Presentations and outcomes of interstitial lung disease and the anti-Ro52 autoantibody.

BACKGROUND: Distinct clinical presentations of interstitial lung disease (ILD) with the myositis-specific antibodies, including anti-synthetase antibodies, are well-recognized. However, the association between ILD and the myositis-associated antibodies, including anti-Ro52, is less established. Our objectives were to compare presenting phenotypes of patients with anti-Ro52 alone versus in combination with myositis-specific autoantibodies and to identify predictors of disease progression or death. METHODS: We performed a retrospective cohort study of 73 adults with ILD and a positive anti-Ro52 antibody. We report clinical features, treatment, and outcomes. RESULTS: The majority of patients with ILD and anti-Ro52 had no established connective tissue disease (78%), and one-third had no rheumatologic symptoms. Thirteen patients (17.8%) required ICU admission for respiratory failure, with 84.6% all-cause mortality. Of the 73 subjects, 85.7% had a negative SS-A, and 49.3% met criteria for idiopathic pneumonia with autoimmune features (IPAF). The 50 patients with anti-Ro52 alone were indistinguishable from patients with anti-Ro52 plus a myositis-specific autoantibody. ICU admission was associated with poor outcomes (HR 12.97, 95% CI 5.07-34.0, p < 0.0001), whereas rheumatologic symptoms or ANA > = 1:320 were associated with better outcomes (HR 0.4, 95% CI 0.16-0.97, p = 0.04, and HR 0.29, 95% CI 0.09-0.81, p = 0.03, respectively). CONCLUSIONS: Presentations of ILD with the anti-Ro52 antibody are heterogeneous, and outcomes are similar when compared to anti-Ro52 plus myositis-specific antibodies. Testing for anti-Ro52 may help to phenotype unclassifiable ILD patients, particularly as part of the serologic criteria for IPAF. Further research is needed to investigate treatment of ILD in the setting of anti-Ro52 positivity.

Resistance Exercise Program in Cognitively Normal Older Adults: CERT-Based Exercise Protocol of the AGUEDA Randomized Controlled Trial.

OBJECTIVES: To provide a comprehensive CERT (Consensus on Exercise Reporting Template)-based description of the resistance exercise program implemented in the AGUEDA (Active Gains in brain Using Exercise During Aging) study, a randomized controlled trial investigating the effects of a 24-week supervised resistance exercise program on executive function and related brain structure and function in cognitively normal older adults. DESIGN AND PARTICIPANTS: 90 cognitively normal older adults aged 65 to 80 were randomized (1:1) to a: 1) resistance exercise group; or a 2) wait-list control group. Participants in the exercise group (n = 46) performed 180 min/week of resistance exercise (3 supervised sessions per week, 60 min/session) for 24 weeks. INTERVENTION: The exercise program consisted of a combination of upper and lower limb exercises using elastic bands and the participant's own body weight as the main resistance. The load and intensity were based on the resistance of the elastic bands (7 resistances), number of repetitions (individualized), motor complexity of exercises (3 levels), sets and rest (3 sets/60 sec rest), execution time (40-60 sec) and velocity (as fast as possible). SETTINGS: The maximum prescribed-target intensity was 70-80% of the participants' maximum rate of perceived exertion (7-8 RPE). Heart rate, sleep quality and feeling scale were recorded during all exercise sessions. Those in the wait-list control group (n = 44) were asked to maintain their usual lifestyle. The feasibility of AGUEDA project was evaluated by retention, adherence, adverse events and cost estimation on the exercise program. RESULTS AND CONCLUSIONS: This study details the exercise program of the AGUEDA trial, including well-described multi-language manuals and videos, which can be used by public health professionals, or general public who wish to implement a feasible and low-cost resistance exercise program. The AGUEDA exercise program seems to be feasible by the high retention (95.6%) and attendance rate (85.7%), very low serious adverse event (1%) and low economic cost (144.23 € /participant/24 weeks). We predict that a 24-week resistance exercise program will have positive effects on brain health in cognitively normal older adults.

Roles of dopamine D1 and D2 receptors in the acquisition and expression of fat-conditioned flavor preferences in rats.

