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The Emerging Role of Exosome Nanoparticles in Regenerative Medicine
Published in Harishkumar Madhyastha, Durgesh Nandini Chauhan, Nanopharmaceuticals in Regenerative Medicine, 2022
Zahra Sadat Hashemi, Mahlegha Ghavami, Saeed Khalili, Seyed Morteza Naghib
One of the popular super resolution fluorescence microscopy techniques is known as the stimulated emission depletion (STED) microscopy. It is developed to avoid the diffraction limit of light microscopy and create images by selectively deactivating fluorophores using stimulated emission. The distribution of fluorescently labelled antigens present at the surface of EVs and the size of EVs could be measured by STED (Tønnesen et al. 2011). Some studies have reported STED resolution limit as 50 nm (even 10 nm) (Hein et al. 2008). The STED microscopy images managed to show the size of synaptic vesicles. The synaptic vesicle contains neurotransmitters and is approximately 40 nm in diameter (Willig et al. 2006).
Proinflammatory Peptides in Sensory Nerves of the Airways
Published in Sami I. Said, Proinflammatory and Antiinflammatory Peptides, 2020
Peter Baluk, Donald M. McDonald
The airways are innervated by three sets of anatomically distinct pathways of sympathetic, parasympathetic, and sensory nerves. All three pathways contain neuropeptides, sometimes coexisting with nonpeptide transmitters, such as acetylcholine, norepinephrine, and nitric oxide. The postganglionic cell bodies of the sympathetic nerves are located in the superior cervical and stellate ganglia, whereas the post-ganglionic cell bodies of the parasympathetic nerves are located in small, local intrinsic ganglia embedded in the walls of the airways (10). Nerve degeneration studies and retrograde tracing studies show that the cell bodies of the tracheal sensory nerves are located in the jugular and nodose ganglion, while the upper thoracic dorsal root ganglia also contribute sensory fibers to the lungs (11–14). It has also been suggested recently that local interneurons or sensory neurons may exist within the intrinsic airway ganglia (15), similar to the intrinsic sensory neurons in enteric ganglia (16). Most sensory nerve fibers in the airways are long, branching, unmyelinated fibers with many varicosities or beads approximately 1–2 μm in diameter, connected by thinner intervaricose portions approximately 0.1–0.5 μm in diameter, thus making the entire nerve fiber within the resolution of the light microscope. Synaptic vesicles within the varicosities contain various transmitters. Some sensory nerve fibers, including those for stretch receptors, are myelinated (17).
Homeostasis of Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
Synaptic vesicles are formed by budding from the endosome or from the presynaptic membrane after their disengagement. Empty vesicles take up DA by a VMAT-mediated active transport into their lumen, utilizing the electrochemical gradient established by the proton pump. Loaded vesicles are translocated by a calcium-mediated process to specialized sites in the presynaptic terminal, termed the “active zones.” Within the active zone, the loaded vesicles are docked and partially fuse with the presynaptic membrane by a complex of SNARE proteins, as described in detail in the subsequent section. In response to action potentials, a calcium influx through voltage-gated channels completes the fusion process, initiates pore opening, and enables the release of the vesicular content into the synaptic cleft.
Efficient simulations of stretch growth axon based on improved HH model
Published in Neurological Research, 2023
Xiao Li, Xianxin Dong, Xikai Tu, Hailong Huang
Neuronal cell is composed of three components: a cell body, an axon, and a dendrite. These components are responsible for receiving, integrating, and delivering information. In general, neurons receive and integrate information from other neurons via their dendrites and cell bodies, and then transfer it to other neurons via their axons. Nerve fibers have great excitability and conductivity, and their primary role is to transmit information between neurons. When a sufficient stimulus excites a nerve fiber, it immediately generates a propagable action potential. Chemical synapses allow action potentials to be passed from one neuron to the next by transporting neurotransmitters through synaptic vesicles. The action potential-induced shift in membrane potential causes the calcium channel on the synaptic terminal membrane to open, allowing a substantial number of calcium ions to flow into the membrane, resulting in an abrupt increase in calcium ions in the synaptic membrane. When synaptic vesicles detect an increase in the number of calcium ions in the surrounding environment, they fuse with the presynaptic membrane and spit neurotransmitters into the synaptic gap. After binding to a protein receptor on the postsynaptic membrane, the neurotransmitter causes excitement or inhibition.
Homocysteine can aggravate depressive like behaviors in a middle cerebral artery occlusion/reperfusion rat model: a possible role for NMDARs-mediated synaptic alterations
Published in Nutritional Neuroscience, 2023
Mengying Wang, Xiaoshan Liang, Qiang Zhang, Suhui Luo, Huan Liu, Xuan Wang, Na Sai, Xumei Zhang
VGLUT1 is a specific presynaptic protein that uploads glutamate in the synaptic vesicle before its release, and thus is one of the synaptic plasticity markers linked to glutamate neurotransmission. Complexins and SNAP-25, as the key players of the synaptic-vesicle fusion machinery, participate in glutamate transmission [44, 45]. These synaptic vesicle-associated proteins, which are required for vesicle fusion and neurotransmitter release, have been identified as possible factors involved in the pathophysiology of psychiatric disorders including depression. At present, many studies have found the changes in synaptic protein expression in neurological diseases including cerebral ischemia, Alzheimer's disease and memory dysfunction. For instance, in an animal model of electroconvulsive therapy, the mRNA levels of 6 synaptic-vesicle proteins were significantly regulated in the hippocampus [46]. Similarly, Kamat et al. [43] found that several synaptic vesicle-associated proteins including synaptophysin and SNAP-25 decreased in HCY-injected mice brain and further impaired the function of memory. Here, VGLUT1, Complexins and SNAP-25 were significantly reduced in HCY-treated MCAO rats and depression-like behavior occurred. This suggests that abnormalities in synaptic function may lead to the progression of depression in HCY-treated MCAO rats.
The neurosciences at the Max Planck Institute for Biophysical Chemistry in Göttingen
Published in Journal of the History of the Neurosciences, 2023
From 1959, Victor Whittaker carried out important and ground-breaking work on the function of the synaptic vesicles and on the role of acetylcholine as a neurotransmitter (Zimmermann and Fonnum 2016). Two technical innovations made this success possible: the availability of adequate centrifuges and introduction of electron microscopy (Zimmermann 2018). Whittaker managed to fractionate the brain tissue of mammals and to enrich different elements through centrifugation (Whittaker 1959). One of these fractions contained large quantities of organelles filled with synaptic vesicles. Under the electron microscope, it was shown that these were pinched off nerve terminals, and Whittaker named them synaptosomes (Gray and Whittaker 1962). The team was able to enrich vesicles from synaptosomes and to find that the neurotransmitter acetylcholine is stored in the vesicles.