, Arimappamagan; Devi, B Indira; Bhat, Dhananjaya I; Sampath, Somanna; Chandramouli, B A

    2016-01-01

    Cervical spine injuries occur infrequently in children but are associated with significant disability and mortality. A retrospective analysis was performed of 84 consecutive pediatric spine injuries treated at our institute from January 2002 to December 2011. The mean age was 14.7 years. There were 18 patients (21%) in group A (0-12 years) and 66 patients (79%) in group B (13-18 years). Overall, injury was more common in boys (ratio of 6:1). Trivial fall was the predominant cause in group A and fall from height in group B. There were 30 children (36%) with injuries of the upper cervical spine, 53 (63%) with injuries of the lower cervical spine and 1 patient (1%) with a combined injury of upper cervical spine and thoracic spine. Overall, 22% of the group A children and 67% of the group B patients had more severe injuries (Frankel grades A, B and C); 21% (18/84) were treated by surgical fusion. Where follow-up was available, 17 out of 22 children (77%) had good outcome (Frankel grade >C). In conclusion, mechanisms and patterns of injury in children are age related and the majority of the children had good outcome.

  13. Three-Dimensional Analysis of Spiny Dendrites Using Straightening and Unrolling Transforms

    PubMed Central

    Morales, Juan; Benavides-Piccione, Ruth; Pastor, Luis; Yuste, Rafael; DeFelipe, Javier

    2014-01-01

    Current understanding of the synaptic organization of the brain depends to a large extent on knowledge about the synaptic inputs to the neurons. Indeed, the dendritic surfaces of pyramidal cells (the most common neuron in the cerebral cortex) are covered by thin protrusions named dendritic spines. These represent the targets of most excitatory synapses in the cerebral cortex and therefore, dendritic spines prove critical in learning, memory and cognition. This paper presents a new method that facilitates the analysis of the 3D structure of spine insertions in dendrites, providing insight on spine distribution patterns. This method is based both on the implementation of straightening and unrolling transformations to move the analysis process to a planar, unfolded arrangement, and on the design of DISPINE, an interactive environment that supports the visual analysis of 3D patterns. PMID:22644869

  14. Differential roles of calcitonin family peptides in the dendrite formation and spinogenesis of the cerebral cortex in vitro.

    PubMed

    Harigai, Yuichi; Natsume, Masaki; Li, Fei; Ohtani, Akiko; Senzaki, Kouji; Shiga, Takashi

    2011-08-01

    We examined roles of calcitonin family peptides in the initial stages of dendrite formation and the maturation of dendritic spines in the rat cerebral cortex in vitro. Embryonic day 18 cortical neurons were dissociated and cultured for 2-3days in the presence of calcitonin gene-related peptide (CGRP), calcitonin, amylin or adrenomedullin. The treatment of cortical neurons with CGRP promoted the formation of primary dendrites of non-GABAergic neurons. In contrast, the treatment with amylin and adrenomedullin for 3days inhibited the dendritic elongation of non-GABAergic neurons. Calcitonin had no effect on the initial dendrite formation. Next, we examined roles of the peptides in the spine formation. Embryonic day 16 cortical neurons were cultured for 14days and then treated acutely with CGRP, amylin or adrenomedullin for 24h. The density of filopodia, puncta/stubby spines and spines were increased by the CGRP treatment, whereas decreased by amylin. Therefore, CGRP and amylin showed opposite effects on the formation of dendritic filopodia, puncta and spines. Adrenomedullin had no effects on the spine formation. In conclusion, the present study showed that calcitonin family peptides have differential effects both in the dendrite formation during the initial stages and the spine formation of cortical neurons in vitro.

  15. Dendrite inhibitor

    DOEpatents

    Miller, William E.

    1989-01-01

    An apparatus for removing dendrites or other crystalline matter from the surface of a liquid in a matter transport process, and an electrolytic cell including such an apparatus. A notch may be provided to allow continuous exposure of the liquid surface, and a bore may be further provided to permit access to the liquid.

  16. Dendrite inhibitor

    DOEpatents

    Miller, W.E.

    1988-06-07

    An apparatus for removing dendrites or other crystalline matter from the surface of a liquid in a matter transport process, and an electrolytic cell including such an apparatus. A notch may be provided to allow continuous exposure of the liquid surface, and a bore may be further provided to permit access to the liquid. 2 figs.

  17. Differentiation of apical and basal dendrites in pyramidal cells and granule cells in dissociated hippocampal cultures.

    PubMed

    Wu, You Kure; Fujishima, Kazuto; Kengaku, Mineko

    2015-01-01

    Hippocampal pyramidal cells and dentate granule cells develop morphologically distinct dendritic arbors, yet also share some common features. Both cell types form a long apical dendrite which extends from the apex of the cell soma, while short basal dendrites are developed only in pyramidal cells. Using quantitative morphometric analyses of mouse hippocampal cultures, we evaluated the differences in dendritic arborization patterns between pyramidal and granule cells. Furthermore, we observed and described the final apical dendrite determination during dendritic polarization by time-lapse imaging. Pyramidal and granule cells in culture exhibited similar dendritic patterns with a single principal dendrite and several minor dendrites so that the cell types were not readily distinguished by appearance. While basal dendrites in granule cells are normally degraded by adulthood in vivo, cultured granule cells retained their minor dendrites. Asymmetric growth of a single principal dendrite harboring the Golgi was observed in both cell types soon after the onset of dendritic growth. Time-lapse imaging revealed that up until the second week in culture, final principal dendrite designation was not stabilized, but was frequently replaced by other minor dendrites. Before dendritic polarity was stabilized, the Golgi moved dynamically within the soma and was repeatedly repositioned at newly emerging principal dendrites. Our results suggest that polarized growth of the apical dendrite is regulated by cell intrinsic programs, while regression of basal dendrites requires cue(s) from the extracellular environment in the dentate gyrus. The apical dendrite designation is determined from among multiple growing dendrites of young developing neurons.

  18. Probe dendritic functions through poking and peeking

    NASA Astrophysics Data System (ADS)

    Xiong, Wenhui; Zhou, Zhishang; Zeng, Shaoqun; Chen, Wei R.

    2003-12-01

    Several photonic approaches have been utilized to study functional dynamics of olfactory bulb dendrites, which plays a critical role in odor discrimination and recognition. Firstly, with infrared differential interference contrast (DIC) video microscopy, we can visualize living nerve cells in an olfactory bulb slice preparation and target glass electrodes to different dendritic locations for direct electrical measurement. This furnishes a high temporal resolution of signal recording from dendrites. Secondly, by using a cooled CCD camera and loading calcium-sensitive dyes into neurons, we have explored the spatial distribution and propagation of spike signals within complex dendritic trees. Thirdly, two-photon microscope enables us to analyze active properties of very tiny dendritic structures such as dendritic spines. Lastly, by using UV light pulse to release calcium ions from caged compounds, we have examined the mechanisms for signal communication between two dendrites with reciprocal synaptic connections. Our research highlights an important contribution of optical imaging methods to functional dissection of neuronal circuitry in the brain.

  19. Spine Injuries and Disorders

    MedlinePlus

    Your backbone, or spine, is made up of 26 bone discs called vertebrae. The vertebrae protect your spinal cord and allow you to ... of problems can change the structure of the spine or damage the vertebrae and surrounding tissue. They ...

  20. Coexistence of glutamatergic spine synapses and shaft synapses in substantia nigra dopamine neurons.

    PubMed

    Jang, Miae; Um, Ki Bum; Jang, Jinyoung; Kim, Hyun Jin; Cho, Hana; Chung, Sungkwon; Park, Myoung Kyu

    2015-10-05

    Dopamine neurons of the substantia nigra have long been believed to have multiple aspiny dendrites which receive many glutamatergic synaptic inputs from several regions of the brain. But, here, using high-resolution two-photon confocal microscopy in the mouse brain slices, we found a substantial number of common dendritic spines in the nigral dopamine neurons including thin, mushroom, and stubby types of spines. However, the number of dendritic spines of the dopamine neurons was approximately five times lower than that of CA1 pyramidal neurons. Immunostaining and morphological analysis revealed that glutamatergic shaft synapses were present two times more than spine synapses. Using local two-photon glutamate uncaging techniques, we confirmed that shaft synapses and spine synapses had both AMPA and NMDA receptors, but the AMPA/NMDA current ratios differed. The evoked postsynaptic potentials of spine synapses showed lower amplitudes but longer half-widths than those of shaft synapses. Therefore, we provide the first evidence that the midbrain dopamine neurons have two morphologically and functionally distinct types of glutamatergic synapses, spine synapses and shaft synapses, on the same dendrite. This peculiar organization could be a new basis for unraveling many physiological and pathological functions of the midbrain dopamine neurons.

  1. Environmental enrichment reveals effects of genotype on hippocampal spine morphologies in the mouse model of Fragile X Syndrome.

    PubMed

    Lauterborn, Julie C; Jafari, Matiar; Babayan, Alex H; Gall, Christine M

    2015-02-01

    Fragile X Syndrome (FXS) and the Fmr1 knockout (KO) mouse model of this disorder exhibit abnormal dendritic spines in neocortex, but the degree of spine disturbances in hippocampus is not clear. The present studies tested if the mutation influences dendritic branching and spine measures for CA1 pyramidal cells in Fmr1 KO and wild-type (WT) mice provided standard or enriched environment (EE) housing. Automated measures from 3D reconstructions of green fluorescent protein (GFP)-labeled cells showed that spine head volumes were ∼ 40% lower in KOs when compared with WTs in both housing conditions. With standard housing, average spine length was greater in KOs versus WTs but there was no genotype difference in dendritic branching, numbers of spines, or spine length distribution. However, with EE rearing, significant effects of genotype emerged including greater dendritic branching in WTs, greater spine density in KOs, and greater numbers of short thin spines in KOs when compared with WTs. Thus, EE rearing revealed greater effects of the Fmr1 mutation on hippocampal pyramidal cell morphology than was evident with standard housing, suggesting that environmental enrichment allows for fuller appreciation of the impact of the mutation and better representation of abnormalities likely to be present in human FXS.

  2. Equiaxed Dendritic Solidification Experiment (EDSE)

    NASA Technical Reports Server (NTRS)

    Beckermann, C.; Steinbach, I.; Karma, A.; deGroh, H. C., III

    1999-01-01

    The objective of the research is to quantitatively determine and understand the fundamental mechanisms that control the microstructural evolution during solidification of an assemblage of equiaxed dendritic crystals. A microgravity experiment will be conducted to obtain benchmark data on the transient growth and interaction of up to four equiaxed crystals of a pure and transparent metal analog (succinonitrile, SCN) under strictly diffusion dominated conditions. Of interest in the experiment are the transient evolution of the primary and secondary dendrite tip speeds, the dendrite morphology (i.e., tip radii, branch spacings, etc.) and solid fraction, the tip selection criterion, and the temperature field in the melt for a range of initial supercoolings and, thus, interaction "strengths" between the crystals. The experiment thus extends the microgravity measurements of Glicksman and coworkers for steady growth of a single dendrite [Isothermal Dendritic Growth Experiment (IDGE), first flown on USMP-2] to a case where growth transients are introduced due to thermal interactions between neighboring dendrites - a situation more close to actual casting conditions. Corresponding earth-based experiments will be conducted to ascertain the influence of melt convection. The experiments are supported by a variety of analytical models and numerical simulations. The data will primarily be used to develop and test theories of transient dendritic growth and the solidification of multiple interacting equiaxed crystals in a supercooled melt.

  3. Equiaxed Dendritic Solidification Experiment (EDSE)

    NASA Technical Reports Server (NTRS)

    Beckermann, C.; Karma, A.; Steinbach, I.; deGroh, H. C., III

    2001-01-01

    The objective of the research is to quantitatively determine and understand the fundamental mechanisms that control the microstructural evolution during equiaxed dendritic solidification. A microgravity experiment will be conducted to obtain benchmark data on the transient growth and interaction of up to four equiaxed crystals of a pure and transparent metal analog (succinonitrile, SCN) under strictly diffusion-dominated conditions. Of interest in the experiment are the transient evolution of the primary and secondary dendrite tip speeds, the dendrite morphology and solid fraction, the tip selection criterion, and the temperature field in the melt for a range of interaction "strengths" between the crystals. The experiment extends the microgravity measurements of Glicksman and co-workers isothermal dendritic growth experiment (IDGE) for steady growth of a single dendrite to a case where growth transients are introduced due to thermal interactions between neighboring dendrites - a situation closer to actual casting conditions. Corresponding Earth-based experiments will be conducted to ascertain the influence of melt convection. The experiments are supported by a variety of analytical models and numerical simulations. The data will be used to develop and test theories of transient dendritic growth and the solidification of multiple interacting equiaxed crystals in a supercooled melt.

