title: Hydrogen peroxide centrally attenuates hyperosmolarity-induced thirst and natriuresis.
abstract: Intragastric hypertonic NaCl that simulates the ingestion of osmotically active substances by food intake induces thirst, vasopressin and oxytocin release, diuresis and natriuresis. Reactive oxygen species (ROS) produced endogenously in central areas may act modulating autonomic and behavioral responses. In the present study, we investigated the effects of H2O2 injected centrally on water intake and renal responses induced by increasing plasma osmolality with intragastric (ig) administration of 2M NaCl (2 ml/rat). Male Holtzman rats (280-320 g) with stainless steel cannula implanted in the lateral ventricle (LV) were used. Injections of H2O2 (2.5 μmol/1 μl) into the LV reduced ig 2M NaCl-induced water intake (3.1 ± 0.7, vs. PBS: 8.6 ± 1.0 ml/60 min, p<0.05), natriuresis (769 ± 93, vs. PBS: 1158 ± 168 μEq/120 min, p<0.05) and diuresis (4.1 ± 0.5, vs. PBS: 5.0 ± 0.5 ml/120 min, p<0.05). Injections of H2O2 into the LV also decreased meal associated water intake (4.9 ± 1.5, vs. PBS: 11.0 ± 1.7 ml/120 min). However, H2O2 into the LV did not modify 2% sucrose intake (3.3 ± 1.5, vs. PBS: 5.4 ± 2.3 ml/120 min) or 24h food deprivation-induced food intake (8.2 ± 2.0, vs. PBS: 11.0 ± 1.6g/120 min), suggesting that this treatment does not produce nonspecific inhibition of ingestive behaviors. The data suggest an inhibitory role for H2O2 acting centrally on thirst and natriuresis induced by hyperosmolarity and on meal-associated thirst.
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: Regis C
authors.initials: RC
authors.lastname: Zanella
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: Mariana Rosso
authors.initials: MR
authors.lastname: Melo
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: Werner Issao
authors.initials: WI
authors.lastname: Furuya
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Colombari
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
authors.forename: José V
authors.initials: JV
authors.lastname: Menani
authors.affiliation: Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil. Electronic address: deborac@foar.unesp.br.
authors.forename: Débora Simões Almeida
authors.initials: DS
authors.lastname: Colombari
mesh_terms: D000818:Animals; D002414:Cations, Monovalent; D004326:Drinking / Q000187:drug effects; D004435:Eating / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D007276:Injections, Intraventricular; D008297:Male; D009318:Natriuresis / Q000187:drug effects*; D009994:Osmolar Concentration; D011188:Potassium / Q000652:urine; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000652:urine; D012965:Sodium Chloride / Q000494:pharmacology; D013395:Sucrose; D013894:Thirst / Q000187:drug effects*
chemical_list: D002414:Cations, Monovalent; D012965:Sodium Chloride; D013395:Sucrose; D012964:Sodium; D006861:Hydrogen Peroxide; D011188:Potassium
keywords: Hypertonic saline; Osmoreceptors; Reactive oxygen species; Renal excretion; Water intake