Amiloride-sensitive sodium signals and salt appetite: multiple gustatory pathways.
In the rat, the ionic specificity of Na+ appetite is thought to rely on amiloride-sensitive Na+ signals conveyed by the chorda tympani (CT) nerve. We evaluated whether robust Na+ appetite relies exclusively on CT-mediated amiloride-sensitive Na+ signals. Amiloride dramatically reduced sham drinking of NaCl (41.9 +/- 9.0 vs. 6.9 +/- 3.7 ml, 0.1 M NaCl without vs. with 100 microM amiloride), which resulted in intake that was not different from intake of a non-Na+ salt solution (8.8 +/- 2.3 ml, 0.15 M KCl). In addition, intake of 0.1 M NaCl in CT-transected (CTX) rats was reduced (35.8 +/- 13.3 vs. 8.67 +/- 3.4 ml, sham-operated vs. CTX rats), but the addition of amiloride (100 microM) further reduced intake in CTX rats (0.5 +/- 0.29 ml). These data support the idea that amiloride-sensitive Na+ channels are the critical gustatory substrate for Na+ identification during Na+ appetite in the rat. However, the data indicate that these amiloride-sensitive signals are not conveyed exclusively by the CT nerve but by an additional afferent pathway.
Roitman
M F
MF
Program in Neurobiology and Behavior, University of Washington, Seattle, Washington 98195, USA. roitman@u.washington.edu
Bernstein
I L
IL
D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D001066:Appetite / Q000502:physiology*; D002814:Chorda Tympani Nerve / Q000502:physiology; D003714:Denervation; D004326:Drinking / Q000187:drug effects; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D051381:Rats; D020318:Rats, Long-Evans; D015398:Signal Transduction / Q000502:physiology*; D012964:Sodium / Q000502:physiology*; D012965:Sodium Chloride; D013649:Taste / Q000502:physiology*
D012965:Sodium Chloride; D000584:Amiloride; D012964:Sodium