title: The role of dorsomedial hypotalamus ionotropic glutamate receptors in the hypertensive and tachycardic responses evoked by Tityustoxin intracerebroventricular injection.
abstract: The scorpion envenoming syndrome is an important worldwide public health problem due to its high incidence and potential severity of symptoms. Some studies address the high sensitivity of the central nervous system to this toxin action. It is known that cardiorespiratory manifestations involve the activation of the autonomic nervous system. However, the origin of this modulation remains unclear. Considering the important participation of the dorsomedial hypotalamus (DMH) in the cardiovascular responses during emergencial situations, the aim of this work is to investigate the involvement of the DMH on cardiovascular responses induced by intracerebroventricular (icv) injection of Tityustoxin (TsTX, a α-type toxin extracted from the Tityus serrulatus scorpion venom). Urethane-anaesthetized male Wistar rats (n=30) were treated with PBS, muscimol or ionotropic glutamate receptor antagonists, bilaterally in DMH and later, with an icv injection of TsTX, or treated only with PBS in both regions. TsTX evoked a marked increase in mean arterial pressure and heart rate in all control rats. Interestingly, injection of muscimol, a GABAA receptor agonist, did not change the pressor and tachycardic responses evoked by TsTX. Remarkably, the injection ionotropic glutamate receptors antagonists in DMH abolished the pressor and the tachycardic response evoked by TsTX. Our data suggest that the central circuit recruited by TsTX, whose activation results in an array of physiological and behavioral alterations, depend on the activation of DMH ionotropic glutamate receptors. Moreover, our data provide new insights on the central mechanisms involved in the development of symptoms in the severe scorpion envenomation syndrome.
authors.affiliation: Laboratório de Fisiologia Cardiovascular, Departamento de Ciências Biológicas, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Morro do Cruzeiro, 35400 000 Ouro Preto, Minas Gerais, Brazil; Programa de Pós-graduação em Ciências Biológicas - NUPEB, Universidade Federal de Ouro Preto, Campus Universitário, Morro do Cruzeiro, 35400 000 Ouro Preto, Minas Gerais, Brazil.
authors.forename: F C
authors.initials: FC
authors.lastname: Silva
authors.affiliation: Núcleo de Neurociências, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, 31270 901 Belo Horizonte, Minas Gerais, Brazil; Centro de Tecnologia e Pesquisa em Magneto-Ressonância, Escola de Engenharia, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, 31270 901 Belo Horizonte, Minas Gerais, Brazil. Electronic address: maiaguidine@gmail.com.
authors.forename: Patrícia Alves Maia
authors.initials: PA
authors.lastname: Guidine
authors.affiliation: Laboratório de Hipertensão, Departamento de Fisiologia e Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, 31270 901 Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Natalia Lima
authors.initials: NL
authors.lastname: Machado
authors.affiliation: Departamento de Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Campus II - Samambaia, saída para Nerópolis - Km 13, Caixa Postal: 131, 74001 970 Goiânia, Goiás, Brazil.
authors.forename: Carlos Henrique
authors.initials: CH
authors.lastname: Xavier
authors.affiliation: Laboratório de Fisiologia Cardiovascular, Departamento de Ciências Biológicas, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Morro do Cruzeiro, 35400 000 Ouro Preto, Minas Gerais, Brazil; Programa de Pós-graduação em Ciências Biológicas - NUPEB, Universidade Federal de Ouro Preto, Campus Universitário, Morro do Cruzeiro, 35400 000 Ouro Preto, Minas Gerais, Brazil.
authors.forename: R C
authors.initials: RC
authors.lastname: de Menezes
authors.affiliation: Centro de Tecnologia e Pesquisa em Magneto-Ressonância, Escola de Engenharia, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, 31270 901 Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Tasso
authors.initials: T
authors.lastname: Moraes-Santos
authors.affiliation: Núcleo de Neurociências, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, 31270 901 Belo Horizonte, Minas Gerais, Brazil; Centro de Tecnologia e Pesquisa em Magneto-Ressonância, Escola de Engenharia, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, 31270 901 Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Márcio Flávio
authors.initials: MF
authors.lastname: Moraes
authors.affiliation: Laboratório de Fisiologia Cardiovascular, Departamento de Ciências Biológicas, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Morro do Cruzeiro, 35400 000 Ouro Preto, Minas Gerais, Brazil; Programa de Pós-graduação em Ciências Biológicas - NUPEB, Universidade Federal de Ouro Preto, Campus Universitário, Morro do Cruzeiro, 35400 000 Ouro Preto, Minas Gerais, Brazil.
authors.forename: Deoclécio Alves
authors.initials: DA
authors.lastname: Chianca
mesh_terms: D000818:Animals; D062186:Arterial Pressure / Q000187:drug effects; D004302:Dorsomedial Hypothalamic Nucleus / Q000187:drug effects* / Q000378:metabolism; D058785:GABA-A Receptor Agonists; D006973:Hypertension / Q000139:chemically induced / Q000378:metabolism*; D007276:Injections, Intraventricular; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000378:metabolism; D058468:Receptors, Ionotropic Glutamate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012604:Scorpion Venoms / Q000008:administration & dosage / Q000633:toxicity*; D013610:Tachycardia / Q000139:chemically induced / Q000378:metabolism*
chemical_list: D058785:GABA-A Receptor Agonists; D011963:Receptors, GABA-A; D058468:Receptors, Ionotropic Glutamate; D012604:Scorpion Venoms; C003609:tityustoxin
keywords: Cardiovascular responses; Dorsomedial hypothalamus; Ionotropic glutamate receptor; Scorpion envenomation; Tityustoxin