Sweet Taste Perception Research Articles

Characterization of the Binding Site of Aspartame in the Human Sweet Taste Receptor.

The sweet taste receptor, a heterodimeric G protein-coupled receptor comprised of T1R2 and T1R3, binds sugars, small molecule sweeteners, and sweet proteins to multiple binding sites. The dipeptide sweetener, aspartame binds in the Venus Flytrap Module (VFTM) of T1R2. We developed homology models of the open and closed forms of human T1R2 and human T1R3 VFTMs and their dimers and then docked aspartame into the closed form of T1R2's VFTM. To test and refine the predictions of our model, we mutated various T1R2 VFTM residues, assayed activity of the mutants and identified 11 critical residues (S40, Y103, D142, S144, S165, S168, Y215, D278, E302, D307, and R383) in and proximal to the binding pocket of the sweet taste receptor that are important for ligand recognition and activity of aspartame. Furthermore, we propose that binding is dependent on 2 water molecules situated in the ligand pocket that bridge 2 carbonyl groups of aspartame to residues D142 and L279. These results shed light on the activation mechanism and how signal transmission arising from the extracellular domain of the T1R2 monomer of the sweet receptor leads to the perception of sweet taste.

Taste receptors in the gastrointestinal system

In the last 15 years, advancements in molecular biology have unraveled the proteins that function as taste receptors. There are at least five taste qualities that are consciously perceived, sweet, sour, salty, bitter, and umami. Of these five, sour and salty are mediated by ion channels, whereas the perception of sweet, umami, and bitter tastes is mediated by G protein-coupled receptors (GPCRs). These taste GPCRs belong to the TAS1R and TAS2R gene families. There are other nutrient-binding GPCRs whose taste function is still being studied such as CaSR, GPRC6A, GPR92, or GPR120. It has been suspected for more than a century that the gut can sense the chemical composition of foods. The description of multiple taste GPCRs in gastrointestinal (GI) cells suggests that there are nutrient-sensing mechanisms in the GI tract, oral, gastric, and intestinal mucosa. Oral sensing seems to mainly influence food discrimination and nutrient appetite, while post-oral chemosensors may relate to nutrient utilization and inhibition of appetite. The most common accepted view is that taste GPCRs are present in enteroendocrine cells among others also known as chemosensory cells. These cells express taste receptors and other taste-related genes. Although, functional cells of the GI mucosa that are not enteroendocrine or brush cells such as enterocytes or gastric cells may also hold receptive mechanisms that transduce the presence of certain nutrients in ingested foods and regulate gastric functions. This paper examines the importance of food chemical signals in their association with the neuroendocrine mechanisms they trigger, which are the core for metabolism and appetite regulation.

Time-intensity profile of pitanga nectar (Eugenia uniflora L.) with different sweeteners: Sweetness and bitterness.

Pitanga has been used by the Brazilian food industry mainly for juice production. This fruit shows good economic potential due to its high concentration of vitamins and minerals. The aim of the present work was to characterize the time-intensity profile of pitanga nectar sweetened with different sweeteners to verify differences on the perception of sweet and bitter tastes. The sweeteners used to replace sucrose were sucralose, aspartame, stevia 40% rebaudioside A, stevia 95% rebaudioside A, neotame, and 2:1 cyclamate/saccharin blend. Fifteen assessors were selected according to their discriminating capability and trained to participate in the time-intensity analysis for sweetness and bitterness. The samples prepared with sucralose and 2:1 cyclamate/saccharin blend presented a similar sweetness profile to the sample prepared with sucrose, and the samples prepared with sucralose and aspartame presented a similar bitterness profile to the sample prepared with sucrose. Thus, sucralose would be the most suitable sweetener to replace sucrose in pitanga nectar.