  4. Striatal plasticity and medium spiny neuron dendritic remodeling in parkinsonism.

    PubMed

    Deutch, Ariel Y; Colbran, Roger J; Winder, Danny J

    2007-01-01

    Current approaches to Parkinson's Disease (PD) are largely based on our current understanding of the mechanisms that contribute to the death of nigrostriatal dopamine neurons. However, our understanding of the consequences of the loss of dopamine on the striatal target cells of nigrostriatal neurons is much less advanced. In particular, the compensatory changes that occur in striatal medium spiny neurons (MSNs) that have lost their normal dopamine input remains poorly understood. The compensatory changes may have either positive or negative effects. Among the alterations that occur in striatal cells of the dopamine-denervated striatum are dystrophic changes in the dendrites of MSNs, with a loss of dendritic length and dendritic spine number. Dendritic spines are the targets of convergent nigrostriatal dopamine and corticostriatal glutamate axons, and integrate these convergent signals to determine the nature of striatal output. The loss of these spines in the dopamine-denervated state may protect the MSN from overt excitotoxic death, but at the price of compromising MSN function. The loss of dendritic spines is thought be responsible for the gradual decrease in levodopa efficacy in late-stage PD, suggesting that therapeutic interventions need to be developed that target key downstream signaling complexes in medium spiny neurons.

  5. Human Rho Guanine Nucleotide Exchange Factor 11 (ARHGEF11) Regulates Dendritic Morphogenesis

    PubMed Central

    Mizuki, Yutaka; Takaki, Manabu; Sakamoto, Shinji; Okamoto, Sojiro; Kishimoto, Makiko; Okahisa, Yuko; Itoh, Masahiko; Yamada, Norihito

    2016-01-01

    Disturbances of synaptic connectivity during perinatal and adolescent periods have been hypothesized to be related to the pathophysiology of schizophrenia. Rho guanine nucleotide exchange factor 11 (ARHGEF11) is a specific guanine nucleotide exchange factors (GEF) for RhoA, which is a critical regulator of actin cytoskeleton dynamics and organization of dendritic spines and inhibitor of spine maintenance. ARHGEF11 variants are reported to be associated with a higher risk for the onset of schizophrenia in a Japanese population; however, how ARHGEF11 contributes to the pathogenesis of schizophrenia in dendritic spines is unknown. Therefore, we first studied the distribution, binding, and function of ARHGEF11 in the dendritic spines of the rat cerebral cortex. After subcellular fractionation of the rat cerebral cortex, ARHGEF11 was detected with synaptophysin and post-synaptic density protein 95 (PSD-95) in the P2 fractions including synaptosomal fractions containing presynaptic and postsynaptic density proteins. Endogenous ARHGEF11 was coimmunoprecipitated with synaptophysin or PSD-95. In cortical primary neurons at 28 days in vitro, immunostaining revealed that ARHGEF11 located in the dendrites and dendritic spines and colocalized with PSD-95 and synaptophysin. Overexpression of exogenous ARHGEF11 significantly decreased the number of spines (p = 0.008). These results indicate that ARHGEF11 is likely to be associated with synaptic membranes and regulation of spine. PMID:28036092

  6. Effect of the environment on the dendritic morphology of the rat auditory cortex.

    PubMed

    Bose, Mitali; Muñoz-Llancao, Pablo; Roychowdhury, Swagata; Nichols, Justin A; Jakkamsetti, Vikram; Porter, Benjamin; Byrapureddy, Rajasekhar; Salgado, Humberto; Kilgard, Michael P; Aboitiz, Francisco; Dagnino-Subiabre, Alexies; Atzori, Marco

    2010-02-01

    The present study aimed to identify morphological correlates of environment-induced changes at excitatory synapses of the primary auditory cortex (A1). We used the Golgi-Cox stain technique to compare pyramidal cells dendritic properties of Sprague-Dawley rats exposed to different environmental manipulations. Sholl analysis, dendritic length measures, and spine density counts were used to monitor the effects of sensory deafness and an auditory version of environmental enrichment (EE). We found that deafness decreased apical dendritic length leaving basal dendritic length unchanged, whereas EE selectively increased basal dendritic length without changing apical dendritic length. On the contrary, deafness decreased while EE increased spine density in both basal and apical dendrites of A1 Layer 2/3 (LII/III) neurons. To determine whether stress contributed to the observed morphological changes in A1, we studied neural morphology in a restraint-induced model that lacked behaviorally relevant acoustic cues. We found that stress selectively decreased apical dendritic length in the auditory but not in the visual primary cortex. Similar to the acoustic manipulation, stress-induced changes in dendritic length possessed a layer-specific pattern displaying LII/III neurons from stressed animals with normal apical dendrites but shorter basal dendrites, while infragranular neurons (Layers V and VI) displayed shorter apical dendrites but normal basal dendrites. The same treatment did not induce similar changes in the visual cortex, demonstrating that the auditory cortex is an exquisitely sensitive target of neocortical plasticity, and that prolonged exposure to different acoustic as well as emotional environmental manipulation may produce specific changes in dendritic shape and spine density.

  7. L-DOPA Oppositely Regulates Synaptic Strength and Spine Morphology in D1 and D2 Striatal Projection Neurons in Dyskinesia

    PubMed Central

    Suarez, Luz M; Solis, Oscar; Aguado, Carolina; Lujan, Rafael; Moratalla, Rosario

    2016-01-01

    Dopamine depletion in Parkinson's disease (PD) produces dendritic spine loss in striatal medium spiny neurons (MSNs) and increases their excitability. However, the synaptic changes that occur in MSNs in PD, in particular those induced by chronic L-3,4-dihydroxyphenylalanine (L-DOPA) treatment, are still poorly understood. We exposed BAC-transgenic D1-tomato and D2-eGFP mice to PD and dyskinesia model paradigms, enabling cell type-specific assessment of changes in synaptic physiology and morphology. The distinct fluorescence markers allowed us to identify D1 and D2 MSNs for analysis using intracellular sharp electrode recordings, electron microscopy, and 3D reconstructions with single-cell Lucifer Yellow injections. Dopamine depletion induced spine pruning in both types of MSNs, affecting mushroom and thin spines equally. Dopamine depletion also increased firing rate in both D1- and D2-MSNs, but reduced evoked-EPSP amplitude selectively in D2-MSNs. L-DOPA treatment that produced dyskinesia differentially affected synaptic properties in D1- and D2-MSNs. In D1-MSNs, spine density remained reduced but the remaining spines were enlarged, with bigger heads and larger postsynaptic densities. These morphological changes were accompanied by facilitation of action potential firing triggered by synaptic inputs. In contrast, although L-DOPA restored the number of spines in D2-MSNs, it resulted in shortened postsynaptic densities. These changes in D2-MSNs correlated with a decrease in synaptic transmission. Our findings indicate that L-DOPA-induced dyskinesia is associated with abnormal spine morphology, modified synaptic transmission, and altered EPSP-spike coupling, with distinct effects in D1- and D2-MSNs. PMID:27613437

  8. Dendritic web silicon for solar cell application

    NASA Technical Reports Server (NTRS)

    Seidensticker, R. G.

    1977-01-01

    The dendritic web process for growing long thin ribbon crystals of silicon and other semiconductors is described. Growth is initiated from a thin wirelike dendrite seed which is brought into contact with the melt surface. Initially, the seed grows laterally to form a button at the melt surface; when the seed is withdrawn, needlelike dendrites propagate from each end of the button into the melt, and the web portion of the crystal is formed by the solidification of the liquid film supported by the button and the bounding dendrites. Apparatus used for dendritic web growth, material characteristics, and the two distinctly different mechanisms involved in the growth of a single crystal are examined. The performance of solar cells fabricated from dendritic web material is indistinguishable from the performance of cells fabricated from Czochralski grown material.

  9. Dendritic integration in pyramidal neurons during network activity and disease.

    PubMed

    Palmer, Lucy M

    2014-04-01

    Neurons have intricate dendritic morphologies which come in an array of shapes and sizes. Not only do they give neurons their unique appearance, but dendrites also endow neurons with the ability to receive and transform synaptic inputs. We now have a wealth of information about the functioning of dendrites which suggests that the integration of synaptic inputs is highly dependent on both dendritic properties and neuronal input patterns. It has been shown that dendrites can perform non-linear processing, actively transforming synaptic input into Na(+) spikes, Ca(2+) plateau spikes and NMDA spikes. These membrane non-linearities can have a large impact on the neuronal output and have been shown to be regulated by numerous factors including synaptic inhibition. Many neuropathological diseases involve changes in how dendrites receive and package synaptic input by altering dendritic spine characteristics, ion channel expression and the inhibitory control of dendrites. This review focuses on the role of dendrites in integrating and transforming input and what goes wrong in the case of neuropathological diseases.

  10. Orientations of dendritic growth during solidification

    NASA Astrophysics Data System (ADS)

    Lee, Dong Nyung

    2017-02-01

    Dendrites are crystalline forms which grow far from the limit of stability of the plane front and adopt an orientation which is as close as possible to the heat flux direction. Dendritic growth orientations for cubic metals, bct Sn, and hcp Zn, can be controlled by thermal conductivity, Young's modulus, and surface energy. The control factors have been elaborated. Since the dendrite is a single crystal, its properties such as thermal conductivity that influences the heat flux direction, the minimum Young's modulus direction that influences the strain energy minimization, and the minimum surface energy plane that influences the crystal/liquid interface energy minimization have been proved to control the dendritic growth direction. The dendritic growth directions of cubic metals are determined by the minimum Young's modulus direction and/or axis direction of symmetry of the minimum crystal surface energy plane. The dendritic growth direction of bct Sn is determined by its maximum thermal conductivity direction and the minimum surface energy plane normal direction. The primary dendritic growth direction of hcp Zn is determined by its maximum thermal conductivity direction and the minimum surface energy plane normal direction and the secondary dendrite arm direction of hcp Zn is normal to the primary dendritic growth direction.

  11. Orientations of dendritic growth during solidification

    NASA Astrophysics Data System (ADS)

    Lee, Dong Nyung

    2017-03-01

    Dendrites are crystalline forms which grow far from the limit of stability of the plane front and adopt an orientation which is as close as possible to the heat flux direction. Dendritic growth orientations for cubic metals, bct Sn, and hcp Zn, can be controlled by thermal conductivity, Young's modulus, and surface energy. The control factors have been elaborated. Since the dendrite is a single crystal, its properties such as thermal conductivity that influences the heat flux direction, the minimum Young's modulus direction that influences the strain energy minimization, and the minimum surface energy plane that influences the crystal/liquid interface energy minimization have been proved to control the dendritic growth direction. The dendritic growth directions of cubic metals are determined by the minimum Young's modulus direction and/or axis direction of symmetry of the minimum crystal surface energy plane. The dendritic growth direction of bct Sn is determined by its maximum thermal conductivity direction and the minimum surface energy plane normal direction. The primary dendritic growth direction of hcp Zn is determined by its maximum thermal conductivity direction and the minimum surface energy plane normal direction and the secondary dendrite arm direction of hcp Zn is normal to the primary dendritic growth direction.

  12. Tumors of the spine

    PubMed Central

    Ciftdemir, Mert; Kaya, Murat; Selcuk, Esref; Yalniz, Erol

    2016-01-01

    Spine tumors comprise a small percentage of reasons for back pain and other symptoms originating in the spine. The majority of the tumors involving the spinal column are metastases of visceral organ cancers which are mostly seen in older patients. Primary musculoskeletal system sarcomas involving the spinal column are rare. Benign tumors and tumor-like lesions of the musculoskeletal system are mostly seen in young patients and often cause instability and canal compromise. Optimal diagnosis and treatment of spine tumors require a multidisciplinary approach and thorough knowledge of both spine surgery and musculoskeletal tumor surgery. Either primary or metastatic tumors involving the spine are demanding problems in terms of diagnosis and treatment. Spinal instability and neurological compromise are the main and critical problems in patients with tumors of the spinal column. In the past, only a few treatment options aiming short-term control were available for treatment of primary and metastatic spine tumors. Spine surgeons adapted their approach for spine tumors according to orthopaedic oncologic principles in the last 20 years. Advances in imaging, surgical techniques and implant technology resulted in better diagnosis and surgical treatment options, especially for primary tumors. Also, modern chemotherapy drugs and regimens with new radiotherapy and radiosurgery options caused moderate to long-term local and systemic control for even primary sarcomas involving the spinal column. PMID:26925382

  13. Vertebroplasty for Spine Fracture Pain

    MedlinePlus

    ... Resources Drugs, Procedures & Devices Procedures & Devices Vertebroplasty for Spine Fracture Pain Vertebroplasty for Spine Fracture Pain Drugs, Procedures & DevicesProcedures & DevicesYour Health Resources ...

  14. Visualization of RelB expression and activation at the single-cell level during dendritic cell maturation in Relb-Venus knock-in mice.

