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PubMed1996

Dynamic response characteristics of CO2-induced air hunger.

The time course of change in 'air hunger', the uncomfortable urge to breathe, was assessed following sudden increases and decreases in PETCO2. Healthy normal men and women were mechanically ventilated at constant tidal volume and frequency, and were required to rate the perceived intensity of air hunger every 10-15 sec. PETCO2 was changed by altering FICO2 unbeknownst to the subject. Air hunger changed to its new level following steps with a median time constant of about 50 sec during hyperoxia. Changes in air hunger following PETCO2 steps were slightly faster when background gas was slightly hypoxic. Although the present results are consistent with the hypothesis that air hunger and ventilatory drive share the same receptors and central neural processes, analysis of dynamic response is probably not sensitive enough to disprove the hypothesis.

Adult↗
PubMed2003

Mechanical chest-wall vibration does not relieve air hunger.

Mechanical vibration of the chest wall can reduce dyspnea. It is unclear which sensations of respiratory discomfort are modulated by vibration (work/effort, air hunger, tightness). We performed two experiments to test whether vibration modifies air hunger: Experiment 1-eight adults performed six breath holds and rated their uncomfortable 'urge to breathe.' Vibration was applied separately at four chest-wall and two control sites, using two amplitudes. Breath-hold duration and ratings were unchanged by vibration at any site or amplitude. Experiment 2-nine adults were mechanically ventilated (mean 8.73 L/min) at constant hypercapnia (mean 48 mmHg) to produce mild to moderate ratings of air hunger (mean 37% of scale) with minimal respiratory muscle work. Vibration at 2nd or 3rd intercostal spaces during either inspiration or expiration did not change air hunger compared to triceps vibration. These experiments demonstrated that vibration does not relieve air hunger; we postulate that the effect of vibration is specific to the form of dyspnea.

Adult↗
PubMed2001

Brain responses associated with consciousness of breathlessness (air hunger).

Little is known about the physiological mechanisms subserving the experience of air hunger and the affective control of breathing in humans. Acute hunger for air after inhalation of CO(2) was studied in nine healthy volunteers with positron emission tomography. Subjective breathlessness was manipulated while end-tidal CO(2-) was held constant. Subjects experienced a significantly greater sense of air hunger breathing through a face mask than through a mouthpiece. The statistical contrast between the two conditions delineated a distributed network of primarily limbic/paralimbic brain regions, including multiple foci in dorsal anterior and middle cingulate gyrus, insula/claustrum, amygdala/periamygdala, lingual and middle temporal gyrus, hypothalamus, pulvinar, and midbrain. This pattern of activations was confirmed by a correlational analysis with breathlessness ratings. The commonality of regions of mesencephalon, diencephalon and limbic/paralimbic areas involved in primal emotions engendered by the basic vegetative systems including hunger for air, thirst, hunger, pain, micturition, and sleep, is discussed with particular reference to the cingulate gyrus. A theory that the phylogenetic origin of consciousness came from primal emotions engendered by immediate threat to the existence of the organism is discussed along with an alternative hypothesis by Edelman that primary awareness emerged with processes of ongoing perceptual categorization giving rise to a scene [Edelman, G. M. (1992) Bright Air, Brilliant Fire (Penguin, London)].

Adult↗
PubMed2001

Neuroimaging evidence implicating cerebellum in the experience of hypercapnia and hunger for air.

Recent neuroimaging and neurological data implicate cerebellum in nonmotor sensory, cognitive, vegetative, and affective functions. The present study assessed cerebellar responses when the urge to breathe is stimulated by inhaled CO(2). Ventilation changes follow arterial blood partial pressure CO(2) changes sensed by the medullary ventral respiratory group (VRG) and hypothalamus, entraining changes in midbrain, pons, thalamus, limbic, paralimbic, and insular regions. Nearly all these areas are known to connect anatomically with the cerebellum. Using positron emission tomography, we measured regional brain blood flow during acute CO(2)-induced breathlessness in humans. Separable physiological and subjective effects (air hunger) were assessed by comparisons with various respiratory control conditions. The conjoint physiological effects of hypercapnia and the consequent air hunger produced strong bilateral, near-midline activations of the cerebellum in anterior quadrangular, central, and lingula lobules, and in many areas of posterior quadrangular, tonsil, biventer, declive, and inferior semilunar lobules. The primal emotion of air hunger, dissociated from hypercapnia, activated midline regions of the central lobule. The distributed activity across the cerebellum is similar to that for thirst, hunger, and their satiation. Four possible interpretations of cerebellar function(s) here are that: it subserves implicit intentions to access air; it provides predictive internal models about the consequences of CO(2) inhalation; it modulates emotional responses; and that while some cerebellar regions monitor sensory acquisition in the VRG (CO(2) concentration), others influence VRG to adjust respiratory rate to optimize partial pressure CO(2), and others still monitor and optimize the acquisition of other sensory data in service of air hunger aroused vigilance.

