Preference For Sweet Solutions Research Articles

Evidence of preference for a high-concentration sucrose solution in alcoholic men

The purpose of this study was to test in humans the finding from animal studies indicating an association between preference for more concentrated sweet solutions and excessive alcohol drinking. The hedonic response to five different concentrations of sucrose solution was evaluated in 20 detoxified alcoholic and 37 nonalcoholic Caucasian men. All subjects repetitively tasted solutions with 0.05, 0.10, 0.21, 0.42, and 0.83 M sucrose concentrations and rated themselves on two scales measuring the intensity of sweetness and the likability of the solutions. A bimodal distribution of responses to the sweet solutions occurred in the nonalcoholic comparison group, with peaks at 0.05 M and 0.42 M. In the alcoholic group, 65% of the subjects preferred the highest sucrose concentration (0.83 M), compared with only 16% of the nonalcoholic group. The results of this exploratory study support the hypothesis suggesting a positive association between the preference for stronger sweet solutions and alcohol dependence.

Hypobaric hypoxia and hedonic matrix in rats.

This study was carried out to evaluate the effect of continuous exposure to hypobaric hypoxia on the feeding behavior and taste responses of rats, under simulated conditions of a high altitude (HA) of 7,620 m for 21 h a day and consecutively for 18 d, which more closely resembles actual field conditions. Their food, water intake and body weight were recorded daily, and blood sugar was estimated once a week. All the parameters were recorded for a period of 18 d each, before, during, and after exposure to simulated HA. The results show a decrease in daily food and water intake and body weight, and mild hypoglycemia during hypoxic exposure. Single-bottle and two-bottle tests showed a preference for sweet solutions over water, citric acid, sodium chloride, and quinine sulfate during exposure. The two-bottle test showed a preference for glucose over calorically-inert saccharine. The continuous exposure in this study produced qualitatively similar but quantitatively accentuated results as compared to intermittent 6 h exposure contiguously for 21 d. High-altitude stress appears to influence food intake such that sensory cues assume greater significance during feeding behavior.

Prenatal exposure to morphine alters analgesic responses and preference for sweet solutions in adult rats

In the present study, we examined long-terra effects of prenatal morphine on pain response and on preference for sweet solutions. Pregnant Fischer 344 rats were given increasing doses of morphine (0.75–12.0 mg/day) in slow-release emulsion, during gestational days 12–18. Control rats were injected with vehicle and were either pair-fed to morphine rats, or ad libitum fed. At birth, all litters were culled to 8–10 pups (half males and half females) and cross-fostered to naive, surrogate dams. Testing began when rats were 10–12 week old. Rats prenatally exposed to morphine exhibited higher analgesia in response to a morphine challenge, and a greater preference for saccharin solution as compared with both control groups. These findings indicate that prenatal morphine induces long-lasting alterations of systems involved in reward processes and in opiate analgesia, perhaps by modulating endogenous opiate systems.

Effect of high-altitude hypoxia on feeding responses and hedonic matrix in rats.

Albino male rats (n = 78) were exposed to a simulated high altitude (HA) equivalent to 7,620 m for 6 h daily, contiguously for a period of 21 days, to study their feeding behavior and gustatory responses. Their food, water intake, and body weight were recorded daily, and blood sugar and blood insulin were estimated once a week. All the parameters were recorded for a period of 3 wk each before, during, and after exposure to simulated HA. The results show a decrease in daily food and water intakes and body weight and mild hyperglycemia and hyperinsulinemia during hypoxic exposure. The 1-h single-bottle taste solution test showed a preference for sweet solutions (13% glucose and 0.2% saccharine) over citric acid (0.16%), sodium chloride (0.9%), and quinine sulfate (0.001%) during exposure to simulated HA. The 1-h two-bottle test containing glucose (calories plus taste) and saccharine (taste but no calories) administration showed a preference for the glucose solution over the saccharine solution. The trend of the 1-h intake of all test solutions also showed a reversal to preexposure levels after termination of HA hypoxia. It would appear that high-altitude stress influences food intake in a manner that sensory cues (e.g., preference for sweet substances) become more important.

Intake of and preference for sweet solutions are attenuated in morphine-withdrawn rats.

Intake of and preference for sweet solutions are attenuated in morphine-withdrawn rats.

Intake of and preference for sweet solutions are attenuated in morphine-withdrawn rats.

The hypothesis that intake of sweet solutions is partially controlled by endogenous opioid peptides was tested in 2 experiments that examined the effects of repetitive morphine administration and withdrawal on subsequent intake of and preference for saccharin solutions in rats. Experiment 1 established that 17 hr after morphine withdrawal, rats consumed less saccharin, but not less water, than did controls. The groups did not differ 8 days later. In Experiment 2, using a 2-bottle saccharin-preference test, rats exhibited a reduced preference to saccharin solutions (1, 3, 9, 30, or 60 mM) for 6 days after morphine withdrawal. The difference between the groups was most pronounced at the most preferred concentrations (9 and 30 mM). The results suggest that cross-tolerance occurs between morphine and the opioid-mediated hedonic effects of sweet solutions.

Effects of ovarian hormones on eating behaviors, body weight, and glucoregulation in rhesus monkeys

The influences of ovarian hormones on food intake, taste preferences, and glucoregulation were examined in intact and ovariectomized rhesus monkeys. Intake of intact monkeys was lowest in the preovulatory stage of the cycle, when estrogen levels are elevated, and exogenous estradiol transiently suppressed food intake of ovariectomized monkeys in a dose-related manner, confirming previous observations. Progesterone treatment did not affect food intake when given alone, but it did attenuate the effect of estradiol when both hormones were given concurrently. Preferences for sweet solutions were not detectably influenced by chronic treatment with estradiol or progesterone, and compensatory responses to ingestion of sugar were unaltered by hormone treatment. Glucose tolerance tests did not reveal significant influences of ovarian hormones on glycemia, but insulin levels were elevated during periods of progesterone treatment. These results do not support the suggestion that fluctuations in caloric intake during the menstrual cycle are secondary to changes in taste preference or glucoregulation. However, possible changes in sweet preference and glucoregulation shortly after initiation of estrogen treatment, i.e., during the time of suppressed food intake, remain to be examined.

Reduced saccharin preference in CXBK (opioid receptor-deficient) mice

The preference for sweet solutions in opioid receptor-deficient (CXBK) and control (C57BL/6By) mice was compared. CXBK and C57BL/6By (C57) mice were presented for 2 h/day with 2 tubes, one always containing water and the other containing either water or various concentrations of saccharin solution. Fifteen minutes before the drinking session, half of the mice in each strain were injected with naltrexone (0.2 mg/kg) and the other half with saline. Compared to C57 mice, CXBK mice had significantly lower saccharin preference. Naltrexone reduced the saccharin preference in both strains, almost completely abolishing preference in CXBK mice. The results support the hypothesis that brain opioid receptors are involved in mediating sweet palatability and suggest that genetic differences in opioid receptor density contribute to differences in the palatability of sweet solutions.

Characteristics of spontaneous obesity in male rhesus monkeys

Adult male rhesus monkeys representing a wide range of adiposity were characterized according to body dimensions, eating behaviors, and endocrinologic/metabolic indices. Body fat, located most prominently on the abdomen, ranged from 30 to 61% of body weight. Three groups were formed on the basis of body composition data: Very Obese (VO), Moderately Obese (MO) and Nonobese (N). These groups did not differ in food intake, preferences for sweet solutions, or compensatory changes in food intake following consumption of sugar solutions. Glucose tolerance was normal, but fasting insulin levels and insulin response to glucose loading increased with increasing adiposity. Fasting triglyceride levels were highly correlated with insulin values and body fat. It is concluded that some adult male rhesus monkeys develop obesity without obvious differences in eating behavior and that obese monkeys, like obese humans, are at risk for diabetes mellitus and its complications.

Saccharin preferences in food deprived aging rats are altered as a function of perinatal drug exposure

The purpose of this long-term experiment was to determine if perinatal exposure to CNS activating drugs resulted in early and/or altered onset of aging, as measured by changes in preference for preferred concentrations of saccharin solutions. Seventy-nine primiparous Sprague-Dawley rats received twice daily subcutaneous injections of either 3.0 mg/kg or pure nicotine, 5.0 mg/kg of methamphetamine HCL, 5.0 mg/kg of saline vehicle, or no injections during the 21 day gestational period and during days 3–21 of the nursing period. Twelve male offspring were randomly selected from each treatment condition, and at six months of age, they were presented with a choice of 0.20, 0.10, 0.05, 0.025, 0.01, and 0.005% of saccharin in a tap water solution and plain tap water at three month intervals. Each concentration was paired with water and presented for a 48 hr period. Eight sessions were analyzed, which spanned the ages of 15 36 months. Multivariate analyses revealed that: (1) The preference for individual saccharin concentrations across time differed as a result of maternal treatment. Differences were primarily due to the drug treatments and not to injection, (2) The pattern of saccharin preference changed over time as a function of maternal treatment but the overall level of saccharin consumption was not affected. These shifts were due to the drug treatments, not injection per se, (3) The total amount of saccharin solution consumed over time did not differ significantly among treatments, (4) The total amount of fluid consumed over the mature lifespan (saccharin solution plus water) decreased for all rats irrespective of maternal treatment. Other differences over time in total fluid consumption paralleled the saccharin index measures described above. Thus, perinatal treatment had a lasting effect upon preference for nonnutritive sweet solutions. The significance of this for aging organisms is discussed.

Pain modulating and reward systems: A single brain mechanism?

The hypothesis that brain rewarding and pain modulating systems could involve a common opiate system, identically blocked by naloxone, has been tested in three experiments. The preferences or aversions for sapid solutions in rats have been employed as reliable measures of responses to rewarding or nociceptive stimulations. In the first experiment, it was shown that the spontaneous aversion to a quinine HCl solution was enhanced when rats were offered the solution 30 min after naloxone at a dose of 1 mg/kg. The same enhanced aversion was observed in the second experiment towards a sweet solution previously made aversive through a conditioned taste aversion paradigm. In the third experiment, by using two different procedures and saccharin or glucose solutions, it was found that naloxone acutely abolished the preference for sweet solutions versus water in rats. It is concluded that: (1) the enhancement by naloxone of the aversion to a sapid solution, similar to the naloxone induced hyperalgesia, allows to assimilate this aversion to other responses to nociceptive stimulations; (2) this suggests that, like other responses to nociceptive stimulations, this aversion is normally attenuated through the release of brain or pituitary opiates; (3) the suppressant effect of naloxone upon both this attenuation of aversion and a preference for a sapid solution supports the notion of a biochemical and functional community between rewarding and pain modulating systems.

Response of Black-Tailed Deer to Various Chemical Taste Stimuli

The response to salty, sour, sweet, and bitter compounds by black-tailed deer (Odocoileus hemiorwus) was determined by use of the two-choice preference test method. Test compounds were sup- plied in water solutions and compared with the consumption of tap water. Chemicals tested were NaCI and Na acetate (salty); HC1, acetic, and butyric acids (sour); saccharin (the non-Na crystalline form), glucose, and sucrose (sweet); and quinine sulfate and quinine monohydrochloride (bitter). Results indi- cated that deer strongly preferred Na acetate solutions ( from 0.04 to 2.S percent) but showed no prefer- ence for NaGl. Deer exhibited a wide range of fairly strong preference for acetic acid (from 0.0067 to 0.16 percent), but not for butyric or HC1 acids. Deer rejected acetic and butyric acids at a much higher pH (3.25 for acetic and 3.95 for butyric) than for HC1 (2.35), which has a less noticeable odor. Deer demonstrated strong preferences for sweet solutions, glucose being preferred over a range from 0.S3 to 20 percent, the highest concentration tested, and sucrose from 0.25 to 10 percent. They also preferred saccharin over a wide range d concentrations (from 0.000625 to 0.160 percent), but to a much lesser degree than for sugars. VVhile no sex differences were observed in responses to sweets, salts, and acids definite sex differences were observed in the response of deer to bitter taste. Bucks demonstrated a marked preference for bitter solutions (from 0.0025 to 0.01 percent for quinine sulfate and from 0.00125 to O.OOS percent for quinine monohydrochloride), whereas the does rejected them at the same concentra- tions.