    PubMed

    Seki, Takao; Yamamoto, Mami; Taguchi, Yuu; Miyauchi, Maki; Akiyama, Nobuko; Yamaguchi, Noritaka; Gohda, Jin; Akiyama, Taishin; Inoue, Jun-ichiro

    2015-12-01

    RelB is activated by the non-canonical NF-κB pathway, which is crucial for immunity by establishing lymphoid organogenesis and B-cell and dendritic cell (DC) maturation. To elucidate the mechanism of the RelB-mediated immune cell maturation, a precise understanding of the relationship between cell maturation and RelB expression and activation at the single-cell level is required. Therefore, we generated knock-in mice expressing a fusion protein between RelB and fluorescent protein (RelB-Venus) from the Relb locus. The Relb(Venus/Venus) mice developed without any abnormalities observed in the Relb(-/-) mice, allowing us to monitor RelB-Venus expression and nuclear localization as RelB expression and activation. Relb(Venus/Venus) DC analyses revealed that DCs consist of RelB(-), RelB(low) and RelB(high) populations. The RelB(high) population, which included mature DCs with projections, displayed RelB nuclear localization, whereas RelB in the RelB(low) population was in the cytoplasm. Although both the RelB(low) and RelB(-) populations barely showed projections, MHC II and co-stimulatory molecule expression were higher in the RelB(low) than in the RelB(-) splenic conventional DCs. Taken together, our results identify the RelB(low) population as a possible novel intermediate maturation stage of cDCs and the Relb(Venus/Venus) mice as a useful tool to analyse the dynamic regulation of the non-canonical NF-κB pathway.

  15. Interferon-α and interleukin-12 are induced, respectively, by double-stranded DNA and single-stranded RNA in human myeloid dendritic cells.

    PubMed

    Katashiba, Yuichi; Miyamoto, Rie; Hyo, Akira; Shimamoto, Keiko; Murakami, Naoko; Ogata, Makoto; Amakawa, Ryuichi; Inaba, Muneo; Nomura, Shosaku; Fukuhara, Shirou; Ito, Tomoki

    2011-02-01

    Dendritic cells (DCs) are initiators of innate immunity and acquired immunity as cells linking these two bio-defence systems through the production of cytokines such as interferon-α (IFN-α) and interleukin-12 (IL-12). Nucleic acids such as DNA from damaged cells or pathogens are important activators not only for anti-microbial innate immune responses but also in the pathogenesis of IFN-related autoimmune diseases. Plasmacytoid DCs are regarded as the main effectors for the DNA-mediated innate immunity by possessing DNA-sensing toll-like receptor 9 (TLR9). We here found that double-stranded DNA (dsDNA) complexed with lipotransfectants triggered activation of human monocyte-derived DCs (moDCs), leading to the preferential production of IFN-α but not IL-12. This indicates that myeloid DCs also function as supportive effectors against the invasion of pathogenic microbes through the DNA-mediated activation in innate immunity. The dsDNA with lipotransfectants can be taken up by moDCs without co-localization of endosomal LAMP1 staining, and the dsDNA-mediated IFN-α production was not impaired by chloroquine. These findings indicate that moDC activation by dsDNA does not involve the endosomal TLR pathway. In contrast, single-stranded RNA (ssRNA) stimulated moDCs to secrete IL-12 but not IFN-α. This process was inhibited by chloroquine, suggesting an involvement of the TLR pathway in ssRNA-mediated moDC activation. As might be inferred from our findings, myeloid DCs may function as a traffic control between innate immunity via IFN-α production and acquired immunity via IL-12 production, depending on the type of nucleic acids. Our results provide a new insight into the biological action of myeloid DCs underlying the DNA-mediated activation of protective or pathogenic immunity.

  16. Clinical Performance and Safety of 108 SpineJack Implantations: 1-Year Results of a Prospective Multicentre Single-Arm Registry Study.

    PubMed

    Noriega, David; Maestretti, Gianluca; Renaud, Christian; Francaviglia, Natale; Ould-Slimane, Mourad; Queinnec, Steffen; Ekkerlein, Helmut; Hassel, Frank; Gumpert, Rainer; Sabatier, Pascal; Huet, Hervé; Plasencia, Miguel; Theumann, Nicolas; Kunsky, Alexander; Krüger, Antonio

    2015-01-01

    This prospective, consecutive, multicentre observational registry aimed to confirm the safety and clinical performance of the SpineJack system for the treatment of vertebral compression fractures (VCF) of traumatic origin. We enrolled 103 patients (median age: 61.6 years) with 108 VCF due to trauma, or traumatic VCF with associated osteoporosis. Primary outcome was back pain intensity (VAS). Secondary outcomes were Oswestry Disability Index (ODI), EuroQol-VAS, and analgesic consumption. 48 hours after surgery, a median relative decrease in pain intensity of 81.5% was observed associated with a significant reduction in analgesic intake. Improvements in disability (91.3% decrease in ODI score) and in quality of life (increase 21.1% of EQ-VAS score) were obtained 3 months after surgery. All results were maintained at 12 months. A reduction in the kyphotic angulation was observed postoperatively (-5.4 ± 6.3°; p < 0.001), remained at 12 months (-4.4 ± 6.0°, p = 0.002). No adverse events were implant-related and none required device removal. Three patients (2.9%) experienced procedure-related complications. The overall adjacent fracture rate up to 1 year after surgery was 2.9%. The SpineJack procedure is an effective, low-risk procedure for patients with traumatic VCF allowing a fast and sustained improvement in quality of life over 1 year after surgery.

  17. Clinical Performance and Safety of 108 SpineJack Implantations: 1-Year Results of a Prospective Multicentre Single-Arm Registry Study

    PubMed Central

    Noriega, David; Maestretti, Gianluca; Renaud, Christian; Francaviglia, Natale; Ould-Slimane, Mourad; Queinnec, Steffen; Ekkerlein, Helmut; Hassel, Frank; Gumpert, Rainer; Sabatier, Pascal; Huet, Hervé; Plasencia, Miguel; Theumann, Nicolas; Kunsky, Alexander; Krüger, Antonio

    2015-01-01

    This prospective, consecutive, multicentre observational registry aimed to confirm the safety and clinical performance of the SpineJack system for the treatment of vertebral compression fractures (VCF) of traumatic origin. We enrolled 103 patients (median age: 61.6 years) with 108 VCF due to trauma, or traumatic VCF with associated osteoporosis. Primary outcome was back pain intensity (VAS). Secondary outcomes were Oswestry Disability Index (ODI), EuroQol-VAS, and analgesic consumption. 48 hours after surgery, a median relative decrease in pain intensity of 81.5% was observed associated with a significant reduction in analgesic intake. Improvements in disability (91.3% decrease in ODI score) and in quality of life (increase 21.1% of EQ-VAS score) were obtained 3 months after surgery. All results were maintained at 12 months. A reduction in the kyphotic angulation was observed postoperatively (−5.4 ± 6.3°; p < 0.001), remained at 12 months (−4.4 ± 6.0°, p = 0.002). No adverse events were implant-related and none required device removal. Three patients (2.9%) experienced procedure-related complications. The overall adjacent fracture rate up to 1 year after surgery was 2.9%. The SpineJack procedure is an effective, low-risk procedure for patients with traumatic VCF allowing a fast and sustained improvement in quality of life over 1 year after surgery. PMID:26844224

  18. Postnatal sellar spine growth

    PubMed Central

    Hosokawa, Takahiro; Yamada, Yoshitake; Sato, Yumiko; Tanami, Yutaka; Kurihara, Jun; Oguma, Eiji

    2016-01-01

    Abstract Background: A sellar spine is a bony spur protruding anteriorly from the central portion of the dorsum sellae. Its etiology is an ossified notochordal remnant of the cephalic end of the notochord. It is presumed to be a congenital malformation based on magnetic resonance imaging (MRI) findings of sellar spine in a 4-year-old boy. A sellar spine should therefore be detectable at birth with or without ossification, and the posterior pituitary lobe should be displaced. Methods and Results: Here we review the literature and report the first case of typical sellar spine in an 8-year-old girl who presented with precocious puberty, but her MRI taken at age 4 months for a febrile convulsion did not show a sellar spine or posterior pituitary lobe deformation. T1-weighted sagittal images at 8 years old showed a bony structure protruding anteriorly from the central portion of the dorsum sellae. The length of this lesion was 3.8 mm on computed tomography (CT) scanning at 9 years old, and it elongated to 4.7 mm on CT at 12 years old. Conclusions: Based on the present case, we speculate that the sellar spine would be too small to detect early in development and would grow in size after birth. In this case, a sellar spine and precocious puberty were potentially associated due to deformation of the growing pituitary gland. PMID:27537588

  19. [Sixty years after Hsiang-Tung Chang's presentation on dendrite at the Cold Spring Harbor Symposium].

    PubMed

    Chen, Yi-Zhang

    2012-10-25

    Sixty years elapsed since Chang (Hsiang-Tung Chang, Xiang-Tong Zhang) presented his seminal report "Cortical neurons with particular reference to the apical dendrite" at the Cold Spring Harbor Symposium. Thanks to the development of elaborated techniques through the 6 decades, our understanding of the dendrite has been pushed forward greatly: the backward and forward conductions during excitation, sodium and calcium conductances, chemical excitation by uncaging glutamate at a dimension of micrometer, and the quantitative study of chemical organization of postsynaptic density (PSD), etc. Though the progression is great, there are still tough problems in dendritic research, especially the integration through dendritic spine.

  20. Channelopathies and Dendritic Dysfunction in Fragile X syndrome

    PubMed Central

    Brager, Darrin H.; Johnston, Daniel

    2014-01-01

    Dendritic spine abnormalities and the metabotropic glutamate receptor theory put the focus squarely on synapses and protein synthesis as the cellular locus of Fragile X syndrome. Synapses however, are only partly responsible for information processing in neuronal networks. Neurotransmitter triggered excitatory postsynaptic potentials (EPSPs) are shaped and integrated by dendritic voltage-gated ion channels. These EPSPs, and in some cases the resultant dendritic spikes, are further modified by dendritic voltage-gated ion channels as they propagate to the soma. If the resultant somatic depolarization is large enough, action potential(s) will be triggered and propagate both orthodromically down the axon, where it may trigger neurotransmitter release, and antidromically back into the dendritic tree, where it can activate and modify dendritic voltage-gated and receptor activated ion channels. Several channelopathies, both soma-dendritic (L-type calcium channels, Slack potassium channels, h-channels, A-type potassium channels) and axo-somatic (BK channels and delayed rectifier potassium channels) were identified in the fmr1-/y mouse model of Fragile X syndrome. Pathological function of these channels will strongly influence the excitability of individual neurons as well as overall network function. In this chapter we discuss the role of voltage-gated ion channels in neuronal processing and describe how identified channelopathies in models of Fragile X syndrome may play a role in dendritic pathophysiology. PMID:24462643

  1. CRMP1 and CRMP2 have synergistic but distinct roles in dendritic development.

    PubMed

    Makihara, Hiroko; Nakai, Shiori; Ohkubo, Wataru; Yamashita, Naoya; Nakamura, Fumio; Kiyonari, Hiroshi; Shioi, Go; Jitsuki-Takahashi, Aoi; Nakamura, Haruko; Tanaka, Fumiaki; Akase, Tomoko; Kolattukudy, Pappachan; Goshima, Yoshio

    2016-09-01

    Collapsin response mediator protein 2, CRMP2, has been identified as an intracellular signaling mediator for Semaphorin 3A (Sema3A). CRMP2 plays a key role in axon guidance, dendritic morphogenesis, and cell polarization. It has been also implicated in a variety of neurological and psychiatric disorders. However, the in vivo functions of CRMP2 remain unknown. We generated CRMP2 gene-deficient (crmp2(-/-) ) mice. The crmp2(-/-) mice showed irregular development of dendritic spines in cortical neurons. The density of dendritic spines was reduced in the cortical layer V pyramidal neurons of crmp2(-/-) mice as well as in those of sema3A(-/-) and crmp1(-/-) mice. However, no abnormality was found in dendritic patterning in crmp2(-/-) compared to wild-type (WT) neurons. The level of CRMP1 was increased in crmp2(-/-) , but the level of CRMP2 was not altered in crmp1(-/-) compared to WT cortical brain lysates. Dendritic spine density and branching were reduced in double-heterozygous sema3A(+/-) ;crmp2(+/-) and sema3A(+/-) ;crmp1(+/-) mice. The phenotypic defects had no genetic interaction between crmp1 and crmp2. These findings suggest that both CRMP1 and CRMP2 mediate Sema3A signaling to regulate dendritic spine maturation and patterning, but through overlapping and distinct signaling pathways.

  2. A Novel Forward Genetic Screen for Identifying Mutations Affecting Larval Neuronal Dendrite Development in Drosophila melanogaster

    PubMed Central

    Medina, Paul Mark B.; Swick, Lance L.; Andersen, Ryan; Blalock, Zachary; Brenman, Jay E.

