title: Calcium channel blockers inhibit the antidipsogenic effect of central injections of zinc in rats.
abstract: Previous data from our laboratory have indicated that acute third ventricle injections of Zn2+ elicit a significant antidipsogenic response in rats in three different situations; dehydration, and central angiotensinergic or cholineric stimulation. In the present study we analyzed whether this response depends on voltage-dependent calcium channels. Dehydrated (14 h of water deprivation, overnight) animals received 2-microliters i.c.v. injections of zinc acetate (Zn(Ac)2; 300 pmol/rat) after pretreatment with the voltage-dependent calcium channel blockers gadolinium (Gd3+; 0.03, 3.0 and 30 pmol/rat) or verapamil (VER; 0.027, 0.05 and 0.11 pmol/rat). Both blockers reserved the antidipsogenic effect of third ventricle injections of Zn2+ in a dose-dependent manner. After 120 min, animals pretreated with saline receiving Zn(Ac)2 drank 3.10 +/- 0.57 ml/100 g body weight while those pretreated with Gd3+ at the highest dose displayed a water intake of 5.45 +/- 0.41 ml/100 body weight (P < 0.01). Animals pretreated with the vehicle of VER receiving Zn(Ac)2 drank 3.15 +/- 0.45 ml/100 g while animals pretreated with VER at the highest dose receiving Zn(Ac)2 drank 6.16 +/- 0.62 ml/100 g (P < 0.01). The antidipsogenic effect of Zn(Ac)2 seems to be specific since the metal (same dose and injection procedures) did not modify food intake in rats after 24 h of food deprivation. It is suggested that Zn2+ exerts its antidipsogenic effect by activation of mechanism(s) depending on the functional integrity of voltage-dependent calcium channels.
authors.affiliation: Departamento de Zoologia, Universidade de Federal de Bahia, Salvador, Brasil.
authors.forename: E
authors.initials: E
authors.lastname: DeCastro-e-Sliva
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: Gonzales
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: DeOliveira
authors.forename: J B
authors.initials: JB
authors.lastname: Fregoneze
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003681:Dehydration; D004326:Drinking / Q000187:drug effects; D005682:Gadolinium / Q000494:pharmacology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014700:Verapamil / Q000494:pharmacology; D015032:Zinc / Q000037:antagonists & inhibitors*
chemical_list: D002121:Calcium Channel Blockers; D005682:Gadolinium; D014700:Verapamil; D015032:Zinc