Fly chemoreceptors: A model system for the taste modifier ziziphin

Abstract

Ziziphin (from Ziziphus jujuba) selectively suppresses sweetness perception in humans. After a 3 min ziziphin treatment of Phormia regina tarsal chemoreceptors, the fly behavioral proboscis response to sucrose was suppressed at the initial test at 0.5 min post-ziziphin. The median time to recovery was 5.5 min postziziphin. A similar treatment significantly ( p<0.02) decreased fly labellar chemoreceptor firing rates to sucrose, with a median reduction of 60% at 1 min posttreatment and a gradual increase in response magnitude to 100% of preziziphin values at 7 min posttreatment. These behavioral and neurophysiological inhibition times are comparable to those in human psychophysical responses. Fly chemoreceptor firing rates to NaCl were not depressed except for a small (30%), but significant ( p<0.01), reduction at 3 min postziziphin. However, as in human psychophysical responses, the fly neural response to NaCl was not reduced at 1 min posttreatment. P. regina is an appropriate model for physiological studies with ziziphin and may permit an understanding of taste modifier action at the chemoreceptor cell.