Adult↗
PubMed2002

Hypoxic and hypercapnic drives to breathe generate equivalent levels of air hunger in humans.

Anecdotal observations suggest that hypoxia does not elicit dyspnea. An opposing view is that any stimulus to medullary respiratory centers generates dyspnea via "corollary discharge" to higher centers; absence of dyspnea during low inspired Po(2) may result from increased ventilation and hypocapnia. We hypothesized that, with fixed ventilation, hypoxia and hypercapnia generate equal dyspnea when matched by ventilatory drive. Steady-state levels of hypoxic normocapnia (end-tidal Po(2) = 60-40 Torr) and hypercapnic hyperoxia (end-tidal Pco(2) = 40-50 Torr) were induced in naive subjects when they were free breathing and during fixed mechanical ventilation. In a separate experiment, normocapnic hypoxia and normoxic hypercapnia, "matched" by ventilation in free-breathing trials, were presented to experienced subjects breathing with constrained rate and tidal volume. "Air hunger" was rated every 30 s on a visual analog scale. Air hunger-Pet(O(2)) curves rose sharply at Pet(O(2)) <50 Torr. Air hunger was not different between matched stimuli (P > 0.05). Hypercapnia had unpleasant nonrespiratory effects but was otherwise perceptually indistinguishable from hypoxia. We conclude that hypoxia and hypercapnia have equal potency for air hunger when matched by ventilatory drive. Air hunger may, therefore, arise via brain stem respiratory drive.

Adult↗
PubMed2000

The perception of respiratory work and effort can be independent of the perception of air hunger.

Dyspnea in patients could arise from both an urge to breathe and increased effort of breathing. Two qualitatively different sensations, "air hunger" and "respiratory work and effort," arising from different afferent sources are hypothesized. In the laboratory, breathing below the spontaneous level may produce an uncomfortable sensation of air hunger, and breathing above it a sensation of work or effort. Measurement of a single sensory dimension cannot distinguish these as separate sensations; we therefore measured two sensory dimensions and attempted to vary them independently. In five normal subjects we obtained simultaneous ratings of air hunger and of work and effort while independently varying PCO(2) or the level of targeted voluntary breathing. We found a difference in response to the two stimulus dimensions: air hunger ratings changed more steeply when PCO(2) was altered and ventilation was constant; work or effort ratings changed more steeply when ventilation was altered and PCO(2) was constant. We conclude that "air hunger" is qualitatively different from "work and effort" and arises from different afferent sources.

Adult↗
PubMed1997

["The Geography of Hunger": from regional logic to universality]

The Geography of Hunger, now the target of reflective reading 50 years after it was first published, shows the author' elegant combination of argumentative skill and scientific confidence. Josué de Castro's provocative focus is both a new way of thinking and acting towards the food and nutritional situation in Brazil and a pioneering approach to the issue of collective hunger as a geographically universal phenomenon. Based on regional specificities, the book admits that partial contributions may help establish a characteristic map of the problem's universal nature, thus helping build a different image of Brazil and the world and opening up the possibility of constructing a universal plan to combat hunger and new perspectives for those seeking to correct regional differences and overcome underdevelopment. In this book, which is also a manifesto, Josué de Castro reinterprets the role of classical geography, taking into account one of the most important explanatory dimensions, i.e., political analysis, to unveil the significance and consequences of uneven spatial development. The concepts and proposals raised by The Geography of Hunger are alive and provide essential tools for critically rethinking Brazilian reality, particularly that of the Northeast. On its fiftieth anniversary, The Geography of Hunger is more current than ever because of stimulating and disturbing message.

Journal Article↗
PubMed1993

The effects on eating of dietary restraint, anxiety, and hunger.