    2006-01-01

    Vertebrate and invertebrate dendrites are information-processing compartments that can be found on both central and peripheral neurons. Elucidating the molecular underpinnings of information processing in the nervous system ultimately requires an understanding of the genetic pathways that regulate dendrite formation and maintenance. Despite the importance of dendrite development, few forward genetic approaches have been used to analyze the latest stages of dendrite development, including the formation of F-actin-rich dendritic filopodia or dendritic spines. We developed a forward genetic screen utilizing transgenic Drosophila second instar larvae expressing an actin, green fluorescent protein (GFP) fusion protein (actin∷GFP) in subsets of sensory neurons. Utilizing this fluorescent transgenic reporter, we conducted a forward genetic screen of >4000 mutagenized chromosomes bearing lethal mutations that affected multiple aspects of larval dendrite development. We isolated 13 mutations on the X and second chromosomes composing 11 complementation groups affecting dendrite outgrowth/branching, dendritic filopodia formation, or actin∷GFP localization within dendrites in vivo. In a fortuitous observation, we observed that the structure of dendritic arborization (da) neuron dendritic filopodia changes in response to a changing environment. PMID:16415365

  3. Schedule-induced polydipsia is associated with increased spine density in dorsolateral striatum neurons.

    PubMed

    Íbias, J; Soria-Molinillo, E; Kastanauskaite, A; Orgaz, C; DeFelipe, J; Pellón, R; Miguéns, M

    2015-08-06

    Schedule-induced polydipsia (SIP) is an adjunctive behavior in which rats exhibit excessive drinking as a consequence of intermittent feeding, and it has been proposed as a candidate model to study the development of compulsive and repetitive behavior. Although several brain structures are involved in compulsive behavior, it has been suggested that alterations in fronto-striatal circuits may underlie compulsive spectrum disorders. In the present work, we examined whether SIP would induce modifications in dorsolateral striatum (DLS) and anterior prefrontal cortex (aPFC) neurons. Specifically, the effects of 20 sessions of SIP were determined in the dendrites of DLS medium spiny neurons and in the basal dendritic arbors of layer V pyramidal cells in the aPFC. The structure, size and branching complexity in aPFC neurons were also studied. Results showed that SIP resulted in an increase in dendritic spine density in DLS neurons. Moreover, dendritic spine density was highly correlated with the level of drinking in animals subjected to SIP. By contrast, we observed no differences either in dendritic spine density or in the morphological structure of the dendrites of the aPFC in SIP rats compared to their control counterparts. We hypothesize that SIP-induced structural plasticity in DLS neurons could be related to inflexible response in compulsive behavior. The findings of this study could provide new insights into the involvement of particular cell populations of the dorsolateral striatum and anterior prefrontal cortex regions in compulsive spectrum disorders.

  4. Growth of single crystalline dendritic Li{sub 2}SiO{sub 3} arrays from LiNO{sub 3} and mesoporous SiO{sub 2}

    SciTech Connect

    Cordoba, Jose M.; Ballem, Mohamed A.; Johansson, Emma M.; Oden, Magnus

    2011-07-15

    A solution based wet chemistry approach has been developed for synthesizing Li{sub 2}SiO{sub 3} using LiNO{sub 3} and mesoporous silica as starting materials at 550 deg. C. A reaction path where NO and O{sub 2} are formed as side-products is proposed. The crystals synthesized exhibit dendritic growth where the as-prepared nanodendrite is a typical 1-fold nanodendrite composed of one several microns long and some tenth of nanometers wide trunk with small branches, which are several hundreds of nanometers long and up to 70 nm in diameter. The effect of the structure of the mesoporous silica for the final morphology is discussed. - Graphical abstract: TG/DSC and gas analysis (inset) curves of the synthesis reaction measured in air and SEM micrograph of the Li{sub 2}SiO{sub 3} dendrite obtained. Highlights: > We present a simple template-based method for preparing unusual 2-D lithium metasilicate (Li{sub 2}SiO{sub 3}) dendritic nanostructures. > The high purity of the final Li{sub 2}SiO{sub 3} is explained by the reaction mechanism proposed. > This templated synthesis method provides a new route for direct growth of dendritic nanostructures.

  5. Lumbosacral spine CT

    MedlinePlus

    ... Pinched nerve Tumor Vertebral fracture (broken spine bone) Risks The most common type of contrast given into ... urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows ...

  6. Thoracic spine CT scan

    MedlinePlus

    ... Narrowing of the spine ( spinal stenosis ) Scoliosis Tumor Risks Risks of CT scans include: Exposure to radiation ... urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows ...

  7. Periscopic Spine Surgery

    DTIC Science & Technology

    2005-01-01

    AD Award Number: W81XWH-04-1-0078 TITLE: Periscopic Spine Surgery PRINCIPAL INVESTIGATOR: Kevin R. Cleary, Ph.D. CONTRACTING ORGANIZATION: Georgetown...2005 Annual (22 Dec 2003 - 21 Dec 2004) 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Periscopic Spine Surgery W81XWH-04-1-0078 6. AUTHOR(S) Kevin R. Cleary... Surgery -specific image acquisition, processing, and display are needed. The two- dimensional (2D) static images typically used today are not sufficient

  8. Spine development for the Echidna fiber positioner

    NASA Astrophysics Data System (ADS)

    Moore, Anna M.; Gillingham, Peter R.; Griesbach, Jason S.; Akiyama, Masayuki

    2003-03-01

    The Echidna multi-object fiber positioner is part of the Fiber Multi-Object Spectrograph (FMOS) project for the prime focus of the Subaru telescope. Given the physical size of the focal plane and the required number of fibers (400), a positioning system based on the Anglo-Australian Observatory's 2dF instrument, that incorporates the placement of magnetic buttons by a single X/Y/Z robot, was considered impractical. Instead, a solution has been developed in which each fiber is mounted on a tilting spine that allows the fiber to be positioned anywhere in a circle of radius 7 mm. Each of the 400 fibers therefore has a fixed "patrol" area in the field of view, with a significant overlap between neighboring spines. A description of a single Echidna spine is presented. Each spine is driven by a quadrant tube piezoelectric actuator (QTP) that, by a ratcheting mechanism, is able to position the fiber to within 10 μm of any coordinate in the corresponding patrol area. Results of positioning tests for eight of the twenty prototype spines reveal better than specification performance, as well as a durability far in excess of the specified lifetime of the instrument.

  9. Computational reconstitution of spine calcium transients from individual proteins

    PubMed Central

    Bartol, Thomas M.; Keller, Daniel X.; Kinney, Justin P.; Bajaj, Chandrajit L.; Harris, Kristen M.; Sejnowski, Terrence J.; Kennedy, Mary B.

    2015-01-01

    We have built a stochastic model in the program MCell that simulates Ca2+ transients in spines from the principal molecular components believed to control Ca2+ entry and exit. Proteins, with their kinetic models, are located within two segments of dendrites containing 88 intact spines, centered in a fully reconstructed 6 × 6 × 5 μm3 cube of hippocampal neuropil. Protein components include AMPA- and NMDA-type glutamate receptors, L- and R-type voltage-dependent Ca2+ channels, Na+/Ca2+ exchangers, plasma membrane Ca2+ ATPases, smooth endoplasmic reticulum Ca2+ ATPases, immobile Ca2+ buffers, and calbindin. Kinetic models for each protein were taken from published studies of the isolated proteins in vitro. For simulation of electrical stimuli, the time course of voltage changes in the dendritic spine was generated with the desired stimulus in the program NEURON. Voltage-dependent parameters were then continuously re-adjusted during simulations in MCell to reproduce the effects of the stimulus. Nine parameters of the model were optimized within realistic experimental limits by a process that compared results of simulations to published data. We find that simulations in the optimized model reproduce the timing and amplitude of Ca2+ transients measured experimentally in intact neurons. Thus, we demonstrate that the characteristics of individual isolated proteins determined in vitro can accurately reproduce the dynamics of experimentally measured Ca2+ transients in spines. The model will provide a test bed for exploring the roles of additional proteins that regulate Ca2+ influx into spines and for studying the behavior of protein targets in the spine that are regulated by Ca2+ influx. PMID:26500546

  10. Components of RNA granules affect their localization and dynamics in neuronal dendrites.

    PubMed

    Mitsumori, Kazuhiko; Takei, Yosuke; Hirokawa, Nobutaka

    2017-04-12

    In neurons, RNA transport is important for local protein synthesis. Messenger RNAs (mRNAs) are transported along dendrites as large RNA granules. The localization and dynamics of Puralpha and Stau1, major components of RNA transport granules, were investigated in cultured hippocampal neurons. Puralpha-positive granules were localized in both the shafts and spines of dendrites. In contrast, Stau1-positive granules tended to be localized mainly in dendritic shafts. More than 90% of Puralpha-positive granules were positive for Stau1 in immature dendrites, while only half were positive in mature dendrites. Stau1-negative Puralpha granules tended to be stationary with fewer anterograde and retrograde movements than Stau1-positive Puralpha granules. After metabotropic glutamate receptor 5 (mGluR5) activation, Stau-1 positive granules remained in the dendritic shafts, while Puralpha granules translocated from the shaft to the spine. The translocation of Puralpha granules was dependent on Myosin Va, an actin-based molecular motor protein. Collectively, our findings suggest the possibility that the loss of Stau1 in Puralpha-positive RNA granules might promote their activity-dependent translocation into dendritic spines, which could underlie the regulation of protein synthesis in synapses.

  11. Constitutive activation of CREB in mice enhances temporal association learning and increases hippocampal CA1 neuronal spine density and complexity

    PubMed Central

    Serita, Tatsurou; Fukushima, Hotaka; Kida, Satoshi

    2017-01-01

    Transcription factor CREB is believed to play essential roles in the formation of long-term memory (LTM), but not in learning and short-term memory (STM). Surprisingly, we previously showed that transgenic mice expressing a dominant active mutant of CREB (DIEDML) in the forebrain (DIEDML mice) demonstrated enhanced STM and LTM in hippocampal-dependent, rapid, one-trial learning tasks. Here we show that constitutive activation of CREB enhances hippocampal-dependent learning of temporal association in trace fear conditioning and delayed matching-to-place tasks. We then show that in DIEDML mice the apical tuft dendrites of hippocampal CA1 pyramidal neurons, required for temporal association learning, display increased spine density, especially of thin spines and of Homer1-negative spines. In contrast, the basal and apical oblique dendrites of CA1 neurons, required for rapid one-trial learning, show increased density of thin, stubby, and mushroom spines and of Homer1-positive spines. Furthermore, DIEDML mice showed increased dendritic complexity in the proximal portion of apical CA1 dendrites to the soma. In contrast, forebrain overexpression of CaMKIV, leading to enhanced LTM but not STM, show normal learning and CA1 neuron morphology. These findings suggest that dendritic region-specific morphological changes in CA1 neurons by constitutive activation of CREB may contribute to improved learning and STM. PMID:28195219

  12. Constitutive activation of CREB in mice enhances temporal association learning and increases hippocampal CA1 neuronal spine density and complexity.

    PubMed

    Serita, Tatsurou; Fukushima, Hotaka; Kida, Satoshi

    2017-02-14

    Transcription factor CREB is believed to play essential roles in the formation of long-term memory (LTM), but not in learning and short-term memory (STM). Surprisingly, we previously showed that transgenic mice expressing a dominant active mutant of CREB (DIEDML) in the forebrain (DIEDML mice) demonstrated enhanced STM and LTM in hippocampal-dependent, rapid, one-trial learning tasks. Here we show that constitutive activation of CREB enhances hippocampal-dependent learning of temporal association in trace fear conditioning and delayed matching-to-place tasks. We then show that in DIEDML mice the apical tuft dendrites of hippocampal CA1 pyramidal neurons, required for temporal association learning, display increased spine density, especially of thin spines and of Homer1-negative spines. In contrast, the basal and apical oblique dendrites of CA1 neurons, required for rapid one-trial learning, show increased density of thin, stubby, and mushroom spines and of Homer1-positive spines. Furthermore, DIEDML mice showed increased dendritic complexity in the proximal portion of apical CA1 dendrites to the soma. In contrast, forebrain overexpression of CaMKIV, leading to enhanced LTM but not STM, show normal learning and CA1 neuron morphology. These findings suggest that dendritic region-specific morphological changes in CA1 neurons by constitutive activation of CREB may contribute to improved learning and STM.

  13. Musculo-tendinous stiffness of head-neck segment in the sagittal plane: an optimization approach for modeling the cervical spine as a single-joint system.

    PubMed

    Portero, Raphaël; Quaine, Franck; Cahouet, Violaine; Thoumie, Philippe; Portero, Pierre

    2013-03-15

    Despite the multi-linked architecture of the cervical spine, all previous studies that have made estimations of mechanical properties of the neck have considered the head-neck segment as a rigid link, with a fixed center of rotation at C7. The aim of this study was to consider the head-neck segment as a changeable geometry system for locating the resultant center of rotation and for calculating the musculo-tendinous stiffness by the quick-release method. Head kinematics during quick-releases was analyzed by recording the trajectory of surface markers. With an optimization procedure, the position of the resultant center of rotation of the head-neck segment was estimated. Thereafter, the angular displacement and acceleration of the head, together with the isometric torque developed by the cervical muscles were used to calculate the segment's stiffness. The results showed a consistent center of rotation and a significant increase of the musculo-tendinous stiffness with increasing torque.

  14. Adolescent nicotine-induced dendrite remodeling in the nucleus accumbens is rapid, persistent, and D1-dopamine receptor dependent.

