Effects of lesions of the gustatory neocortex on taste aversion learning in the rat.

In 5 experiments, 110 normal male Long-Evans hooded rats and 125 Ss with lesions of the gustatory neocortex (GN) were compared for their ability to learn aversions to taste cues paired with toxicosis. When the taste presentation was followed immediately by toxicosis, normal Ss and 8 Ss with lesions of the posterior (visual) neocortex learned aversions to sucrose, sodium chloride, quinine hydrochloride, and hydrochloric acid solutions. Ss with GN lesions learned aversions to all solutions except sucrose. In preference tests, all solutions were shown to be discriminable from water by both normal and GN-lesioned Ss. Under conditions in which a 6-hr delay separated taste presentation and toxicosis, normals again learned specific aversions to all 4 solutions, but Ss with GN lesions failed to learn specific aversions to sucrose, sodium chloride, and hydrochloric acid solutions. It was shown that the ability of Ss with GN lesions to learn aversions to sucrose and quinine depended on stimulus concentration. It is proposed that the data can be accounted for by postulating a change in the threshold for taste illness associations following GN lesions. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Taste as a dipsogenic stimulus.

Studied solution drinking in 50 male, nondeprived, Sprague-Dawley albino rats to determine how much animals will drink for reasons of taste alone. 4 different taste stimuli (sucrose, glucose, sodium saccharin, and sodium chloride) were used, each covering a wide range of concentrations. The same Ss were then retested after 16 hr. of water deprivation, and intakes under deprived and nondeprived conditions were compared. Results show that Ss ingested large volumes of sweet solutions in the absence of any need, and that water deprivation added only a small increment to the already high intakes of sweet solutions. Sodium chloride solutions, on the other hand, were ingested in relatively small quantities by nondeprived Ss, but water deprivation produced a large increase in intake. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of potassium depletion on mineral appetite in the rat.

Studied potassium appetite in normal female Sprague-Dawley rats and in rats in which the total body potassium had been reduced by 15-20%. Potassium depletion resulted in increased ingestion of solutions of NaCl, KCl, CaCl2, and quinine sulphate in concentrations that were unacceptable to normal Ss. The amount of potassium ingested was related to the degree of potassium depletion and repletion was usually completed within 24 hr. when potassium was offered. Potassium-depleted Ss also drank large quantities of aversive concentrations of sodium chloride. This was preferred to potassium chloride and its ingestion appeared to be unrelated to need. The appetite state was reversed by prior intragastric repletion with potassium but not with sodium salts. (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavior of sodium-deficient rats: The search for a salty taste.

Tested whether 188 Na-deficient rats would search for the taste of Na or the taste of salt. Ss were subjected to various conditions of food and water deprivation before being given a choice between solutions of varying saltiness. Na-deficient Ss displayed an appetite for solutions that humans judged as salty-tasting whether or not the solutions contained sodium salts. When offered a choice between a pair of sodium salts, Ss generally preferred the more salty-tasting solution. They tended to do the same for a pair of nonsodium salts and for a pair of sodium and nonsodium salts. Results show that human psychophysical judgments of saltiness are a good predictor of the choices that rats will make when Na-deficient. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Heredity and experience: Their relative importance in the development of taste preference in man.

Heritability estimates for sucrose, lactose, and sodium chloride taste preferences were uniformly low in a total of 311 pairs of monozygotic and like-sex dizygotic twins between 9 and 15 yrs of age. Black Ss preferred more concentrated solutions of all 3 tastants than did Caucasian Ss. This effect was independent of socioeconomic status in the total sample. Males preferred more concentrated solutions of sucrose and lactose than did females, but there were no sex differences in sodium chloride preference. The possibility that early intake experiences may play a role in the determination of enduring taste preferences in humans is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related differences in the pleasantness of chemosensory stimuli.

Investigated the existence of changes in preference for various concentrations of single tastes and of the same single tastes in more complex chemosensory mixtures, using 300 participants from 3 different age groups (i.e., 18–26, 32–45, and 65–93 yrs). Ss rated for pleasantness 4 concentrations of sodium chloride, sucrose, and citric acid presented in both aqueous and beverage bases. Results show significant effects of age, stimulus background, stimulus, concentration, and of several interactions, and they suggest that elderly Ss find salt and sugar pleasanter at higher concentrations than younger Ss do. It is suggested that an investigation of chemosensory preference and chemosensory intensity be conducted simultaneously in a single group of elderly and young persons. (47 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Taste in acceptance of sugars by human infants.