In this study a comparison was made between the amounts eaten by restrained and unrestrained eaters following an anxiety-induction procedure. Subjects' level of perceived hunger was assessed and the interactive effects on eating of anxiety and perceived hunger were examined. Results revealed a significant three-way interaction. Unrestrained subjects did not alter their eating in response to either anxiety or hunger. When relaxed, restrained subjects ate more when hungry than when not hungry. However, in restrained subjects, anxiety appeared to counteract the disinhibiting effect of hunger, so that anxious hungry subjects ate less than relaxed hungry subjects and the same amount as relaxed subjects who were not hungry.

Adult↗
PubMed1993

Age-related changes in spontaneous food intake and hunger in humans.

Elderly people eat less than younger individuals. The nature of the changes in the meal pattern that occur with age were investigated by having 307 healthy adults, ages 20 to 80, maintain 7-day diaries of everything they ingested, the timing and conditions present, and subjective hunger, anxiety, depression, and activity. The lower intakes that occur with age were a consequence of the ingestion of smaller meals, eaten relatively slowly. The elderly were as responsive as younger subjects to a number of influences on intake, the time of day, the number of other people present, the subjective state of hunger, and the premeal contents of the stomach. These results suggest that the lower intakes in the elderly are a normal response to lower caloric expenditures. The state of hunger in the elderly affected intake equivalently to the young but intake did not affect hunger to the same extent as in younger subjects. This suggests that the internal state becomes less able to influence the subjective state as aging progresses and as a result the intake of the elderly may become primarily influenced by external factors.

Adult↗
PubMed1999

Changes in food attitudes as a function of hunger.

This experiment investigated whether hunger selectively influences attitudes toward common food items. Participants completed a take-home questionnaire on which they rated their attitudes toward food and non-food items when they were either hungry (45 participants) or not hungry (45 participants); after returning the questionnaire, participants completed a second take-home questionnaire in the opposite hunger condition. Results of both between-subject and within-subject analyses revealed that participants rated foods more positively when hungry compared to not hungry and that there was no difference in the ratings of non-foods when hungry vs. not hungry. Moreover, attitudes toward high-fat foods changed more as a function of hunger than attitudes toward low-calorie foods. As attitudes are important for guiding behavior, these results suggest that food attitudes influence daily eating patterns and consumer decisions regarding food purchases. The findings may also have important health implications because hunger exerts a greater influence on attitudes toward high-fat foods.

Adult↗
PubMed1980

The effect of small and moderate doses of d-amphetamine on hunger, mood, and arousal in man.

In rats, low doses of d-amphetamine (d-amp) increase rather than decrease food intake. A double-blind study was carried out in nine healthy female subjects to compare the effects of a low (1 mg) and a moderate (10 mg) dose of d-amp and placebo on hunger, mood and arousal. Each subject participated in three experimental sessions, 1 week apart, when they received either 1 mg d-amp, 10 mg d-amp or placebo, according to a random double-blind design. Visual analogue rating scales for hunger, mood and arousal were completed prior to drug administration and at 30-min intervals for 4 h. A questionnaire relating to sleep pattern and side effects was completed the morning after each experimental session. d-Amp (10 mg) produced a significant reduction in hunger ratings as compared with placebo at 2 h and 2.5 h after administration, while 1 mg d-amp had no significant effect on hunger. Mood and arousal were only slightly elevated by 10 mg d-amp, and not at all by 1 mg.

Adult↗
PubMed1995

A step towards developing the expertise to control hunger and satiety: regulatory role of satiomem--a membrane proteoglycan.

Regulation of hunger and satiety is a complex process thought to be controlled by a complex interplay of neurotransmitters in the hypothalamic region of the brain. Reduced food intake or anorexia has also been observed under various disease or disorder conditions including AIDS and cancer. On the other hand, increased appetite because of some impairment of central mechanisms regulating the food intake could also cause/obesity. A large number of substances including neuropeptides, hormones, drugs, and synthetic peptides have been implicated in the regulation of appetite and food intake behavior in normal as well as disease or disorder conditions. Most of these substances are not directly involved in the regulation of normal hunger and satiety but exert their effect indirectly via other media. Some of them are involved under certain pathologic conditions and during the course they become involved directly or indirectly in the triggering of hunger and satiety regulatory mechanism. Recently, we have been able to isolate and purify an endogenous proteoglycan from membranes of animal and plant sources. This membrane anchored proteoglycan termed as 'Satiomem' reduces food intake without any rebound effects and has no apparent toxicity. It also fulfils all the criteria of a true satiety or anorexigenic substance. The release of satiomem from the cell surface could be mediated by a specific phospholipase-C. Satiomem seems to be involved in transducing activating signals and may also act as a source of second messenger for the regulatory mechanism of appetite. This article summarizes the regulatory aspects of hunger and satiety mechanisms controlled by endogenous substances with the emphasis on our present knowledge about satiomem.