    PubMed

    Ehlinger, D G; Bergstrom, H C; Burke, J C; Fernandez, G M; McDonald, C G; Smith, R F

    2016-01-01

    Chronic nicotine exposure during adolescence induces dendritic remodeling of medium spiny neurons (MSNs) in the nucleus accumbens (NAcc) shell. While nicotine-induced dendritic remodeling has frequently been described as persistent, the trajectory of dendrite remodeling is unknown. Specifically, no study to date has characterized the structural plasticity of dendrites in the NAcc immediately following chronic nicotine, leaving open the possibility that dendrite remodeling emerges gradually over time. Further, the neuropharmacological mechanisms through which nicotine induces dendrite remodeling are not well understood. To address these questions, rats were co-administered chronic nicotine (0.5 mg/kg) and the D1-dopamine receptor (D1DR) antagonist SCH-23390 (0.05 mg/kg) subcutaneously every other day during adolescence. Brains were then processed for Golgi-Cox staining either 1 day or 21 days following drug exposure and dendrites from MSNs in the NAcc shell digitally reconstructed in 3D. Spine density was also measured at both time points. Our morphometric results show (1) the formation of new dendritic branches and spines 1 day following nicotine exposure, (2) new dendritic branches, but not spine density, remains relatively stable for at least 21 days, (3) the co-administration of SCH-23390 completely blocked nicotine-induced dendritic remodeling of MSNs at both early and late time points, suggesting the formation of new dendritic branches in response to nicotine is D1DR-dependent, and (4) SCH-23390 failed to block nicotine-induced increases in spine density. Overall this study provides new insight into how nicotine influences the normal trajectory of adolescent brain development and demonstrates a persistent form of nicotine-induced neuroplasticity in the NAcc shell that develops rapidly and is D1DR dependent.

  15. Mutational analysis of dendritic Ca2+ kinetics in rodent Purkinje cells: role of parvalbumin and calbindin D28k

    PubMed Central

    Schmidt, Hartmut; Stiefel, Klaus M; Racay, Peter; Schwaller, Beat; Eilers, Jens

    2003-01-01

    The mechanisms governing the kinetics of climbing fibre-mediated Ca2+ transients in spiny dendrites of cerebellar Purkinje cells (PCs) were quantified with high-resolution confocal Ca2+ imaging. Ca2+ dynamics in parvalbumin (PV−/−) and parvalbumin/calbindin D28k null-mutant (PV/CB−/−) mice were compared with responses in wild-type (WT) animals. In the WT, Ca2+ transients in dendritic shafts were characterised by double exponential decay kinetics that were not due to buffered Ca2+ diffusion or saturation of the indicator dye. Ca2+ transients in PV−/− PCs reached the same peak amplitude as in the WT but the biphasic nature of the decay was less pronounced, an effect that could be attributed to PV's slow binding kinetics. In contrast, peak amplitudes in PV/CB−/− PCs were about two times higher than in the WT and the decay became nearly monophasic. Numerical simulations indicate that the residual deviation from a single exponential decay in PV/CB−/− is due to saturation of the Ca2+ indicator dye. Furthermore, the simulations imply that the effect of uncharacterised endogenous Ca2+ binding proteins is negligible, that buffered diffusion and dye saturation significantly affects spineous Ca2+ transients but not those in the dendritic shafts, and that neither CB nor PV undergoes saturation in spines or dendrites during climbing fibre-evoked Ca2+ transients. Calbindin's medium-affinity binding sites are fast enough to reduce the peak amplitude of the Ca2+ signal. However, similar to PV, delayed binding by CB leads to biphasic Ca2+ decay kinetics. Our results suggest that the distinct kinetics of PV and CB underlie the biphasic kinetics of synaptically evoked Ca2+ transients in dendritic shafts of PCs. PMID:12813159

  16. Isothermal Dendritic Growth Experiment - PVA Dendrites

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Isothermal Dendritic Growth Experiment (IDGE), flown on three Space Shuttle missions, is yielding new insights into virtually all industrially relevant metal and alloy forming operations. IDGE used transparent organic liquids that form dendrites (treelike structures) similar to those inside metal alloys. Comparing Earth-based and space-based dendrite growth velocity, tip size and shape provides a better understanding of the fundamentals of dentritic growth, including gravity's effects. Shalowgraphic images of pivalic acid (PVA) dendrites forming from the melt show the subtle but distinct effects of gravity-driven heat convection on dentritic growth. In orbit, the dendrite grows as its latent heat is liberated by heat conduction. This yields a blunt dendrite tip. On Earth, heat is carried away by both conduction and gravity-driven convection. This yields a sharper dendrite tip. In addition, under terrestrial conditions, the sidebranches growing in the direction of gravity are augmented as gravity helps carry heat out of the way of the growing sidebranches as opposed to microgravity conditions where no augmentation takes place. IDGE was developed by Rensselaer Polytechnic Institute and NASA/Glenn Research Center. Advanced follow-on experiments are being developed for flight on the International Space Station. Photo Credit: NASA/Glenn Research Center

  17. Arg kinase signaling in dendrite and synapse stabilization pathways: memory, cocaine sensitivity, and stress.

    PubMed

    Kerrisk, Meghan E; Koleske, Anthony J

    2013-11-01

    The Abl2/Arg nonreceptor tyrosine kinase is enriched in dendritic spines where it is essential for maintaining dendrite and synapse stability in the postnatal mouse brain. Arg is activated downstream of integrin α3β1 receptors and it regulates the neuronal actin cytoskeleton by directly binding F-actin and via phosphorylation of substrates including p190RhoGAP and cortactin. Neurons in mice lacking Arg or integrin α3β1 develop normally through postnatal day 21 (P21), however by P42 mice exhibit major reductions in dendrite arbor size and complexity, and lose dendritic spines and synapses. As a result, mice with loss of Arg and Arg-dependent signaling pathways have impairments in memory tasks, heightened sensitivity to cocaine, and vulnerability to corticosteroid-induced neuronal remodeling. Therefore, understanding the molecular mechanisms of Arg regulation may lead to therapeutic approaches to treat human psychiatric and neurodegenerative diseases in which neuronal structure is destabilized.

  18. Plasticity-related Gene 5 Promotes Spine Formation in Murine Hippocampal Neurons*

    PubMed Central

    Coiro, Pierluca; Stoenica, Luminita; Strauss, Ulf; Bräuer, Anja Ursula

    2014-01-01

    The transmembrane protein plasticity-related genes 3 and 5 (PRG3 and PRG5) increase filopodial formation in various cell lines, independently of Cdc42. However, information on the effects of PRG5 during neuronal development is sparse. Here, we present several lines of evidence for the involvement of PRG5 in the genesis and stabilization of dendritic spines. First, PRG5 was strongly expressed during mouse brain development from embryonic day 14 (E14), peaked around the time of birth, and remained stable at least until early adult stages (i.e. P30). Second, on a subcellular level, PRG5 expression shifted from an equal distribution along all neurites toward accumulation only along dendrites during hippocampal development in vitro. Third, overexpression of PRG5 in immature hippocampal neurons induced formation of spine-like structures ahead of time. Proper amino acid sequences in the extracellular domains (D1 to D3) of PRG5 were a prerequisite for trafficking and induction of spine-like structures, as shown by mutation analysis. Fourth, at stages when spines are present, knockdown of PRG5 reduced the number but not the length of protrusions. This was accompanied by a decrease in the number of excitatory synapses and, consequently, by a reduction of miniature excitatory postsynaptic current frequencies, although miniature excitatory postsynaptic current amplitudes remained similar. In turn, overexpressing PRG5 in mature neurons not only increased Homer-positive spine numbers but also augmented spine head diameters. Mechanistically, PRG5 interacts with phosphorylated phosphatidylinositols, phospholipids involved in dendritic spine formation by different lipid-protein assays. Taken together, our data propose that PRG5 promotes spine formation. PMID:25074937

  19. The degenerative cervical spine.

    PubMed

    Llopis, E; Belloch, E; León, J P; Higueras, V; Piquer, J

    2016-04-01

    Imaging techniques provide excellent anatomical images of the cervical spine. The choice to use one technique or another will depend on the clinical scenario and on the treatment options. Plain-film X-rays continue to be fundamental, because they make it possible to evaluate the alignment and bone changes; they are also useful for follow-up after treatment. The better contrast resolution provided by magnetic resonance imaging makes it possible to evaluate the soft tissues, including the intervertebral discs, ligaments, bone marrow, and spinal cord. The role of computed tomography in the study of degenerative disease has changed in recent years owing to its great spatial resolution and its capacity to depict osseous components. In this article, we will review the anatomy and biomechanical characteristics of the cervical spine, and then we provide a more detailed discussion of the degenerative diseases that can affect the cervical spine and their clinical management.

  20. Territories of heterologous inputs onto Purkinje cell dendrites are segregated by mGluR1-dependent parallel fiber synapse elimination

    PubMed Central

    Ichikawa, Ryoichi; Hashimoto, Kouichi; Miyazaki, Taisuke; Uchigashima, Motokazu; Yamasaki, Miwako; Aiba, Atsu; Kano, Masanobu; Watanabe, Masahiko

    2016-01-01

    In Purkinje cells (PCs) of the cerebellum, a single “winner” climbing fiber (CF) monopolizes proximal dendrites, whereas hundreds of thousands of parallel fibers (PFs) innervate distal dendrites, and both CF and PF inputs innervate a narrow intermediate domain. It is unclear how this segregated CF and PF innervation is established on PC dendrites. Through reconstruction of dendritic innervation by serial electron microscopy, we show that from postnatal day 9–15 in mice, both CF and PF innervation territories vigorously expand because of an enlargement of the region of overlapping innervation. From postnatal day 15 onwards, segregation of these territories occurs with robust shortening of the overlapping proximal region. Thus, innervation territories by the heterologous inputs are refined during the early postnatal period. Intriguingly, this transition is arrested in mutant mice lacking the type 1 metabotropic glutamate receptor (mGluR1) or protein kinase Cγ (PKCγ), resulting in the persistence of an abnormally expanded overlapping region. This arrested territory refinement is rescued by lentivirus-mediated expression of mGluR1α into mGluR1-deficient PCs. At the proximal dendrite of rescued PCs, PF synapses are eliminated and free spines emerge instead, whereas the number and density of CF synapses are unchanged. Because the mGluR1-PKCγ signaling pathway is also essential for the late-phase of CF synapse elimination, this signaling pathway promotes the two key features of excitatory synaptic wiring in PCs, namely CF monoinnervation by eliminating redundant CF synapses from the soma, and segregated territories of CF and PF innervation by eliminating competing PF synapses from proximal dendrites. PMID:26858447

  1. Dorsal spine osteoblastoma

    PubMed Central

    Bhargava, Pranshu; Singh, Rahul; Garg, Bharat B.

    2016-01-01

    Benign osteoblastoma is a rare primary neoplasm comprising less than 1% of primary bone tumors.[1] We report a case of a 20-year-old female patient presenting with progressive paraparesis over one year and back pain over the dorsal spine gradually increasing in severity over a year. Computerised tomomography (CT) of the spine revealed a well-defined 3.5 × 3.0 cm mass heterodense expansile bony lesion arising from the lamina of the D12 vertebra, having lytic and sclerotic component and causing compromise of the bony spinal canal. D12 laminectomy and total excision of the tumor was done. PMID:27057242

  2. Multiplanar CT of the spine

    SciTech Connect

    Rothman, S.L.G.; Glenn, W.V.

    1985-01-01

    This book contains 16 chapters. Some of the topics are: CT of the Sacrum, The Postoperative Spine, Film Organizations and Case Reporting, Degeneration and Disc Disease of the Intervertebral Joint, Lumbar Spinal Stenosis, and Cervical and Thoracic Spine.

  3. Thoracic spine x-ray

    MedlinePlus

    Vertebral radiography; X-ray - spine; Thoracic x-ray; Spine x-ray; Thoracic spine films; Back films ... The test is done in a hospital radiology department or in the health care provider's office. You will lie on the x-ray table in different positions. If the x-ray ...

  4. Spine surgery - discharge

    MedlinePlus

    ... symptoms should get better in a few weeks. Recovery after laminectomy and fusion surgery is longer. You will not be able ... discharge; Anterior spinal fusion - discharge; Spine surgery - spinal fusion - discharge Images Spinal surgery -- cervical - series References Agrawal BM, Zeidman SM, Rhines L, ...

  5. Symptomatic pseudarthrosis in ochronotic spine: case report.

    PubMed

    Rahimizadeh, Abolfazl; Soufiani, Housain; Hassani, Valliolah; Rahimizadeh, Ava

    2017-02-01

    In this study the authors report the first example of spinal pseudarthrosis in a patient with ochronosis, and they describe the application of posterior-only 360° surgery as an alternative approach to combined anterior-posterior surgery in the management of pseudarthrosis of an ankylosed spine, regardless of its etiology. Spinal involvement in ochronosis produces loss of flexibility and ankylosis of thoracic and lumbar segments. Pseudarthrosis is a serious complication of the diseases that present with ankylosis of the spine. However, its occurrence in ochronotic spine has not been reported previously. Evaluation of progressive paraparesis in a 68-year-old man with ochronosis revealed pseudarthrosis at the T11-12 level. Circumferential dural sac decompression, debridement of the disc space, interbody fusion, and screw-rod fixation were all done via a posterior-only approach. Postoperatively the patient exhibited a marked recovery in terms of pain and neurological status. At the 3-month follow-up, he was able to walk independently. Ochronosis should be included in the etiology of pseudarthrosis. With aggravation of back pain and the appearance of neurological deficits in an already stable patient with any ankylosing disease, pseudarthrosis should be suspected. Furthermore, single-stage, 360°, posterior-only surgery may obviate the need for single-stage or staged anterior-posterior surgical intervention in patients with pseudarthrosis of the thoracic and lumbar spine.

