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Biomedical subjects

A Sclafani

Publications and source records attributed to A Sclafani.

At least 109 records · Page 6Linked to original sources
PubMed1987

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.

Adult↗
PubMed1987

Sex differences in polysaccharide and sugar preferences in rats.

The preferences of adult male and female rats for sucrose and polysaccharide (Polycose) solutions were measured in three experiments. In Experiment 1, male and female rats did not differ in their preference for molar solutions of sucrose or Polycose as measured by 24-hr solution vs. water tests. In Experiment 2, however, male rats displayed a greater preference for Polycose, and females a greater preference for sucrose as measured in 3-min and 30-min/day sucrose vs. Polycose tests. Both sexes preferred Polycose to sucrose at low concentrations, but switched their preference at higher concentrations. Experiment 3 revealed that both male and female rats strongly preferred 32% sucrose to 32% Polycose in 30-min/day two-solution tests, but this preference did not persist when the rats were given 24-hr/day access to the two solutions. Male rats lost their sucrose preference, while female rats developed a preference for Polycose over sucrose. The sexes also differed in that the female rats increased their total caloric intake more and consumed proportionately more carbohydrate than did the male rats during the 24-hr/day test. The findings demonstrate that while both male and female rats have an avid appetite for polysaccharide and sucrose solutions, they differ in their short-term and long-term relative preferences for the two carbohydrates, as well as in their caloric and diet selection responses to the carbohydrate solutions. The possible functional significance of these sex differences are discussed.

Animals↗
PubMed1987

Starch preference in rats.

Several experiments examined the preference of adult female rats for starch and starch-derived polysaccnarides using short- and long-term two-choice tests. In Experiment 1, food-deprived rats displayed an immediate preference for powdered corn starch over powdered cellulose in 30-min/day tests. This supports the hypothesis that rats have starch (polysaccharide) taste receptors. The rats also preferred the starch powder to Polycose powder. This preference was unexpected since Polycose, being partially hydrolyzed corn starch, should be a more effective taste stimulus than corn starch. Experiment 2 revealed that nondeprived rats also preferred starch to Polycose in 30-min/day tests, but reversed their preference in 24-hr/day tests; the preference reversal was attributed to postingestive factors. Additional experiments demonstrated that rats preferred branched-chain starch (amylopectin) to unbranched starch (amylose) in both short- and long-term tests. Rats also preferred amylopectin to Polycose in short-term tests when the saccharides were in powder form, but preferred Polycose to amylopectin when the saccharides were in liquid or gel form. The preference for amylopectin powder was not due to the noncarbohydrate constituents (fatty acids, proteins, others) in the starch since rats also preferred chemically purified amylopectin to Polycose powder. Additional tests suggested that texture differences do not explain the rats' preference for starch powder over Polycose powder. Taken together, the results demonstrate that rats have a robust preference for starch but the orosensory determinants of this preference are not completely understood.

Amylopectin↗
PubMed1987

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.

Animals↗
PubMed1987

Effects of gastrointestinal surgery on ingestive behavior in animals.

Surgical manipulations of the gastrointestinal system can have a major impact on the ingestive behavior of animals. Particularly well-documented are the feeding and drinking effects of JIB and vagotomy. These two surgical procedures are similar in that they reduce the food intake and body weight of obese animals more than that of lean animals, and of hypothalamic obese rats more than that of genetically obese rats. Intermediate effects are obtained with other obesity models. Given the multiple etiologies of human obesity, it is not surprising that gastrointestinal surgery has variable effects in obese humans. The effects of gastric surgery on the ingestive behavior of animals have received relatively little attention. This is unfortunate because gastric bypass is now one of the most widely used methods for surgical treatment of human obesity. In light of recent developments in gastric surgical techniques and new findings concerning the gastric modulation of food intake, the effects of gastric surgery on the feeding behavior of animals should be further investigated. Much remains to be learned about the physiologic and behavioral mechanisms by which gastrointestinal surgery influences ingestive behavior and body weight. Surgical manipulations of the gastrointestinal system may affect ingestive behavior by directly altering the neural and hormonal feedback signals to the brain from the stomach, intestines, and other organs (liver, pancreas), or they may indirectly alter these feedback signals by modifying the preabsorptive and/or postabsorptive flow of nutrients. Seen from a functional perspective, the gut sends to the brain different types of messages that modulate ingestive behavior. Most attention has focused on gut satiety signals, but the gut can also be the source of painful sensations that suppress ingestive behavior. The distinction between satiety and discomfort is not always clear-cut. For example, gut distention may be satiating when it is moderate, but painful when it is extreme. Nevertheless, the distinction is an important one, and the nature of the feeding-inhibitory effects obtained in animal studies must be carefully evaluated. Ideally, obesity surgery should produce minimal aversive consequences, although whether it is possible to reduce food intake and body weight without producing any discomfort remains to be established. In addition to being a source of feeding-inhibitory cues, the gastrointestinal system may also provide excitatory cues that stimulate feeding and modify food preferences. For example, intestinal infusions of carbohydrates increase subsequent food intake under certain conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Rats show only a weak preference for the artificial sweetener aspartame.