Variation in the TAS1R2 Gene, Sweet Taste Perception and Intake of Sugars

Background/Aims: To determine whether variation in the TAS1R2 gene affects sucrose taste perception and sugar intake. Methods: Participants were men (n = 238) and women (n = 458) aged 20-29 years. A subset (n = 95) with body mass index (BMI) data available completed a sensory analysis study. A food frequency questionnaire assessed dietary intake, and eight polymorphisms were genotyped (rs12033832, rs12137730, rs35874116, rs3935570, rs4920564, rs4920566, rs7513755 and rs9701796). Sucrose taste thresholds were determined by staircase procedure (solutions: 9 × 10^-6 to 0.5 mol/l). Suprathreshold sensitivity to 0.01-1.0 mol/l sucrose solutions was assessed using general Labeled Magnitude Scales. Results: A significant genotype-BMI interaction was observed for rs12033832 (G>A) for suprathreshold sensitivity (p = 0.01) and sugar intake (p = 0.003). Among participants with a BMI ≥25, G allele carriers had lower sensitivity ratings (mean incremental area under the taste sensitivity curve ± SE; GG/GA 54.4 ± 4.1 vs. AA 178.5 ± 66.6; p = 0.006), higher thresholds (GG/GA 9.3 ± 1.1 vs. AA 4.4 ± 4.3 mmol/l; p = 0.004) and consumed more sugars (GG/GA 130 ± 4 vs. AA 94 ± 13 g/day; p = 0.009). G allele carriers with a BMI <25 had lower thresholds (GG/GA 8.6 ± 0.5 vs. AA 16.7 ± 5.7 mmol/l; p = 0.02) and consumed less sugars (GG/GA 122 ± 2 vs. AA 145 ± 8 g/day; p = 0.004). Conclusion: The rs12033832 single nucleotide polymorphism in TAS1R2 is associated with sucrose taste and sugar intake, but the effect differs depending on BMI.

Examination of the perception of sweet- and bitter-like taste qualities in sucralose preferring and avoiding rats

Sucralose avoiding rats detect a bitter-like taste quality in concentrations of sucralose that are strongly preferred over water by sucralose preferring rats. Here, we investigated whether sucralose preferrers (SP) also detect a bitter-like quality in sucralose that may be masked by an increased perception of sucralose's sweet-like quality. A microstructural analysis of sucralose intake revealed that, at concentrations they avoided in preference tests, sucralose avoiders (SA) consumed smaller and fewer bouts of sucralose than SP. Interestingly, the concentration-dependent increase in sucralose preference in SP was not associated with larger bouts or increased lick rate, two measures that are expected to increase with increasing perceived sweetness. This suggests that SP can detect an aversive quality in sucralose, but this perception of a presumably bitter-like quality may be masked by increased salience of a sweet-like quality that sustains high levels of intake in SP. Further evidence for increased sweet-taste perception in SP, relative to SA, was obtained in a second study in which SP consumed more of a palatable sweet-milk diet than SA. These are the first data to suggest that SP are not blind to the bitter-like quality in sucralose, and that there may be differences in sweet-taste perception between SP and SA.

Sensory biology. Evolution of sweet taste perception in hummingbirds by transformation of the ancestral umami receptor.

Sensory systems define an animal's capacity for perception and can evolve to promote survival in new environmental niches. We have uncovered a noncanonical mechanism for sweet taste perception that evolved in hummingbirds since their divergence from insectivorous swifts, their closest relatives. We observed the widespread absence in birds of an essential subunit (T1R2) of the only known vertebrate sweet receptor, raising questions about how specialized nectar feeders such as hummingbirds sense sugars. Receptor expression studies revealed that the ancestral umami receptor (the T1R1-T1R3 heterodimer) was repurposed in hummingbirds to function as a carbohydrate receptor. Furthermore, the molecular recognition properties of T1R1-T1R3 guided taste behavior in captive and wild hummingbirds. We propose that changing taste receptor function enabled hummingbirds to perceive and use nectar, facilitating the massive radiation of hummingbird species.

The makings of a powerful sweet tooth

The main attraction of nectar, a hummingbird favorite, is the sweet taste of sugar. Oddly, though, birds lack the main vertebrate receptor for sweet taste, T1R2. Baldwin et al. show that a related receptor, T1R1-T1R3, which generally controls savory taste in vertebrates, adapts in hummingbirds to detect sweet (see the Perspective by Jiang and Beauchamp). This repurposing probably allowed hummingbirds to specialize in nectar feeding and may have assisted the evolution of the many and varied hummingbird species seen today. M. W. Baldwin, Y. Toda, T. Nakagita, M. J. O’Connell, K. C. Klasing, T. Misaka, S. V. Edwards, S. D. Liberles, Evolution of sweet taste perception in hummingbirds by transformation of the ancestral umami receptor. Science 345 , 929–933 (2014). [Abstract][Full Text] P. Jiang, G. K. Beauchamp, Sensing nectar’s sweetness. Science 345 , 878–879 (2014). [Abstract][Full Text]

Effect of ethylene and temperature conditioning on sensory attributes and chemical composition of ‘Bartlett’ pears

