1. Purification of a neuroprotective component of Parawixia bistriata spider venom that enhances glutamate uptake.
- Author
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Fontana AC, Guizzo R, de Oliveira Beleboni R, Meirelles E Silva AR, Coimbra NC, Amara SG, dos Santos WF, and Coutinho-Netto J
- Subjects
- Animals, Brazil, Carbon Isotopes, Cerebral Cortex cytology, Chromatography, High Pressure Liquid methods, Chromatography, Ion Exchange, Disease Models, Animal, Dose-Response Relationship, Drug, Glaucoma drug therapy, Glaucoma physiopathology, Glutamic Acid drug effects, Glutamic Acid metabolism, Ion Channels drug effects, Ion Channels metabolism, Ion Channels physiopathology, Male, Neuroprotective Agents chemistry, Rats, Rats, Wistar, Receptors, Metabotropic Glutamate drug effects, Receptors, Metabotropic Glutamate physiology, Retina drug effects, Retina pathology, Retina ultrastructure, Spider Venoms chemistry, Spider Venoms pharmacology, Spiders, Synaptosomes drug effects, Synaptosomes metabolism, Tritium, gamma-Aminobutyric Acid drug effects, gamma-Aminobutyric Acid metabolism, gamma-Aminobutyric Acid pharmacokinetics, Glutamic Acid pharmacokinetics, Neuroprotective Agents isolation & purification, Neuroprotective Agents pharmacology, Spider Venoms isolation & purification, Tissue Extracts pharmacology
- Abstract
(1) In this study, we examined the effects of crude venom from the spider Parawixia bistriata on glutamate and GABA uptake into synaptosomes prepared from rat cerebral cortex. Addition of venom to cortical synaptosomes stimulated glutamate uptake and inhibited GABA uptake in a concentration-dependent manner. (2) The venom was fractionated using reverse-phase high-performance liquid chromatography on a preparative column. The fraction that retained glutamate uptake-stimulating activity was further purified on a reverse-phase analytical column followed by ion-exchange chromatography. (3) The active fraction, referred to as PbTx1.2.3, stimulated glutamate uptake in synaptosomes without changing the K(M) value, and did not affect GABA uptake. Additional experiments showed that the enhancement of glutamate uptake by PbTx1.2.3 occurs when ionotropic glutamate receptors or voltage-gated sodium and calcium channels are completely inhibited or when GABA receptors and potassium channels are activated, indicating that the compound may have a direct action on the transporters. (4) In an experimental model for glaucoma in which rat retinas are subjected to ischemia followed by reperfusion, PbTx1.2.3 protected neurons from excitotoxic death in both outer and inner nuclear layers, and ganglion cell layers. (5) This active spider venom component may serve as a basis for designing therapeutic drugs that increase glutamate clearance and limit neurodegeneration.
- Published
- 2003
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