The preference of adult female rats for aspartame (L-asparty L-phenylalamine methyl ester) was measured using 24 hr/day and 30 min/day two bottle preference tests. At aspartame concentrations that humans find sweet (0.0125% to 0.05%) the rats failed to prefer aspartame to water. At higher concentrations (0.1% to 1.0%) half (n = 11) of the rats tested displayed mild (64%) to moderate (83%) aspartame preferences. The other half of the rats were indifferent or avoided the aspartame. Even at the most preferred concentration (1.0%) the rats' aspartame preference was much less than their preference for saccharin or sucrose, and they showed little increase in total fluid intake when given the aspartame solution. The results indicate that aspartame is not very palatable to rats, and suggest that it has little or no sweet, i.e., sucrose-like, taste to rats as it does to humans.

Animals↗
PubMed1985

Aversive consequences of jejunoileal bypass in the rat: a conditioned taste aversion analysis.

Jejunoileal bypass (JIB) surgery reduces food intake and body weight in obese humans and rats. Human bypass patients report visceral discomfort following surgery, and the present study assessed the aversive consequences of JIB in rats using a conditioned taste aversion paradigm. In Experiment 1 rats given a cherry-flavored solution immediately after JIB surgery subsequently displayed a strong aversion to the cherry flavor compared to Bypass and Sham-Bypass control groups. Rats in Experiment 2 were familiarized with cherry solution prior to surgery and they did not display an aversion to the solution after receiving a JIB. In Experiment 3, Bypass rats who developed a cherry flavor aversion after JIB subsequently lost this aversion following reconnection of their intestinal tract. The rats in Experiment 4 displayed an aversion to a saccharin-flavored chow that was eaten shortly after JIB surgery, although the aversion was not as pronounced as that obtained with the cherry solution. The results suggest that JIB produces a persisting malaise in rats that may contribute to the feeding and weight inhibitory effects of the operation.

Animals↗
PubMed1985

Aversive effects of vagotomy in the rat: a conditioned taste aversion analysis.

Subdiaphragmatic vagotomy suppresses food intake and water intake in normal rats. Since human patients report some nausea and discomfort following vagotomy, the present study assessed the aversive consequences of vagotomy in rats using a conditioned taste aversion paradigm. Rats were given a total subdiaphragmatic vagotomy or sham vagotomy, and were then maintained on either plain water (Vag-Water and Sham-Water groups) or a novel cherry solution (Vag-Cherry and Sham-Cherry groups). When subsequently tested for their water vs. cherry preferences on postoperative days 6, 16, and 26, the Vag-Cherry group displayed a greater aversion to the cherry solution than did the remaining three groups. This result suggests that vagotomy produces visceral malaise in rats which may contribute to the feeding and drinking suppressive effects of the surgery.

Animals↗
PubMed1985

On the role of the mouth and gut in the control of saccharin and sugar intake: a reexamination of the sham-feeding preparation.

Adult female rats, each fitted with a gastric fistula, were tested for their "normal-feeding" (fistula closed) and "sham-feeding" (fistula open) response to saccharin and sugar solutions under a variety of conditions. When hungry, rats consumed no more of a 0.2% saccharin solution with their fistula open than they did with their fistula closed. Increasing or decreasing the saccharin concentration did not increase the amount of solution sham fed, but adding a small amount of glucose (3%) to the saccharin solution did increase the amount sham fed. Thirsty rats, unlike hungry, significantly increased their 0.2% saccharin solution intake when tested with an open fistula. When tested with a 32% glucose solution, hungry rats consumed up to six times more solution with their fistula open than with their fistula closed. The hungry rats also sham fed significantly more of the 32% glucose solution than of the 0.2% saccharin solution or 0.2% saccharin + 3% glucose solution. Sham-feeding of a 32% sucrose solution significantly elevated blood glucose levels, but blocking this effect by adding acarbose, a drug that inhibits sucrose digestion, did not reduce the amount of solution sham fed. Several possible explanations for the differential sham-feeding response to saccharin and sugar solutions are discussed.

Animals↗
PubMed1985

Is gastric sham feeding really sham feeding?