Offered 96 male and 96 female 23-84 hr old infants water and a solution of glucose, fructose, lactose, or sucrose for 3-min periods. Volumes ingested were measured. Ss discriminated between water and a solution of sugar, demonstrating a distinct preference for the latter. The effectiveness of sugars in evoking ingestion varied with both the compound and the solution concentration. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Taste salience depends on novelty, not concentration, in taste-aversion learning in the rat.

Conducted 2 experiments with 12 rat litters of albino-hooded-Brown-Swarthmore strain derivation. Ss formed stronger aversions to solutions that were either more concentrated or more novel than other solutions. From the results it is proposed that the data can be reinterpreted in terms of just one of these factors-novelty-since the more concentrated solution is also ordinarily more novel. When Ss were poisoned after drinking 2 concentrations of the same solute, Ss reared on water acquired aversions mainly to the more concentrated solution. Ss reared on a still more concentrated solution acquired aversions mainly to the less concentrated solution which for them was more novel. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal and Qualitative Dynamics of Conditioned Taste Aversion Processing: Combined Generalization Testing and Licking Microstructure Analysis.

The pattern of licking microstructure during various phases of a conditioned taste aversion (CTA) was evaluated. In Experiment 1, rats ingested lithium chloride (LiCl) for 3 trials and were then offered sodium chloride (NaCl) or sucrose on 3 trials. A CTA to LiCl developed and generalized to NaCl but not to sucrose. CTA intake suppression was characterized by reductions in burst size, average ingestion rate, and intraburst lick rate, and increases in brief pauses and burst counts. Compared with previous studies, LiCl licking shifted from a pattern initially matching that for normally accepted NaCl to one matching licking for normally avoided quinine hydrochloride by the end of the 1st acquisition trial. In Experiment 2, a novel paradigm was developed to show that rats expressed CTA generalization within 9 min of their first LiCl access. These results suggest that licking microstructure analysis can be used to assay changes in hedonic evaluation caused by treatments that produce aversive states. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of chlorhexidine on human taste perception

Chlorhexidine gluconate at a dose used to control bacteria in the mouth has a reversible effect on taste perception. Taste-intensity ratings and taste-quality identification for concentration series of sucrose, sodium chloride, citric acid and quinine hydrochloride were obtained from 15 healthy humans. The participants rinsed with 0.12% chlorhexidine for 3 min twice a day. Each individual was tested 3 times: before the 4-day rinse period, 30 min after the final rinse, and 4 days after the rinse period. Chlorhexidine rinses reduced the perceptual intensity of sodium chloride and quinine hydrochloride, not sucrose or citric acid. No effects on taste perception were detected 4 days after the rinse period. The identification of sodium chloride as salty was seriously impaired by chlorhexidine but the identification of quinine hydrochloride as bitter was not affected. Specific sites of action of chlorhexidine on the taste epithelium are not known but its effects on salty taste may be related to its strong positive charge and its effect on bitter taste may be related to its amphiphilicity. Chlorhexidine has promise as a probe of taste transduction, as well as for the management of salty/bitter dysgeusias in humans.     

Failure of sodium- and calcium-deficient rats to acquire conditioned taste aversions to the object of their specific hunger.

Attempted to condition taste aversions to the objects of 2 mineral-specific hungers in 2 experiments with a total of 116 male Sprague-Dawley rats. Both the innate preference of adrenalectomized Ss for sodium and the learned preference of parathyroidectomized Ss for calcium were studied. None of the sodium-deficient Ss poisoned after drinking NaCl reached a taste-avoidance criterion, even after 9 pairings of salt ingestion with aversive lithium chloride injections. 6 of 11 calcium-deficient Ss did not meet the salt-avoidance criterion after 10 pairings. Nondeficient control Ss learned to avoid these salt solutions completely after an average of only 3 such pairings. Besides unmasking a surprising degree of similarity between the learned and innate specific hungers studied, results clearly demonstrate a powerful influence of physiological need on aversion conditioning. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A study on the relationship between antisense EGFR cDNA fragments and nuclear matrix proteins in glioblastoma cells

The effects of physical exercise on preference for various sapid solutions was studied in 58 healthy university students. After 30 min of exercise using a bicycle ergometer at 50% VO2max (maximal oxygen uptake) intensity, a rating scale test on taste hedonic tone and the triangle test for taste absolute threshold were done. The test solutions were sucrose, NaCl, citric acid, caffeine and monosodium glutamate (MSG). Preference scale values for sucrose and citric acid increased after exercise, whereas the values for NaCl, caffeine and MSG were not changed. The absolute thresholds for all the sapid solutions did not differ for pre- and post-exercise. These findings indicate that in humans preference for sucrose and citric acid increase after physical exercise.     

