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Purification of a neuroprotective component of Parawixia bistriata spider venom that enhances glutamate uptake
Author(s) -
Fontana Andréia Cristina Karklin,
Guizzo Renato,
Beleboni Renê de Oliveira,
Meirelles e Silva Antonio Renato,
Coimbra Norberto Cysne,
Amara Susan G,
Santos Wagner Ferreira dos,
CoutinhoNetto Joaquim
Publication year - 2003
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0705352
Subject(s) - glutamate receptor , spider toxin , pharmacology , ionotropic effect , venom , biophysics , chemistry , metabotropic glutamate receptor 5 , metabotropic glutamate receptor , biochemistry , biology , receptor
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. 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. 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. 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. This active spider venom component may serve as a basis for designing therapeutic drugs that increase glutamate clearance and limit neurodegeneration.British Journal of Pharmacology (2003) 139 , 1297–1309. doi: 10.1038/sj.bjp.0705352