Reversal of the sodium chloride aversion of Fischer 344 rats by chorda tympani nerve transection.
Fischer 344 (F344) rats are atypical in their lack of preference for any concentration of NaCl solution over water. It was hypothesized that abnormal signals mediated by the chorda tympani nerve (CT) could be causally involved in NaCl avoidance by F344 rats. This study assessed whether CT transection would normalize the salt preference of F344 rats. Preference for NaCl solutions (0.6%, 0.8%, and 1.0%) versus water was assessed using two-bottle preference tests. At all concentrations tested, CT-transected animals preferred NaCl solutions to water. This preference differed dramatically from the avoidance of these solutions by controls. These findings are striking, particularly because CT transections have generally failed to significantly affect NaCl preference in other rat strains. The results are consistent with the hypothesis that in F344 rats the avoidance of the taste of NaCl stems from input mediated by the CT.