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

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

Autor Oliveira, L. de Google Scholar
Cunha, AOS Google Scholar
Mortari, M. R. Google Scholar
Pizzo, A. B. Google Scholar
Miranda, A. Google Scholar
Coimbra, N. C. Google Scholar
Santos, W. F. dos Google Scholar
Instituição Universidade de São Paulo (USP)
Universidade Federal de São Paulo (UNIFESP)
Resumo Several investigations have provided information that defensive behaviors evoked by stimulation of deep layers of the superior colliculus (dISC) 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 dISC saline or bicuculline microinjections, considering that wasp venom has some influence on the uptake of GABA and/or glutamate neurotransmitters. GABA(A) receptor blockade in the dISC evoked a vigorous escape behavior, expressed by rapid running, jumps and turns, as compared to control. These defensive reactions were maximized after the intranigral GABA(A) agonism with muscimol, but not after in situ GABA(B) agonism. Nigral microinjection of AvTx8 induced similar effects to those of baclofen, decreasing the intensity of behavioral defensive reactions caused by GABA(A) receptor blockade in the dorsal mesencephalon. These findings suggest that AvTx8 has some effects on GABAergic neurotransmission, increasing the activity of the inhibitory nigrocollicular 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. (C) 2004 Elsevier B.V. All rights reserved.
Assunto wasp venom
substantia nigra
GABA(A) receptor
GABA(B) receptor
GABAergic striato-nigro-tectal pathways
excitatory amino acid-mediated mechanisms
Idioma Inglês
Data 2005-01-07
Publicado em Brain Research. Amsterdam: Elsevier B.V., v. 1031, n. 1, p. 74-81, 2005.
ISSN 0006-8993 (Sherpa/Romeo, fator de impacto)
Editor Elsevier B.V.
Extensão 74-81
Fonte http://dx.doi.org/10.1016/j.brainres.2004.10.027
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:000226422700008
URI http://repositorio.unifesp.br/handle/11600/28111

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