Release of Feeding by the Sweet Taste in Rats: The specificity of Oral Satiety

doi:10.1016/S0195-6663(81)80016-5

Appetite

Volume 2, Issue 4, December 1981, Pages 267-280

https://doi.org/10.1016/S0195-6663(81)80016-5 Get rights and content

Saccharin intake in hungry rats occurs in discrete “meals”, indicating that a period of saccharin drinking produces a temporary “oral satiety”. We show that such satiety does not suppress the intake of solid food (powdered rat chow), of liquid food (milk), or even of a nutritive sweet solution (glucose) unless it is very dilute. Therefore, oral satiety does not reflect the reduction of a generalized hunger state or of a specific carbohydrate hunger. Having drunk one concentration of saccharin to satiety, the rat will resume drinking if offered a higher concentration but not if offered a lower one, even if the lower one is more palatable than the original concentration. Therefore, in the saccharin-satiated rat, the resumption of drinking requires an increase in stimulus intensity, even if it means a decrease in palatability of the solution offered. We suggest that it is gustatory adaptation that terminates a saccharin meal in the hungry rat.

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Cited by (21)

Memory and eating: A bidirectional relationship implicated in obesity
2022, Neuroscience and Biobehavioral Reviews
Citation Excerpt :
In these experiments, animals are given limited exposure to saccharin to reduce the likelihood of any conditioned responses to the taste. Under such conditions, saccharin has minimal postingestive consequences (Foletto et al., 2016; Mook et al., 1980; Renwick, 1985, 1986; Sclafani and Nissenbaum, 1985) and unlike sucrose, saccharin meal size and meal frequency are controlled primarily by oropharyngeal satiety (Kushner and Mook, 1984; Mook et al., 1980, 1981; Renwick, 1985, 1986; Sclafani and Nissenbaum, 1985). Nonetheless, the possibility remains that dHC inhibition disrupts saccharin intake by interfering with the processing of any mechanical stimulation produced by the saccharin solution in the gut (Waise et al., 2018).
This paper reviews evidence demonstrating a bidirectional relationship between memory and eating in humans and rodents. In humans, amnesia is associated with impaired processing of hunger and satiety cues, disrupted memory of recent meals, and overconsumption. In healthy participants, meal-related memory limits subsequent ingestive behavior and obesity is associated with impaired memory and disturbances in the hippocampus. Evidence from rodents suggests that dorsal hippocampal neural activity contributes to the ability of meal-related memory to control future intake, that endocrine and neuropeptide systems act in the ventral hippocampus to provide cues regarding energy status and regulate learned aspects of eating, and that consumption of hypercaloric diets and obesity disrupt these processes. Collectively, this evidence indicates that diet-induced obesity may be caused and/or maintained, at least in part, by a vicious cycle wherein excess intake disrupts hippocampal functioning, which further increases intake. This perspective may advance our understanding of how the brain controls eating, the neural mechanisms that contribute to eating-related disorders, and identify how to treat diet-induced obesity.
The effect of economy type on reinforcer value
2019, Behavioural Processes
Citation Excerpt :
The half-life of saccharin in rats is only about 30 min (Sweatman and Renwick, 1980; Renwick, 1985), which would mean that any saccharin consumed on one day would have been eliminated well before the start of the next day’s work session. Additionally, earlier research indicates that saccharin satiety in rats is controlled by immediate oral sensory stimulation rather than by longer-term post-ingestive consequences such as fullness of the stomach or overhydration (Mook et al., 1981). The short-half life and the lack of post-ingestive consequences for saccharin drinking suggest that the effect of economy type on saccharin reinforcer value observed by Kim et al. (2018) was not due to differences in satiation across economies.
This article reviews studies investigating the effect of economy type on reinforcer value. In a closed economy, consumption of the reinforcer depends entirely on the subject’s behavior, whereas in an open economy it does not, due, for example, to the provision of free reinforcers after the session. In theory, reinforcers should have higher value in a closed economy than in an open economy. Experimental results relevant to this prediction and methods used to test economy type effects are summarized and discussed here. Studies have tested the effect of economy type on the value of a variety of reinforcers, including food, water, saccharin, various drugs, and video games. Subjects used have varied also and include humans, monkeys, rats, and mice. Whether economy type had an effect on reinforcer value appears to depend on the particular reinforcer studied and on the species used. In general, where there was a difference in reinforcer value across economies, the effect was consistent with the prediction that value should be lower in the open economy. In some studies, however, satiation across economy types may have been responsible for the difference, or at least contributed to it. Potential explanations for the economy type effect, including substitution of future reinforcers for current reinforcers, contingency degradation, anticipatory contrast, and optimal foraging, are discussed.
The effect of economy type on demand and preference for cocaine and saccharin in rats
2018, Drug and Alcohol Dependence
Citation Excerpt :
It should be noted, however, that the half-life of saccharin in rats is also short enough (∼30 min; Sweatman and Renwick, 1980; Renwick, 1985) so that saccharin consumed on one day would have been eliminated prior to the start of the next day’s work session. Further, saccharin satiety in rats is controlled by immediate oral sensory stimulation rather than by any longer-term post-ingestive consequences such as fullness of the stomach or overhydration (Mook et al., 1981). Nonetheless, the neurobiological mechanisms involved in saccharin satiety are poorly understood and it is possible that residual satiety-like effects of prior saccharin exposure could have been responsible for the OpenSac group’s results.
