Abstract
Genetically diabetic db/db mice showed greater neural and behavioral responses to sugar than lean contorol mice. The present study examined chorda tympani responses of db/db mice to nonsugar sweeteners and their inhibition by a sweet response inhibitor, gurmarin. We made crosses between C 57BLIKsJ-+/db, heterozygotes at the db locusa nd showing sweet taster esponsest o D-phe(ddp+), and BALB mice, lacking sweet responses to D-phe (dpa-), and produced diabetic and lean mice with mixed genetic backgrounds of two inbred strains in their F 2 generations. Behavioral preferences for D-phenylalanine, sucrose and saccharin Na, mesured by a two bottle test were compared among diabetic and lean contorol F 2 mice. Diabetic and contorol mice were divided into two subgroups (dpa+ and dpa-) according to their preferences for D-phe, and in total four groups, such as dpa+ -db/db, dpa--db/db, dpa+-+/?and dpa--+/?. The resultss howed thatr esponsest o sucrose, saccharin Na, glycine, L-alanine and D-tryptophan, but not to D-phenylalanine, were greater in db/db mice than in the control mice. The preferences for sucrose and saccharin Na of dpa--db/db mice were significantly higher than thoseo f dpa--+/?mice, whereas no such difbrencew as observed between dpa+-db/db and dpa+-+/?mice. The resultss uggestt hat enhanced preferencesf or sweet substanceso f db/db mice are evident in dpa- but not dpa+ groups, and mixing of genetic backgrounds of BALB with C 57 may reduce differences in sweet preferences between db/db and lean contorol mice.
