title: Ventromedial hypothalamus lesions increase the dipsogenic responses and reduce the pressor responses to median preoptic area activation.
abstract: In this study, we investigated the participation of adrenergic receptors of the median preoptic area (MnPO) and the participation of ventromedial hypothalamus (VMH) in angiotensin II-(ANG II)-induced water intake and pressor responses. Male rats with sham or electrolytic VMH lesions and a stainless steel cannula implanted into the MnPO were used. Noradrenaline, clonidine (an alpha2-adrenergic receptor agonist), or phenylephrine (an alpha1-adrenergic receptor agonist) injected into the MnPO of sham-lesioned rats reduced water ingestion induced by ANG II injected into the same area. In VMH-lesioned rats ANG II-induced water intake increased with a previous injection of noradrenaline, phenylephrine, or isoproterenol. The pressor response induced by ANG II injected into the MnPO was reduced in VMH-lesioned rats, whereas the pressor response induced by clonidine was abolished. Previous treatment with noradrenaline and phenylephrine into the MnPO of sham-lesioned rats produced a pressor response, and a hypotensive response was obtained with the previous administration of noradrenaline, phenylephrine or isoproterenol into the MnPO of VMH-lesioned rats. These results show that VMH is essential for the dipsogenic and pressor responses induced by adrenergic and angiotensinergic activation of the MnPO in rats.
authors.affiliation: Department of Physiology, School of Dentistry, Paulista State University (UNESP), Araraquara, SP, Brazil.
authors.forename: R
authors.initials: R
authors.lastname: Bastos
authors.forename: J V
authors.initials: JV
authors.lastname: Menani
authors.forename: W A
authors.initials: WA
authors.lastname: Saad
authors.forename: A
authors.initials: A
authors.lastname: Renzi
authors.forename: J E
authors.initials: JE
authors.lastname: Silveira
authors.forename: L A
authors.initials: LA
authors.lastname: Camargo
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000494:pharmacology; D000804:Angiotensin II / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002404:Catheterization; D003000:Clonidine / Q000008:administration & dosage / Q000494:pharmacology; D004327:Drinking Behavior / Q000187:drug effects / Q000502:physiology*; D004567:Electrodes, Implanted; D007545:Isoproterenol / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008845:Microinjections; D009638:Norepinephrine / Q000008:administration & dosage / Q000494:pharmacology; D010656:Phenylephrine / Q000008:administration & dosage / Q000494:pharmacology; D011301:Preoptic Area / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014697:Ventromedial Hypothalamic Nucleus / Q000502:physiology*
chemical_list: D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D010656:Phenylephrine; D007545:Isoproterenol; D003000:Clonidine; D009638:Norepinephrine