title: Characterization of the actions of AvTx 7 isolated from Agelaia vicina (Hymenoptera: Vespidae) wasp venom on synaptosomal glutamate uptake and release.
abstract: It has previously been shown that the denatured crude extract of Agelaia vicina wasp venom inhibits glutamate and GABA uptake in rat cerebral cortex synaptosomes. To identify the components responsible for these effects, the neurotoxin AvTx 7 (molecular weight of 1210 Da) was isolated from A. vicina venom and its effects on glutamate neurotransmission investigated. AvTx 7 inhibits glutamate uptake in a dose-dependent and uncompetitive manner. AvTx 7 was found to stimulate the glutamate release in the presence of calcium and sodium channel blockers, suggesting that its action is not mediated through these channels. AvTx 7 potentiates glutamate release in the presence of K(+) channel blockers tetraethylammonium and 4-aminopyridine, indicating that the toxin may act through these drugs-sensible K(+) channels. We suggest that AvTx 7 can be a valuable tool to enhance our understanding of K(+) channels' involvement in the release of glutamate.
authors.affiliation: Laboratory of Neurobiology and Venoms, Faculty of Philosophy, Sciences and Literature, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Andrea B
authors.initials: AB
authors.lastname: Pizzo
authors.forename: Renê O
authors.initials: RO
authors.lastname: Beleboni
authors.forename: Andréia C K
authors.initials: AC
authors.lastname: Fontana
authors.forename: Alessandra M
authors.initials: AM
authors.lastname: Ribeiro
authors.forename: Antonio
authors.initials: A
authors.lastname: Miranda
authors.forename: Joaquim
authors.initials: J
authors.lastname: Coutinho-Netto
authors.forename: Wagner F
authors.initials: WF
authors.lastname: dos Santos
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D018698:Glutamic Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D013058:Mass Spectrometry; D009498:Neurotoxins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects* / Q000378:metabolism*; D014862:Wasp Venoms / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D014863:Wasps / Q000737:chemistry
chemical_list: D015220:Calcium Channels; D009498:Neurotoxins; D015221:Potassium Channels; D015222:Sodium Channels; D014862:Wasp Venoms; D018698:Glutamic Acid