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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
Secretory vesicles of neuroendocrine cells (exemplified by adrenal medullary chromaffin granules) differ from synaptic vesicles of the CNS in size, morphology, content, biogenesis, and speed of release [57]. Secretory vesicles are larger; have a diameter of 270 nm; contain biogenic amines, ions, peptides, and proteins; are derived from the Golgi apparatus; and are retrieved after exocytosis, but they do not directly recycle. The condensed proteins within the secretory vesicles are visualized in electron micrographs as a solid core and have, therefore, been identified as dense core secretory granules or vesicles. On the other hand, synaptic vesicles are much smaller, have a diameter of 40–60 nm, contain only neurotransmitters, and appear as clear vesicles in electron micrographs. Synaptic vesicles are derived from the endosome, the major sorting compartment within the cell. Synaptic vesicles also release their content very rapidly, and they completely recycle by endocytosis after emptying. Given that synaptic vesicles are not formed at the Golgi complex, they do not contain newly synthesized proteins. Instead, they take up the neurotransmitters from the cytoplasm, using the VMAT intracellular transporters.
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.
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.
Datumetine exposure alters hippocampal neurotransmitters system in C57BL/6 mice
Published in Drug and Chemical Toxicology, 2022
Azeez Olakunle Ishola, Aminu Imam, Moyosore Salihu Ajao
Electron microscopy studies on the synapse revealed that datumetine exposed animals showed a reduction in the number of viable synapses with 1.0 mg/kg Datumetine animals showing the greatest reduction compared to controls. It is on record that overactivation of NMDAR leads to synaptic loss (Talantova et al.2013, Zhou et al.2013, Lewerenz and Maher 2015). This observation may be due to the persistent interaction of datumetine with NMDAR (Ishola et al.2020). The postsynaptic density was thicker in datumetine exposed animals with a great reduction in presynaptic vesicles. Chemical neurotransmission is through the release of synaptic vesicles (Trkanjec and Demarin 2001, Ikeda and Bekkers 2009) which are tightly regulated by re-uptake back to the presynaptic neurons (Piedras-Renteria et al.2004, Dickman et al.2012, Davis and Muller 2015). Datumetine greatly reducing the number of synaptic vesicles showed that either reuptake of the vesicles is altered, or rate of production is not balanced with the rate of release (Wang et al.2016, Li and Kavalali 2017). Another possible explanation may be that NMDAR binding with datumetine increases the affinity of presynaptic NMDAR for glutamate thereby increasing the release of neurotransmitters (Reimer et al.1998, Takamori 2016).