EFFECTS OF DIETARY BIOTIN ON ENHANCED SUCROSE INTAKE AND ENHANCED GUSTATORY NERVE RESPONSES TO SUCROSE SEEN IN DIABETIC OLETF RAT

We used the sucrose preference test and taste nerve recording to inves tigate the effect of dietary biotin on the abnormal sucrose taste sens itivity and preferences seen during the course of diabetes mellitus, F or this, we used Otsuka Long-Evans Tokushima fatty (OLETF) rats. The c horda tympani nerve (CT nerve) response to sucrose ( > 1 M) was of gre ater relative magnitude in OLETF rats than in non-diabetic control (Lo ng-Evans Tokushima Lean, LETO) rats, but the responses to other basic taste stimuli (such as HCl, quinine-HCl and L-glutamic acid) did not d iffer between the two groups. In behavioral experiments using a two-bo ttle preference test, solution intake for sucrose( > 50 mM) was higher in OLETF rats than in LETO rats. The neural responses to sucrose (1.5 -2 M) in OLETF rats were lower when given a biotin-high diet (BH-OLETF ) than when given a biotin-basal diet (BB-OLETF), but this was not tru e of the other basic tastes. However, there were no significant differ ences between BH-OLETF and BB-OLETF rats in terms of sucrose solution intake. These findings suggest that the enhanced sugar sensitivity obs erved in OLETF rats is probably the result of a genetic difference bet ween OLETF and LETO rats, though the discrepancy can be modified by th e dietary biotin level.