Sugars and fats elicit innate and learned flavor preferences with the latter mediated by flavor-flavor (orosensory) and flavor-nutrient (post-ingestive) processes. Systemic dopamine (DA) D1 (SCH23390: SCH) and D2 (raclopride: RAC), but not opioid antagonists blocked the acquisition and expression of flavor-flavor preferences conditioned by sugars. In addition, systemic D1, but not D2 or opioid antagonists blocked the acquisition of flavor-nutrient preferences conditioned by intragastric (IG) sugar infusions. Given that DA antagonists reduce fat intake, the present study examined whether systemic D1 or D2 antagonists altered the acquisition and/or expression of conditioned flavor preferences (CFP) produced by pairing one novel flavor (CS+, e.g., cherry) with a 3.5% corn oil (CO: fat) solution relative to another flavor (CS-, e.g., grape) paired with a 0.9% CO solution. In an expression study, food-restricted rats were trained to drink either flavored 3.5% or 0.9% CO solutions on alternate days. Subsequent two-bottle tests with the CS+ and CS- flavors mixed in 0.9% CO solutions occurred 0.5h after systemic administration of vehicle (VEH), SCH (50-800 nmol/kg) or RAC (50-800 nmol/kg). The rats displayed a robust CS+ preference following VEH treatment (87-88%) the expression of which was attenuated by treatment with moderate doses of RAC, and to a lesser degree, SCH. In an acquisition study, six groups of rats received VEH, SCH (25, 50, 200 nmol/kg) or RAC (50, 200 nmol/kg) 0.5 h prior to 1-bottle training trials with CS+ flavored 3.5% and CS- flavored 0.9% (CS-) CO solutions. A seventh Limited VEH group was trained with its training intakes limited to that of the SCH and RAC groups. Subsequent two-bottle tests were conducted with the CS+ and CS- flavors presented in 0.9% CO without injections. Significant and persistent CS+ preferences were observed in VEH (75-82%), Limited VEH (70-88%), SCH25 (75-84%), SCH50 (64-87%), SCH200 (78-91%) and RAC200 (74-91%) groups. In contrast, the group trained with RAC50 displayed a significant initial CS+ preference (76%) which declined over testing to 61%. These data indicate limited DA D1 and D2 receptor signaling involvement in the expression and acquisition of a fat-CFP relative to previous robust effects for sugar-CFP.

Critical role of NMDA but not opioid receptors in the acquisition of fat-conditioned flavor preferences in rats.

Animals learn to prefer flavors associated with the intake of dietary fats such as corn oil (CO) solutions. We previously reported that fat-conditioned flavor preferences in rats were relatively unaffected by systemic treatment with dopamine D1 and D2 antagonsits. The present study examined whether systemic opioid (naltrexone, NTX) or NMDA (MK-801) receptor antagonists altered the acquisition and/or expression of CO-CFP. The CFP was produced by training rats to drink one novel flavor (CS+, e.g., cherry) mixed in a 3.5% CO solution and another flavor (CS-, e.g., grape) in a 0.9% CO solution. In expression studies, food-restricted rats drank these solutions in one-bottle sessions (2 h) over 10 d. Subsequent two-bottle tests with the CS+ and CS- flavors mixed in 0.9% CO solutions occurred 0.5h after systemic administration of vehicle (VEH), NTX (0.1-5 mg/kg) or MK-801 (50-200 µg/kg). Rats displayed a robust CS+ preference following VEH treatment (85-88%) which was significantly though moderately attenuated by NTX (69-70%). The lower doses of MK-801 slightly reduced the CS+ preference; the high dose blocked the CS+ preference (49%) but also markedly reduced overall CS intake. In separate acquisition studies, rats received VEH or NTX (0.1, 0.5, 1mg/kg) or MK-801 (100 µg/kg) 0.5h prior to 1-bottle training trials with CS+/3.5% CO and CS-/0.9% CO training solutions. Additional Limited VEH groups were trained with intakes limited to that of the NTX and MK-801 groups. Subsequent two-bottle CS+ vs. CS- tests were conducted without injections. Significant and persistent CS+ preferences were observed in VEH (77-84%) and Limited VEH (88%) groups. NTX treatment during training failed to block the acquisition of CO-CFP although the magnitude of the CS+ preference was reduced by 0.5 (70%) and 1.0 (72%) mg/kg doses relative to the Limited VEH treatment (88%). In contrast, MK-801 (100 µg/kg) treatment during training blocked the acquisition of the CO-CFP. These data suggest a critical role for NMDA, but not opioid receptor signaling in the acquisition of a fat conditioned flavor preferences, and at best limited involvement of NMDA and opioid receptors in the expression of a previously learned preference.

