Development of Taste Nerves Responses in Mice

Abstract

The taste sensitivity of preweanling mice was studied by examining the responses of the chorda tympani (CT) and glossopharyngeal (GL) nerves to various taste stimuli, and comparing them with those of adult mice. In mice of 7-10 days age, compared to that of the CT nerve, the threshold of the GL nerve for glutamate was low, while those for Sucrose and NaCl were high.
Sensitivities to HCl and Quinine-HCl were similar between the CT and GL nerves, although that to Quinine-HCl was larger in the GL nerve than in the CT nerve in adult mice. Enhancement of MSG responses by addition of GMP was observed in the CT nerve but not in the GL nerve in this age group. In mice of 8-16 weeks of age, the threshold of the GL nerve for MSG became higher while that for NaCl became lower.
Enhancement of MSG responses by addition of GMP appeared also in the GL nerve. The inhibition of NaCl responses by Amiloride was observed in the CT nerve, but not in the GL nerve. These results suggest that, in mice, the GL nerve is an important taste input for umami substances especially during the preweanling period, whereas the CT nerve is important for sweet and salty substances. Properties of the umami and salty receptor systems change during the postweanling period.