  6. Free dendritic growth

    NASA Technical Reports Server (NTRS)

    Glicksman, M. E.

    1984-01-01

    Free dendritic growth refers to the unconstrained development of crystals within a supercooled melt, which is the classical 'dendrite problem'. Great strides have been taken in recent years in both the theoretical understanding of dendritic growth and its experimental status. The development of this field will be sketched, showing that transport theory and interfacial thermodynamics (capillarity theory) were sufficient ingredients to develop a truly predictive model of dendrite formation. The convenient, but incorrect, notion of 'maximum velocity' was used for many years to estimate the behavior of dendritic transformations until supplanted by modern dynamic stability theory. The proper combinations of transport theory and morphological stability seem to able to predict the salient aspects of dendritic growth, especially in the neighborhood of the tip. The overall development of cast microstructures, such as equiaxed zone formation, rapidly solidified microstructures, etc., also seems to contain additional non-deterministic features which lie outside the current theories discussed here.

  7. Dendritic polyurea polymers.

    PubMed

    Tuerp, David; Bruchmann, Bernd

    2015-01-01

    Dendritic polymers, subsuming dendrimers as well as hyperbranched or highly branched polymers are well established in the field of polymer chemistry. This review article focuses on urea based dendritic polymers and summarizes their synthetic routes through both isocyanate and isocyanate-free processes. Furthermore, this article highlights applications where dendritic polyureas show their specific chemical and physical potential. For these purposes scientific publications as well as patent literature are investigated to generate a comprehensive overview on this topic.

  8. Temporal Dynamics of Acute Stress-Induced Dendritic Remodeling in Medial Prefrontal Cortex and the Protective Effect of Desipramine.

    PubMed

    Nava, Nicoletta; Treccani, Giulia; Alabsi, Abdelrahman; Kaastrup Mueller, Heidi; Elfving, Betina; Popoli, Maurizio; Wegener, Gregers; Nyengaard, Jens Randel

    2015-11-01

    Stressful events are associated with increased risk of mood disorders. Volumetric reductions have been reported in brain areas critical for the stress response, such as medial prefrontal cortex (mPFC), and dendritic remodeling has been proposed as an underlying factor. Here, we investigated the time-dependent effects of acute stress on dendritic remodeling within the prelimbic (PL) region of the PFC, and whether treatment with the antidepressant desipramine (DMI) may interfere. Rodents were subjected to foot-shock stress: dendritic length and spine density were analyzed 1 day, 7 days, and 14 days after stress. Acute stress produced increased spine density and decreased cofilin phosphorylation at 1 day, paralleled with dendritic retraction. An overall shift in spine population was observed at 1 day, resulting in a stress-induced increase in small spines. Significant atrophy of apical dendrites was observed at 1 day, which was prevented by chronic DMI, and at 14 days after stress exposure. Chronic DMI resulted in dendritic elaboration at 7 days but did not prevent the effects of FS-stress. Collectively, these data demonstrate that 1) acute stressors may induce rapid and sustained changes of PL neurons; and 2) chronic DMI may protect neurons from rapid stress-induced synaptic changes.

  9. Functional Redundancy of Septin Homologs in Dendritic Branching

    PubMed Central

    Kaplan, Charlotte; Steinmann, Mayra; Zapiorkowska, Natalia A.; Ewers, Helge

    2017-01-01

    Septins are cytoskeletal GTPases present in nonpolar heteromeric complexes that assemble in a palindromic fashion from two to eight subunits. Mammalian septins function in several fundamental cellular processes at the membrane-cytoskeleton interface including dendritic branching in neurons. Sequence homology divides the 13 mammalian septin genes into four homology groups. Experimental findings suggest that septin function is redundant among septins from one homology group. This is best understood for the isoforms of the SEPT2 group, which form a homodimer at the center of septin complexes. In vitro, all SEPT2-group septins form recombinant hexameric complexes with two copies of SEPT6 and SEPT7. However, it remains unclear to what extent homologs septins can substitute for each other in specific cellular processes. Here, we use the experimental paradigm of dendritic branching in hippocampal rat neurons to ask, to what extent septins of the SEPT2-group are functionally redundant. Dendritic branching is significantly reduced when SEPT5 is downregulated. In neurons expressing SEPT5-shRNA, simultaneously expressed SEPT2-GFP, and SEPT4-GFP colocalize with SEPT7 at dendritic spine necks and rescue dendritic branching. In contrast, SEPT1-GFP is diffusely distributed in the cytoplasm in SEPT5 downregulated neurons and cannot rescue dendritic branching. Our findings provide a basis for the study of septin-specific functions in cells. PMID:28265560

  10. Intrawound Vancomycin Powder for Spine Tumor Surgery

    PubMed Central

    Okafor, Richard; Molinari, William; Molinari, Robert; Mesfin, Addisu

    2015-01-01

    Study Design Retrospective evaluation of prospectively collected data. Objective To evaluate infection rates following intrawound vancomycin powder application during spine tumor surgery. Methods Patients ≥18 years old undergoing spine tumor surgery and receiving intrawound vancomycin powder at a single center between January 2008 and January 2015 were enrolled. Patient demographics (age, sex, body mass index [BMI]), tumor type (metastatic, primary) and location, surgical data (estimated blood loss [EBL], levels fused, type of decompression, length of surgery and hospitalization, discharge status from hospital), radiation therapy use, and infection rates (surgery to a minimum of 30 days postoperative) were evaluated. Results Forty patients (46 procedures) undergoing spine tumor surgery and intrawound vancomycin powder application were identified. Five were excluded because of death less than 30 days postoperatively, and 35 patients (41 procedures) were enrolled: 11 women and 24 men with an average age of 61.4 years (range 19 to 92) and average BMI of 27.3 (range 17.4 to 36.8). Three cases were primary spine tumors. Five were hematologic malignancies, and 27 were metastatic cancers. Twenty-one tumors were in the thoracic spine, 12 in the lumbar spine, and 8 in the cervical spine. Average EBL was 899 mL (range 25 to 3,500), average length of surgery was 241 minutes (range 78 to 495), and average hospital stay was 15.1 days (range 3 to 49). Two culture-proven infections (Staphylococcus aureus, Enterobacter cloacae) were noted in 41 procedures (4.9%). Ten patients (28.6%) had preoperative radiation only; 14 (40%) had postoperative radiation only, 5 (14.3%) had both preoperative and postoperative radiation, and 6 (17.1%) had no radiation. There were no associations between radiation treatment and postsurgical infections (p = 0.19). Conclusion In this first study evaluating intrawound vancomycin powder for spine tumor surgery, we report an infection rate

  11. Intrawound Vancomycin Powder for Spine Tumor Surgery.

    PubMed

    Okafor, Richard; Molinari, William; Molinari, Robert; Mesfin, Addisu

    2016-05-01

    Study Design Retrospective evaluation of prospectively collected data. Objective To evaluate infection rates following intrawound vancomycin powder application during spine tumor surgery. Methods Patients ≥18 years old undergoing spine tumor surgery and receiving intrawound vancomycin powder at a single center between January 2008 and January 2015 were enrolled. Patient demographics (age, sex, body mass index [BMI]), tumor type (metastatic, primary) and location, surgical data (estimated blood loss [EBL], levels fused, type of decompression, length of surgery and hospitalization, discharge status from hospital), radiation therapy use, and infection rates (surgery to a minimum of 30 days postoperative) were evaluated. Results Forty patients (46 procedures) undergoing spine tumor surgery and intrawound vancomycin powder application were identified. Five were excluded because of death less than 30 days postoperatively, and 35 patients (41 procedures) were enrolled: 11 women and 24 men with an average age of 61.4 years (range 19 to 92) and average BMI of 27.3 (range 17.4 to 36.8). Three cases were primary spine tumors. Five were hematologic malignancies, and 27 were metastatic cancers. Twenty-one tumors were in the thoracic spine, 12 in the lumbar spine, and 8 in the cervical spine. Average EBL was 899 mL (range 25 to 3,500), average length of surgery was 241 minutes (range 78 to 495), and average hospital stay was 15.1 days (range 3 to 49). Two culture-proven infections (Staphylococcus aureus, Enterobacter cloacae) were noted in 41 procedures (4.9%). Ten patients (28.6%) had preoperative radiation only; 14 (40%) had postoperative radiation only, 5 (14.3%) had both preoperative and postoperative radiation, and 6 (17.1%) had no radiation. There were no associations between radiation treatment and postsurgical infections (p = 0.19). Conclusion In this first study evaluating intrawound vancomycin powder for spine tumor surgery, we report an infection rate

  12. Postnatal development of dendritic structure of layer III pyramidal neurons in the medial prefrontal cortex of marmoset.

    PubMed

    Sasaki, Tetsuya; Aoi, Hirosato; Oga, Tomofumi; Fujita, Ichiro; Ichinohe, Noritaka

    2015-11-01

    In the primate cerebral cortex, dendritic spines rapidly increase in number after birth up to infancy or mid-childhood, and then decrease towards adulthood. Abnormalities in these processes accompany several psychiatric disorders. In this study, we examined developmental changes of basal dendrites and spines of layer III pyramidal cells in the medial prefrontal cortex (mPFC) of the common marmoset. The mPFC consists of several areas with distinct features in layer organization, histochemistry, connections, and, in humans, vulnerability to psychiatric disorders. We selected three areas for examination: granular dorsomedial prefrontal (area 8B/9), dysgranular ventromedial prefrontal (area 14r), and agranular anterior cingulate (area 24) cortices. Dendritic field areas, lengths, number of branching points, and total spine number reached a peak at 2-3 postnatal months in all three areas. However, the profiles of spine formation and pruning differed across the three areas with different degrees of granularity; the amount of spine loss from the peak to adulthood was less in areas 24 (33%) and 14r (29%) than in area 8B/9 (43%). Disturbance of this modest spine pruning in the less granular cortical areas may lead to an excessive loss of spines reported for areas 24 and 14r of schizophrenic patients.

  13. The unfolded protein response is required for dendrite morphogenesis.

    PubMed

    Wei, Xing; Howell, Audrey S; Dong, Xintong; Taylor, Caitlin A; Cooper, Roshni C; Zhang, Jianqi; Zou, Wei; Sherwood, David R; Shen, Kang

    2015-06-08

    Precise patterning of dendritic fields is essential for the formation and function of neuronal circuits. During development, dendrites acquire their morphology by exuberant branching. How neurons cope with the increased load of protein production required for this rapid growth is poorly understood. Here we show that the physiological unfolded protein response (UPR) is induced in the highly branched Caenorhabditis elegans sensory neuron PVD during dendrite morphogenesis. Perturbation of the IRE1 arm of the UPR pathway causes loss of dendritic branches, a phenotype that can be rescued by overexpression of the ER chaperone HSP-4 (a homolog of mammalian BiP/grp78). Surprisingly, a single transmembrane leucine-rich repeat protein, DMA-1, plays a major role in the induction of the UPR and the dendritic phenotype in the UPR mutants. These findings reveal a significant role for the physiological UPR in the maintenance of ER homeostasis during morphogenesis of large dendritic arbors.

  14. Transcranial magnetic stimulation (TMS) inhibits cortical dendrites

    PubMed Central

    Murphy, Sean C; Palmer, Lucy M; Nyffeler, Thomas; Müri, René M; Larkum, Matthew E

    2016-01-01

    One of the leading approaches to non-invasively treat a variety of brain disorders is transcranial magnetic stimulation (TMS). However, despite its clinical prevalence, very little is known about the action of TMS at the cellular level let alone what effect it might have at the subcellular level (e.g. dendrites). Here, we examine the effect of single-pulse TMS on dendritic activity in layer 5 pyramidal neurons of the somatosensory cortex using an optical fiber imaging approach. We find that TMS causes GABAB-mediated inhibition of sensory-evoked dendritic Ca2+ activity. We conclude that TMS directly activates fibers within the upper cortical layers that leads to the activation of dendrite-targeting inhibitory neurons which in turn suppress dendritic Ca2+ activity. This result implies a specificity of TMS at the dendritic level that could in principle be exploited for investigating these structures non-invasively. DOI: http://dx.doi.org/10.7554/eLife.13598.001 PMID:26988796

  15. Nectin-1 spots as a novel adhesion apparatus that tethers mitral cell lateral dendrites in a dendritic meshwork structure of the developing mouse olfactory bulb.

