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Neurotrophins are a family of trophic factors that has been established as pivotal players in the regulation of neuronal survival and differentiation throughout development and adulthood. The prototypic neurotrophin, nerve-growth ...
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Neurotrophins are a family of trophic factors that has been established as pivotal players in the regulation of neuronal survival and differentiation throughout development and adulthood. The prototypic neurotrophin, nerve-growth factor (NGF), was isolated and purified more than 50 years ago as a target-derived trophic factor for developing neurons. Since then, not only were more members added to the family, but as our understanding of the neurotrophins advances, it became clear that the neurotrophins are involved in almost all aspects of neuronal development. Here we will summarize the critical roles of neurotrophins in the regulation of neuronal survival and apoptosis.
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We report here studies on isolated neurons from the mollusk Lymnaea stagnalis using enucleation of neurons to prepare cytoplasts, which were then fused with other neurons to obtain hybrids. These experiments showed that isolated n...
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We report here studies on isolated neurons from the mollusk Lymnaea stagnalis using enucleation of neurons to prepare cytoplasts, which were then fused with other neurons to obtain hybrids. These experiments showed that isolated neurons were able to fuse with each other to form binucleate cells and that they could be enucleated to form cyto- and karyoplasts which were able to form complex fusion products: cell body/cytoplast, cytoplast/karyoplast, etc. All incontrovertible indications of fusion as described for nerve cell body fusion were observed. These studies demonstrated the possibility of artificial fusion of amputated fragments of neuroplasm with neuron bodies, i.e., the metabolic centers of other cells. In theory, this means that in vivo amputated neuron processes can also be fused with new cells.
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Energetic status often affects reproductive function, glucose homeostasis, and feeding in mammals. Malnutrition suppresses pulsatile release of the gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) and increases gluco...
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Energetic status often affects reproductive function, glucose homeostasis, and feeding in mammals. Malnutrition suppresses pulsatile release of the gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) and increases gluconeogenesis and feeding. The present study aims to examine whether beta-endorphin-mu-opioid receptor (MOR) signaling mediates the suppression of pulsatile GnRH/LH release and an increase in gluconeogenesis/feeding induced by malnutrition. Ovariectomized female rats treated with a negative feedback level of estradiol-17 beta (OVX + low E-2) receiving 2-deoxy-D-glucose (2DG), an inhibitor of glucose utilization, intravenously (iv) were used as a malnutrition model. An administration of D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH 2 (CTOP), a selective MOR antagonist, into the third ventricle blocked the suppression of the LH pulse and increase in gluconeogenesis/feeding induced by iv 2DG administration. Histological analysis revealed that arcuate Kiss1 (kisspeptin gene)-expressing cells and preoptic Gnrh1 (GnRH gene)-expressing cells co-expressed little Oprm1 (MOR gene), while around 10% of arcuate Slc17a6 (glutamatergic marker gene)-expressing cells co-expressed Oprm1. Further, the CTOP treatment decreased the number of fos-positive cells in the paraventricular nucleus (PVN) in OVX + low E-2 rats treated with iv 2DG but failed to affect the number of arcuate fos-expressing Slc17a6-positive cells. Taken together, these results suggest that the central beta-endorphin-MOR signaling mediates the suppression of pulsatile LH release and that the beta-endorphin may indirectly suppress the arcuate kisspeptin neurons, a master regulator for GnRH/LH pulses during malnutrition. Furthermore, the current study suggests that central beta-endorphin-MOR signaling is also involved in gluconeogenesis and an increase in food intake by directly or indirectly acting on the PVN neurons during malnutrition in female rats.
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Abstract The study of neuron morphology requires robust and comprehensive methods to quantify the differences between neurons of different subtypes and animal species. Several software packages have been developed for the analysis...
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Abstract The study of neuron morphology requires robust and comprehensive methods to quantify the differences between neurons of different subtypes and animal species. Several software packages have been developed for the analysis of neuron tracing results stored in the standard SWC format. The packages, however, provide relatively simple quantifications and their non-extendable architecture prohibit their use for advanced data analysis and visualization. We developed nGauge, a Python toolkit to support the parsing and analysis of neuron morphology data. As an application programming interface (API), nGauge can be referenced by other popular open-source software to create custom informatics analysis pipelines and advanced visualizations. nGauge defines an extendable data structure that handles volumetric constructions (e.g. soma), in addition to the SWC linear reconstructions, while remaining lightweight. This greatly extends nGauge’s data compatibility.
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The aim of this research work is to investigate the synchronization and desynchronization of an array of non-identical Izhikevich neurons in a star-like configuration. Both regular spiking neurons and fast spiking neurons are cons...
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The aim of this research work is to investigate the synchronization and desynchronization of an array of non-identical Izhikevich neurons in a star-like configuration. Both regular spiking neurons and fast spiking neurons are considered in the analysis. The equilibrium points and their stability for a single neuron are determined, and an adaptive stable filter is applied to suppress the spiking of the neuron. A star coupling array configuration is applied to synchronize an array of isolated neurons. Next, the adaptive stable filter is employed to suppress the spiking of the synchronized array of coupled neurons. Appreciably, one filter is enough to suppress the entire star-like array. Numerical simulations demonstrate the success of the proposed technique. The parameters that govern the performance of the filter are specified, the limitations of the methodology are identified, and the required conditions for application are identified.
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First-order somatosensory neurons transduce and convey information about the external or internal environment of the body to the central nervous system. They are pseudo unipolar neurons with cell bodies residing in one of several ...
