Development of the enhanced neural response to NaCl in Fischer 344 rats.

To examine the development of strain differences in the response of the chorda tympani nerve (CT) to NaCl, integrated CT responses to NaCl were recorded from Wistar and F344 rats between 15 and 36 days old. NaCl responses before and after the application of amiloride were expressed relative to 0.5 M NH4Cl as a standard. At 15-17 days old, there were no significant strain differences in the magnitude of NaCl responses. Strain differences emerged at 21-23 days old with responses of F344 rats significantly higher than those of Wistars; these differences became more pronounced at 34-36 days old. Amiloride significantly reduced responses to NaCl at all ages and eliminated any differences between the strains. Changes in neural responsiveness correspond with the emergence of the behavioral expression of F344 salt aversion.