Economy type is an important determinant of reinforcer value. This study investigated the effect of open and closed economies on demand and preference for cocaine and saccharin in rats.
In the first phase, rats were trained to lever press for cocaine infusions or saccharin. The number of presses required for each reinforcer increased across sessions. Cocaine and saccharin economy type was manipulated over groups by varying post-session availability of these reinforcers. One group of rats had three hours’ post-session access to unlimited cocaine (open economy). A second group had three hours’ post-session access to unlimited saccharin. A third group had no post-session access to either reinforcer (closed economy). In a second phase, rats in the three conditions could make mutually exclusive choices for cocaine or saccharin.
Post-session access to saccharin caused saccharin demand to become more elastic. Post-session access to cocaine had no effect on demand for cocaine but made demand for saccharin more elastic. Results from the choice phase generally paralleled those from the demand phase, the main finding being that post-session saccharin access caused an increase in cocaine preference.
These results show that manipulating economy type can affect cocaine and non-drug reinforcers differently. Opening the saccharin economy decreased saccharin’s value. Opening the cocaine economy did not decrease cocaine’s value, but instead led to a devaluation of saccharin. These results suggest that cocaine choice may be determined not only by the reinforcers immediately available, but also by those reinforcers’ broader contexts of availability.
Effect of dexfenfluramine on saccharin drinking: Behavioural and pharmacological studies
1994, Pharmacology, Biochemistry and Behavior
We have previously reported that the 5-hydroxytryptamine (5-HT) releaser/reuptake blocker dexfenfluramine suppresses voluntary ethanol intake. To further analyse the generality of these findings, in the present study we examined the effect of equivalent doses of dexfenfluramine (0.5–2.5 mg/kg) on the intake of another preferred fluid, saccharin. Saccharin was made available for 2 h daily across a wide concentration range chosen to promote varying degrees of intake. Following stable levels of intake, the behaviour of vehicle-pretreated rats was assessed immediately prior to (anticipatory/preparatory phase) and during (consumatory phase) saccharin access. These behaviours were compared and contrasted with those produced following dexfenfluramine pretreatment at the optimally preferred saccharin concentration (0.2%). In a preliminary study the effects of various 5-HT antagonists were also examined against the dexfenfluramine response. The present results suggest that dexfenfluramine produced a dose-related suppression of saccharin intake at doses similar to those which reduced ethanol intake. However, the magnitude of this suppression was similar across each saccharin concentration. Behavioural analysis indicated that the profile of the dexfenfluramine (0.5- and 1-mg/kg doses only) suppression of the 0.2% solution was similar to that observed in vehicle-pretreated rats presented with saccharin solutions of lesser palatability to this concentration. Pharmacological studies indicated a 5-HT₁ (non-5-HT_1C) receptor involvement in the dexfenfluramine response. These studies imply that at certain doses dexfenfluramine may produce a subtle alteration in the motivation to consume a preferred fluid.
Orosensory suppression of saccharin drinking in rat: The response, not the taste
1989, Appetite
Hungry rats drink saccharin solutions with avidity, but the ingestion is self-limited: rate of lapping slows down progressively. Since postingestive changes do not produce this suppression, it must depend on a feedback signal generated by lapping the fluid. We show that the suppression depends on the number of laps emitted, not on the taste of the fluid; a given number of laps early in the session produces the same suppression later in the session, whether those early laps are accompanied by a moderate saccharin taste, a weak taste, or no sweet taste at all. Therefore, the feedback signal is provided by the act of lapping; taste does not contribute to it. Yet taste does influence amount ingested. Perhaps it provides a feed-forward signal, that in turn sets the amount of feedback required to end the bout.
Drinking saccharin increases food intake and preference-I. Comparison with other drinks
1989, Appetite
To examine the orosensory and postingestive effects of saccharin solution on food intake and food preference, freely feeding rats were given flavored food to eat and a solution to drink for 2 h on eight to ten occasions. Relative to trials with a different flavored food and only water to drink, food intake was increased by drinking 0.2% saccharin or 0.45% NaCl, unaffected by drinking 1% almond extract, and decreased by drinking 10% glucose. Food preference, which was assessed in a choice test with simultaneous access to the two flavored foods, was increased by drinking 0.2% saccharin or 10% glucose and unaffected by drinking 1% almond extract or 0.45% NaCl. These results are consistent with the possibility that a combination of the oral and hydrational properties of saccharin solution increase food intake. Saccharin's sweet taste may be responsible for its effects on food preference.

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View full text

Release of Feeding by the Sweet Taste in Rats: The specificity of Oral Satiety

Appetite: Journal for Intake Research

Appetite: Journal for Intake Research

Urges to eat and drink in rats

American Journal of Physiology

Drinking termination: interactions among hydrational, orogastric, and behavioral control in rats

Psychological Review

Hyperreactivity to quinine associated with osmotic thirst in the rat

Journal of Comparative and Physiological Psychology

Feeding behavior of the blowfly

Gustatory cross adaptation between sweet-tasting compounds

Perception and Psychophysics