Glucose appetition in C57BL/6J mice: Influence of nonnutritive sweetener experience, food deprivation state and sex differences.

In addition to its sweet taste, glucose has potent and rapid postoral actions (appetition) that enhance its reward value. This has been demonstrated by the experience-induced preference for glucose over initially preferred nonnutritive sweetener solutions in 24-h choice tests. However, some sweetener solutions (e.

Glucose appetition in C57BL/6J mice: Influence of nonnutritive sweetener experience, food deprivation state and sex differences.

In addition to its sweet taste, glucose has potent and rapid postoral actions (appetition) that enhance its reward value. This has been demonstrated by the experience-induced preference for glucose over initially preferred nonnutritive sweetener solutions in 24-h choice tests. However, some sweetener solutions (e.

Fat preference deficits and experience-induced recovery in global taste-deficient Trpm5 and Calhm1 knockout mice.

There is much evidence that gustation mediates the preference for dietary fat in rodents. Several studies indicate that mice have fat taste receptors that activate downstream signaling elements, including TRPM5 and CALHM1 ion channels and P2×2/P2×3 purinergic gustatory nerve receptors. Experiment 1 further documented the involvement of TRPM5 in fat appetite by giving Trpm5 knockout (KO) mice, which show global taste deficits, 24-h two-bottle choice tests with ascending concentrations of soybean oil (0.

Learning of food preferences: mechanisms and implications for obesity & metabolic diseases.

Omnivores, including rodents and humans, compose their diets from a wide variety of potential foods. Beyond the guidance of a few basic orosensory biases such as attraction to sweet and avoidance of bitter, they have limited innate dietary knowledge and must learn to prefer foods based on their flavors and postoral effects. This review focuses on postoral nutrient sensing and signaling as an essential part of the reward system that shapes preferences for the associated flavors of foods.

Nutrient-conditioned intake stimulation does not require a distinctive flavor cue in rats.

The postoral actions of nutrients in rodents can stimulate intake and condition flavor preferences through an appetition process. Appetition is revealed in rodents by their increased intake of and preference for a flavored solution paired with intragastric (IG) nutrient infusions. Here we determined if IG 16% maltodextrin (MD) infusions can stimulate intake and preference in the absence of a distinctive flavor cue.

Residual Glucose Taste in T1R3 Knockout but not TRPM5 Knockout Mice.

Knockout (KO) mice missing the sweet taste receptor subunit T1R3 or the signaling protein TRPM5 have greatly attenuated sweetener preferences. Yet both types of KO mice develop preferences for glucose but not fructose in 24-h tests, which has been attributed to the postoral reinforcing actions of glucose. Here we probed for residual sugar taste sensitivity in KO mice.

Capsaicin-induced visceral deafferentation does not attenuate flavor conditioning by intragastric fat infusions in mice.

The postoral actions of sugar and fat can rapidly stimulate the intake of and preference for flavors associated with these nutrients via a process known as appetition. Prior findings revealed that postoral glucose appetition is not attenuated following capsaicin-induced visceral deafferentation. The present experiment determined if capsaicin treatment altered fat appetition in C57BL/6 mice.

Profound differences in fat versus carbohydrate preferences in CAST/EiJ and C57BL/6J mice: Role of fat taste.

In a nutrient self-selection study, CAST/EiJ mice consumed more carbohydrate than fat while C57BL/6J (B6) mice showed the opposite preference. The present study revealed similar strain differences in preferences for isocaloric fat (Intralipid) and carbohydrate (sucrose, maltodextrin) solutions in chow-fed mice. In initial 2-day choice tests, percent fat intakes of CAST and B6 mice were 4-9% and 71-81% respectively.

Greater reductions in fat preferences in CALHM1 than CD36 knockout mice.

Several studies indicate an important role of gustation in intake and preference for dietary fat. The present study compared fat preference deficits produced by deletion of CD36, a putative fatty acid taste receptor, and CALHM1, an ion channel responsible for release of the ATP neurotransmitter used by taste cells. Naïve CD36 knockout (KO) mice displayed reduced preferences for soybean oil emulsions (Intralipid) at low concentrations (0.

Role of lipolysis in postoral and oral fat preferences in mice.

Fatty acid receptors in the mouth and gut are implicated in the appetite for fat-rich foods. The role of lipolysis in oral- and postoral-based fat preferences of C57BL/6J mice was investigated by inhibiting lipase enzymes with orlistat. Experiment 1 showed that postoral lipolysis is required: mice learned to prefer (by 70%) a flavored solution paired with intragastric infusions of 5% soybean oil but not a flavor paired with soybean oil + orlistat (4 mg/g fat) infusions.

Flavor preferences conditioned by nutritive and non-nutritive sweeteners in mice.

Recent studies suggest that preferences are conditioned by nutritive (sucrose) but not by non-nutritive (sucralose) sweeteners in mice. Here we compared the effectiveness of nutritive and non-nutritive sweeteners to condition flavor preferences in three mouse strains. Isopreferred sucrose and sucralose solutions both conditioned flavor preferences in C57BL/6J (B6) mice but sucrose was more effective, consistent with its post-oral appetition action.

CAST/EiJ and C57BL/6J Mice Differ in Their Oral and Postoral Attraction to Glucose and Fructose.