    PubMed

    Inoue, Takahito; Fujiwara, Takeshi; Rikitake, Yoshiyuki; Maruo, Tomohiko; Mandai, Kenji; Kimura, Kazushi; Kayahara, Tetsuro; Wang, Shujie; Itoh, Yu; Sai, Kousyoku; Mori, Masahiro; Mori, Kensaku; Mizoguchi, Akira; Takai, Yoshimi

    2015-08-15

    Mitral cells project lateral dendrites that contact the lateral and primary dendrites of other mitral cells and granule cell dendrites in the external plexiform layer (EPL) of the olfactory bulb. These dendritic structures are critical for odor information processing, but it remains unknown how they are formed. In immunofluorescence microscopy, the immunofluorescence signal for the cell adhesion molecule nectin-1 was concentrated on mitral cell lateral dendrites in the EPL of the developing mouse olfactory bulb. In electron microscopy, the immunogold particles for nectin-1 were symmetrically localized on the plasma membranes at the contacts between mitral cell lateral dendrites, which showed bilateral darkening without dense cytoskeletal undercoats characteristic of puncta adherentia junctions. We named the contacts where the immunogold particles for nectin-1 were symmetrically accumulated "nectin-1 spots." The nectin-1 spots were 0.21 μm in length on average and the distance between the plasma membranes was 20.8 nm on average. In 3D reconstruction of serial sections, clusters of the nectin-1 spots formed a disc-like structure. In the mitral cell lateral dendrites of nectin-1-knockout mice, the immunogold particles for nectin-1 were undetectable and the plasma membrane darkening was electron-microscopically normalized, but the plasma membranes were partly separated from each other. The nectin-1 spots were further identified between mitral cell lateral and primary dendrites and between mitral cell lateral dendrites and granule cell dendritic spine necks. These results indicate that the nectin-1 spots constitute a novel adhesion apparatus that tethers mitral cell dendrites in a dendritic meshwork structure of the developing mouse olfactory bulb.

  16. Rendering the Topological Spines

    SciTech Connect

    Nieves-Rivera, D.

    2015-05-05

    Many tools to analyze and represent high dimensional data already exits yet most of them are not flexible, informative and intuitive enough to help the scientists make the corresponding analysis and predictions, understand the structure and complexity of scientific data, get a complete picture of it and explore a greater number of hypotheses. With this in mind, N-Dimensional Data Analysis and Visualization (ND²AV) is being developed to serve as an interactive visual analysis platform with the purpose of coupling together a number of these existing tools that range from statistics, machine learning, and data mining, with new techniques, in particular with new visualization approaches. My task is to create the rendering and implementation of a new concept called topological spines in order to extend ND²AV's scope. Other existing visualization tools create a representation preserving either the topological properties or the structural (geometric) ones because it is challenging to preserve them both simultaneously. Overcoming such challenge by creating a balance in between them, the topological spines are introduced as a new approach that aims to preserve them both. Its render using OpenGL and C++ and is currently being tested to further on be implemented on ND²AV. In this paper I will present what are the Topological Spines and how they are rendered.

  17. The dendritic branch is the preferred integrative unit for protein synthesis-dependent LTP

    PubMed Central

    Govindarajan, Arvind; Israely, Inbal; Huang, Shu-Ying; Tonegawa, Susumu

    2011-01-01

    Summary The late-phase of long-term potentiation (L-LTP), the cellular correlate of long-term memory, induced at some synapses facilitates L-LTP expression at other synapses receiving stimulation too weak to induce L-LTP by itself. Using glutamate uncaging and two-photon imaging, we demonstrate that the efficacy of this facilitation decreases with increasing time between stimulations, increasing distance between stimulated spines and with the spines being on different dendritic branches. Paradoxically, stimulated spines compete for L-LTP expression if stimulated too closely together in time. Furthermore, the facilitation is temporally bidirectional but asymmetric. Additionally, L-LTP formation is itself biased towards occurring on spines within a branch. These data support the Clustered Plasticity Hypothesis which states that such spatial and temporal limits lead to stable engram formation, preferentially at synapses clustered within dendritic branches rather than dispersed throughout the dendritic arbor. Thus, dendritic branches rather than individual synapses are the primary functional units for long-term memory storage. PMID:21220104

  18. The Arp2/3 Complex Is Essential for Distinct Stages of Spine Synapse Maturation, Including Synapse Unsilencing

    PubMed Central

    Spence, Erin F.; Kanak, Daniel J.; Carlson, Benjamin R.

    2016-01-01

    Dendritic filopodia are actin-rich structures that are thought to contribute to early spine synapse formation; however, the actin regulatory proteins important for early synaptogenesis are poorly defined. Using organotypic hippocampal slice cultures and primary neuron hippocampal cultures from Arp2/3 conditional knock-out mice, we analyze the roles of the Arp2/3 complex, an actin regulator that creates branched actin networks, and demonstrate it is essential for distinct stages of both structural and functional maturation of excitatory spine synapses. Our data show that initially the Arp2/3 complex inhibits the formation of dendritic filopodia but that later during development, the Arp2/3 complex drives the morphological maturation from filopodia to typical spine morphology. Furthermore, we demonstrate that although the Arp2/3 complex is not required for key spine maturation steps, such as presynaptic contact and recruitment of MAGUK (membrane-associated guanylate kinase) scaffolding proteins or NMDA receptors, it is necessary for the recruitment of AMPA receptors. This latter process, also known as synapse unsilencing, is a final and essential step in the neurodevelopment of excitatory postsynaptic synaptogenesis, setting the stage for neuronal interconnectivity. These findings provide the first evidence that the Arp2/3 complex is directly involved in functional maturation of dendritic spines during the developmental period of spinogenesis. SIGNIFICANCE STATEMENT Excitatory spine synapse formation (spinogenesis) is a poorly understood yet pivotal period of neurodevelopment that occurs within 2–3 weeks after birth. Neurodevelopmental disorders such as intellectual disability and autism are characterized by abnormal spine structure, which may arise from abnormal excitatory synaptogenesis. The initial stage of spinogenesis is thought to begin with the emergence of actin-rich dendritic filopodia that initiate contact with presynaptic axonal boutons. However, it

  19. Charcot Spine and Parkinson's Disease

    PubMed Central

    Loriaut, Philippe; Rozenberg, Sylvie; Boyer, Patrick; Dallaudière, Benjamin; Khiami, Frederic; Sariali, Elhadi; Pascal-Moussellard, Hugues

    2014-01-01

    Charcot spine is rare condition whose association with Parkinson's disease (PD) has not been reported yet. The authors reported the cases of two patients with PD who developed Charcot spine. Both patients presented with a history of back pain and bilateral radicular leg pain. They had complete clinical and radiological assessment. Lumbar spine was involved in both patients. Clinical features and response to treatment were described. In the first case, circumferential fusion and stabilization were performed on the dislocated vertebral levels. A solid and stable fusion of the spine was obtained with satisfactory clinical outcome. Surgical treatment has been recommended to the other patient. In both cases, no other neurological etiology was found to account for Charcot spine. In conclusion, Charcot spine is associated with several neurological affections but has not previously been reported in association with Parkinson's disease. PMID:25165591

  20. Pea3 Transcription Factors, Etv4 and Etv5, Are Required for Proper Hippocampal Dendrite Development and Plasticity.

    PubMed

    Fontanet, Paula Aldana; Ríos, Antonella Soledad; Alsina, Fernando Cruz; Paratcha, Gustavo; Ledda, Fernanda

    2016-11-30

    The proper formation and morphogenesis of dendrites is essential to the establishment of neuronal connectivity. We report that 2 members of the Pea3 family of transcription factors, Etv4 and Etv5, are expressed in hippocampal neurons during the main period of dendritogenesis, suggesting that they have a function in dendrite development. Here, we show that these transcription factors are physiological regulators of growth and arborization of pyramidal cell dendrites in the developing hippocampus. Gain and loss of function assays indicate that Etv4 and Etv5 are required for proper development of hippocampal dendritic arbors and spines. We have found that in vivo deletion of either Etv4 or Etv5 in hippocampal neurons causes deficits in dendrite size and complexity, which are associated with impaired cognitive function. Additionally, our data support the idea that Etv4 and Etv5 are part of a brain-derived neurotrophic factor-mediated transcriptional program required for proper hippocampal dendrite connectivity and plasticity.

  1. Moderate or deep local hypothermia does not prevent the onset of ischemia-induced dendritic damage

    PubMed Central

    Tran, Sherri; Chen, Shangbin; Liu, Ran R; Xie, Yicheng; Murphy, Timothy H

    2012-01-01

    We studied the acute (up to 2 hours after reperfusion) effects of localized cortical hypothermia on ischemia-induced dendritic structural damage. Moderate (31°C) and deep (22°C) hypothermia delays, but does not block the onset of dendritic blebbing or spine loss during global ischemia in mouse in vivo. Hypothermic treatment promoted more consistent recovery of dendritic structure and spines during reperfusion. These results suggest that those using therapeutic hypothermia will need to consider that it does not spare neurons from structural changes that are the result of ischemia, but hypothermia may interact with mechanisms that control the onset of damage and recovery during reperfusion. PMID:22167237

  2. Dendrite Model Explained

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Angie Jackman, a NASA project manager in microgravity research, explains a model of a dendrite to a visitor to the NASA exhibit at AirVenture 2000 sponsored by the Experimental Aircraft Association in Oshkosh, WI. The model depicts microscopic dendrites that grow as molten metals solidify. NASA sponsored three experiments aboard the Space Shuttle that used the microgravity environment to study the formation of large (1 to 4 mm) dendrites without Earth's gravity disrupting their growth. Three advanced follow-on experiments, managed by Jackman, are being developed for the International Space Station (ISS).

  3. Gonadal Hormones Rapidly Enhance Spatial Memory and Increase Hippocampal Spine Density in Male Rats

    PubMed Central

    Jacome, Luis F.; Barateli, Ketti; Buitrago, Dina; Lema, Franklin; Frankfurt, Maya

    2016-01-01

    17β-estradiol (E2) rapidly, within minutes, activates behaviors and cognition by binding to membrane estrogen receptors, activating cell signaling cascades and increasing dendritic spines. In female rodents, E2 enhances spatial memory within 2–4 hours, and spine density is increased in the CA1 area of the hippocampus within 30–60 minutes. Although chronic gonadal hormone treatments in male rats alter cognition and spines/spine synapses and acute hormone effects occur in hippocampal slices, effects of acute, in vivo hormone administration in males are unknown. Therefore, we assessed rapid effects of E2 (20 μg/kg) and testosterone (T) (750 μg/kg) on spatial memory using the object placement task and on hippocampal spine density using Golgi impregnation. Orchidectomized rats received hormones immediately after the training trial and were tested for retention 2 hours later. Vehicle-injected orchidectomized males spent equal time exploring objects in the old and new locations, but E2- or T-treated subjects spent more time exploring objects at the new location, suggesting enhanced memory. Both hormones also increased spine density in CA1, but not the dentate gyrus, by 20%–40% at 30 minutes and 2 hours after injections. This report is the first, to our knowledge, to show E2 and T enhancements of memory and spine density within such a short time frame in male rats. PMID:26844375

  4. MST3 Kinase Phosphorylates TAO1/2 to Enable Myosin Va Function in Promoting Spine Synapse Development

    PubMed Central

    Ultanir, Sila K.; Yadav, Smita; Hertz, Nicholas T.; Oses-Prieto, Juan A.; Claxton, Suzanne; Burlingame, Alma L.; Shokat, Kevan M.; Jan, Lily Y.; Jan, Yuh-Nung

    2014-01-01

    Summary Mammalian Sterile 20 (Ste20)-like kinase 3 (MST3) is a ubiquitously expressed kinase capable of enhancing axon outgrowth. Whether and how MST3 kinase signaling might regulate development of dendritic filopodia and spine synapses is unknown. Through shRNA-mediated depletion of MST3 and kinase-dead MST3 expression in developing hippocampal cultures, we found that MST3 is necessary for proper filopodia, dendritic spine, and excitatory synapse development. Knockdown of MST3 in layer 2/3 pyramidal neurons via in utero electroporation also reduced spine density in vivo. Using chemical genetics, we discovered thirteen candidate MST3 substrates and identified the phosphorylation sites. Among the identified MST3 substrates, TAO kinases regulate dendritic filopodia and spine development, similar to MST3. Furthermore, using stable isotope labeling by amino acids in culture (SILAC), we show that phosphorylated TAO1/2 associates with Myosin Va and is necessary for its dendritic localization, thus revealing a mechanism for excitatory synapse development in the mammalian CNS. PMID:25456499

  5. MST3 kinase phosphorylates TAO1/2 to enable Myosin Va function in promoting spine synapse development.

    PubMed

    Ultanir, Sila K; Yadav, Smita; Hertz, Nicholas T; Oses-Prieto, Juan A; Claxton, Suzanne; Burlingame, Alma L; Shokat, Kevan M; Jan, Lily Y; Jan, Yuh-Nung

    2014-12-03

    Mammalian Sterile 20 (Ste20)-like kinase 3 (MST3) is a ubiquitously expressed kinase capable of enhancing axon outgrowth. Whether and how MST3 kinase signaling might regulate development of dendritic filopodia and spine synapses is unknown. Through shRNA-mediated depletion of MST3 and kinase-dead MST3 expression in developing hippocampal cultures, we found that MST3 is necessary for proper filopodia, dendritic spine, and excitatory synapse development. Knockdown of MST3 in layer 2/3 pyramidal neurons via in utero electroporation also reduced spine density in vivo. Using chemical genetics, we discovered thirteen candidate MST3 substrates and identified the phosphorylation sites. Among the identified MST3 substrates, TAO kinases regulate dendritic filopodia and spine development, similar to MST3. Furthermore, using stable isotope labeling by amino acids in culture (SILAC), we show that phosphorylated TAO1/2 associates with Myosin Va and is necessary for its dendritic localization, thus revealing a mechanism for excitatory synapse development in the mammalian CNS.

