propylthiouracil and sucrose-octaacetate

Topics: Animals; Cycloheximide; Dose-Response Relationship, Drug; Male; Propylthiouracil; Quaternary Ammonium Compounds; Quinine; Random Allocation; Rats; Rats, Long-Evans; Stimulation, Chemical; Sucrose; Taste

In the course of our ongoing studies of odor-cued taste avoidance (OCTA) to measure olfactory capabilities in animals, we observed that mice could rapidly learn to use the vapor of the classical bitterant quinine hydrochloride to avoid contact with the tastant. Here we expand on this observation to determine which among several compounds generally classed as bitter could be detected at a distance. Since mice were initially naïve we were able to assess whether the vapors of the bitter compounds tested were innately aversive as are their tastes. CD-1 mice could readily use vapor cues from quinine hydrochloride, denatonium benzoate (DB), and 6-propyl-2-thiouracil to avoid their taste. Although mice did not hesitate to make contact with these solutions on their first exposure, they did learn to do so typically after only 1 or 2 exposures. Bilaterally bulbectomized mice did not learn or retain the ability to avoid quinine and DB solutions by vapor alone, implicating olfaction as the mode of detection. Saturated aqueous solutions of sucrose octaacetate and caffeine which are bitter to humans and some strains of mice were not aversive in our studies. The very low vapor concentrations of the 3 bitterant solutions that mice detected at a distance, suggest that impurities in the reagent grade solutions, rather than the bitter molecules themselves were the basis of detection. Implications of these findings for taste testing and the role of odor in food acceptance/rejections decisions are discussed.

Topics: Animals; Aversive Agents; Avoidance Learning; Caffeine; Cues; Female; Mice; Olfactory Bulb; Propylthiouracil; Quaternary Ammonium Compounds; Quinine; Smell; Sucrose; Taste

The perceived bitterness intensity for bitter solutions of propylthiouracil (PROP), sucrose octa-acetate (SOA), quinine HCl and caffeine were examined in a genetically informative sample of 392 females and 313 males (mean age of 17.8 +/- 3.1 years), including 62 monozygotic and 131 dizygotic twin pairs and 237 sib pairs. Broad-sense heritabilities were estimated at 0.72, 0.28, 0.34, and 0.30 for PROP, SOA, quinine, and caffeine, respectively, for perceived intensity measures. Modeling showed 1) a group factor which explained a large amount of the genetic variation in SOA, quinine, and caffeine (22-28% phenotypic variation), 2) a factor responsible for all the genetic variation in PROP (72% phenotypic variation), which only accounted for 1% and 2% of the phenotypic variation in SOA and caffeine, respectively, and 3) a modest specific genetic factor for quinine (12% phenotypic variation). Unique environmental influences for all four compounds were due to a single factor responsible for 7-22% of phenotypic variation. The results suggest that the perception of PROP and the perception of SOA, quinine, and caffeine are influenced by two distinct sets of genes.

Topics: Adolescent; Adult; Caffeine; Child; Female; Genetic Variation; Humans; Inheritance Patterns; Male; Models, Genetic; Phenotype; Propylthiouracil; Quinine; Sensitivity and Specificity; Siblings; Sucrose; Taste; Twins, Dizygotic; Twins, Monozygotic