Search results for "Sialic acid"
showing 10 items of 91 documents
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…
Polysialic Acid Acute Depletion Induces Structural Plasticity in Interneurons and Impairs the Excitation/Inhibition Balance in Medial Prefrontal Cort…
2016
The structure and function of the medial prefrontal cortex (mPFC) is affected in several neuropsychiatric disorders, including schizophrenia and major depression. Recent studies suggest that imbalances between excitatory and inhibitory activity (E/I) may be responsible for this cortical dysfunction and, therefore, may underlie the core symptoms of these diseases. This E/I imbalance seems to be correlated with alterations in the plasticity of interneurons but there is still scarce information on the mechanisms that may link these phenomena. The polysialylated form of the neural cell adhesion molecule (PSA-NCAM) is a good candidate, because it modulates the neuronal plasticity of interneurons…
Polysialic acid chains exhibit enhanced affinity for ordered regions of membranes.
2018
Polysialic acid (polySia) forms linear chains which are usually attached to the external surface of the plasma membrane mainly through the Neural Cell Adhesion Molecule (NCAM) protein. It is exposed on neural cells, several types of cancer cells, dendritic cells, and egg and sperm cells. There are several lipid raft-related phenomena in which polySia is involved; however the mechanisms of polySia action as well as determinants of its localization in lipid raft microdomains are still unknown, although the majority of NCAM molecules in the liquid-ordered raft membrane fractions of neural cells appear to be polysialylated. Here we investigate the affinity of polySia (both soluble and NCAM-depe…
Substantial deficiency of free sialic acid in muscles of patients with GNE myopathy and in a mouse model
2017
GNE myopathy (GNEM), also known as hereditary inclusion body myopathy (HIBM), is a late- onset, progressive myopathy caused by mutations in the GNE gene encoding the enzyme responsible for the first regulated step in the biosynthesis of sialic acid (SA). The disease is characterized by distal muscle weakness in both the lower and upper extremities, with the quadriceps muscle relatively spared until the late stages of disease. To explore the role of SA synthesis in the disease, we conducted a comprehensive and systematic analysis of both free and total SA levels in a large cohort of GNEM patients and a mouse model. A sensitive LC/MS/MS assay was developed to quantify SA in serum and muscle h…
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 …
Effects of the Genetic Depletion of Polysialyltransferases on the Structure and Connectivity of Interneurons in the Adult Prefrontal Cortex
2019
Polysialic acid (polySia) is a complex sugar that in the nervous system appears mainly as a posttranslational modification of the neural cell adhesion molecule (NCAM). PolySia plays important roles during brain development, but also in its plasticity during adulthood. Two polysialyltransferases (polyST), ST8SIA2 and ST8SIA4, are involved in the synthesis and attachment of polySia. Both polyST are relevant for developmental migration of cortical interneurons and their establishment in the prefrontal cortex (PFC). In contrast, only ST8SIA4 appears to be important for the structural plasticity of a subpopulation of cortical interneurons in the adult. Interestingly, ST8SIA2 and NCAM are candida…
Anatomy, immunohistochemistry, and numerical distribution of human splenic microvessels.
2019
Abstract The microvascular architecture of the spleen plays an important role in the immunological function of this organ. The different types of vessels are related to different reticular cells each with their own immunomodulatory functions. The present study describes an immunohistochemical and morphometric analysis of the various types of vessels in 21 human autopsy non-pathological splenic samples. On an area of 785,656.37 μm2 for each sample, we classified and quantified the type and number of vascular structures, each according to their morphology and immunohistochemical profile, and obtained the ratios between them. The distribution of trabecular vessels and the characteristics of th…
Brain Control of Plasma Cholesterol Involves Polysialic Acid Molecules in the Hypothalamus
2017
IF 3.566; International audience; The polysialic acid (PSA) is a large glycan that is added to cell-surface proteins during their post-translational maturation. In the brain, PSA modulates distances between cells and controls the plasticity of the nervous system. In the hypothalamus, PSA is involved in many aspects of energy balance including food intake, osmoregulation, circadian rhythm, and sleep. In this work, we investigated the role of hypothalamic PSA in the regulation of plasma cholesterol levels and distribution. We report that HFD consumption in mice rapidly increased plasma cholesterol, including VLDL, LDL, and HDL-cholesterol. Although plasma VLDL-cholesterol was normalized withi…
Effects of PSA Removal from NCAM on the Critical Period Plasticity Triggered by the Antidepressant Fluoxetine in the Visual Cortex.
2016
Neuronal plasticity peaks during critical periods of postnatal development and is reduced towards adulthood. Recent data suggests that windows of juvenile-like plasticity can be triggered in the adult brain by antidepressant drugs such as Fluoxetine. Although the exact mechanisms of how Fluoxetine promotes such plasticity remains unknown, several studies indicate that inhibitory circuits play an important role. The polysialylated form of the neural cell adhesion molecules (PSA-NCAM) has been suggested to mediate the effects of Fluoxetine and it is expressed in the adult brain by mature interneurons. Moreover, the enzymatic removal of PSA by neuroaminidase-N not only affects the structure of…
Glycoprotein and ganglioside changes in human trophoblasts after exposure to pulsed doppler ultrasound
1995
Changes in glycoprotein and ganglioside composition in human trophoblasts (eighth week of gestation) after in vitro exposure to pulsed Doppler ultrasound (pulse duration 1.22 microseconds; repetition frequency 11.1 kHz; center frequency 4 MHz; ISPPA = 175.5 W/cm2; ISPTA = 0.59 W/cm2) were investigated. Evacuated trophoblasts were divided in two halves and insonated for 10 min on top of a 6-cm layer of 5% gelatin in 50-mL tubes (Falcon) at 37 degrees C. One half of each trophoblast was sham insonated and served as an internal control. After insonation trophoblasts were maintained at 37 degrees C for 24 h. Glycoproteins were detected using alpha-D-mannose specific lectins from Galanthus nival…