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Hearing Research Jun 2024The disruption of ribbon synapses in the cochlea impairs the transmission of auditory signals from the cochlear sensory receptor cells to the auditory cortex. Although...
The disruption of ribbon synapses in the cochlea impairs the transmission of auditory signals from the cochlear sensory receptor cells to the auditory cortex. Although cisplatin-induced loss of ribbon synapses is well-documented, and studies have reported nitration of cochlear proteins after cisplatin treatment, yet the underlying mechanism of cochlear synaptopathy is not fully understood. This study tests the hypothesis that cisplatin treatment alters the abundance of cochlear synaptosomal proteins, and selective targeting of nitrative stress prevents the associated synaptic dysfunction. Auditory brainstem responses of mice treated with cisplatin showed a reduction in amplitude and an increase in latency of wave I, indicating cisplatin-induced synaptic dysfunction. The mass spectrometry analysis of cochlear synaptosomal proteins identified 102 proteins that decreased in abundance and 249 that increased in abundance after cisplatin treatment. Pathway analysis suggested that the dysregulated proteins were involved in calcium binding, calcium ion regulation, synapses, and endocytosis pathways. Inhibition of nitrative stress by co-treatment with MnTBAP, a peroxynitrite scavenger, attenuated cisplatin-induced changes in the abundance of 27 proteins. Furthermore, MnTBAP co-treatment prevented the cisplatin-induced decrease in the amplitude and increase in the latency of wave I. Together, these findings suggest a potential role of oxidative/nitrative stress in cisplatin-induced cochlear synaptic dysfunction.
Topics: Cisplatin; Animals; Cochlea; Evoked Potentials, Auditory, Brain Stem; Synapses; Proteomics; Synaptosomes; Oxidative Stress; Mice, Inbred CBA; Male; Ototoxicity; Mice
PubMed: 38705005
DOI: 10.1016/j.heares.2024.109022 -
Journal of Neurochemistry Oct 1981Experimental galactose toxicity was induced by weaning rats onto an isocaloric 40% galactose diet. Synaptosomes were prepared from cerebra of rats at 2-9 weeks...
Experimental galactose toxicity was induced by weaning rats onto an isocaloric 40% galactose diet. Synaptosomes were prepared from cerebra of rats at 2-9 weeks post-weaning and incubated with [33P][i and myo-[2-3H]inositol in the presence or absence of 0.2 mM-acetylcholine. The acetylcholine-stimulated [33P]Pi labeling of phosphatidylinositol and the changes in amounts of phosphatidylinositol were similar in the normal and galactose-toxic rats; however, acetylcholine-stimulated myo-[2-3H]inositol labeling of phosphatidylinositol was markedly decreased in the galactose-toxic rats. The impairment of acetylcholine-stimulated myo-[2-3H]inositol incorporation into phosphatidylinositol observed after 2 weeks on the diet did not vary after more prolonged exposure to galactose.
Topics: Acetylcholine; Animals; Brain; Dietary Carbohydrates; Galactose; Phosphatidylinositols; Rats; Rats, Inbred Strains; Synaptosomes
PubMed: 7320728
DOI: 10.1111/j.1471-4159.1981.tb04475.x -
Scandinavian Journal of Work,... Feb 1989The possible mechanism of the depressive effect of organic solvents on the central nervous system (CNS) was studied with synaptosome membranes as a model. The changes in...
The possible mechanism of the depressive effect of organic solvents on the central nervous system (CNS) was studied with synaptosome membranes as a model. The changes in the activities of the membrane-bound integral enzymes acetylcholinesterase, total adenosinetriphosphatase, and magnesium-activated adenosinetriphosphatase were determined after treatment with different concentrations of organic solvents in vitro. Aromatic hydrocarbons and chlorinated aliphatic hydrocarbons inhibited all the enzyme activities concentration dependently. Alcohols had no significant effect at the same dose levels. The results of the present study suggest that the CNS depressive effect of organic solvents may be based on their interaction with membrane integral proteins.
