Investigation of the Effect of Polyphenol Euphorbin on the Transport of L Glutamate and Calcium Channels to Synaptosomes of Rat Brain
Authors: N.N. Khoshimov, R.N. Rakhimov, G.B. Akhmedova, V.G. Azizov
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Background: The purpose of this study was to determine the effect of L glutamate and polyphenol euphorbin on the transport of NMDA-receptor mediators in rat’s brain synaptosomes. This makes it possible to adjust the transport of antagonists and agonists NMDA-receptors brain synaptosomes in rats.
Methods: The study was carried out using the Weilers method. Synaptosomes were isolated from the brain of rats by a two-step centrifugation method. The entire isolation procedure was carried out at 4°C. To measure the amount of cytosolic Ca2+ synaptosomes were calculated by the Grinkevich equation.
Results: Increase in the concentration of [Ca2+]in caused by L glutamate, primarily due to activation of membrane permeability, movement of Ca2+ into the cell and release of Ca2+ from intracellular stores. The two-phase L glutamate process of induced release of protons from synaptic vesicles of rat brain nerve terminals is correlated with a two-step increase in the concentration of calcium under the influence of L glutamate. Euphorbin competes with L glutamate for glutamate binding site of NMDA-receptors. L glutamate partially reduces the action of euphorbin, which may indicate that part of the external calcium comes under the influence of euphorbin also through the open L glutamate binding site and in place of calcium channels NMDA-receptors.
Conclusion: In these studies, it was found that euphorbin slightly increases the fluorescence and the level of [Ca2+]in, respectively, in the synaptic membranes compared with the control. The obtained results indicate a possible competition between euphorbin and L glutamate for the site of regulation of the opening of ion channels of NMDA-receptors. It was found that the effect of euphorbin responsible for the opening of calcium channels with other sites of NMDA-receptors against the background of magnesium ions, argiolobatin and nifedipine, a change in the level of [Ca2+]in synaptosomes was not observed.