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First-order somatosensory neurons transduce and convey information about the external or internal environment of the body to the central nervous system. They are pseudo unipolar neurons with cell bodies residing in one of several ganglia located near the central nervous system, with the short branch of the axon connecting to the spinal cord or the brain stem and the long branch extending towards the peripheral organ they innervate. Besides their sensory transducer and conductive role, somatosensory neurons also have trophic functions in the tissue they innervate and participate in local reflexes in the periphery. The cell bodies of these neurons are remarkably diverse in terms of size, molecular constitution,and electrophysiological properties. These parameters have provided criteria for classification that have proved useful to establish and study their functions. In this review, we discuss ways to measure and classify populations of neurons based on their size and action potential firing pattern. We also discuss attempts to relate the different populations to specific sensory modalities.
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The cerebral neocortex is segregated into six horizontal layers, each containing unique populations of molecularly and functionally distinct excitatory projection (pyramidal) neurons and inhibitory interneurons. Development of the...
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The cerebral neocortex is segregated into six horizontal layers, each containing unique populations of molecularly and functionally distinct excitatory projection (pyramidal) neurons and inhibitory interneurons. Development of the neocortex requires the orchestrated execution of a series of crucial processes, including the migration of young neurons into appropriate positions within the nascent neocortex, and the acquisition of layer-specific neuronal identities and axonal projections. Here, we discuss emerging evidence supporting the notion that the migration and final laminar positioning of cortical neurons are also co-regulated by cell type-and layerspecific transcription factors that play concomitant roles in determining the molecular identity and axonal connectivity of these neurons. These transcriptional programs thus provide direct links between the mechanisms controlling the laminar position and identity of cortical neurons.
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This paper addresses the problem of obtaining new neuron features capable of improving results of neuron classification. Most studies on neuron classification using morphological features have been based on Euclidean geometry. Her...
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This paper addresses the problem of obtaining new neuron features capable of improving results of neuron classification. Most studies on neuron classification using morphological features have been based on Euclidean geometry. Here three one-dimensional (1D) time series are derived from the three-dimensional (3D) structure of neuron instead, and afterwards a spatial time series is finally constructed from which the features are calculated. Digitally reconstructed neurons were separated into control and pathological sets, which are related to three categories of alterations caused by epilepsy, Alzheimer's disease (long and local projections), and ischemia. These neuron sets were then subjected to supervised classification and the results were compared considering three sets of features: morphological, features obtained from the time series and a combination of both. The best results were obtained using features from the time series, which outperformed the classification using only morphological features, showing higher correct classification rates with differences of 5.15, 3.75, 5.33% for epilepsy and Alzheimer's disease (long and local projections) respectively. The morphological features were better for the ischemia set with a difference of 3.05%. Features like variance, Spearman auto-correlation, partial auto-correlation, mutual information, local minima and maxima, all related to the time series, exhibited the best performance. Also we compared different evaluators, among which ReliefF was the best ranked.
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Graphene unique physicochemical properties made it prominent among other allotropic forms of carbon, in many areas of research and technological applications. Interestingly, in recent years, many studies exploited the use of graph...
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Graphene unique physicochemical properties made it prominent among other allotropic forms of carbon, in many areas of research and technological applications. Interestingly, in recent years, many studies exploited the use of graphene family nanomaterials (GNMs) for biomedical applications such as drug delivery, diagnostics, bioimaging, and tissue engineering research. GNMs are successfully used for the design of scaffolds for controlled induction of cell differentiation and tissue regeneration. Critically, it is important to identify the more appropriate nano/bio material interface sustaining cells differentiation and tissue regeneration enhancement. Specifically, this review is focussed on graphene-based scaffolds that endow physiochemical and biological properties suitable for a specific tissue, the nervous system, that links tightly morphological and electrical properties. Different strategies are reviewed to exploit GNMs for neuronal engineering and regeneration, material toxicity, and biocompatibility. Specifically, the potentiality for neuronal stem cells differentiation and subsequent neuronal network growth as well as the impact of electrical stimulation through GNM on cells is presented. The use of field effect transistor (FET) based on graphene for neuronal regeneration is described. This review concludes the important aspects to be controlled to make graphene a promising candidate for further advanced application in neuronal tissue engineering and biomedical use.
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Human sPLA(2)-III [group III secreted PLA(2) (phospholipase A(2))] is an atypical sPLA, isoenzyme that consists of a central group III sPLA(2) domain flanked by unique N- and C-terminal domains. In the present study, we found that...
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Human sPLA(2)-III [group III secreted PLA(2) (phospholipase A(2))] is an atypical sPLA, isoenzyme that consists of a central group III sPLA(2) domain flanked by unique N- and C-terminal domains. In the present study, we found that sPLA(2)-III is expressed in neuronal cells, such as peripheral neuronal fibres, spinal DRG (dorsal root ganglia) neurons and cerebellar Purkinje cells. Adenoviral expression of sPLA(2)-III in PC12 cells (pheochromocytoma cells) or DRG explants facilitated neurite outgrowth, whereas expression of a catalytically inactive sPLA(2)-III mutant or use of sPLA(2)-III-directed siRNA (small interfering RNA) reduced NGF (nerve growth factor)-induced neuritogenesis. sPLA(2)-III also suppressed neuronal death induced by NGF deprivation. Lipid MS revealed that sPLA(2)-III overexpression increased the cellular level of lysophosphatidylcholine, a PLA(2) reaction product with neuritogenic and neurotropic activities, whereas siRNA knockdown reduced the level of lysophosphatidylcholine. These observations suggest the potential contribution of sPLA(2)-III to neuronal differentiation and its function under certain conditions.
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