title: Central mechanisms involved in pilocarpine-induced pressor response.
abstract: Pilocarpine (cholinergic muscarinic agonist) injected peripherally may act centrally to produce pressor responses; in the present study, using c-fos immunoreactive expression, we investigated the forebrain and brainstem areas activated by pressor doses of intravenous (i.v.) pilocarpine. In addition, the importance of vasopressin secretion and/or sympathetic activation and the effects of lesions in the anteroventral third ventricle (AV3V) region in awake rats were also investigated. In male Holtzman rats, pilocarpine (0.04 to 4μmol/kg b.w.) i.v. induced transitory hypotension followed by long lasting hypertension. Sympathetic blockade with prazosin (1mg/kg b.w.) i.v. or AV3V lesions (1 day) almost abolished the pressor response to i.v. pilocarpine (2μmol/kg b.w.), whereas the vasopressin antagonist (10μg/kg b.w.) i.v. reduced the response to pilocarpine. Pilocarpine (2 and 4μmol/kg b.w.) i.v. increased the number of c-fos immunoreactive cells in the subfornical organ, paraventricular and supraoptic nuclei of the hypothalamus, organ vasculosum of the lamina terminalis, median preoptic nucleus, nucleus of the solitary tract and caudal and rostral ventrolateral medulla. These data suggest that i.v. pilocarpine activates specific forebrain and brainstem mechanisms increasing sympathetic activity and vasopressin secretion to induce pressor response.
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, (UNESP), 14801-903, Araraquara, SP, Brazil.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Takakura
authors.forename: Thiago S
authors.initials: TS
authors.lastname: Moreira
authors.forename: Thais L
authors.initials: TL
authors.lastname: Borella
authors.forename: Renata F
authors.initials: RF
authors.lastname: Paulin
authors.forename: Débora S A
authors.initials: DS
authors.lastname: Colombari
authors.forename: Laurival A
authors.initials: LA
authors.lastname: De Luca
authors.forename: Eduardo
authors.initials: E
authors.lastname: Colombari
authors.forename: José V
authors.initials: JV
authors.lastname: Menani
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D001933:Brain Stem / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology; D010862:Pilocarpine / Q000494:pharmacology*; D016548:Prosencephalon / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology
chemical_list: D018721:Muscarinic Agonists; D010862:Pilocarpine