Cessation of drinking following intracranial injections of angiotensin in the rat.

Injection of angiotensin amide into the preoptic area is known to elicit drinking in rats that are in water balance. 2 experiments were conducted with a total of 15 male hooded rats. When Ss were injected with 10 ng. angiotensin and access to water was delayed for varying times, the dipsogenic effect of angiotensin lasted for 60-90 min. When access to water was not delayed, Ss stopped drinking after 8.5 min., indicating that the ingestion of water is satiating. When Ss were offered isotonic saline, they stopped drinking 11 min. after injection, indicating that satiation or inhibition of angiotensin-induced thirst can also occur when there are no osmotic changes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Protein binding effects of salivary excretion of phenobarbital in dogs

The salivary excretion of phenobarbital was investigated by collecting parotid saliva (Pr) and mandibular-sublingual saliva (MS) separately after intravenous administration in beagle dogs. (1) The alterations in the proportions of saliva secreted by the different glands were produced by salivation stimulants such as citric acid, ascorbic acid, sodium chloride and sodium glutamate. (2) The phenobarbital concentrations in both Pr amd MS were lower than those in plasma. The drug concentrations in MS were significantly lower than in Pr with stimulus of 10% citric acid of 15% sodium chloride (p less than 0.05). There was a significant correlation between phenobarbital concentration in each saliva and plasma specimen ( p less than 0.05). (3) The stimulation with 10% citric acid produced higher saliva /plasma drug concentration ratios (S/P ratios: 0.923 +/- 0.175 for Pr, 0.633 +/- 0.073 for MS) than that with 15% sodium chloride (S/P ratios: 0.597 +/- 0.071 for Pr, 0.509 +/- 0.067 or MS). (4) The S/P ratios were hardly influenced by salivary flow rates, at least under the experimental conditions examined in this study. (5) The increased S/P ratios were observed with higher salivary pH and then the equation of Matin et al. 3) seemed to hold for the average values of salivary pH and S/P ratio. (6) The stimulation with 10% citric acid produced higher protein concentration in saliva and higher S/P ratio than that with 15% sodium chloride following alternate stimulations in the same dog.     

Production of satiety with small intraduodenal infusions in the rat.

9 male Sprague-Dawley rats equipped with chronic intragastric and intraduodenal catheters received small infusions of various solutions through 1 catheter during spontaneous meals. Regardless of which compartment or which solution was infused, the Ss maintained a constant daily nutrient intake. However, all hypertonic solutions reduced mean meal size and increased the frequency of feeding when injected intraduodenally, while only nutritive solutions reduced mean meal size when infused intragastrically. Water ingestion varied with the effective osmotic pressure of the injected solutions, but there were no differences in water ingestion as a function of the compartment infused. Data suggest both the presence of a duodenal satiety mechanism and the validity of interpreting the meal patterns of vagotomized Ss eating a liquid diet as resulting from the rapid emptying of the diet into the duodenum. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of illness in producing learned taste aversions in rats: A comparison of several rodenticides.

Compared several toxic agents to test the effect of various types of illness in producing learned taste aversions. Ss in 2 experiments were 90 female and 26 male Sprague-Dawley rats. After a 10-min sucrose drinking trial, groups of Ss were injected ip with lithium chloride or with a strong, near lethal dose of a rodenticide. Strong sucrose aversions were acquired by groups injected with lithium chloride, copper sulfate, sodium fluoroacetate, or red squill, and very weak or no aversions were learned by groups injected with thallium, warfarin, cyanide or strychnine. Results are discussed in terms of onset of symptoms, duration of symptoms, and kinds of physiological effects necessary to produce aversions. It is concluded that the effects of different drugs may be mediated by different physiological systems in producing learned taste aversions. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bait shyness: Avoidance of the taste without escape from the illness in rats.