A sipometer for measuring motivation to consume and reward value of foods and beverages in humans: Description and proof of principle.

New methods, derived from animal work, for measuring food reward value (i.e. reinforcing value of food), and motivation (i.e. strength of desire) to consume, in humans are described and validated. A sipping device (sipometer) was developed that permits access to a liquid food or beverage on two reward schedules: continuous reinforcement (CR) and progressively increasing time spent exerting pressure on a straw (PR-schedule). In addition, a pictorial scale showing a cup, from which the 'amount wanted' could be marked was used to pre-test potential consumption. Intake, time spent sipping, breakpoint, and pressure exerted were the main dependent variables measured. Three pilot experiments were conducted. In Experiment 1, participants (n=8) consumed yogurt shakes after a 1-h or 21-h food deprivation period on both schedules. In Experiment 2, participants (n=8) sham-consumed (i.e. spit out) sweet and non-sweet beverages, utilizing both schedules. In Experiment 3, sham-consuming sweet and non-sweet beverages on both schedules and working for shake on the PR schedule were repeated, after three nights of either habitual sleep or short sleep duration (n=7) in a crossover design. In Experiment 1, participants sipped longer after 21-h vs. 1-h of food deprivation (13±3.0 vs. 8.0±2.1s; p=0.04), on the PR schedule. In Experiment 2, sham-intake (p=0.01) and sipping time (p=0.04) were greater for sweet than non-sweet beverages on the PR schedule and a similar, though not conventionally significant, effect was observed for exerted pressure (p=0.09). In both Experiment 2 and Experiment 3 after habitual sleep, on the PR schedule, cumulative pressure difference between sweet and non-sweet beverage increased with difference in amount wanted in the taste test. In contrast, after short sleep participants were less willing to work for sweet taste as their wanting increased, suggesting that sleep deprivation raises desire, but lowers behavioral output. Taken together these results demonstrate that the sipometer and associated ratings are reliable and useful measures of motivation to consume and reward value in humans. Participants were more motivated to obtain access to sweet beverages, especially when these were better liked than to obtain access to non-sweet beverages.

Insulin receptor activation in the nucleus accumbens reflects nutritive value of a recently ingested meal.

With respect to feeding, insulin is typically thought of as a satiety hormone, acting in the hypothalamus to limit ingestive behavior. However, accumulating evidence suggests that insulin also has the ability to alter dopamine release in the striatum and influence food preferences. With increased access to high calorie foods, Western societies have a high prevalence of obesity, accompanied by insulin insensitivity. Little is known about how insulin is trafficked into the brain following food consumption and whether insulin insensitivity in the periphery is mirrored in the central nervous system. We investigated insulin receptor activation in the ventral striatum of rats receiving water or 16% glucose either orally or intragastrically. We also investigated whether glucose-induced insulin receptor activation was altered in food-restricted (FR) or diet-induced obesity (OB) rat models. Lastly, we examined whether insulin plays a significant role in flavor-nutrient preference learning. Glucose intake stimulated a rapid increase in insulin receptor activity in the ventral striatum of FR and ad libitum (AL) fed rats, but not OB rats. Similarly, both AL and FR, but not OB rats demonstrated significant flavor-nutrient preferences. However AL rats receiving brief inhibition of insulin activity during conditioning failed to acquire a significant flavor-nutrient preference. These findings suggest that impaired insulin receptor activation in the ventral striatum may result in inaccurate valuation of nutritive foods, which could lead to overconsumption of food or the selection of foods that don't accurately meet the body's current physiological needs.

The role of hyperinsulinema and the vagus nerve in hypothalamic hyperphagia reexamined.