Rats were fitted with gastric cannulas, food deprived, and allowed to drink a sugar solution that drained out of the opened cannula; i.e., the rats sham-fed. Although this procedure is thought to prevent absorption of ingested food, it was found that the sham feeding of a 32% glucose or sucrose solution significantly elevated blood glucose levels. The addition of acarbose, a drug that inhibits the digestion of sucrose, to the 32% sucrose solution blocked the blood glucose rise, as did closing the pylorus with an inflatable pyloric cuff. Neither the drug nor the cuff, however, reduced the amount of sucrose solution consumed. These findings indicate that gastric sham feeding does not necessarily prevent the digestion and absorption of food, although absorption is not essential for the appearance of a vigorous sham-feeding response. Nevertheless the possibility that neural or hormonal feedback from the stomach contributes to the sham-feeding response cannot be excluded, and until this issue is resolved the results of gastric sham-feeding studies should be interpreted with caution.

Acarbose↗
PubMed1984

Influence of diet form on the hyperphagia-promoting effect of polysaccharide in rats.

Adult female rats were fed chow only, or chow plus the polysaccharide Polycose presented as a solution (32% w/v), as a powder, or as a powder mixed into the chow diet. The rats fed the Polycose solution overate and gained three times as much weight as did the control rats in the 30-day test period. The rats fed the Polycose powder or mixed diet, on the other hand, did not differ from controls in food intake or weight gain. The solution-fed rats consumed more Polycose than did the powder-fed rats, but the two groups were equivalent in their chow intake. The absolute and percent body fat of the solution-fed rats exceeded that of control rats, as well as that of powder and mixed-diet animals. The percent body fat of the powder and mixed-diet groups exceeded that of the control animals. The findings demonstrate that the form of diet presentation has a major impact on the rat's feeding and body weight responses to polysaccharide diets.

Adipose Tissue↗
PubMed1984

Sucrose and polysaccharide induced obesity in the rat.

Adult male rats were fed, in addition to chow and water, solutions (32%) of either sucrose, Polycose (a bland-tasting polysaccharide), or Polycose sweetened with 0.2% saccharin. The solutions were available for two 30-day periods when the rats were 90-120, and 180-210 days of age. A control group received only chow and water during these periods. During the second 30-day test the Polycose and Saccharin- Polycose groups were hyperphagic and gained as much excess weight as did the Sucrose group. The sucrose-fed rats, however, did not overeat relative to the control animals. Adding saccharin to the Polycose failed to increase total caloric intake or weight gain, but did increase Polycose intake and percent carbohydrate intake. The intakes of both Polycose solutions were greater than that of the sucrose solution, although in brief two-bottle preference tests the sucrose solution was preferred over the Polycose and saccharin- Polycose solutions. A similar pattern of results was obtained during the first test period, but the group differences were less pronounced. The findings demonstrate that carbohydrate-induced obesity is not unique to sweet-tasting sugars, but can also be produced by bland-tasting polysaccharides. Sweet taste does increase polysaccharide preference and intake, however.

Animals↗
PubMed1984

Diet-dependent hyperplastic growth of adipose tissue in hypothalamic obese rats.

Accelerated production of fat cells is often seen in dietary obesity in rats but not in obesity occurring in response to damage to the medial area of the hypothalamus (MH). The basis for this difference was examined. MH damage (MHD) was produced in rats by either electric current or small knife cuts. Rats were then fed either chow or a high-fat high-sugar diet (HFS) for up to 6 mo. Fat cell production did not accelerate during the 1st 16 wk after MHD in rats fed only chow, but acceleration clearly occurred in rats fed HFS during only 4 wk. At 18 wk after MHD rats fed only chow showed evidence of accelerated fat cell production. However, there was greater acceleration after MHD in HFS-fed rats held to the same weight gain as chow-fed rats. Rats allowed to freely eat HFS for 6 mo after MHD showed extremely large increases in body weight and fat cell number. The plateau in body weight often seen in rats fed only chow after MHD did not occur. Because HFS-feeding promoted unimpeded production of fat cells, accelerated weight gain induced by MHD could continue indefinitely. These findings suggest that enlargement of fat cells and components of the diet act synergistically in the promotion of adipocyte hyperplasia in adult rats and also suggest that accelerated weight gain after MHD is not due to elevation of a set point for body weight or body fat.

Adipose Tissue↗
PubMed1983

Dietary selection in vagotomized rats.

