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.
Flaherty
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Rutgers University, Department of Psychology, Piscataway, NJ 08854-8086, USA. flaherty@psych-b.rutgers.edu
Mitchell
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C
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