Three series of experiments investigated the role of hyperinsulinemia and the vagus nerve in the hyperphagia and obesity syndrome produced in female rats by knife cuts in the ventromedial hypothalamus (VMH). The findings of the first series revealed that VMH cuts do not produce hyperinsulinemia when the rats are prevented from overeating, but insulin levels are elevated in rats allowed to overeat. The second series of experiments demonstrated that VMH-cut rats overconsume sweet sugar solutions during daily short-term tests, and that pharmacological blockade of vagal efferent activity with atropine methyl nitrate fails to inhibit this overconsumption. The third study revealed that subdiaphragmatic vagotomy completely blocks VMH hyperphagia and obesity on a chow diet, but does not prevent overeating and rapid weight gain in rats fed an assortment of highly palatable foods. These findings indicate that vagally mediated insulin release is not an essential component to the VMH knife cut syndrome.

Carbohydrate taste, appetite, and obesity: an overview.

This paper reviews previous research on sugar appetite and sugar-induced overeating and obesity in the rat, and previews new findings reported in this issue on the rat's taste and appetite for starch and starch-derived polysaccharides. A variety of behavioral methods demonstrate that rats are very attracted to the taste of sugars. At low molar concentrations their order of preference is maltose greater than sucrose greater than glucose = fructose, while at high concentrations it is sucrose greater than maltose greater than glucose = fructose. New findings indicate that rats are also very attracted to starch-derived polysaccharides, such as Polycose. In fact, Polycose is preferred to sucrose and maltose at low concentrations, and is second only to sucrose in preference at high concentrations. Furthermore, rats taste Polycose as qualitatively different from sucrose. These and other findings suggest that rats as well as other rodents have different taste receptors for sugar and starch. The role of these two taste systems in carbohydrate-induced overeating and obesity is discussed. Rats tend to overeat and become obese when fed sugar or polysaccharide diets, but this response depends critically on the form of the diet. Presenting the carbohydrate as a solution or gel supplement to the diet is much more effective in promoting hyperphagia and obesity than is presenting it as a powder supplement or as part of a composite diet. The differential response to hydrated and dehydrated foods may occur because carbohydrates are absorbed at a faster rate in hydrated forms than in dehydrated forms. The postingestive actions of carbohydrates also modulate the rat's preference for carbohydrate tastes and flavors. Other factors that influence carbohydrate appetite and intake include the availability of the carbohydrate source and the macronutrient composition of the diet. Thus, several factors in addition to taste determine the response of rats to carbohydrate foods.

Carbohydrate-induced hyperphagia and obesity in the rat: effects of saccharide type, form, and taste.

Adult female rats were fed, in addition to chow and water, a carbohydrate source that differed in type (glucose, sucrose, or polysaccharide), form (32% solution, powder, or gel), or taste (very sweet, minimally sweet, or bitter). A control group was fed only chow and water during the 40-day experiment. The groups fed the glucose solution, sucrose solution, or one of three polysaccharide solutions (Polycose, maltose-dextrin 10, maltose-dextrin 42) all overrate and gained more body weight and fat than did the control group. The carbohydrate solution groups did not differ in their total caloric intake, weight gain, percent body fat, or basal insulin level. The polysaccharide groups, however, consumed more carbohydrate than did the sugar groups. The groups fed glucose, sucrose, or Polycose in powder form consumed less carbohydrate and total calories, gained less weight and fat, and had lower insulin levels than did the groups fed the saccharides in solution form. The powder groups did not reliably differ from the control group on these measures. Rats fed Polycose in solution form or in a solid gel form (32% Polycose + 1% agar) were similar in their carbohydrate intake, total caloric intake, weight gain, and percent body fat. Rats fed Polycose solutions that were minimally sweet (32% Polycose), sweet (0.2% saccharin + 32% Polycose), or bitter [0.05% sucrose octa acetate (SOA) + 32% Polycose] did not differ in their Polycose intake, total caloric intake, weight gain, or percent body fat. The results demonstrate that saccharide form is more important than saccharide type or taste in promoting hyperphagia and obesity in rats. The Polycose gel findings further indicate that it is the water of hydration, not liquidity that is responsible for the hyperphagia-inducing effect of carbohydrate solutions.

Effects of SOA and saccharin adulteration on Polycose preference in rats.

