Genetics of intake of umami-tasting solutions by mice

Inbred strains of mice provide a powerful tool for genetic dissection of quantitative behavioral traits. We have investigated intake of the umami-tasting substances monosodium glutamate (MSG) and inosine 5'-monophosphate (IMP) in inbred mice. Studies with two inbred strains, C57BL/6ByJ and I29P3/J have revealed strain differences in voluntary consumption of 300 mM MSG which depend, at least partially, on postingestive effects of solution consumption, as well as on strain differences in preferences for much lower MSG concentrations, which depend on perception. The strain difference in MSG acceptance was in the opposite direction to the strain difference in NaCl acceptance and was unrelated to sweetener preference in the F(2) generation. Thus, the strain differences in MSG acceptance are not related to the strain differences in salty or sweet taste responsiveness and most likely represent specific umami taste responsiveness. High acceptance of MSG solutions by the C57BL/6ByJ mice was inherited us a recessive trait in the F(2) hybrid generation. Further genetic linkage analyses using the F(2) hybrids are being conducted to map chromosomal locations of genes determining the strain difference in MSG acceptance. At the same time, a wider range of inbred strains is being phenotyped in a search for new model systems for studying umami substance acceptance.