Conducted 3 experiments with 50 young adult Sprague-Dawley rats. Thirsty Ss habituated to drinking .12 M sodium chloride accepted .12 M lithium chloride for 5 min on the 1st trial but stopped short of their sodium baseline. With repeated trials they reduced consumption of the toxin by either (a) detecting subtle oral CS differences, thus avoiding toxicosis (UCS) or (b) detecting earlier signs of malaise (UCS), thus escaping further distress. When both solutions were masked with saccharin, discrimination was more difficult but still possible. When both solutions were mixed in a solution masking all 4 taste qualities, discrimination was severely disrupted. When oral sensors were bypassed with nasopharyngeal tubes, intragastric pumping Ss were unable to use postingestional cues to escape, even though such cues were proximal to the ultimate malaise. Oral cues at the distal end of the consummatory chain were extremely effective. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thalamocortical relations in taste aversion learning: II. Involvement of the medial ventrobasal thalamic complex in taste aversion learning.

Examined the involvement of the gustatory thalamic nuclei in fundamental taste reactivity, gastrointestinal reactivity, and conditioned taste aversion (CTA) learning. In Exp I, using 72 male Long-Evans rats, bilateral electrolytic lesions were produced in the medial ventrobasal thalamic complex (VBm), including the thalamic gustatory nuclei, in 1 group of Ss. For a 2nd group, at the conclusion of conditioning, lesions were produced in the anterior insular gustatory neocortex (AIGN). Results indicate that destruction of VBm thalamus attenuated taste reactivity to sucrose, citric acid, and quinine hydrochloride. Elimination of VBm thalamus markedly attenuated CTA learning. Results of neocortical lesion manipulations showed that the AIGN contributed to initial CTA learning in Ss lacking a mediodorsal-periventricular thalamus. Whether Ss lacking VBm thalamus used olfactory cues associated with drinking solutions to acquire CTAs was evaluated in Exp II, using 72 male Long-Evans rats. Results demonstrate that Ss lacking VBm thalamus and the olfactory bulbs could not acquire aversions to ingested LiCl following 8 conditioning trials. (54 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improving the palatability of oral rehydration solutions has implications for salt and water transport: a study in animal models

It is believed that improving the taste of oral rehydration solutions (ORSs) might lead to greater patient acceptability. A pilot trial showed that replacing glucose with sucrose and increasing the citrate concentration at the expense of chloride improves palatability. However, the transport implications of such modifications are not known. Three hypotonic experimental ORSs (Suc/cit-ORS, 211 mosmol/kg; Suc/Cl-ORS, 224 mosmol/kg; and Glu-ORS, 224 mosmol/kg) were compared with a standard European ORS (Euro-ORS, 265 mosmol/kg) by in vivo perfusion of entire rat small intestine in normal adult rats and rotavirus-infected neonates. All ORSs were of identical sodium, potassium, chloride, and citrate content except that in the Suc/cit-ORS, chloride was removed in favor of increased citrate, and the chloride concentration in Euro-ORS was higher than in the others. Suc/cit-ORS and Suc/Cl-ORS had glucose partially replaced by sucrose while Glu-ORS and Euro-ORS contained only glucose. In normal small intestine, water absorption was greater from Glu-ORS than Suc/cit-ORS or Euro-ORS, although water absorption was similar from Suc/cit-ORS and Suc/Cl-ORS. In the rotavirus model, Glu-ORS produced more water absorption than Euro-ORS or either sucrose ORS. In both models, Suc/cit-ORS caused sodium and chloride secretion. Glucose absorption was similar from all ORSs. These findings indicate that attempts to improve ORS palatability by adding sucrose or increasing citrate at the expense of chloride would incur a significant penalty in terms of salt and water absorption.     

Sucrose-water preference reversal in the water-deprived rat.

Exposed 4 water-deprived male albino Carworth rats to each of 3 preference conditions. When given a 15-min preference test between a 7.4% sucrose solution and water, Ss ingested 81-91% of their total fluid intake from the sucrose bottle. When given a choice between 1 lick of water and 1 lick of the sucrose solution, Ss consistently preferred water. To determine if this water preference was related to dehydration, Ss were allowed to drink water immediately before the 1-lick preference test. In general, water preference was inversely proportional to amount of pretest drinking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)