Female rats were tested for their preference for a 32% Polycose solution, and for 32% Polycose solutions made bitter or sweet by adulteration with either 0.05% sucrose octa acetate (SOA) or 0.2% saccharin during 24 hr/day two-bottle tests. The rats preferred the saccharin-Polycose to the Polycose, the Polycose to the SOA-Polycose, and strongly preferred the saccharin-Polycose to the SOA-Polycose solution. Additional rats that were given only a Polycose or an SOA-polycose solution, in addition to chow and water, consumed similar amounts of solution, and consumed as much as did the rats given the saccharin-Polycose solution. Thus, while SOA adulteration reduces, and saccharin adulteration increases, the relative palatability of Polycose, they do not alter the animal's intake when only one solution is available. In a second experiment rats were given the choice between a 32% Polycose solution and pure Polycose powder, between an SOA-Polycose solution and Polycose powder, or between an SOA-Polycose solution and sucrose powder during both 30-min/day and 24-hr/day preference tests. During the initial short-term test the rats preferred the Polycose solution and, to a lesser degree, the SOA-Polycose solution to the Polycose powder, but they strongly preferred the sucrose powder to the SOA-Polycose solution. During the subsequent long-term test, however, the rats developed a preference for the SOA-Polycose solution over the sucrose powder. The mechanism responsible for this preference switch is not certain, but it may be related to the postingestive effects of the solution, and may also be responsible for the rat's hyperphagic response to carbohydrates in solution form but not in powder form.

Effects of anosmia on Polycose appetite in the rat.

Female rats made temporarily anosmic by intranasal treatment with zinc sulphate showed little or no reduction in their intake of a polysaccharide (Polycose) solution. This finding, along with the previous finding that experimentally-induced hypoguesia suppresses Polycose intake, indicates that olfaction is much less important than gustation in the mediation of polysaccharide appetite.

Hedonic response of rats to polysaccharide and sugar solutions.

The palatability of glucose, sucrose, maltose and polysaccharide (Polycose) was assessed by examining the consummatory response of nondeprived female rats to equicaloric or equimolar solutions of these saccharides. Both 30-min one-bottle acceptance and 30-min two-bottle preference tests were conducted: initial (3-min) lick rates were also recorded. At low molar concentrations the relative palatability of the saccharides was ordered as follows: Polycose greater than maltose greater than sucrose greater than glucose. At higher concentrations the rats were more attracted to sucrose than to Polycose; however Polycose remained more palatable than maltose at all but the highest concentration. In the one-bottle tests gram solute intakes varied as a function of percentage concentration, and was not influenced by saccharide type or solution osmolarity. The results along with other recent findings indicate that rats can taste starch-derived polysaccharides and find them quite palatable.

Oral versus postingestive origin of polysaccharide appetite in the rat.

Previous studies have revealed that rats consume substantial amounts of polysaccharide solutions, even if the solutions are made bitter with the addition of sucrose octa acetate (SOA). The present experiment used the gastric sham-feeding preparation to determine if it is the orosensory or postingestive properties of polysaccharides that motivate rats to consume polysaccharide (Polycose) solutions. In Experiment 1, food deprived rats sham fed less of a 0.05% SOA + 32% Polycose solution than they did of a 32% glucose solution, but their SOA-Polycose intake was still considerable (44 ml/hr). The same rats refused to sham feed SOA-gum and SOA-sugar solutions that were similar to the SOA-Polycose solution in bitter taste, viscosity and free sugar content. In Experiment 2, rats sham fed as much of a 32% Polycose solution as they did of a 32% sucrose solution. Despite the gastric fistula, some of the ingested Polycose was absorbed as evidenced by an increase in the rats' blood glucose levels. The addition of acarbose, a drug that inhibits polysaccharide digestion, to the Polycose solution blocked the increase in blood glucose, but did not reduce the rats' sham feeding of the solution. These findings indicate that it is the orosensory (presumably taste) properties of polysaccharide solutions, not their postingestive effects, that initially attract rats to the solutions. The results question the assumption that polysaccharides are "tasteless" to animals.

Taste preference thresholds for Polycose, maltose, and sucrose in rats.

