ENHANCED RESPONSES OF THE CHORDA TYMPANI NERVE TO NONSUGAR SWEETENERSIN THE DIABETIC DB DB MOUSE/

Genetically diabetic db/db mice show greater neural and behavioral res ponses to sugars than lean control mice. The present study examined ch orda tympani responses of db/db mice to nonsugar sweeteners and their inhibition by a sweet response inhibitor, gurmarin. The results showed that responses to sucrose, saccharin, glycine, L-alanine, and D-trypt ophan, but not to D-phenylalanine, were similar to 1.5 times greater i n db/db mice than in control mice. Treatment of the tongue with gurmar in suppressed responses to these sweeteners in db/db and control mice, but the extent of suppression was considerably smaller in db/db mice. The magnitudes of gurmarin-sensitive components of the response to sw eeteners in db/db mice were not significantly different from those in control mice, whereas the magnitudes of gurmarin-insensitive component s in db/db mice were about twice as large as those in control mice. Th ese results suggest that the enhancement of chorda tympani responses i n db/db mice to sucrose and other nonsugar sweeteners may occur throug h gurmarin-insensitive membrane components.