‘Bartlett’ pears are resistant to ripening after harvest. Ethylene and temperature conditioning have been successfully used to stimulate fruit ripening with improved eating quality over non-conditioned fruit. However, few studies have evaluated the effect of different conditioning treatments on the sensory attributes of the fruit. In this study, we compared a descriptive sensory evaluation with the chemical composition of ‘Bartlett’ pears after the fruit were exposed to the following conditioning treatments: 2d 100μlL−1 ethylene, 14 or 7d at 0°C, 7 or 3d at 10°C, or untreated control at 20°C. Fruit were softened to 27, 18 and 9N firmness before evaluation. At 9N, fruit conditioned at 0°C produced high levels of esters, and fruit conditioned at 0°C for 14d also were high in sweet taste and fruity flavor attributes. Fruit treated at 10°C had lower concentrations of esters, but fruit treated at 10°C for 3d was high in sweet taste perception. Ethylene treated fruit produced low levels of esters and high levels of aldehydes and were associated with apple aroma, similar to the untreated control fruit. Water soluble pectin levels were highly and positively correlated with juiciness and sweetness and negatively correlated with firmness, crunchiness, and grittiness. Future studies should determine whether consumer liking of ‘Bartlett’ pear fruit is also influenced by conditioning treatment.

Effect of ethylene and temperature conditioning on sensory attributes and chemical composition of 'Comice' pears.

'Comice' is among the pear varieties most difficult to ripen after harvest. Ethylene, cold temperature, and intermediate (10 °C) temperature conditioning have been successfully used to stimulate the ability of 'Comice' pears to ripen. However, the sensory quality of pears stimulated to ripen by different conditioning treatments has not been evaluated. In this study, a descriptive sensory analysis of 'Comice' pears conditioned to soften to 27, 18, and 9 N firmness with ethylene exposure for 3 or 1 days, storage at 0 °C for 25 or 15 days, or storage at 10 °C for 10 days was performed. Sensory attributes were then related to changes in chemical composition, including volatile components, water-soluble polyuronides, soluble solids content (SSC), and titratable acidity (TA). The sensory profile of fruit conditioned with ethylene was predominant in fibrous texture and low in fruity and pear aroma. Fruit conditioned at 0 °C was described as crunchy at 27 and 18 N firmness and became juicy at 9 N firmness. Fruit conditioned at 0 °C produced the highest quantity of alcohols and fewer esters than fruit conditioned at 10 °C, and they had higher fruity and pear aroma than fruit conditioned with ethylene, but lower than fruit conditioned at 10 °C. Fruit held at 10 °C were predominant in fruity and pear aroma and had the highest concentration of esters. Water-soluble polyuronides were strongly, positively correlated (r > 0.9) with sensory attributes generally associated with ripeness, including juiciness, butteriness, and sweetness and negatively correlated (r > -0.9) with sensory attributes generally associated with the unripe stage, such as firmness and crunchiness. However, water-soluble polyuronides were not significantly different among conditioning treatments. Sensory sweetness was not significantly correlated with SSC, but TA and SSC/TA were significantly correlated with sensory tartness. However, there were no significant differences among the conditioning treatments in sweet or sour taste perception when the fruit fully softened. The results indicate that the various methods of conditioning 'Comice' pear fruits for ripening had different effects on their sensory and chemical properties that may influence their sensory quality.

Functional roles of the sweet taste receptor in oral and extraoral tissues.

Purpose of reviewThis review summarizes and discusses the current knowledge about the physiological roles of the sweet taste receptor in oral and extraoral tissues.Recent findingsThe expression of a functional sweet taste receptor has been reported in numerous extragustatory tissues, including the gut, pancreas, bladder, brain and, more recently, bone and adipose tissues. In the gut, this receptor has been suggested to be involved in luminal glucose sensing, the release of some satiety hormones, the expression of glucose transporters, and the maintenance of glucose homeostasis. More recently, the sweet taste receptor was proposed to regulate adipogenesis and bone biology.SummaryThe perception of sweet taste is mediated by the T1R2/T1R3 receptor, which is expressed in the oral cavity, wherein it provides input on the caloric and macronutrient contents of ingested food. This receptor recognizes all the chemically diverse compounds perceived as sweet by human beings, including natural sugars and sweeteners. Importantly, the expression of a functional sweet taste receptor has been reported in numerous extragustatory tissues, wherein it has been proposed to regulate metabolic processes. This newly recognized role of the sweet taste receptor makes this receptor a potential novel therapeutic target for the treatment of obesity and related metabolic dysfunctions, such as diabetes and hyperlipidemia.

