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Neuroscience Letters Feb 2004A pronounced glutamate release has been related to neuronal death in several structures due to status epilepticus (SE). We investigated the glutamate uptake and release... (Comparative Study)
Comparative Study
A pronounced glutamate release has been related to neuronal death in several structures due to status epilepticus (SE). We investigated the glutamate uptake and release by both cortical and hippocampal synaptosome in pilocarpine model of epilepsy. Animals were submitted to long-lasting SE (12 h) induced by pilocarpine and compared with non-treated animals. Animals presenting SE did not modify the glutamate uptake by synaptosomes. An increase in the glutamate efflux in the absence (1.43-fold) and in the presence of KCl (1.25-fold) was found in hippocampal synaptosomes. Pilocarpine added to the medium did not modify the glutamate release profile, showing that SE is necessary to modify the glutamate release. As the glutamate uptake is not modified, the hippocampal excitotoxicity may be related to impairment only in the mechanism of the glutamate release.
Topics: Animals; Glutamic Acid; Hippocampus; Male; Pilocarpine; Rats; Rats, Wistar; Status Epilepticus; Synaptosomes
PubMed: 14746897
DOI: 10.1016/j.neulet.2003.11.019 -
Biochemical Society Transactions Jun 1990
Topics: Animals; Calcium; Glucose; Homeostasis; In Vitro Techniques; Lactates; Oxygen; Potassium; Rats; Synaptosomes; Veratrine
PubMed: 2373229
DOI: 10.1042/bst0180428 -
Journal of Neurocytology Jun 1983The morphological effects of alpha-latrotoxin, the major component of black widow spider venom, were studied quantitatively in a crude synaptosome fraction (prepared...
The morphological effects of alpha-latrotoxin, the major component of black widow spider venom, were studied quantitatively in a crude synaptosome fraction (prepared from rat brain cortices) which was incubated at 37 degrees C for 10 min in Ringer solutions. Two toxin concentrations were employed, one causing a very large stimulation of transmitter release (approximately 65% and approximately 43% release of [3H]noradrenaline from preloaded synaptosomes, with and without Ca2+ in the incubation buffer), the other 50-60% as active. Incubated synaptosomes, fixed in suspension with aldehydes, were evenly dispersed in agarose before embedding, to assure randomized sampling in the subsequent morphometric analysis. In all the experimental conditions investigated, alpha-latrotoxin treatment caused a significant decrease in the density (number/unit area) of synaptic vesicles in synaptosome profiles. Such an effect was dose-dependent and partially Ca2+-dependent, in good agreement with the data on transmitter release. At high toxin concentration a moderate increase of synaptosome volume and surface area was observed, both with and without Ca2+. Mitochondrial swelling appeared only in synaptosomes treated in Ca2+ containing medium. These effects of alpha-latrotoxin are similar to those described previously at the neuromuscular junction. Thus, the toxin might be a tool of general use for studying vertebrate synapses.
Topics: Animals; Arthropod Venoms; Cerebral Cortex; Female; Norepinephrine; Rats; Rats, Inbred Strains; Spider Venoms; Synaptosomes; Tritium
PubMed: 6875622
DOI: 10.1007/BF01159388 -
International Journal of Biological... Apr 2014Acetylcholinesterase (AChE) is the enzyme that controls the acetylcholine (ACh) concentrations in cholinergic synaptic clefts by hydrolyzing ACh to choline and acetate....