The taste preference thresholds of adult female rats for polysaccharide (Polycose), maltose, and sucrose were compared. The nondeprived animals were given 24-hr two-bottle preference tests (saccharide solution vs. water) and, starting at 0.008%, the saccharide concentration was increased daily. The rats first preferred the Polycose solution to water at 0.01% (0.0001 M), the maltose solution to water at 0.09% (0.0025 M), and the sucrose solution to water at 0.09% (0.0026 M). Thus, on a molar basis the rats' Polycose threshold was 25 to 26 times lower than their maltose and sucrose threshold. It was postulated that the low taste threshold for polysaccharides allows the rat to detect starch which, unlike sugar, is very low in solubility.

Qualitative differences in polysaccharide and sugar tastes in the rat: a two-carbohydrate taste model.

A conditioned taste aversion paradigm was used to assess the qualitative similarities between the tastes of a polysaccharide (Polycose) solution and sugar solutions (sucrose, maltose, glucose, fructose). In Experiment I, three groups of female rats were water deprived and conditioned to avoid a 0.025 M Polycose, a 0.1 M sucrose, or a 0.1 M maltose solution by pairing solution consumption with a lithium chloride (LiCl) injection; in a control group water consumption was paired with the LiCl injection. The extent to which the experimental groups generalized their conditioned aversion to the other three solutions was then assessed. The Polycose-conditioned group avoided the maltose solution more than the sucrose solution, and the maltose-conditioned group avoided the Polycose solution more than the sucrose solution. The sucrose-conditioned group avoided the maltose and Polycose solutions to the same relatively low degree. In additional tests the three experimental groups showed similar aversions to a glucose solution, but only the sucrose-conditioned rats avoided a fructose solution. Rats in a second experiment also displayed relatively little cross-generalization between Polycose and sucrose aversions even though they were tested with different solution concentrations. Additional tests confirmed the results obtained in Experiment 1 with maltose, glucose, and fructose solutions, and also revealed that the sucrose-conditioned group, but not the Polycose-conditioned group avoided saccharin solutions. Neither Polycose- nor sucrose-conditioned groups avoided quinine, sodium chloride, or hydrochloric acid solutions. These results, along with other recent findings, suggest that rats have two types of "carbohydrate" taste receptors, one for polysaccharides and one for sucrose, which produce qualitatively distinct gustatory sensations.

Sham-feeding response of rats to Polycose and sucrose.

Adult female rats were fitted with gastric fistulas and maintained at 85% of their ad lib body weight. Their real-feeding (fistula closed) and sham-feeding (fistula open) responses to polysaccharide (Polycose) and sucrose solutions were measured during 30 min/day one-bottle tests. The rats consumed similar amounts of a 1% Polycose solution during real- and sham-feeding tests, but their sham-intakes of 4%, 16% and 32% Polycose solutions greatly exceeded their real-intakes of these solutions. Similar results were obtained with sucrose solutions. The rats sham-fed more Polycose than sucrose at the 1% and 4% concentrations, while their sham-intakes of the 16% and 32% Polycose and sucrose solutions were comparable. In subsequent two-solution sham-feeding tests, the rats preferred 1% Polycose to 1% sucrose, but preferred sucrose to Polycose at 4%, 16% and 32% concentrations. These preference results indicate that rats find Polycose more palatable than sucrose at low concentrations, but sucrose more palatable at high concentrations. In addition, the findings that the rats preferred 4% sucrose to 4% Polycose in the two-bottle test, but sham-fed more 4% Polycose than 4% sucrose in the one-bottle tests, suggest that sucrose is more "orally-satiating" than is Polycose. These results provide further evidence for qualitative differences in the tastes of sucrose and polysaccharide. They also indicate that the amount of solution sham-fed does not necessarily reflect the palatability of the solution.

Effects of gustatory deafferentation on Polycose and sucrose appetite in the rat.