Adult female vagotomized and control (sham-vagotomized) rats were compared in their consumption of saccharin solutions, intake of solid and liquid sucrose, and selection of purified macronutrient diets. In 30 min/day tests the vagotomized rats drank more saccharin solution (0.05, 0.1, 0.2%) than did control rats, while in a 24 h/day test they drank considerably less saccharin solution (0.2%) than did controls. When offered ad libitum access to granular sucrose and lab chow vagotomized rats did not differ from controls in their sucrose intake, chow intake, or total caloric intake. With a 20% sucrose solution and chow available, however, the vagotomized rats consumed significantly less sucrose and total calories than did the controls. Also, unlike the controls, the vagotomized rats did not consume more of the liquid sucrose than of the granular sucrose, and failed to gain weight on the sucrose diets. When maintained on solid macronutrient diets the vagotomized rats were similar to controls in their selection of the fat, carbohydrate and protein diets. The results demonstrate that vagotomy selectively inhibits the intake of sugar solutions and not high-carbohydrate diets in general. Possible explanations for this effect are discussed.

Animals↗
PubMed1983

Conditioned taste aversion in lean and obese rats with ventromedial hypothalamic knife cuts.

The development of a conditioned taste aversion (CTA) was assessed in rats made hyperphagic with parasagittal knife cuts in the ventromedial hypothalamus (VMH). The animals were water deprived and presented with a .1% saccharin solution paired with injections of either lithium chloride or sodium chloride. In Experiment 1, VMH rats tested at a nonobese weight level did not differ from sham-operated control rats in the acquisition and extinction of the CTA. In Experiment 2, moderately obese VMH rats displayed a stronger CTA than did sham-operated control rats as evidenced by a slower rate of extinction. This effect was not due to the higher absolute dose of LiCl given to the obese VMH rats. A second group of obese VMH rats given an amount of LiCl equivalent to that given to the control rats also displayed retarded extinction of the CTA. The results of these experiments demonstrate that hyperphagia-inducing knife cuts do not alter aversive taste conditioning in rats but that hypothalamic obesity does enhance conditioned taste aversions. This may reflect an obesity-induced suppression in appetitive motivation.

Animals↗
PubMed1983

Paraventricular hypothalamic lesions and medial hypothalamic knife cuts produce similar hyperphagia syndromes.

The hyperphagia/obesity syndrome produced by paraventricular hypothalamic (PVH) lesions and that produced by medial hypothalamic (MH) knife cuts were compared in adult female rats. Each treatment produced hyperphagia and overweight on a chow diet, although the PVH effect was less than the knife-cut effect. Each treatment also produced qualitatively similar ingestive responses to unpalatable quinine- and sucrose octaacetate-adulterated diets and to palatable dextrose and fat diets during the dynamic and static weight-gain phases. The PVH lesions and MH cuts disrupted day/night feeding patterns and elevated water intakes but not water/food intake ratios. However, PVH lesions, unlike MH cuts, did not increase emotional reactivity. The relation of the PVH syndrome to the classic hypothalamic hyperphagia syndrome is discussed. Also considered is the neuroanatomical substrate responsible for the PVH hyperphagic effect.

Animals↗
PubMed1983

Macronutrient self-selection in three forms of hypothalamic obesity.

Adult female rats were adapted to a macronutrient self-selection regimen which allowed them ad libitum access to separate sources of protein, carbohydrate, and fat. The rats were then given either ventromedial hypothalamic (VMH) lesions, paraventricular hypothalamic (PVH) lesions, parasagittal knife cuts through the medial hypothalamus (CUT), or sham lesions and their macronutrient selection was studied for 60 days. Following surgery the VMH, PVH, and CUT rats overate and became obese compared with controls. The hyperphagias of the three groups were similar, although the CUT group gained more weight than did the PVH and VMH groups. All groups overate primarily by increasing their carbohydrate intake. The VMH and CUT groups, in addition, increased their protein intake such that their percent protein intake remain unchanged. The PVH group failed to increase its absolute protein intake and thus decreased its percent protein intake. Except for a transient increase, fat consumption was not affected by the lesions or knife cuts. During the 2nd postoperative mo (static phase) the total caloric intakes and the carbohydrate intakes of the VMH, PVH, and CUT groups returned to near normal levels. Rats with misplaced PVH lesions displayed minimal hyperphagia and failed to outgain controls but yet showed the same altered macronutrient selection pattern as did rats with obesity-inducing PVH lesions. Measurements of resting insulin levels at the end of the experiment revealed hyperinsulinemia in the VMH and CUT groups but normal insulin values in the PVH group. These results demonstrate that VMH lesions, PVH lesions, and medial knife cuts produce similar hyperphagia syndromes associated with carbohydrate-specific overeating, but that they differentially affect protein selection and resting insulin levels.

Animals↗