The sweet taste inhibitor methyl 4,6-dichloro-4,6-dideoxy-{alpha}-D-galactopyranoside inhibits sucrose stimulation of the chorda tympani nerve and of the adenylate cyclase in anterior lingual membranes of rats

The effects of the sweet taste inhibitor methyl 4,6-dichloro-4,6-dideoxy--D-galactopyranoside(MAD-diCl-Gal) and a few disaccharides, on the electrophysiologicalresponses of the chorda tympani nerve and on adenylate cyclasein membranes prepared from the anterior tongue epithelium, werestudied in rats. MAD-diCl-Gal inhibited the sucrose stimulationof whole chords tympani responses, and this inhibition was reversible.In addition, MAD-diCl-Gal inhibited the sucrose stimulationof adenylate cyclase activity in lingual (gustatory) membranesin a dose-dependent manner. High concentrations of MAD-diCl-Galabolished the sucrose induced adenylate cyclase activity. Thedisaccharides sucrose, maltose, trehalose and melibiose stimulatedboth chords tympani nerve responses and adenylate cyclase activity.These stimulations were dose dependent. Sucrose was the mostpotent stimulator of the chorda tympani nerve. Other disaccharidesresulted in lower responses than sucrose. Sucrose was also amore effective stimulus than maltose for adenylate cyclase activity.In contrast to electrophysiological data, trehalose and melibiosestimulated the adenylate cyclase activity to the same extentas sucrose. The results of this study support the suggestionof cAMP involvement in the cellular transduction of sweet tastein the rat.