A recent study indicated that CAST/EiJ and C57BL/6J mice differ in their taste preferences for maltodextrin but display similar sucrose preferences. The present study revealed strain differences in preferences for the constituent sugars of sucrose. Whereas B6 mice preferred 8% glucose to 8% fructose in 2-day tests, the CAST mice preferred fructose to glucose.

Maltodextrin and sucrose preferences in sweet-sensitive (C57BL/6J) and subsensitive (129P3/J) mice revisited.

Mice are attracted to the tastes of sugar and maltodextrin solutions. Sugar taste is mediated by the T1R2/T1R3 sweet taste receptor, while maltodextrin taste is dependent upon a different as yet unidentified receptor. In a prior study sweet-sensitive C57BL/6J (B6) mice displayed similar preferences for sucrose and maltodextrin solutions in 24-h saccharide vs.

Flavor Preferences Conditioned by Dietary Glutamate.

Our understanding of the molecular basis of umami taste and its appetitive qualities has been greatly aided by studies in laboratory rodents. This review describes methods for testing responses to the prototypical umami substance monosodium glutamate (MSG) in rodents. Two techniques, forced exposure to MSG and 2-bottle choice tests with ascending concentrations, were used to evaluate the responses to the taste of umami itself, and 2 other methods used oral or postoral MSG to modify the responses to other flavors.

MCH receptor deletion does not impair glucose-conditioned flavor preferences in mice.

The post-oral actions of glucose stimulate intake and condition flavor preferences in rodents. Hypothalamic melanin-concentrating hormone (MCH) neurons are implicated in sugar reward, and this study investigated their involvement in glucose preference conditioning in mice. In Exp.

SGLT1 sugar transporter/sensor is required for post-oral glucose appetition.

Recent findings suggest that the intestinal sodium-glucose transporter 1 (SGLT1) glucose transporter and sensor mediates, in part, the appetite-stimulation actions of intragastric (IG) glucose and nonmetabolizable α-methyl-d-glucopyranoside (MDG) infusions in mice. Here, we investigated the role of SGLT1 in sugar conditioning using SGLT1 knockout (KO) and C57BL/6J wild-type (WT) mice. An initial experiment revealed that both KO and WT mice maintained on a very low-carbohydrate diet display normal preferences for saccharin, which was used in the flavored conditioned stimulus (CS) solutions.

Operant licking for intragastric sugar infusions: Differential reinforcing actions of glucose, sucrose and fructose in mice.

Intragastric (IG) flavor conditioning studies in rodents indicate that isocaloric sugar infusions differ in their reinforcing actions, with glucose and sucrose more potent than fructose. Here we determined if the sugars also differ in their ability to maintain operant self-administration by licking an empty spout for IG infusions. Food-restricted C57BL/6J mice were trained 1 h/day to lick a food-baited spout, which triggered IG infusions of 16% sucrose.

Ghrelin signaling is not essential for sugar or fat conditioned flavor preferences in mice.

The oral and post-oral actions of sugar and fat stimulate intake and condition flavor preferences in rodents through a process referred to as appetition. Ghrelin is implicated in food reward processing, and this study investigated its involvement in nutrient conditioning in mice. In Exp.

Intragastric fat self-administration is impaired in GPR40/120 double knockout mice.

Mice acquire strong preferences for flavors paired with intragastric (IG) fat infusions. This IG fat conditioning is attenuated in double knockout (DoKO) mice missing GPR40 and GPR120 fatty acid receptors. Here we determined if GPR40/120 DoKO mice are also impaired in IG fat self-administration in an operant lick task.

Postoral glucose sensing, not caloric content, determines sugar reward in C57BL/6J mice.

Recent studies suggest that because of their energy value, sugars are more rewarding than non-caloric sweeteners. However, intragastric infusion data indicate that sugars differ in their postoral appetite-stimulating effects. We therefore compared the preference for isocaloric 8% sucrose, glucose, and fructose solutions with that of a non-caloric sweetener solution (0.

Advantame sweetener preference in C57BL/6J mice and Sprague-Dawley rats.

Advantame is a new ultrahigh-intensity noncaloric sweetener derived from aspartame and approved for human use. Rats and mice are not attracted to the taste of aspartame and this study determined their preference for advantame. In 24-h choice tests with water, C57BL/6J mice and Sprague-Dawley rats were indifferent to advantame at concentrations of 0.

Flavor preference conditioning by different sugars in sweet ageusic Trpm5 knockout mice.

Knockout (KO) mice missing the taste signaling protein Trpm5 have greatly attenuated sweetener preferences but develop strong preferences for glucose in 24-h tests, which is attributed to post-oral sugar conditioning. Trpm5 KO mice express mild preferences for galactose but no preferences for fructose in 24-h tests, which suggests that these sugars differ in their post-oral reinforcing effects. Here we investigated sugar-conditioned flavor preferences in Trpm5 KO and C57BL/6J wildtype (B6) mice.

Flavor change and food deprivation are not critical for post-oral glucose appetition in mice.

When mice trained to consume a CS- flavored solution paired with intragastric (IG) water self-infusion are given a new CS+ flavor paired with IG glucose self-infusion, their intake is stimulated within minutes in the first CS+ test. They also display a preference for the CS+ over the CS- in two-bottle tests. These indicators of post-oral appetite stimulation (appetition) have been studied in food-restricted mice, with novel CS+ and CS- flavors.