Intake of umami-tasting solutions by mice: A genetic analysis

In two-bottle preference tests with water and solutions of monosodium gluta mate (MSG) and inosine-5'-monophosphate (IMP), mice from the C57BL/6ByJ inb red strain consumed more and had higher preferences for these solutions com pared with mice from the 129/J strain. The C57BL/6ByJ mice consumed 300 mmo l/L MSG in large amounts, which were comparable to intakes of highly prefer red solutions of sweeteners. The strain differences in voluntary consumptio n of 300 mmol/L MSG depended at least in part on postingestive effects beca use prior experience with MSG influenced the expression of the strain diffe rence in MSG acceptance. The strain difference in MSG acceptance was in the opposite direction to the strain difference in NaCl acceptance and was not affected by previous consumption of saccharin. Although the C57BL/6ByJ mic e had higher avidity for both MSG and sweeteners than did the 129/J mice, t here was no correlation between preferences for these solutions in the seco nd hybrid generation (F-2) derived from these two strains. 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 uma mi taste responsiveness. High acceptance of MSG solutions by the C57BL/6ByJ mice was inherited as a recessive trait in the F-2 generation. Further gen etic linkage analyses using the F-2 hybrids are being conducted to map chro mosomal locations of genes determining the strain difference in MSG accepta nce.