Differences in saccharin preference and genetic alterations of the Tas1r3 gene among senescence-accelerated mouse strains and their parental AKR/J strain

The senescence-accelerated mouse (SAM) is used as an animal model of senescence acceleration and age-associated disorders. SAM is derived from unexpected crosses between the AKR/J and unknown mouse strains. There are nine senescence-prone (SAMP) strains and three senescence-resistant (SAMR) strains. Although SAMP strains exhibit strain-specific and age-related pathological changes, the genes responsible for the pathologic changes in SAMP strains have not been comprehensively identified. In the present study, we evaluated sweet taste perception using the two-bottle test. We compared genotypes of the taste related gene, Tas1r3, using SAM strains and the parental AKR/J strain. The two-bottle test revealed that SAMR1 (R1), SAMP6 (P6), SAMP8 (P8), and SAMP10 (P10) mice were saccharin-preferring strains, whereas AKR/J did not prefer saccharin. All genotypes of the R1, P6, P8, and P10 strains at the polymorphic sites in Tas1r3, which is known to influence saccharin preference, were identical to those of C57BL6/J, a well-known saccharin-preferring strain, and were completely different from those of the parental AKR/J strain. These genetic alterations in SAM strains appear to arise from an unknown strain that is thought to have been crossed with AKR/J initially.

The Masking Effect of Sucrose on Perception of Bitter Compounds in Brassica Vegetables

AbstractThis study offers insight into how taste qualities interact in food. The influence of sucrose on the perceived bitter taste of sinigrin and goitrin (compounds naturally present in cabbage) was studied. A sensory panel evaluated the tastes of sucrose; the bitter compounds goitrin, sinigrin and quinine; and binary mixtures where each bitter compound was mixed with sucrose. The compounds were dispersed in water and in food model system consisting of white cabbage juice. The results were compared with those from sensory evaluation and chemical analysis of five white cabbage cultivars.Results showed that taste interactions occurred, and results from the liquid samples showed that sucrose had a masking effect on the bitter taste of sinigrin, goitrin and quinine. The perception of sweet taste depended on concentration and media. Examination of raw cabbage showed that bitterness correlated strongly with the total glucosinolate content, whereas sweetness correlated strongly with sucrose content.Practical ApplicationsThe bitter taste of Brassica vegetables is a sensory restraint for vegetable acceptance. However, reducing the content of bitter‐tasting glucosinolates (GLSs) in these vegetables is not the optimal solution as several studies demonstrate health beneficial effects associated with intake of GLSs. The sweet taste is a positive predictor for acceptance, and sugar is central for its ability to mask a taste perceived as bitter. This study provides a new approach for studying interactions between the perceived sweet and bitter taste of Brassica vegetables using three progressively more complex matrices. It is part of a larger study addressing sensory aspects of food choice with focus on bitter‐tasting vegetables, and in line with this knowledge about interaction effects between bitter and sweet‐tasting compounds naturally present in vegetables is crucial. Knowledge that might lead the way to maintain the vegetable's health benefits while also improving consumer acceptance and potentially increasing the intake.

The Bamboo-Eating Giant Panda (Ailuropoda melanoleuca) Has a Sweet Tooth: Behavioral and Molecular Responses to Compounds That Taste Sweet to Humans

A growing body of behavioral and genetic information indicates that taste perception and food sources are highly coordinated across many animal species. For example, sweet taste perception is thought to serve to detect and motivate consumption of simple sugars in plants that provide calories. Supporting this is the observation that most plant-eating mammals examined exhibit functional sweet perception, whereas many obligate carnivores have independently lost function of their sweet taste receptors and exhibit no avidity for simple sugars that humans describe as tasting sweet. As part of a larger effort to compare taste structure/function among species, we examined both the behavioral and the molecular nature of sweet taste in a plant-eating animal that does not consume plants with abundant simple sugars, the giant panda (Ailuropoda melanoleuca). We evaluated two competing hypotheses: as plant-eating mammals, they should have a well-developed sweet taste system; however, as animals that do not normally consume plants with simple sugars, they may have lost sweet taste function, as has occurred in strict carnivores. In behavioral tests, giant pandas avidly consumed most natural sugars and some but not all artificial sweeteners. Cell-based assays revealed similar patterns of sweet receptor responses toward many of the sweeteners. Using mixed pairs of human and giant panda sweet taste receptor units (hT1R2+gpT1R3 and gpT1R2+hT1R3) we identified regions of the sweet receptor that may account for behavioral differences in giant pandas versus humans toward various sugars and artificial sweeteners. Thus, despite the fact that the giant panda's main food, bamboo, is very low in simple sugars, the species has a marked preference for several compounds that taste sweet to humans. We consider possible explanations for retained sweet perception in this species, including the potential extra-oral functions of sweet taste receptors that may be required for animals that consume plants.

