| Abstract: | The gustatory responses from the chorda tympani nerve of theMongolian gerbil Meriones unguiculatus were tested with somemethyl glycopyranosides and inhibitors. Except for one compound,methyl 4,6 dichloro-4,6-dideoxy  -D-galactopyranoside, all sugarsstimulated the taste nerve. In our previous research, we foundone of the most effective methyl glycosides was methyl -D-glycopyranoside(MAD-Glu). We also found that methyl glycosides, which differedfrom MAD-Glu by the orientation of a substituent group at C-1,C-2 and C-4, were always less effective taste stimuli. In ourpresent study, we have extended this finding to include theC-3 epimer which was also found to be less effective than MAD-Glu.In a second set of experiments, we looked at deoxy sugars. Incontrast to orientation effects found in the epimers, substitutionof the hydroxyl groups of MAD-Glu by hydrogen atoms (deoxy-sugars)had variable effects. The 3-deoxy and 6-deoxy derivatives werefound to be as effective as MAD-Glu, while the 4-deoxy derivativewas less effective. In addition, substituting chlorine atomsfor the hydroxyl groups appears to have a deleterious effect.For example, the 6-chloro derivative was less effective thanMAD-Glu while the 4,6-dichloro derivative of methyl -D-galactopyranosidedid not stimulate the nerve at all. Finally, in addition tostructure-activity experiments mentioned above, we examinedthe possibility that the sugar taste response may involve otherphysiological factors. In this vein, we found that the sugartransport inhibitors phloretin and phlorhizin and the sodiumchannel blocker, amilonde had no effect on the gerbil's sucroseor glucose taste responses |