  6. Dendritic structural plasticity in the basolateral amygdala after fear conditioning and its extinction in mice.

    PubMed

    Heinrichs, Stephen C; Leite-Morris, Kimberly A; Guy, Marsha D; Goldberg, Lisa R; Young, Angela J; Kaplan, Gary B

    2013-07-01

    Previous research suggests that morphology and arborization of dendritic spines change as a result of fear conditioning in cortical and subcortical brain regions. This study uniquely aims to delineate these structural changes in the basolateral amygdala (BLA) after both fear conditioning and fear extinction. C57BL/6 mice acquired robust conditioned fear responses (70-80% cued freezing behavior) after six pairings with a tone cue associated with footshock in comparison to unshocked controls. During fear acquisition, freezing behavior was significantly affected by both shock exposure and trial number. For fear extinction, mice were exposed to the conditioned stimulus tone in the absence of shock administration and behavioral responses significantly varied by shock treatment. In the retention tests over 3 weeks, the percentage time spent freezing varied with the factor of extinction training. In all treatment groups, alterations in dendritic plasticity were analyzed using Golgi-Cox staining of dendrites in the BLA. Spine density differed between the fear conditioned group and both the fear extinction and control groups on third order dendrites. Spine density was significantly increased in the fear conditioned group compared to the fear extinction group and controls. Similarly in Sholl analyses, fear conditioning significantly increased BLA spine numbers and dendritic intersections while subsequent extinction training reversed these effects. In summary, fear extinction produced enduring behavioral plasticity that is associated with a reversal of alterations in BLA dendritic plasticity produced by fear conditioning. These neuroplasticity findings can inform our understanding of structural mechanisms underlying stress-related pathology can inform treatment research into these disorders.

  7. Dystrophic dendrites in prefrontal cortical pyramidal cells of dopamine D1 and D2 but not D4 receptor knockout mice

    PubMed Central

    Wang, Hui-Dong; Stanwood, Gregg D.; Grandy, David K.; Deutch, Ariel Y.

    2009-01-01

    Recent data indicate that cortical dopamine denervation results in dystrophic changes in the dendrites of pyramidal cells, including decreases in dendritic spine density and length. However, it is not known if the loss of signaling through specific dopamine receptors subserves these dendritic changes. We examined the dendritic structure of layer V pyramidal cells in the prefrontal cortex of D1, D2, and D4 dopamine receptor null mutant mice and their wild-type littermates. Decreased basal dendritic length and spine density were observed in the D1 knockout mice. Similarly, a decrease in basal dendritic spine density was uncovered in the D2 knockout mice relative to wild-type littermates. No changes in any dendritic parameter were observed in the D4 knockout mice. These observations suggest that the dystrophic changes observed in prefrontal cortical pyramidal cell dendrites are due to loss of signaling through D1 and possibly D2 receptors. The current data also suggest that caution should be exercised in the interpretation of behavioral, physiological and biochemical studies of the PFC in dopamine receptor knockout mice. PMID:19747903

  8. Dystrophic dendrites in prefrontal cortical pyramidal cells of dopamine D1 and D2 but not D4 receptor knockout mice.

    PubMed

    Wang, Hui-Dong; Stanwood, Gregg D; Grandy, David K; Deutch, Ariel Y

    2009-12-01

    Recent data indicate that cortical dopamine denervation results in dystrophic changes in the dendrites of pyramidal cells, including decreases in dendritic spine density and length. However, it is not known if the loss of signaling through specific dopamine receptors subserves these dendritic changes. We examined the dendritic structure of layer V pyramidal cells in the prefrontal cortex of D(1), D(2), and D(4) dopamine receptor null mutant mice and their wild-type littermates. Decreased basal dendritic length and spine density were observed in the D(1) knockout mice. Similarly, a decrease in basal dendritic spine density was uncovered in the D(2) knockout mice relative to wild-type littermates. No changes in any dendritic parameter were observed in the D(4) knockout mice. These observations suggest that the dystrophic changes observed in prefrontal cortical pyramidal cell dendrites are due to loss of signaling through D(1) and possibly D(2) receptors. The current data also suggest that caution should be exercised in the interpretation of behavioral, physiological, and biochemical studies of the prefrontal cortex in dopamine receptor knockout mice.

  9. Pin1 and PKMζ Sequentially Control Dendritic Protein Synthesis

    PubMed Central

    Westmark, Pamela R.; Westmark, Cara J.; Wang, SuQing; Levenson, Jonathan; O’Riordan, Kenneth J.; Burger, Corinna; Malter, James S.

    2010-01-01

    Some forms of learning and memory, and their electrophysiologic correlate, long-term potentiation (LTP), require dendritic translation. We demonstrate that Pin1, a peptidyl-prolyl isomerase, is present in dendritic spines and shafts and inhibits protein synthesis induced by glutamatergic signaling. Pin1 suppression increased dendritic translation, possibly through eIF4E binding proteins 1 and 2 (4E-BP1/2) and eukaryotic translation initiation factor 4E (eIF4E). Consistent with increased protein synthesis, hippocampal slices from Pin−/− mice had normal early LTP (E-LTP) but significantly enhanced late LTP (L-LTP) compared to wild-type controls. Protein kinase C ζ (PKCζ) and protein kinase M ζ (PKMζ) were increased in Pin1−/− mouse brain and their activity was required to maintain dendritic translation. PKMζ interacted with and inhibited Pin1 by phosphorylating Ser16. Therefore, glutamate-induced, dendritic protein synthesis is sequentially regulated by Pin1 and PKMζ signaling. PMID:20215645

  10. Dendritic Growth Investigators

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Representatives of NASA materials science experiments supported the NASA exhibit at the Rernselaer Polytechnic Institute's Space Week activities, April 5 through 11, 1999. From left to right are: Angie Jackman, project manager at NASA's Marshall Space Flight Center for dendritic growth experiments; Dr. Martin Glicksman of Rennselaer Polytechnic Instutute, Troy, NY, principal investigator on the Isothermal Dendritic Growth Experiment (IDGE) that flew three times on the Space Shuttle; and Dr. Matthew Koss of College of the Holy Cross in Worcester, MA, a co-investigator on the IDGE and now principal investigator on the Transient Dendritic Solidification Experiment being developed for the International Space Station (ISS). The image at far left is a dendrite grown in Glicksman's IDGE tests aboard the Shuttle. Glicksman is also principal investigator for the Evolution of Local Microstructures: Spatial Instabilities of Coarsening Clusters.

  11. De novo spine surgery as a predictor of additional spine surgery at the same or distant spine regions

    PubMed Central

    Walid, M. Sami; Robinson, Joe Sam; Abbara, Moataz; Tolaymat, Abdullah; Robinson, Joe Sam

    2011-01-01

    Introduction: Degenerative spine disorders are steadily increasing parallel to the aging of the population with considerable impact on cost and productivity. In this paper we study the prevalence and risk factors for multiple spine surgery and its impact on cost. Methods: Data on 1,153 spine surgery inpatients operated between October 2005 and September 2008 (index spine surgery) in regard to the number of previous spine surgeries and location of surgeries (cervical or lumbar) were retrospectively collected. Additionally, prospective follow-up over a period of 2-5 years was conducted. Results: Retrospectively, 365 (31.7%) patients were recurrent spine surgery patients while 788 (68.3%) were de novo spine surgery patients. Nearly half of those with previous spine surgery (51.5%) were on different regions of the spine. There were no significant differences in length of stay or hospital charges except in lumbar decompression and fusion (LDF) patients with multiple interventions on the same region of the spine. Significant differences (P<.05) in length of stay (5.4 days vs. 7.4 days) and hospital charges ($55,477 vs. $74,878) between LDF patients with one previous spine versus those with ≥3 previous spine surgeries on the same region were noted. Prospectively, the overall reoperation rate was 10.4%. The risk of additional spine surgery increased from 8.0% in patients with one previous spine surgery (index surgery) to 25.6% in patients with ≥4 previous spine surgeries on different regions of the spine (including index surgery). After excluding patients with previous spine surgeries on different regions of the spine, 17.2% of reoperated patients had additional spine surgery on a different spine region. The percentage of additional spine surgery on a distant spine region increased from 14.0% in patients with one spine surgery to 33.0% in patients with two spine surgeries on the same region. However, in patients with three or more spine surgeries on the same spine

  12. Lumbosacral spine x-ray

    MedlinePlus

    X-ray - lumbosacral spine; X-ray - lower spine ... The test is done in a hospital x-ray department or your health care provider's office by an x-ray technician. You will be asked to lie on the x-ray table ...

  13. Autocrine action of BDNF on dendrite development of adult-born hippocampal neurons.

    PubMed

    Wang, Liang; Chang, Xingya; She, Liang; Xu, Duo; Huang, Wei; Poo, Mu-ming

    2015-06-03

    Dendrite development of newborn granule cells (GCs) in the dentate gyrus of adult hippocampus is critical for their incorporation into existing hippocampal circuits, but the cellular mechanisms regulating their dendrite development remains largely unclear. In this study, we examined the function of brain-derived neurotrophic factor (BDNF), which is expressed in adult-born GCs, in regulating their dendrite morphogenesis. Using retrovirus-mediated gene transfection, we found that deletion and overexpression of BDNF in adult-born GCs resulted in the reduction and elevation of dendrite growth, respectively. This effect was mainly due to the autocrine rather than paracrine action of BDNF, because deletion of BDNF only in the newborn GCs resulted in dendrite abnormality of these neurons to a similar extent as that observed in conditional knockout (cKO) mice with BDNF deleted in the entire forebrain. Furthermore, selective expression of BDNF in adult-born GCs in BDNF cKO mice fully restored normal dendrite development. The BDNF autocrine action was also required for the development of normal density of spines and normal percentage of spines containing the postsynaptic marker PSD-95, suggesting autocrine BDNF regulation of synaptogenesis. Furthermore, increased dendrite growth of adult-born GCs caused by voluntary exercise was abolished by BDNF deletion specifically in these neurons and elevated dendrite growth due to BDNF overexpression in these neurons was prevented by reducing neuronal activity with coexpression of inward rectifier potassium channels, consistent with activity-dependent autocrine BDNF secretion. Therefore, BDNF expressed in adult-born GCs plays a critical role in dendrite development by acting as an autocrine factor.

  14. Altered daylength affects dendritic structure in a song-related brain region in red-winged blackbirds.

    PubMed

    Hill, K M; DeVoogd, T J

    1991-11-01

    Substantial neural and behavioral plasticity occurs in the avian song system in adulthood. Changes in the volume of one of the song control nuclei, robustus archistriatalis (RA), have been associated with seasonal changes in singing behavior in adult canaries (Serinus canarius) and red-winged blackbirds (Agelaius phoeniceus). The present work assessed the effects of changed daylength on dendritic morphology in RA in adult male red-winged blackbirds. Brains from hand-reared red-winged blackbirds maintained on long days or long days followed by short days were stained with a Golgi-Cox procedure. Dendritic morphology and spine density of type IV neurons from nucleus RA were compared between long and short day birds. Neurons from short day birds have smaller dendritic fields than neurons from long day birds, with the difference greatest for distal dendrites. In addition, the density of dendritic spines is significantly smaller for neurons from short day birds. Together, these changes result in the loss of approximately 40% of the spines on this neuron class. In previous work in adult female canaries, external testosterone administration has been shown to be associated with increases in dendritic field size and synapse number. The similarity of the neuronal changes in RA that are associated with the two sorts of manipulations suggest that some consequences of altered daylength are mediated by changes in the levels of gonadal steroids.

  15. Anatomical and morphological spine variation in Gymnocalycium kieslingii subsp. castaneum (Cactaceae)

    PubMed Central

    Gebauer, Roman; Řepka, Radomír; Šmudla, Radek; Mamoňová, Miroslava; Ďurkovič, Jaroslav

    2016-01-01

    Abstract Although spine variation within cacti species or populations is assumed to be large, the minimum sample size of different spine anatomical and morphological traits required for species description is less studied. There are studies where only 2 spines were used for taxonomical comparison amnog species. Therefore, the spine structure variation within areoles and individuals of one population of Gymnocalycium kieslingii subsp. castaneum (Ferrari) Slaba was analyzed. Fifteen plants were selected and from each plant one areole from the basal, middle and upper part of the plant body was sampled. A scanning electron microscopy was used for spine surface description and a light microscopy for measurements of spine width, thickness, cross-section area, fiber diameter and fiber cell wall thickness. The spine surface was more visible and damaged less in the upper part of the plant body than in the basal part. Large spine and fiber differences were found between upper and lower parts of the plant body, but also within single areoles. In general, the examined traits in the upper part had by 8–17% higher values than in the lower parts. The variation of spine and fiber traits within areoles was lower than the differences between individuals. The minimum sample size was largely influenced by the studied spine and fiber traits, ranging from 1 to 70 spines. The results provide pioneer information useful in spine sample collection in the field for taxonomical, biomechanical and structural studies. Nevertheless, similar studies should be carried out for other cacti species to make generalizations. The large spine and fiber variati