Homology Modeling of Human Sweet Taste Receptors: T1R2-T1R3

The sweet taste perception in human is mainly due to the specific G protein- copulated heterodimeric receptors (GPCR) T1R2-T1R3 and these receptors gathered in the taste buds of the tongue. The sweet protein acts as an important rule for molecular understanding of the taste mechanisms. Therefore, the Homology modeling of the closely related sweet taste receptors (T1R2-T1R3), is crucial to provide an understanding of the interactions between the sweetens and the receptors. 3A21 and 3Q41 were selected as possible templates for T1R2 and T1R3, respectively based on the phylogenetic evaluations. The models of the target sequences were generated using the program MODELLER V9.10. From the Ramachandran plot analysis it was shown that 79% and 84% of the residues reside in the core region for T1R2 model and T1R3 model, respectively.  ABSTRACT The sweet taste perception in human is mainly due to the specific G protein- copulated heterodimeric receptors T1R2-T1R3 and these receptors gathered in the taste buds of the tongue. The sweet protein acts as an important rule for molecular understanding of the taste mechanisms. Therefore, the Homology modeling of the closely related sweet taste receptors (T1R2-T1R3), is crucial to provide an understanding of the interactions between the sweetens and the receptors. 3A21 and 3Q41 were selected as possible templates for T1R2 and T1R3, respectively based on the phylogenetic evaluations. The models of the target sequences were generated using the programm MODELLER V9.10. From the Ramachandran plot analysis it was shown that 79% and 84% of the residues reside in the core region for T1R2 model and T1R3 model, respectively.

Longitudinal Analysis of Calorie Restriction on Rat Taste Bud Morphology and Expression of Sweet Taste Modulators

Calorie restriction (CR) is a lifestyle intervention employed to reduce body weight and improve metabolic functions primarily via reduction of ingested carbohydrates and fats. Taste perception is highly related to functional metabolic status and body adiposity. We have previously shown that sweet taste perception diminishes with age; however, relatively little is known about the effects of various lengths of CR upon taste cell morphology and function. We investigated the effects of CR on taste bud morphology and expression of sweet taste-related modulators in 5-, 17-, and 30-month-old rats. In ad libitum (AL) and CR rats, we consistently found the following parameters altered significantly with advancing age: reduction of taste bud size and taste cell numbers per taste bud and reduced expression of sonic hedgehog, type 1 taste receptor 3 (T1r3), α-gustducin, and glucagon-like peptide-1 (GLP-1). In the oldest rats, CR affected a significant reduction of tongue T1r3, GLP-1, and α-gustducin expression compared with age-matched AL rats. Leptin receptor immunopositive cells were elevated in 17- and 30-month-old CR rats compared with age-matched AL rats. These alterations of sweet taste-related modulators, specifically during advanced aging, suggest that sweet taste perception may be altered in response to different lengths of CR.

English

&nbsp; Sensory characteristics of coconut water from four coconut cultivars (Cocos nucifera&nbsp;L.) were investigated during nuts ripening. The study was carried out on the West African Tall, the Malaysian Yellow Dwarf, the Equatorial Guinea Green Dwarf and the improved hybrid PB121. Tested parameters were tastes (sweet, salty and sour), gustatory preferences and sugars contents. Obtained results showed significant interactions between cultivars and maturity stages for analyzed parameters. So, during the ripening of nuts, the sweet taste of coconut water predominated according to the maturity stages. It was maximal at the rank 21 of dwarf cultivars with perception equivalent from 5.80 to 6.10% sugars contents. At full maturity, the coconut water sweet taste lowers because its sugars enhance the formation of the kernel. The results of hedonic tests led to the preference of the coconut water according to its sweet taste. So, the water of dwarf cultivars immature nuts, more sweetened, was the most appreciated. Sugars contents are specific for cultivars and maturity stages. Their values were maximal at ranks 19 and 21 of dwarf cultivars. Moreover, gustative data were closed to those of the sweet taste perception. This study allowed to determinate the sensory characteristics of the coconut water in order to give indicators for its efficient technological promotion. &nbsp; Key words:&nbsp;Coconut water, sensory tests, sugars contents, cultivars, ripening.