Topics: Acetylcholinesterase; Adenosine Triphosphatases; Animals; Ca(2+) Mg(2+)-ATPase; Cell Membrane; Male; Rats; Rats, Inbred Strains; Solvents; Synaptosomes
PubMed: 2522239
DOI: 10.5271/sjweh.1890 -
The Biochemical Journal Jul 1985The evoked effects of the negatively charged drugs phenobarbital and barbituric acid, the positively charged imipramine, perphenazine and trifluoperazine, and the...
The evoked effects of the negatively charged drugs phenobarbital and barbituric acid, the positively charged imipramine, perphenazine and trifluoperazine, and the neutral primidone, on the synaptosome-associated acetylcholinesterase activity were studied. A marked increase in the enzyme activity was exhibited in the presence of low concentrations (up to 3 mM) of phenobarbital, barbituric acid and primidone. Higher concentrations (up to 10 mM), however, led to a progressive inhibition of the enzyme activity. However, the activity of the enzyme was not affected by imipramine, but it was decreased by perphenazine and trifluoperazine. Arrhenius plots of acetylcholinesterase activity exhibited a break point at 23.4 degrees C for the untreated (control) synaptosomes, which was shifted to around 16 degrees C in the synaptosomes treated with the charged drugs. The allosteric inhibition by F- of acetylcholinesterase was studied in control synaptosomes and in those treated with the charged drugs. Changes in the Hill coefficients in combination with changes in Arrhenius activation energy produced by the charged drugs would be expected if it is assumed that charged drugs 'fluidize' the synaptosomal plasma membranes.
Topics: Acetylcholinesterase; Animals; Antidepressive Agents; Barbiturates; Brain; Dogs; Imipramine; Perphenazine; Phenobarbital; Primidone; Synaptosomes; Trifluoperazine
PubMed: 4038267
DOI: 10.1042/bj2290081 -
Cold Spring Harbor Protocols May 2015The human brain is estimated to contain trillions of synaptic nerve terminals. These are the connections between neurons that are responsible for transmitting...
The human brain is estimated to contain trillions of synaptic nerve terminals. These are the connections between neurons that are responsible for transmitting information and are modified as a result of learning. A valuable tool for studying synapses is the isolated nerve terminal, or synaptosome, which is obtained by homogenizing the brain in such a way that individual synapses pinch off to form metabolically active compartments that can recapitulate neurotransmitter release. This protocol describes the stepwise fractionation of rat brain tissue to yield synaptosomes and synaptic vesicles, which can be used in many different experimental approaches to study the structure and protein composition of the synapse and even dissect the molecular mechanisms of neurotransmission.
Topics: Animals; Brain; Brain Chemistry; Cell Fractionation; Rats; Synaptic Vesicles; Synaptosomes
PubMed: 25934934
DOI: 10.1101/pdb.prot083469 -
Neuroscience Research Mar 2013Synaptosomal-associated protein 25 (SNAP-25) plays an essential role in exocytotic neurotransmitter release as a t-SNARE protein. SNAP-25 is phosphorylated at Ser(187)...
Synaptosomal-associated protein 25 (SNAP-25) plays an essential role in exocytotic neurotransmitter release as a t-SNARE protein. SNAP-25 is phosphorylated at Ser(187) in a protein kinase C (PKC)-dependent manner, but the mechanism for dephosphorylation has yet to be clarified. We investigated SNAP-25 dephosphorylation by comparing it to growth associated protein 43 (GAP-43), another PKC-dependent presynaptic phosphoprotein, in crude mouse brain synaptosome preparations. Phosphorylation levels for both SNAP-25 and GAP-43 increased significantly after treatment with PKC activator phorbol 12, 13-dibutyrate (PDB), and ionomycin treatment induced a striking reduction in a time-dependent manner. This dephosphorylation occurred only in the presence of extracellular Ca(2+), indicating involvement of a Ca(2+)-dependent phosphatase. Ca(2+)-dependent dephosphorylation was not suppressed by calcineurin/PP2B inhibitors such as FK506 and cyclosporine A. SNAP-25 dephosphorylation, however, was suppressed by calyculin A, a non-selective inhibitor of PP1 and PP2A, and okadaic acid selective for PP2A, but not by tautomycin selective for PP1. In contrast, none of these inhibitors suppressed GAP-43 dephosphorylation. PDB-induced SNAP-25 phosphorylation was enhanced by okadaic acid in a concentration-dependent manner. These results suggest that PP2A participates in SNAP-25 dephosphorylation through Ca(2+)-dependent and Ca(2+)-independent mechanisms but is not involved in GAP-43 dephosphorylation.
