Conditioned Flavor Avoidance, Preference, and Indifference Produced by Intragastric Infusions of Galactose, Glucose, and Fructose in Rats

Sclafani, Anthony; Fanizza, Lawrence J; Azzara, Anthony V.

doi:10.1016/s0031-9384(99)00053-0

Cited by 108 publications

(121 citation statements)

References 19 publications

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“…Taken together, these results suggest that in the absence of postingestive nutrient effects, maltodextrin is ineffective as a reinforcer in flavor conditioning. The mechanism by which maltodextrin acts as a reinforcer is highlighted by a comparison to fructose, which does not condition a preference in brief sessions when infused directly into the stomach or when there is a delay between the CS and US (Sclafani & Ackroff, 1994;Sclafani, Cardieri, Tucker, Blusk, & Ackroff, 1993;Sclafani, Fanizza, & Azzara, 1999). Thus, any flavor preference conditioned by fructose is attributable to its palatable taste alone.…”

Section: Discussionmentioning

confidence: 99%

Microstructural analysis of conditioned and unconditioned responses to maltodextrin

Dwyer

2008

Learning & Behavior

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The microstructure of licking responses was analyzed to investigate the interaction between unconditioned responses to maltodextrin and the responses to flavor cues previously associated with maltodextrin. Experiment 1 demonstrated that although the consumption of maltodextrin peaked at intermediate concentrations, the mean lick cluster size showed a positive, monotonic increase with concentration. In Experiment 2, a (conditioned stimulus) CS flavor was paired with 16% maltodextrin, whereas a CS flavor was paired with 2% maltodextrin. During test, consumption of the CS was higher than that of the CS when the flavors were combined with 2% maltodextrin, but not when combined with 16% maltodextrin. In contrast, cluster size was larger with the CS than with the CS , regardless of the concentration of maltodextrin present on test. Previous analyses of licking microstructure indicate that cluster size reflects the palatability of the ingested solution. Thus, the present results indicate that flavor conditioning can change the palatability of the cue flavors. Adding the CS flavor to maltodextrin produced results analogous to increasing the concentration of maltodextrin (in terms of both consumption and licking microstructure measures), which is consistent with the idea that after conditioning, responses to the CS flavor and to the unconditioned stimulus are mediated via the same representation.

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Section: Discussionmentioning

confidence: 99%

Microstructural analysis of conditioned and unconditioned responses to maltodextrin

Dwyer

2008

Learning & Behavior

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“…Although fructose has osmotic and caloric properties in addition to a preferred taste, the primary reinforcing effect of fructose is attributable to taste, with little or no postingestive contribution (Sclafani and Ackroff, 1994;Sclafani et al, 1993;Sclafani et al, 1999). Thus, gastric infusion of fructose is a weak US for conditioning a flavor preference (Ackroff et al, 2001;Sclafani et al, 1993;Sclafani et al, 1999), while sham-feeding of flavors in sweet solutions is sufficient to form flavor preferences (Yu et al, 1999;Yu et al, 2000a, b).…”

Section: Discussionmentioning

confidence: 99%

NMDA receptor in conditioned flavor-taste preference learning: Blockade by MK-801 and enhancement by D-cycloserine

Golden

Houpt

2007

Pharmacology Biochemistry and Behavior

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Conditioned flavor-taste preference (CFTP) is a robust form of learning in which animals acquire a preference for a flavor (e.g. Kool-Aid) previously mixed with a highly preferred tastant (e.g. fructose) over a flavor previously mixed with a less preferred tastant (e.g. saccharin). Here, the role of the Nmethyl-D-aspartate (NMDA) glutamate-glycine receptor (NR) was probed using systemic MK-801, a non-competitive antagonist, and D-cycloserine (DCS), a glycine agonist. Rats were injected with MK-801 (100 μg/kg) or vehicle 30 min prior to a daily 2-h conditioning session with 1-bottle access to a Kool-Aid flavor (grape or cherry) mixed with either 8% fructose (CS+/F) or 0.2% saccharin (CS −/S). CFTP expression was measured in 2-bottle preference tests between the Kool-Aid flavors mixed with 0.2% saccharin (CS+/S vs. CS−/S). While vehicle-treated rats acquired a preference for CS+/ S over CS−/S, MK-801 prior to conditioning completely blocked CFTP learning. The effect of MK-801 was specific to CFTP acquisition, because follow-up experiments demonstrated that MK-801 did not induce a conditioned taste aversion, cause state-dependent learning, or affect CFTP expression. In a second approach, rats were injected with DCS (15 mg/kg) 60 min prior to daily conditioning. In contrast to MK-801, adminstration of DCS prior to conditioning enhanced CFTP learning (but not reversal conditioning). These results demonstrate that NR neurotransmission is critical for CFTP learning. Furthermore, enhancement of CFTP learning by DCS suggests that endogenous levels of glycine or D-serine may be a limiting factor in CFTP learning.