Sweet taste perception not altered after acute sleep deprivation in healthy young men

BackgroundWe hypothesized that acutely sleep-deprived participants would rate ascending concentrations of sucrose as more intense and pleasant, than they would do after one night of normal sleep. Such a finding would offer a potential mechanism through which acute sleep loss could promote overeating in humans.MethodA total of 16 healthy normal-weight men participated in 2 conditions: sleep (permitted between 22:30 and 06:30 h) and total sleep deprivation (TSD) respectively. On the morning after regular sleep and TSD, circulating concentrations of ghrelin and glucose were measured. In addition, participants hunger level was assessed by means of visual analogue scales, both before and after a caloric preload. Finally, following the preload, participants rated both intensity and pleasantness of six orally presented yogurt probes with varying sucrose concentrations (2–29 %).ResultsFeelings of hunger were significantly more intense under both fasted and sated conditions when subjects were sleep-deprived. In contrast, the change in hunger induced by the preload was similar between the sleep and TSD conditions. Plasma concentrations of ghrelin were significantly higher under conditions of TSD, whereas plasma glucose did not differ between the conditions. No effects were found either on sweet taste intensity or on pleasantness after TSD.ConclusionOne night of TSD increases morning plasma concentrations of the hunger-promoting hormone ghrelin in healthy young men. In contrast, sweet taste perception was not affected by nocturnal wakefulness. This suggests that an altered sweet taste perception is an unlikely mechanism by which TSD enhances food intake.

Tasting the bitter and the sweet, honeybee memories, and visualizing calcium throughout entire astrocytes

This month’s installment of Generally Physiological concerns identification of a channel crucial for the perception of sweet, bitter, and umami tastes; a role for caffeine in honeybee associative olfactory memory; and methods for imaging calcium throughout entire astrocytes. ![Figure][1]

CALHM1 ion channel mediates purinergic neurotransmission of sweet, bitter and umami tastes

Recognition of sweet, bitter and umami tastes requires the non-vesicular release from taste bud cells of adenosine 5′-triphosphate (ATP), which acts as a neurotransmitter to activate afferent neural gustatory pathways1. However, how ATP is released to fulfill this function is not fully understood. Here we show that calcium homeostasis modulator 1 (CALHM1), a voltage-gated ion channel2,3, is indispensable for taste stimuli-evoked ATP release from sweet-, bitter- and umami-sensing taste bud cells. Calhm1 knockout mice have severely impaired perceptions of sweet, bitter and umami compounds, whereas sour and salty taste recognition remains mostly normal. Calhm1 deficiency affects taste perception without interfering with taste cell development or integrity. CALHM1 is expressed specifically in sweet/bitter/umami-sensing type II taste bud cells. Its heterologous expression induces a novel ATP permeability that releases ATP from cells in response to manipulations that activate the CALHM1 ion channel. Knockout of Calhm1 strongly reduces voltage-gated currents in type II cells and taste-evoked ATP release from taste buds without affecting the excitability of taste cells to taste stimuli. Thus, CALHM1 is a voltage-gated ATP release channel required for sweet, bitter and umami taste perception.

Opiate agonists and antagonists modulate taste perception in opiate-maintained and recently detoxified subjects

Heroin addicts consume large quantities of refined sugars. This study investigated the effect of opiate use and antagonism on sweet taste in opiate-maintained drug users and detoxified former chronic opiate users, using a within-subject design. Seven opiate users received methadone and seven buprenorphine maintenance. Six detoxified subjects received naltrexone. Sucrose recognition thresholds and measurements of pleasantness and intensity were determined before and four hours after 1) a single dose of methadone or buprenorphine or 2) naltrexone. Control data were taken from a cohort of healthy volunteers including smokers. All measures of sweet and salt taste perception were significantly greater in opiate users and recently detoxified subjects compared to control subjects, with the exception of sweet pleasantness, which returned to control level after detoxification. Acute methadone administration reduced salt thresholds and unpleasantness to control levels. Increased sweet thresholds and salt unpleasantness in detoxified subjects were reversed by acute opioid antagonism, returning to control levels. These results suggest that opiate use and antagonism alters taste perception. Some of the alterations reverse on detoxification (sweet pleasantness), and others can be reversed by opioid antagonism (sweet threshold, salt unpleasantness). Changes in taste perception may underlie altered consumption of refined sugars in opiate users.