Acetylcholinesterase (AChE) is the enzyme that controls the acetylcholine (ACh) concentrations in cholinergic synaptic clefts by hydrolyzing ACh to choline and acetate. Cholinergic synapses are involved in important functions such as learning, memory and cognition. In this study, we investigated the effects of a wide range of extremely low frequency electromagnetic fields (ELF-EMFs) on synaptic ACh concentrations through AChE enzyme activity assay. Synaptosome suspensions were prepared as a neural terminus from cerebral cortex of sheep brain. Prepared synaptosomes were exposed to ELF-EMFs with frequency ranging from 50 Hz to 230 Hz for duration between 15 and 120 min and flux intensity between 0.1 mT and 1.7 mT. Consequently, AChE activity was measured by Ellman method. Raw data were analyzed by neural network based software, Inform 4.02, to predict AChE activity pattern through nine 3D curves. These curves showed that AChE activity decreases when exposed to ELF-EMFs of 1.2 mT to 1.7 mT intensity and 50 Hz to 90 Hz frequency. Thus, it is proposed that exposure to fields of in this range of frequency-intensity would be effective in clinical treatments of cholinergic disorders to increase synaptic ACh concentration. However, more in vivo experiments are needed to develop this suggested treatment.
Topics: Acetylcholine; Acetylcholinesterase; Animals; Cerebral Cortex; Electromagnetic Fields; Neural Networks, Computer; Sheep; Synapses; Synaptosomes
PubMed: 24418344
DOI: 10.1016/j.ijbiomac.2014.01.006 -
Brain Research May 1979The subunit structure of rat brain synaptosomal tubulin was examined by high resolution two-dimensional gel fractionation. Whole brain cytoplasmic tubulin consists of...
The subunit structure of rat brain synaptosomal tubulin was examined by high resolution two-dimensional gel fractionation. Whole brain cytoplasmic tubulin consists of two groups of alpha subunits (alpha1 and alpha2), and a minimum of two beta subunits (beta1 and beta2). Both alpha subunits consist of a major relatively acidic form and minor relatively basic forms. In contrast, tubulin purified from synaptoplasm contains an additional subunit, alpha3, which has the same isoelectric point but slightly faster electrophoretic mobility than alpha1 and alpha2. All synaptosomal alpha subunits are the relatively acidic forms and the minor basic forms are absent. The synaptosomal beta subunits have electrophoretic properties similar to the corresponding cytoplasmic forms. The alpha3 synaptosomal tubulin subunit has affinity for colchicine, has a tryptic peptide map similar to whole brain cytoplasmic alpha tubulin, and can be purified by a standard tubulin purification method.
Topics: Animals; Glycoproteins; Isoelectric Focusing; Microtubules; Molecular Weight; Peptide Fragments; Rats; Synaptosomes; Tubulin
PubMed: 455072
DOI: 10.1016/0006-8993(79)90265-8 -
Zhurnal Evoliutsionnoi Biokhimii I... 1977The activity of synaptosomal Mg- and Na, K-ATPases has been compared during natural hibernation and active periods in ground squirrels. Being assayed in vitro at...
The activity of synaptosomal Mg- and Na, K-ATPases has been compared during natural hibernation and active periods in ground squirrels. Being assayed in vitro at temperature 37 degrees, the activity of Na, K-ATPase decreases during hibernation by 25%, that of Mg-ATPase--by 37%. The decreased level of the activity of these enzymic systems may result from structural alterations in the brain membranes during hibernation of the animals.
Topics: Adenosine Triphosphatases; Animals; Brain; Hibernation; Magnesium; Potassium; Rodentia; Sciuridae; Sodium; Synaptosomes
PubMed: 143169
DOI: No ID Found -
Neuroscience 1979
Topics: Animals; Bicuculline; Cerebral Cortex; Male; Rats; Receptors, Neurotransmitter; Sodium; Synaptosomes; gamma-Aminobutyric Acid
PubMed: 233270
DOI: 10.1016/0306-4522(79)90174-x -
Experimental Eye Research Jun 1980
Topics: Animals; Cattle; Rabbits; Radioligand Assay; Receptors, Dopamine; Retina; Spiperone; Synaptosomes
PubMed: 7418747
DOI: 10.1016/0014-4835(80)90068-8 -
Journal of Medicinal Food May 2015The excessive release of glutamate is a critical element in the neuropathology of acute and chronic brain disorders. The purpose of the present study was to investigate...
