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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Effects of microinjections of neurotoxin AvTx8, isolated from the social wasp Agelaia vicina (Hymenoptera, Vespidae) venom, on GABAergic nigrotectal pathways

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Autor(es):
Oliveira, Luciana de ; Cunha, Alexandra Olimpio Siqueira ; Mortari, Márcia Renata ; Pizzo, Andréa Baldocchi ; Miranda, Antonio ; Coimbra, Norberto Cysne ; Santos, Wagner Ferreira dos
Número total de Autores: 7
Tipo de documento: Artigo Científico
Fonte: Brain Research; v. 1031, n. 1, p. 74-81, Jan. 2004.
Área do conhecimento: Ciências Biológicas - Farmacologia
Assunto(s):Etnofarmacologia   Venenos de origem animal   Receptores de GABA   Aminoácidos   GABA
Resumo

Several investigations have provided information that defensive behaviors evoked by stimulation of deep layers of the superior colliculus (dlSC) are subjected to inhibitory nigral modulation. This inhibition is made mainly through GABAergic neurons from substantia nigra, pars reticulata (SNpr), that sends outputs toward neural networks of the deep layers of the superior colliculus and dorsal periaqueductal gray matter involved with the organization of fear-like responses. In this work, we compared the effects of two GABAergic agonists, muscimol and baclofen, with the effect of neurotoxin AvTx8 (1567 Da), isolated from the venom of the social wasp Agelaia vicina, microinjected into SNpr of Rattus norvegicus (Wistar rats) prior to dlSC saline or bicuculline microinjections, considering that wasp venom has some influence on the uptake of GABA and/or glutamate neurotransmitters. GABA receptor blockade in the dlSC evoked a vigorous escape behavior, expressed by rapid running, jumps and turns, as compared to control. These defensive reactions were maximized after the intranigral GABAA agonism with muscimol, but not after in situ GABAB agonism. Nigral microinjection of AvTx8 induced similar effects to those of baclofen, decreasing the intensity of behavioral defensive reactions caused by GABAA receptor blockade in the dorsal mesencephalon. These findings suggest that AvTx8 has some effects on GABAergic neurotransmission, increasing the activity of the inhibitory nigro-collicular pathways, causing an anti-panic (antiaversive) effect. Therefore, our work suggests AvTx8 as a novel pharmacological tool to study differences between the two types of GABAergic receptors and excitatory amino acid-mediated mechanisms in the brain and brainstem networks. (AU)

Processo FAPESP: 02/03705-0 - Neurobiologia do medo e do stress
Beneficiário:Marcus Lira Brandão
Linha de fomento: Auxílio à Pesquisa - Temático
Processo FAPESP: 02/01497-1 - Estudo do envolvimento do núcleo magno da rafe, do núcleo gigantocelular e núcleo pré-tectal anterior, e de receptores opiódes, kappa e delta serotoninérgicos 5HT2/1C, e noradrenérgicos alfa, beta, na analgesia pós-cital: um estudo neuroanatômico e neuropsicofisiológico em um modelo experimental de epilepsia
Beneficiário:Daoud Hibrahim Elias Filho
Linha de fomento: Bolsas no Brasil - Programa Capacitação - Treinamento Técnico
Processo FAPESP: 02/01496-5 - Estudo do envolvimento do núcleo magno da rafe, do núcleo gigantocelular e núcleo pré-tectal anterior, e de receptores opióides, mu, kappa e delta serotininérgicos 5-HT2A/2C e noradrenérgicos alfa e beta na analgesia pós-ictal: um estudo neuroanatômico e neuropsicofisiológico em um modelo experimental de epilepsia
Beneficiário:Norberto Cysne Coimbra
Linha de fomento: Auxílio à Pesquisa - Regular