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Rapid onset sodium appetite and orofacial responses to intraoral capsaicin and hypertonic NaCl in the rat

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Author(s):
Rodrigues Fernandes, Natalie Aparecida ; Santos, Bruna Maitan ; Fabricio de Andrade-Franze, Glaucia Maria ; de Paula, Patricia Maria ; Fabricio de Andrade, Carina Aparecida ; Menani, Jose Vanderlei ; De Luca Jr, Laurival Antonio
Total Authors: 7
Document type: Journal article
Source: APPETITE; v. 174, p. 6-pg., 2022-04-09.
Abstract

Sodium appetite reverts from aversive to hedonic the orofacial responses to intraoral hypertonic NaCl in a taste reactivity test (TRT). An electrophysiological-based hypothesis suggests that aversion to salty taste results from oral nociception (e.g., like that produced by intraoral capsaicin). In the present work, we used the TRT to investigate whether sodium appetite and its sensitization produce similar effects on the orofacial responses to the intraoral infusion of either capsaicin or hypertonic NaCl. We produced rapid onset sodium appetite by subcutaneous injection of furosemide combined with a low dose of captopril (Furo/Cap) in adult rats instrumented with intraoral cannula. Then, the animals had 1-h free access to water (thirst test). Immediately after, they entered the TRT receiving a first intraoral infusion (1 ml for a total of 1 min) of (0.5 mu M) capsaicin and, 20 min later, a second one of (0.3 M) NaCl. The sequence, Furo/Cap injection thirst test TRT, was repeated twice more every three days. The repetition of the Furo/Cap increased the frequency of hedonic responses, decreased the frequency of aversive responses, and increased the hedonic:neutral response ratio to NaCl. The repetition of Furo/Cap reduced transiently the neutral orofacial responses and ended decreasing the aversive:neutral response ratio to capsaicin. The results suggest that repeated Furo/Cap sensitizes the palatability of hypertonic NaCl. They also suggest that sensitization of sodium appetite involves increased sodium "liking". Finally yet importantly, we found that sensitization of sodium appetite can influence orofacial responses to capsaicin. Rapid onset sodium appetite and orofacial responses to intraoral capsaicin and hypertonic NaCl in the rat. (AU)

FAPESP's process: 15/20500-3 - Role of lateral parabrachial nucleus and forebrain angiotensinergic receptors in the control of hydro mineral balance during primary hypertension.
Grantee:Carina Aparecida Fabrício de Andrade
Support Opportunities: Regular Research Grants
FAPESP's process: 11/50770-1 - Neural mechanisms involved of hydroelectrolytic balance and cardiorespiratory control
Grantee:José Vanderlei Menani
Support Opportunities: Research Projects - Thematic Grants