Effects of the crude venom of the social wasp Agelaia vicina on gamma-aminobutyric acid and glutamate uptake in synaptosomes from rat cerebral cortex.
Glutamate (L-glu) is the most important excitatory neurotransmitter in the mammalian central nervous system. Its action is terminated by transporters located in the plasma membrane of neurons and glial cells, which have a critical role in preventing glutamate excitotoxicity under normal conditions. The neurotransmitter gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian central nervous system. Venoms of solitary wasps and orb-spiders are composed of large proteins, medium-size peptides, polyamine amides (PAs), and other neuroactive components that are highly selective to nervous tissues. The abnormal operation of uptake systems is involved in several failures. Several studies indicate alterations in extracellular GABA and glutamate concentrations in epilepsy conditions that may relate to transporter functions. The effects of the crude and boiled venom of the social wasp Agelaia vicina, "cassununga," on GABA and L-glu uptake in rat cerebral cortex synaptosomes are related. The venom uncompetitively inhibited high- and low-affinity GABA uptake by 91.2% and by 76%, respectively. This kind of inhibition was also found to affect high- (99.6%) and low-affinity (90%) uptake of L-glu. These results suggest that the effects observed in these experiments indicate the venom of A. vicina to be a useful tool to further characterize GABA- and L-glu-uptake systems.
Pizzo
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AB
Department of Biology, Faculty of Philosophy, Sciences, and Letters, University of São Paulo, Ribeirão Preto, Brazil.
Fontana
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AC
Coutinho-Netto
J
J
dos Santos
W F
WF
D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013574:Synaptosomes / Q000187:drug effects* / Q000378:metabolism; D014862:Wasp Venoms / Q000633:toxicity*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D014862:Wasp Venoms; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid