Behavioral correlates of oral and postingestive satiety in the rat

Hungry rats display the characteristic "satiety sequence" after drinking a glucose solution: The end of ingestion is accompanied by grooming and exploring, followed by resting. With saccharin solutions over a range of concentrations, however, ingestion is accompanied and followed by persistent grooming and exploring; resting rarely occurs. Gastric preloads of glucose solution promote resting to reinstate the "satiety sequence" after a bout of saccharin ingestion. Therefore, the systemic effects of glucose are sufficient to promote resting. In the absence of postingestive factors, the "satiety sequence" is incomplete following saccharin ingestion as it is after sham-feeding.

Sweeteners: consumer acceptance in tea

Sucrose, fructose, aspartame, and saccharin were compared for consumer preference, aftertaste, and cost to determine acceptability of the sweeteners. A 23-member taste panel evaluated tea samples for preference and aftertaste. Mean retail cost of the sweeteners were calculated and adjusted to take sweetening power into consideration. Sucrose was the least expensive and most preferred sweetener. No significant difference in preference for fructose and aspartame was found, but both sweeteners were rated significantly lower than sucrose. Saccharin was the most disliked sweetener. Fructose was the most expensive sweetener and aspartame the next most expensive. Scores for aftertaste followed the same pattern as those for preference. Thus, a strong, unpleasant aftertaste seems to be associated with a dislike for a sweetener. From the results of this study, it seems that there is no completely acceptable low-calorie substitute for sucrose available to consumers.

Behavioral and physiological consequences of intragastric oil feeding in rats

Four experiments were conducted to examine the appropriateness of intragastric feeding of vegetable oil. The first three experiments demonstrated that pairing intragastric feeding with a taste of saccharin, reduced subsequent saccharin preference slightly. A dose of lithium chloride which did not reduce food intake, produced a very strong conditioned aversion. It is therefore difficult to argue on the basis of taste aversions, that any reduction in food intake resulting from intragastric fat feeding is due to malaise. Intragastric fat feeding did not always reduce subsequent food intake; a large reduction in food intake was observed only when non-starved animals were given at least two previous spaced exposures to fat. The effects of oral and intragastric oil feeding on blood levels of triglycerides and free glycerol were examined. Blood triglycerides and glycerol rose sooner and fell sooner following intragastric than after oral oil feeding. Emulsifying the oil did not correct the abnormality; indeed it exaggerated the early rise in blood triglycerides and glycerol. These results indicate that interpretation of studies involving intragastric fat feeding is more complicated than generally recognized.

Attenuation of ethanol-induced conditioned taste aversion by naloxazone: behavioral evidence for an opiate receptor-mediated morphine-ethanol interaction

When rats are presented with a novel saccharin solution and immediately injected with either morphine or ethanol, they subsequently develop a conditioned taste aversion (CTA) to the saccharin solution which reflects the aversive component of the conditioning drug. The present study provides evidence which suggests that both morphine-induced and ethanol-induced CTAs can be blocked by the specific high-affinity binding opiate antagonist, naloxazone.

High frequency oscillations improve nasal mucociliary transport

The saccharin clearance time technique was used to determine the effect upon nasal mucociliary transport of sine wave oscillations. Nasal air was oscillated at 8 Hz, 14 Hz, and 20 Hz by a loudspeaker attached to a nasal mask. Mucociliary transport was significantly increased at all frequencies with an overall mean rise of 161%. Because sine waves have zero mean pressure and flow, the improvement is more likely to be caused by changes in mucus viscoelasticity or ciliary function rather than by a direct physical effect on mucus velocity. This simple and comfortable technique may have practical application in patients with overproduction or retention of mucus within the nasal passages or intrathoracic airways.

Behavioral conditioned responses across multiple conditioning/testing trials elicited by lithium- and amphetamine-paired flavors

The present experiment measured the pattern of conditioned responses across 10 conditioning/testing trials which were elicited by an intraoral presentation of either a lithium- or an amphetamine-paired flavor. A nonspecific conditioned response pattern of suppressed limb flicking after five conditioning trials and of suppressed scratching after six conditioning trials was supported by both drugs. Lithium-specific increased activity level after one conditioning trial and chin rubbing after two conditioning trials were observed across conditioning/testing days. The lithium-specific conditioned responses were not the result of a stronger flavor aversion, because both lithium and amphetamine produced equivalent flavor avoidance responses across the 10 conditioning/testing trials. The results support previous research which suggests that flavor aversions produced by lithium and amphetamine are produced by different unconditioned response mechanisms.

Preference for sugars and nonnutritive sweeteners in young beagles

Two-bowl choice tests were used to examined preference of puppies aged two to four months for compounds tasting sweet to humans. Puppies found many, but not all of the compounds highly palatable, and were sensitive to both type and amount of sugar or nonnutritive sweetener contained in a semi-moist dog food recipe. Lactose, fructose, and sucrose were well accepted, whereas maltose elicited indifference or rejection. Sodium cyclamate, but not sodium saccharin, was preferred at some concentrations to 15 percent sucrose sweetened semi-moist food used as the standard. Solutions of lactose, fructose, glucose and galactose were preferred to plain tap water.

Taste aversion learning in preweanling rats exposed to alcohol prenatally

The effects of prenatal alcohol exposure on the development of a conditioned taste aversion were examined in preweanling rat pups. Mothers of these pups were fed isocaloric liquid diets containing either 35 or 0% ethanol-derived calories (EDC) from gestation days 6 through 20. A pair-feeding procedure was employed, and an ad lib lab chow control group was also included. At 5, 10, or 15 days of age, pups were infused with a saccharin solution through a cannula implanted in the oral cavity. Half of the pups in each group were then injected with lithium chloride (LiCl), which served as the poisoning agent, and the other half with sodium chloride (NaCl) as a control. Animals were subsequently tested for a conditioned aversion to the saccharin solution. At 15 days of age, all of the pups in the LiCl-poisoned group demonstrated a conditioned taste aversion to the saccharin solution, but the degree of this aversion was less in alcohol-exposed offspring. At 10 days of age, a taste aversion was learned, although it was not as strong as that shown by 15-day-old pups, and it appeared to be learned equally well by all of the prenatal treatment groups. At 5 days of age, there was marginal support for taste aversion learning. Again, it did not interact with prenatal treatment. The ontogenic differences in taste aversion learning exhibited by alcohol-exposed offspring relative to controls are discussed in terms of altered hippocampal development.

Evaluation of saccharin qualitative fitting test for respirators

The results of a qualitative fitting test for half-mask respirators utilizing a sodium saccharin aerosol were compared to the results of a quantitative fitting test utilizing an oil mist aerosol. For a respirator-wearer combination having a fit factor less than 10, as determined by the quantitative test, the point estimate of the probability of that combination not being rejected by the saccharin qualitative test was found to be 0.00 with 95% confidence that this statistic is not expected to exceed 0.05. For a respirator-wearer combination having a fit factor less than 100, the point estimate of the probability of that combination not being rejected by the qualitative test was found to be 0.03 with 95% confidence that this statistic is not expected to exceed 0.08. The effects of temperature and relative humidity on the size distribution of the saccharin aerosol were also investigated and found to be slight.

Prenatal alcohol exposure alters adult expression of sexually dimorphic behavior in the rat

Saccharin preference and performance in a Lashley III maze were found to be altered in adult male and female rats that had been exposed to alcohol during gestation. Specifically, the sexual dimorphism normally observed in both behaviors was absent in fetal alcohol-exposed animals. The lack of sexual dimorphism appeared to result from a masculinization of the exposed females and a feminization of the exposed males.

Neural and behavioral responses to taste stimuli in the mouse

Neural responses to lingual stimulations with varying kinds of chemicals were recorded from the chorda tympani nerve of the ddy mouse and preferences for NaCl, sucrose and Na saccharin were measured using the two bottle-choice technique. Sucrose, Na saccharin, HCl, and quinine produced large neural responses compared with that for NaCl. Divalent salts also elicited larger responses than NaCl response. The effectiveness of cations was in the order of Sr greater than Mg = Ca greater than Li not equal to Na not equal to NH4 greater than K. Neural response magnitudes for Na salts with varying anions decrease with the relative hydrated size of anions. Mice highly preferred sucrose and Na saccharin but showed a poor preference for NaCl. Similarity in the gustatory responses between mice and hamsters as well as macaque monkeys, and difference between mice and rats are pointed out.

A general probabilistic model of carcinogenesis: analysis of experimental urinary bladder cancer

A theoretical model of two-stage carcinogenesis has been hypothesized. Variables that are modeled include the populations of normal, initiated, and transformed cells; mitotic rates of these cells; hyperplasia; and the probabilities of cell initiation and transformation during replication. The size of the cell populations can be estimated and mitotic rates determined directly from animal studies. Tumor occurrences at different time intervals following varying periods of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) and sodium saccharin administration are known and are used in the indirect estimation of values for unobservable model variables. Model-based analyses suggest FANFT markedly increases the probability of cell initiation in addition to its experimentally verifiable effects on increasing the stem cell population and mitotic rates. Further, experimental results appear inconsistent with the hypothesis that FANFT increases the probability of cell transformation over background levels. Similarly, the effect of sodium saccharin was found to be attributable entirely to increases in stem cell populations and mitotic rates without influencing either the probability of initiation or the probability of transformation.

The effects of LiCl preexposure on amphetamine-induced taste aversions: an assessment of blocking

Preexposure to lithium chloride attenuated the subsequent acquisition of amphetamine-induced taste aversions. This attenuation was independent of the similarity of the preexposure and conditioning environments, an effect inconsistent with an associative interpretation of the effects of LiCl preexposure. These results were discussed in terms of the mechanism underlying the effects of drug preexposure on taste aversion learning.

[Formation of taste aversions in the rat]

The presence of correlation between the initial attitude of animals to a certain taste agent and the intensity of conditioned taste aversion (CTA) after LiCl poisoning was studied in nonlineal male white rats. 4 types of behavioural reactions were revealed: 1) the nonspecific inhibitory reaction to the situation in which CTA was elaborated; 2) specific associative-adaptive connection of CTA with the taste agent used (0,1% saccharine solution); 3) complex reaction consisting of the two first ones; 4) the same drinking behaviour as that before CTA elaboration. Moreover, a correlation was found between the initial attitude of animals to certain taste agent and the intensity of CTA after pairing of this agent with subsequent poisoning.

Differential aversive stimulus properties of beta-phenylethylamine and of d-amphetamine

In a conditioned taste-aversion experiment with male Wistar rats (two-bottle test, single pairing), the effects of beta-phenylethylamine (PEA 12.5, 25.0, 50.0, 100.0 mg/kg IP) and of d-amphetamine (2.5 mg/kg IP) were compared with the effect of the saline vehicle. The amphetamine-treated group exhibited a marked aversion to saccharin on each of four retention trials. A decrease in saccharin intake after PEA was limited to the highest dose group (100 mg/kg) and the first retention trial for that group. Doses of up to 50 mg/kg of PEA were also ineffective with a single-bottle conditioned taste-aversion procedure involving multiple conditioning trials, although doses of 25 and 50 mg/kg of PEA induced marked changes in spontaneous motor activity. These data demonstrate that behaviourally active doses of PEA are ineffective in inducing a conditioned taste aversion to saccharin. This result extends previous reports that structurally similar compounds may have different potencies in this paradigm. It is proposed that further studies of structure-activity relationships may help to reveal the features of drug action that are necessary for the induction of a conditioned taste aversion.

Naloxone reduces alcohol intake in a free-choice procedure even when both drinking bottles contain saccharin sodium or quinine substances

Male Wistar rats were able to drink water and different percentages of ethyl alcohol in a free-choice paradigm. Our results showed a clear-cut preference for 2 and 3% ethanol concentration. Addition of quinine in both drinking bottles increased preference for alcohol, while dilution of saccharin in both bottles totally suppressed this preference for the alcohol bottle. In this alcohol-water choice procedure, naloxone decreased the amount of alcohol intake without altering the amount drunk from the water bottle. This decrease was independent of the palatable or nonpalatable substances added to alcohol and also independent of the percentage of alcohol. Interpretation was done in terms of action of naloxone on the rewarding property of alcohol, or in terms of satiety mechanism for alcohol regulated by naloxone.

Potentiation of a conditioned taste aversion in preweanling and adult rats

Preweanling (18 days old) and adult rats were made ill with LiCl either 2 min or 1 hr after tasting controlled amounts of either one of two single flavors (saccharin or NaCl) or a compound mixture of the two. Conditioning was assessed with a single test 4 days later relative to explicitly unpaired control conditions. Generally, potentiation of the aversions to either flavor occurred for animals conditioned to the compound. The potentiation effect was decreased or eliminated by nonreinforced exposure to the alternative flavor of the compound. These effects tended to be stronger for the younger rats. Specifically, adult animals did not express potentiation of the saccharin aversion whereas preweanlings expressed potentiated salt aversions. Nonreinforced exposure to the alternative element eliminated the potentiation effect. Conditions conducive to potentiation are discussed in light of investigators who have not observed this effect in similar studies with compound stimuli.

Effects of body weight on taste of male and female rats

Single-choice taste (solution and mixed-diet) tests revealed that ad lib fed male rats with increasing body weight showed increased intake on sweet taste as compared to intake of identically aged ad lib fed female rats with static body weight. On meal-time (3 hr) and meal-size (50% diet) restrictions though rats of either sex increased on intake of sweet taste, the increment shown by female was higher and it was correlated with their greater % loss in bw. Hence it appears that the basis for sweet taste preference is the mismatch between actual and target body weight irrespective of sex of animal.

Efficacy of a saccharin test for screening to detect abnormal mucociliary clearance

A simple, inexpensive and reproducible clinical test for determining abnormal mucociliary clearance is proposed which identifies those patients in whom in vitro study of ciliary motility and mucus properties should be carried out.

Endophinergic modulation of acceptability of putative reinforcers

A series of experiments was conducted in order to gain additional insight into how endogenous opioids may modulate taste reactivity and, thus, hedonic processes. Using a wide range of saccharin concentrations ranging from mildly preferred to aversive, it was demonstrated that naloxone reduced preference for saccharin over water. This reduction was not dependent upon concentration of saccharin and resulted in a downward displacement of the preference/aversion curve. Naltrexone was shown to result in a greater decrease in intake in animals drinking a mildly aversive quinine solution, as compared to animals drinking tap water. In conclusion, endogenous opioids may serve to broaden the range of food-related stimuli which are avidly accepted, perhaps by inhibiting any aversive component associated with ingestion.

Naloxone suppresses intake of highly preferred saccharin solutions in food deprived and sated rats

In repeated tests naloxone (1 mg/kg, sc) suppressed intake of a narrow range of highly preferred saccharin concentrations (0.1 and 1.0%) in nondeprived male rats but a wider range of concentrations (.001-1.0%) following 10 hr. food deprivation. In sated rats a low dose of morphine (0.1 mg/kg, sc) had no effect on intake of low concentrations of saccharin but significantly facilitated intake of the highest (10%) and least preferred concentration. These data support the hypothesis that endogenous opioids can modulate the affective quality of gustatory stimuli.

Pavlovian drug-sickness pairings result in the conditioning of an antisickness response

After a drug conditioned stimulus (CS) has been injected prior to lithium chloride as the unconditioned stimulus (US) on five occasions, the drug CS becomes able to evoke a conditioned antisickness response (CAR). This CAR is implied by the finding that the CS drug mitigates the conditioned saccharin aversion produced by lithium when it is administered in the interval between saccharin consumption and lithium injection. The following drugs were tested and are listed in approximate order of their effectiveness in producing a conditioned antisickness effect: pentobarbital, ethanol, morphine, amphetamine, and chlordiazepoxide.