Dipsogenic stimulation in ibotenic DRN-lesioned rats induces concomitant sodium appetite.
The main purpose of this study was to investigate whether dipsogenic stimuli influences the sodium appetite of rats with ibotenic acid lesion of the dorsal raphe nucleus (IBO-DRN). Compared to control, rats microinjected with phosphate buffer (PB-DRN), the ingestion of 0.3M NaCl was enhanced in IBO-DRN at 21 and 35 days after DRN lesion under a protocol of fluids and food deprivation. Despite of similar dipsogenic response observed both in IBO-DRN and PB-DRN treated with isoproterenol (ISO, 300 microg/kg, sc), the 0.3M NaCl intake was again significantly enhanced in IBO-DRN at 21 and 35 days post-lesion. Finally, treatment with polyethylene glycol (PEG, MW=20,000, 20%, w/v, 16.7 ml/kg, sc) induced higher dipsogenic response in IBO-DRN than PB-DRN at 21 day after lesion. In addition, IBO-DRN also expressed higher sodium appetite than PB-DRN, concomitantly with a drinking response. These results suggest that ibotenic lesion of DRN promote an increase of the brain angiotensinergic response, possibly settled within the subfornical organ, through paradigms which increase circulating ANG II levels. The current paper supports the hypothesis that the ibotenic lesion of DRN suppresses a serotonergic component implicated on the modulation of the sodium appetite and, therefore, furthering homeostatic restoration of extracellular fluid volume.
Cavalcante-Lima
Haerishton Rubim
HR
Department of Physiological Sciences, Institute of Biology, Federal Rural University of Rio de Janeiro, BR465, Km 7, 23890-000 Seropédica, RJ, Brazil.
Lima
Hawlinston Rubim Cavalcante
HR
Costa-e-Sousa
Ricardo Henrique
RH
Olivares
Emerson Lopes
EL
Cedraz-Mercez
Pedro Leonardo
PL
Reis
Rafael Oliveira
RO
Badauê-Passos
Daniel
D
De-Lucca
Waldecy
W
de Medeiros
Magda Alves
MA
Côrtes
Wellington da Silva
Wda S
Reis
Luís Carlos
LC
D000818:Animals; D001066:Appetite / Q000187:drug effects / Q000502:physiology*; D004326:Drinking / Q000187:drug effects / Q000502:physiology; D007051:Ibotenic Acid / Q000633:toxicity*; D008297:Male; D009498:Neurotoxins / Q000633:toxicity; D011903:Raphe Nuclei / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000008:administration & dosage*; D012982:Sodium, Dietary / Q000032:analysis*; D013894:Thirst / Q000187:drug effects* / Q000502:physiology*
D009498:Neurotoxins; D012982:Sodium, Dietary; D007051:Ibotenic Acid; D012964:Sodium