Topics: Animals; Brain; GAP-43 Protein; Mice; Mice, Inbred C57BL; Phosphorylation; Protein Phosphatase 2; Synaptosomal-Associated Protein 25; Synaptosomes
PubMed: 23376809
DOI: 10.1016/j.neures.2013.01.002 -
Journal of Neurochemistry Oct 2012Amphetamine (AMPH) and methamphetamine (METH) alter dopamine transporter (DAT) function. In vitro heterologous cell line and synaptosome studies demonstrate AMPH-induced...
Amphetamine (AMPH) and methamphetamine (METH) alter dopamine transporter (DAT) function. In vitro heterologous cell line and synaptosome studies demonstrate AMPH-induced DAT internalization, implicating relocalization in reduced DAT uptake following drug exposure. However, few studies have evaluated DAT localization following in vivo AMPH/METH administration. To determine DAT subcellular localization following drug administration, a centrifugation technique was developed to isolate striatal synaptosomal membrane and vesicle fractions. DAT was distributed between the synaptosomal membrane (60%) and endosomal vesicles (40%), and in vitro application of the protein kinase C activator phorbol 12-myristate 13-acetate to striatal synaptosomes caused DAT internalization into the vesicle fractions. In contrast, neither single nor repeated in vivo AMPH and/or METH administrations altered DAT localization 5, 15, 30, or 60 min post-treatment, despite reduced DAT uptake. Importantly, repeated METH injections uniformly decreased total DAT immunoreactivity within all fractions 7 days post-treatment. These findings suggest that factors other than internalization can contribute to the observed acute and persistent DAT dysfunction and dopaminergic deficits following in vivo AMPH or METH administration.
Topics: Amphetamine; Animals; Corpus Striatum; Dopamine Plasma Membrane Transport Proteins; Male; Methamphetamine; Rats; Rats, Sprague-Dawley; Synaptosomes
PubMed: 22804716
DOI: 10.1111/j.1471-4159.2012.07875.x -
Acta Biochimica Et Biophysica;... 1984
Comparative Study
Topics: Animals; Cell Fractionation; Cerebral Cortex; Microscopy, Electron; Rats; Synaptosomes
PubMed: 6545633
DOI: No ID Found -
Intervirology 1986The association between scrapie infectivity and scrapie-associated fibrils (SAF) during a partial purification procedure for infectivity was investigated. Scrapie...
The association between scrapie infectivity and scrapie-associated fibrils (SAF) during a partial purification procedure for infectivity was investigated. Scrapie infectivity and SAF can be separated from most membrane components by subcellular fractionation of infected mouse brain to obtain a synaptosomal fraction, followed by detergent treatment and density gradient centrifugation. After different detergent treatments, with either octyl glucoside or sodium N-lauroyl sarcosinate, SAF showed differing sedimentation characteristics but nevertheless cosedimented with scrapie infectivity in both cases. Copurification under two different conditions provides more evidence that SAF may be a form of the infectious agent of scrapie.
Topics: Animals; Brain; Brain Chemistry; Detergents; Glucosides; Mice; Mice, Inbred C57BL; Molecular Weight; Nerve Tissue Proteins; PrP 27-30 Protein; Prions; Sarcosine; Synaptic Membranes; Synaptosomes
PubMed: 2422138
DOI: 10.1159/000149654 -
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