title: Lead (Pb2+) and cadmium (Cd2+) inhibit the dipsogenic action of central beta-adrenergic stimulation by isoproterenol.
abstract: We have previously demonstrated that acute third ventricle injections of both Pb2+ and Cd2+ impair the dipsogenic response elicited by three different situations: dehydration and central cholinergic or angiotensinergic stimulation. beta-Adrenergic activation is part of the multifactorial integrated systems operating in drinking behavior control in the central nervous system. In the present study acute third ventricle injections of Pb2+ (3, 30 and 300 pmol/rat) or Cd2+ (0.3, 3 and 30 pmol/ rat) blocked the dipsogenic response induced by third ventricle injections of isoproterenol (ISO; 160 nmol/rat) in a dose-dependent manner. Normohydrated animals receiving ISO + NaAc (sodium acetate) or saline (controls) displayed a high water intake after 120 min (ISO+saline = 5.78 +/- 0.54 ml/100 g; ISO+NaAc = 6.00 +/- 0.6 ml/100 g). After the same period, animals receiving ISO but pretreated with PbAc at the highest dose employed (300 pmol/rat) drank 0.78 +/- 0.23 ml/100 g while those receiving ISO and pretreated with the highest dose of CdCl2 (30 pmol/rat) presented a water intake of 0.7 +/- 0.30 ml/100 g. Third ventricle injections of CdCl2 (3 nmol/rat) or PbAc (3 nmol/rat) did not modify food intake in rats deprived of food for 24 h. Thus, general central nervous system depression explaining the antidipsogenic action of the metals can be safely excluded. It is concluded that both Pb2+ and Cd2+ inhibit water intake induced by central beta-adrenergic stimulation.
authors.affiliation: Departamento de Zoologia, Universidade Federal da Bahia, Salvador, Brasil.
authors.forename: J B
authors.initials: JB
authors.lastname: Fregoneze
authors.forename: C A
authors.initials: CA
authors.lastname: Marinho
authors.forename: T
authors.initials: T
authors.lastname: Soares
authors.forename: L
authors.initials: L
authors.lastname: Castro
authors.forename: C
authors.initials: C
authors.lastname: Sarmento
authors.forename: M
authors.initials: M
authors.lastname: Cunha
authors.forename: V
authors.initials: V
authors.lastname: Gonzalez
authors.forename: P
authors.initials: P
authors.lastname: Oliveira
authors.forename: T
authors.initials: T
authors.lastname: Nascimento
authors.forename: C P
authors.initials: CP
authors.lastname: Luz
authors.forename: P
authors.initials: P
authors.lastname: Santana Júnior
authors.forename: I R
authors.initials: IR
authors.lastname: De-Oliveira
authors.forename: E
authors.initials: E
authors.lastname: De-Castro-e-Silva
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D002104:Cadmium / Q000494:pharmacology*; D002552:Cerebral Ventricles / Q000187:drug effects*; D004326:Drinking / Q000187:drug effects*; D007545:Isoproterenol / Q000037:antagonists & inhibitors*; D007854:Lead / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000319:Adrenergic beta-Antagonists; D002104:Cadmium; D007854:Lead; D007545:Isoproterenol