| Abstract: | A persistent problem with attempts to examine bitter taste mechanismshas been the lack of adequate behavioral methodology providingdata which parallels that obtained from physiological investigations.We developed a brief contact procedure to assess the abilityof rats to detect the presence of a weak bitter compound dissolvedin a strong sucrose solution. Male Fischer 344 rats were trainedto drink immediately to multiple 10-s presentations of acetaminophen(2, 8, 32, 128 mM), chlorpheniramine maleate (1, 3, 9, 27 mM)L-tryptophan (13.5, 27, 54, 108 mM), pseudoephedrine hydrochloride(1, 4, 16, 64 mM) and quinine hydrochloride (0.008, 0.04, 0.2,1.0 mM) dissolved in 0.8 M sucrose. The number of licks to sucroseand water were also measured. A microcomputer controlled stimuluspresentations and measured the animal's licks of each solutionduring each 10-s presentation. The responses to the bitter +sucrose mixture were significantly decreased at most concentrationswith increasing levels of the bitter component. This was truefor all five bitter-tasting compounds, but over different concentrationranges relatively unique to each compound. The present studyis the first to characterize the sensory effects of acetaminophen,pseudoephedrine, and chlorpheniramine maleate, all purportedto taste bitter to humans. These results demonstrate rats' acuteability to discriminate by taste not only the presence but theconcentration of a dilute bitter compound dissolved in a strongsucrose solution. Chem. Senses 20: 305–312, 1995. |
