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Chronic excitotoxic lesion of the dorsal raphe nucleus induces sodium appetite.

Authors :
Cavalcante-Lima HR
Badauê-Passos D Jr
de-Lucca W Jr
Lima HR
Costa-e-Sousa RH
Olivares EL
Cedraz-Mercez PL
Reis RO
Medeiros MA
Côrtes WS
Reis LC
Source :
Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas [Braz J Med Biol Res] 2005 Nov; Vol. 38 (11), pp. 1669-75. Date of Electronic Publication: 2005 Oct 26.
Publication Year :
2005

Abstract

We determined if the dorsal raphe nucleus (DRN) exerts tonic control of basal and stimulated sodium and water intake. Male Wistar rats weighing 300-350 g were microinjected with phosphate buffer (PB-DRN, N = 11) or 1 microg/0.2 microl, in a single dose, ibotenic acid (IBO-DRN, N = 9 to 10) through a guide cannula into the DRN and were observed for 21 days in order to measure basal sodium appetite and water intake and in the following situations: furosemide-induced sodium depletion (20 mg/kg, sc, 24 h before the experiment) and a low dose of dietary captopril (1 mg/g chow). From the 6th day after ibotenic acid injection IBO-DRN rats showed an increase in sodium appetite (12.0 +/- 2.3 to 22.3 +/- 4.6 ml 0.3 M NaCl intake) whereas PB-DRN did not exceed 2 ml (P < 0.001). Water intake was comparable in both groups. In addition to a higher dipsogenic response, sodium-depleted IBO-DRN animals displayed an increase of 0.3 M NaCl intake compared to PB-DRN (37.4 +/- 3.8 vs 21.6 +/- 3.9 ml 300 min after fluid offer, P < 0.001). Captopril added to chow caused an increase of 0.3 M NaCl intake during the first 2 days (IBO-DRN, 33.8 +/- 4.3 and 32.5 +/- 3.4 ml on day 1 and day 2, respectively, vs 20.2 +/- 2.8 ml on day 0, P < 0.001). These data support the view that DRN, probably via ascending serotonergic system, tonically modulates sodium appetite under basal and sodium depletion conditions and/or after an increase in peripheral or brain angiotensin II.

Details

Language :
English
ISSN :
0100-879X
Volume :
38
Issue :
11
Database :
MEDLINE
Journal :
Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas
Publication Type :
Academic Journal
Accession number :
16258637
Full Text :
https://doi.org/10.1590/s0100-879x2005001100015