The excessive release of glutamate is a critical element in the neuropathology of acute and chronic brain disorders. The purpose of the present study was to investigate the effect and possible mechanism of myricetin, a naturally occurring flavonoid with a neuroprotective profile, on endogenous glutamate release in the nerve terminals (synaptosomes) of the rat cerebral cortex. The release of glutamate was evoked by the K(+) channel blocker 4-aminopyridine (4-AP) and measured by one-line enzyme-coupled fluorometric assay. We also used a membrane potential-sensitive dye to assay the synaptosomal plasma membrane potential, and a Ca(2+) indicator Fura-2 to monitor cytosolic Ca(2+) concentrations ([Ca(2+)]C). Results show that myricetin inhibited 4-AP-evoked glutamate release, and this effect was prevented by chelating extracellular Ca(2+) ions and the vesicular transporter inhibitor bafilomycin A1. However, the glutamate transporter inhibitor dl-threo-beta-benzyl-oxyaspartate had no effect on myricetin action. Myricetin did not alter the synaptosomal membrane potential, but decreased 4-AP-induced increases in the cytosolic free Ca(2+) concentration. Furthermore, the myricetin effect on 4-AP-evoked glutamate release was prevented by blocking the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channels, but not by blocking intracellular Ca(2+) release. These results suggest that myricetin inhibits glutamate release from cerebrocortical synaptosomes by attenuating voltage-dependent Ca(2+) entry. This implies that the inhibition of glutamate release is an important pharmacological activity of myricetin that may play a critical role in the apparent clinical efficacy of this compound.
Topics: Animals; Calcium; Calcium Channels, N-Type; Cells, Cultured; Cerebral Cortex; Flavonoids; Glutamic Acid; Male; Nerve Endings; Rats; Rats, Sprague-Dawley; Synaptosomes
PubMed: 25340625
DOI: 10.1089/jmf.2014.3219 -
Spectrochimica Acta. Part A, Molecular... Mar 2020Aluminium (Al) is reported to promote free radical production, decrease the antioxidant enzyme status and disturb the enzyme activity involved in acetylcholine...
Aluminium (Al) is reported to promote free radical production, decrease the antioxidant enzyme status and disturb the enzyme activity involved in acetylcholine metabolism leading to cognitive dysfunction that are strongly associated with Alzheimer's disease (AD) pathogenesis. This work aimed at investigating the effect of Al-toxicity on synaptosomal membrane biophysical properties and lipid peroxidation during 65 days. We utilized ATR-IR spectroscopy to study the changes in membrane biochemical structure and biophysical properties of isolated rat cortical synaptosomes, and EPR spin trapping and labeling to follow NADPH oxidase activity and changes of membrane order parameter, respectively. The results showed increase in membrane fluidity and disorder in early 21d of AlCl treatment, while after 42d the membrane rigidity, packing, and order increased. The late (65d) an increase in the amount of unsaturated fatty acids, the accumulation of lipid peroxide end products, and ROS production were detected in rat cortex synaptosomes mediated by Al toxicity and oxidative stress (OS). A dramatic increase was also detected in Ca level, synaptic membrane polarity, and EPR-detected order S-parameter. These outcomes strongly suggest that the synaptosomal membrane phospholipids underwent free radical attacks mediated by AlCl due to greater NOX activity, and the release of synaptic vesicles into synaptic cleft might be hindered. The adopted spectroscopic techniques have shed light on the biomolecular structure and membrane biophysical changes of isolated cortical synaptosomes for the first time, allowing researchers to move closer to a complete understanding of pathological tissues.
Topics: Aluminum; Animals; Calcium; Cerebral Cortex; Cluster Analysis; Electron Spin Resonance Spectroscopy; Hydrocarbons; Ions; Lipids; Male; Rats, Wistar; Spectrophotometry, Infrared; Stress, Physiological; Synaptosomes
PubMed: 31748152
DOI: 10.1016/j.saa.2019.117535