Search results for "spines"
showing 10 items of 28 documents
The morphology, ontogeny, and inferred behaviour of the deep-sea echinoid Calymne relicta (Holasteroida).
2009
The deep-sea holasteroid Calymne relicta was first described from a few fragments discovered by the HMS ‘Challenger’ in the Bermuda abyssal plain more than a century ago. In addition to re-examining the type material, we describe herein new specimens from unpublished material collected between 3720 and 4860 m during three scientific expeditions that took place on both sides of the North Atlantic between 1966 and 1991. The new material includes juvenile and adult specimens in sufficiently good preservational state to allow a full redescription, including all types of appendages, some of which have never been described. These new observations confirm the atypical characteristics of C. relicta…
Effects of Chronic Dopamine D2R Agonist Treatment and Polysialic Acid Depletion on Dendritic Spine Density and Excitatory Neurotransmission in the mP…
2016
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 n…
Chronic benzodiazepine treatment decreases spine density in cortical pyramidal neurons.
2015
The adult brain retains a substantial capacity for synaptic reorganization, which includes a wide range of modifications from molecular to structural plasticity. Previous reports have demonstrated that the structural remodeling of excitatory neurons seems to occur in parallel to changes in GABAergic neurotransmission. The function of neuronal inhibitory networks can be modified through GABAA receptors, which have a binding site for benzodiazepines (BZ). Although BZs are among the most prescribed drugs, is not known whether they modify the structure and connectivity of pyramidal neurons. In the present study we wish to elucidate the impact of a chronic treatment of 21 days with diazepam (2mg…
The activation of NMDA receptors alters the structural dynamics of the spines of hippocampal interneurons
2017
N-Methyl-d-Aspartate receptors (NMDARs) are present in both pyramidal neurons and interneurons of the hippocampus. These receptors play a key role in the structural plasticity of excitatory neurons, but to date little is known about their influence on the remodeling of interneurons. Among hippocampal interneurons, the somatostatin expressing cells in the CA1 stratum oriens are of special interest because of their functional importance and structural characteristics: they display dendritic spines, which change their density in response to different stimuli. In order to understand the role of NMDAR activation on the structural dynamics of the spines of somatostatin expressing interneurons in …
Regulation of Dendritic Spine Morphology in Hippocampal Neurons by Copine-6.
2015
Dendritic spines compartmentalize information in the brain, and their morphological characteristics are thought to underly synaptic plasticity. Here we identify copine-6 as a novel modulator of dendritic spine morphology. We found that brain-derived neurotrophic factor (BDNF) - a molecule essential for long-term potentiation of synaptic strength - upregulated and recruited copine-6 to dendritic spines in hippocampal neurons. Overexpression of copine-6 increased mushroom spine number and decreased filopodia number, while copine-6 knockdown had the opposite effect and dramatically increased the number of filopodia, which lacked PSD95. Functionally, manipulation of post-synaptic copine-6 level…
NEGR1 and FGFR2 cooperatively regulate cortical development and core behaviours related to autism disorders in mice.
2018
See Contreras and Hippenmeyer (doi:10.1093/brain/awy218) for a scientific commentary on this article. Autism spectrum disorders (ASDs) are complex conditions with diverse aetiologies. Szczurkowska et al. demonstrate that two ASD-related molecules – FGFR2 and Negr1 – physically interact to act on the same downstream pathway, and regulate cortical development and ASD-relevant behaviours in mice. Identifying common mechanisms in ASDs may reveal targets for pharmacological intervention.
Reduced interneuronal dendritic arborization in CA1 but not in CA3 region of mice subjected to chronic mild stress
2016
Abstract Introduction Chronic stress induces dendritic atrophy and decreases spine density in excitatory hippocampal neurons, although there is also ample evidence indicating that the GABAergic system is altered in the hippocampus after this aversive experience. Chronic stress causes dendritic remodeling both in excitatory neurons and interneurons in the medial prefrontal cortex and the amygdala. Methods In order to know whether it also has an impact on the structure and neurotransmission of hippocampal interneurons, we have analyzed the dendritic arborization, spine density, and the expression of markers of inhibitory synapses and plasticity in the hippocampus of mice submitted to 21 days …
Functional hypoxia drives neuroplasticity and neurogenesis via brain erythropoietin.
2020
Erythropoietin (EPO), named after its role in hematopoiesis, is also expressed in mammalian brain. In clinical settings, recombinant EPO treatment has revealed a remarkable improvement of cognition, but underlying mechanisms have remained obscure. Here, we show with a novel line of reporter mice that cognitive challenge induces local/endogenous hypoxia in hippocampal pyramidal neurons, hence enhancing expression of EPO and EPO receptor (EPOR). High-dose EPO administration, amplifying auto/paracrine EPO/EPOR signaling, prompts the emergence of new CA1 neurons and enhanced dendritic spine densities. Single-cell sequencing reveals rapid increase in newly differentiating neurons. Importantly, i…
The TrkB agonist 7,8-dihydroxyflavone changes the structural dynamics of neocortical pyramidal neurons and improves object recognition in mice
2018
This is a pre-print of an article published in Brain Structure and Function. The final authenticated version is available online at: https://doi.org/10.1007/s00429-018-1637-x. BDNF and its receptor TrkB have important roles in neurodevelopment, neural plasticity, learning, and memory. Alterations in TrkB expression have been described in different CNS disorders. Therefore, drugs interacting with TrkB, specially agonists, are promising therapeutic tools. Among them, the recently described 7,8-dihydroxyflavone (DHF), an orally bioactive compound, has been successfully tested in animal models of these diseases. Recent studies have shown the influence of this drug on the structure of pyramidal …
Modulating Neuronal Competition Dynamics in the Dentate Gyrus to Rejuvenate Aging Memory Circuits.
2015
The neural circuit mechanisms underlying the integration and functions of adult-born dentate granule cell (DGCs) are poorly understood. Adult-born DGCs are thought to compete with mature DGCs for inputs to integrate. Transient genetic overexpression of a negative regulator of dendritic spines, Kruppel-like factor 9 (Klf9), in mature DGCs enhanced integration of adult-born DGCs and increased NSC activation. Reversal of Klf9 overexpression in mature DGCs restored spines and activity and reset neuronal competition dynamics and NSC activation, leaving the DG modified by a functionally integrated, expanded cohort of age-matched adult-born DGCs. Spine elimination by inducible deletion of Rac1 in …