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“…The two sensors differ in that glucose and galactose are substrates for SGLT1 but only glucose binds to SGLT3. In rats and mice, IG galactose failed to condition flavor preferences (49,51), which would appear to implicate SGLT3 as the sensor responsible for post-oral glucose appetition. However, a recent study reported that IG intubation of glucose and galactose, but not fructose, conditioned place preferences in mice (30).…”

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confidence: 90%

Post-oral appetite stimulation by sugars and nonmetabolizable sugar analogs

Zukerman

Ackroff

Sclafani

2013

American Journal of Physiology-Regulatory, Integrative and Comp

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131

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Zukerman S, Ackroff K, Sclafani A. Post-oral appetite stimulation by sugars and nonmetabolizable sugar analogs. Am J Physiol Regul Integr Comp Physiol 305: R840 -R853, 2013. First published August 7, 2013 doi:10.1152/ajpregu.00297.2013.-Post-oral sugar actions enhance the intake of and preference for sugar-rich foods, a process referred to as appetition. Here, we investigated the role of intestinal sodium glucose cotransporters (SGLTs) in sugar appetition in C57BL/6J mice using sugars and nonmetabolizable sugar analogs that differ in their affinity for SGLT1 and SGLT3. In experiments 1 and 2, food-restricted mice were trained (1 h/day) to consume a flavored saccharin solution [conditioned stimulus (CSϪ)] paired with intragastric (IG) self-infusions of water and a different flavored solution (CSϩ) paired with infusions of 8 or 12% sugars (glucose, fructose, and galactose) or sugar analogs (␣-methyl-D-glucopyranoside, MDG; 3-O-methyl-D-glucopyranoside, OMG). Subsequent twobottle CSϩ vs. CSϪ choice tests were conducted without coinfusions. Infusions of the SGLT1 ligands glucose, galactose, MDG, and OMG stimulated CSϩ licking above CSϪ levels. However, only glucose, MDG, and galactose conditioned significant CSϩ preferences, with the SGLT3 ligands (glucose, MDG) producing the strongest preferences. Fructose, which is not a ligand for SGLTs, failed to stimulate CSϩ intake or preference. Experiment 3 revealed that IG infusion of MDGϩphloridzin (an SGLT1/3 antagonist) blocked MDG appetition, whereas phloridzin had minimal effects on glucose-induced appetition. However, adding phloretin (a GLUT2 antagonist) to the glucoseϩphloridzin infusion blocked glucose appetition. Taken together, these findings suggest that humoral signals generated by intestinal SGLT1 and SGLT3, and to a lesser degree, GLUT2, mediate post-oral sugar appetition in mice. The MDG results indicate that sugar metabolism is not essential for the post-oral intake-stimulating and preference-conditioning actions of sugars in mice.post-oral sugar conditioning; glucose; fructose; galactose FOOD INTAKE AND PREFERENCE are guided by oral sensations (taste, odor, and mouth feel) that contribute to the identification and hedonic evaluation of food flavor. Considerable progress has been made in identifying the taste receptors that respond to sugar, fat, and amino acids that provide attractive sweet, fatty, and umami flavors to foods (8). The appetite for such foods is further enhanced by the post-oral actions of ingested nutrients (50). This is demonstrated in laboratory rodents by the intake stimulation and learned preferences for arbitrary flavors (conditioned stimuli, CS) that are paired with gastric or intestinal infusions of sugar, fat, and proteins (or glutamate) (50). However, relatively little is known about the sites and identities of the sensors that mediate the post-oral appetite-stimulating actions of nutrients, a process we refer to as appetition (48). In the case of sugars, several findings implicate the upper small intestine as a primary site of a...

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Conditioned Flavor Avoidance, Preference, and Indifference Produced by Intragastric Infusions of Galactose, Glucose, and Fructose in Rats

Cited by 108 publications

References 19 publications

Microstructural analysis of conditioned and unconditioned responses to maltodextrin

Microstructural analysis of conditioned and unconditioned responses to maltodextrin

NMDA receptor in conditioned flavor-taste preference learning: Blockade by MK-801 and enhancement by D-cycloserine

Post-oral appetite stimulation by sugars and nonmetabolizable sugar analogs

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