Absolute and relative rewarding properties of fructose, glucose, and saccharin mixtures as reflected in anticipatory contrast.
Rats preferred 2% fructose (F) to 2% glucose (G) in daily 5-min two-bottle preference tests, but preferred 8% G to 8% F with the same testing procedure. In four subsequent experiments brief (3 min) once-per-day sequential presentations of two F or two G solutions showed the following results. Anticipatory negative contrast (suppressed intake of the initial solution) was greater with quantitative variations in fructose (2% F followed by either 8, 16, or 32% F) than was the case when the same concentrations of G were paired. No contrast occurred with qualitative pairings of the two sugars--instead G enhanced the intake of F whether it was presented before or after F. A solution of 0.15% saccharin produced more suppression (contrast) of 2% glucose than of 2% fructose. Also, mixtures of 0.15% saccharin with either sugar (2 or 8% F or G) enhanced absolute intake of the sugars but did not substantially increase their contrast-producing properties--suggesting a distinction between absolute and relative rewarding properties of sugar/saccharin mixtures. In summary, anticipatory negative contrast can be produced by either taste or postingestive factors but the relationship between two-bottle preference, absolute reward value (as reflected in consumption in noncontrast conditions), and relative reward value (measured by the capacity to produce contrast) is complex.
Rutgers University, Department of Psychology, Piscataway, NJ 08854-8086, USA. flaherty@psych-b.rutgers.edu
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Mitchell
D000818:Animals; D002755:Choice Behavior / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005247:Feeding Behavior / Q000502:physiology*; D005632:Fructose / Q000008:administration & dosage; D005947:Glucose / Q000008:administration & dosage; D007266:Inhibition, Psychological; D008297:Male; D011601:Psychophysics; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D012439:Saccharin / Q000008:administration & dosage; D013649:Taste / Q000502:physiology*; D013997:Time Factors
D005632:Fructose; D012439:Saccharin; D005947:Glucose