Recent studies have revealed that rats are strongly attracted to the taste of starch-derived polysaccharides, and suggest that the taste receptors involved differ from those that respond to sucrose. The present study examined the possibility that different gustatory nerves mediate the rat's taste and appetite for polysaccharides and sucrose. This was accomplished by measuring the effects of selective gustatory nerve transection on the intake of Polycose and sucrose solutions in nondeprived female rats. Bilateral transection of the chorda tympani nerve produced comparable reductions in Polycose and sucrose intake, but bilateral transection of the glossopharyngeal nerve selectively reduced the intake of Polycose. Bilateral transection of the greater superficial petrosal nerve, and to a lesser degree, the pharyngeal branch of the vagus nerve, increased sucrose intake without affecting Polycose intake. These results indicate that while no single gustatory nerve mediates sucrose or polysaccharide taste, there is some specialization of function within the peripheral gustatory system. Combined bilateral transections of all four gustatory nerves produced the greatest reduction in solution intake, and reduced Polycose and sucrose consumption to the same degree. The suppressive effect was only partial, however, which indicates that relatively few intact taste receptors are required to maintain the rat's appetite for sugar and polysaccharide solutions.

Influence of saccharin on Polycose, sucrose, and glucose intake and preference in rats.

The effect of adding 0.125% saccharin to 3% or 32% solutions of Polycose, sucrose and glucose on the fluid intake and preference of adult female rats was examined. In Experiment 1, the rats consumed more of a 3% Polycose + 0.125% saccharin solution (P + s) than of either a 3% Polycose or 0.125% saccharin solution; similar results were obtained with sucrose + saccharin (S + s) and glucose + saccharin (G + s) solutions. The polydipsic effects of the P + s, S + s, and G + s solutions were comparable (225 to 278 ml/day). Adding saccharin to 32% Polycose, sucrose, or glucose solutions did not increase solution intake. In two-solution preference tests, though, the rats preferred the 32% Polycose + saccharin and 32% glucose + saccharin solutions to 32% Polycose and 32% glucose solutions, respectively. Saccharin did not reliably affect the preference for the 32% sucrose solution. In Experiment 2, the preference for 3% carbohydrate solutions was assessed using two-solution tests. The rats preferred 3% sucrcose to 3% Polycose or 3% glucose; they also preferred 3% Polycose to 3% glucose. When saccharin was added to the solutions, the rats displayed equal preferences for the S + s and P + s solutions, and for the P + s and G + s solutions but they strongly preferred the S + s to the G + s solution. Recent findings suggest that polysaccharides such as Polycose taste qualitatively different from sucrose and saccharin to rats, i.e., have a "nonsweet" taste.(ABSTRACT TRUNCATED AT 250 WORDS)

Species differences in polysaccharide and sugar taste preferences.

This study compared the polysaccharide and sugar taste preferences of humans and four rodent species (laboratory rats, Rattus norvegicus; Golden Syrian hamsters, Mesocricetus auratus; Mongolian gerbils, Meriones unguiculatus; Egyptian spiny mice, Acomys cahirinus). In Experiment 1 human subjects rated the pleasantness, sweetness, and flavor intensity of polysaccharide (Polycose), sucrose, and maltose solutions at concentrations of 0.0125 M to 0.4 M, and 1% to 32% concentrations. At the higher molar concentrations Polycose was rated as less sweet and less pleasant than the sucrose and maltose solutions; there were no differences in the flavor intensity ratings. With the percent concentrations Polycose was rated as less sweet and less flavorable as the sucrose and maltose solutions; there were no reliable differences in the pleasantness ratings. In Experiment 2, the Polycose, sucrose, and maltose preferences of rats, hamsters, gerbils, and spiny mice were compared using 24 hr two-bottle tests (saccharide vs. water) at concentrations of 0.001 M, 0.005 M, 0.01 M, and 0.1 M. In general, the rats displayed stronger preferences for Polycose and maltose than did the other three species. In addition, the gerbils showed a stronger Polycose preference at the 0.1 M concentration than did the hamsters and spiny mice, and the spiny mice display a weaker preference for sucrose than did the other three species. Within species comparisons revealed that all four species displayed preferences for Polycose that were as strong or stronger than their preferences for sucrose and maltose. With only a few exceptions, male and female rodents did not differ in their saccharide preferences. Thus, while rats show the most robust Polycose preference of the four rodent species, all four species were attracted to the taste of polysaccharides. Humans, on the other hand, reported that Polycose solutions were unpleasant. The results suggest that rodents have taste receptors for starch-derived polysaccharides that humans lack.