Gustatory neural responses during sodium appetite induced by three different regimens

Dietary sodium deprivation induces salt appetite and alters the responsiveness of gustatory neurons to NaCl solutions. We replicated this experiment while recording from the nucleus of the solitary tract of chronically prepared rats using diet, diuretic, or a hormone to raise the appetite. As in previous experiments, dietary deprivation reduced the response magnitude of NaCl-best taste neurons but, unlike in those reports, the effect was relatively non-specific. The mean response to NaCl, sucrose, citric acid, and quinine all decreased by roughly the same amount (range 41.84%). In addition, the mean responses of sucrose-best cells also were reduced. When we used a diuretic, furosemide, to induce an appetite in a similar preparation, NaCl-best neurons responded more, rather than less, and the effect was specific to NaCl. Intraventricular injections of renin also induce salt appetite. This regimen resulted in a modest reduction in the response of NaCl-best neurons to NaCl, but only at higher concentrations (0.3 and 1.0 M). (Supported by NIH MH 3787, DC 00240, and MH 00653.).