Animals↗
PubMed1991

Acute effects of nicotine on hunger and caloric intake in smokers and nonsmokers.

The inverse relationship between smoking and body weight may be due in part to nicotine's effects on reducing hunger and eating. Male smokers and nonsmokers (n = 10 each), abstinent overnight from smoking and food, participated in four sessions, involving consumption of a liquid caloric load or water followed by nicotine (15 micrograms/kg) or placebo via nasal spray every 20 min for 2 h. Hunger and satiety ("fullness") ratings were obtained prior to each dose presentation. At the end of the two sessions involving the caloric load (simulating breakfast), subjects were also presented with typical lunch/snack food items varying in sweet taste and fat content for ad lib consumption. Results indicated that, for both smokers and nonsmokers, the hunger-reducing effects of nicotine occurred only following caloric load consumption, and there was no effect of nicotine on hunger afer water consumption. Smokers unexpectedly reported greater satiation than nonsmokers following the caloric load regardless of nicotine or placebo condition. Nicotine also resulted in less caloric intake during the meal, and the decrease was not specific to consumption of sweet, high-fat foods. These results indicate that nicotine reduces appetite, possibly helping to explain the influence of smoking on body weight.

Adult↗
PubMed1998

Association of dietary restraint and disinhibition with eating behavior, body mass, and hunger.

This study investigated the association of dietary restraint and disinhibition with self-reported and actual eating behavior, body mass, and hunger. A sample of 124 women were categorized into one of four groups based upon high and low scores on measures of Dietary Restraint and Disinhibition using the Three Factor Eating Questionnaire. Half of the participants in each group consumed a high sugar/high fat chocolate pudding as a dietary preload. All participants were given a meal comprised of a standard macaroni and beef product. The interaction of Dietary Restraint and Disinhibition was related to differences in body mass. The Dietary Restraint factor was related to self-reported pathological eating behavior and influenced both perceived hunger and subjective hunger ratings. However, actual eating behavior measured by calories consumed and rate of intake was unrelated to the Dietary Restraint factor. Disinhibition was associated with excessive eating, an increased rate of eating, self-reports of eating disorder symptomatology, and perceived hunger. Hence, actual eating behavior was significantly influenced by the ingestive motivational factor, Disinhibition, but not by the cognitive factor, Dietary Restraint. These data also suggest that the Disinhibition construct is measuring overeating rather than disinhibited eating which implies the disruption of Dietary Restraint.

Adolescent↗
PubMed2006

Effects of posture on gastric emptying, transpyloric flow, and hunger after a glucose drink in healthy humans.

Previous studies suggest that posture has relatively little effect on gastric emptying of high-nutrient liquids; these studies have, however, only assessed overall rates of gastric emptying, whereas gastric emptying is known to be predominantly a pulsatile phenomenon. In healthy subjects perceptions of appetite, such as hunger, are inversely related to antral area and content; hence, changes in intragastric meal distribution induced by posture may affect appetite. Gastric emptying is a major determinant of postprandial glycemia. The aims of this study were to evaluate the effects of posture on patterns of transpyloric flow (TF), gastric emptying (GE), antral area (AA), hunger, and the glycemic response to oral glucose. Eight healthy young subjects (five males, three females; mean age, 24.0 +/- 2.4 years; BMI, 21.2 +/- 0.6 kg/m2) were studied twice in random order, once in the sitting position and once in the lying (supine) position. After consuming 600 ml water with 75 g glucose, labeled with 20 MBq 99mTc-sulfur colloid, subjects had simultaneous measurements of (i) TF during consumption of the drink by Doppler ultrasonography, (ii) GE with scintigraphy, (iii) AA at t = -5 and t = 30 min by ultrasonography, and (iv) perceptions of appetite with a visual analogue scale. During drink ingestion TF was greater in the sitting, compared with the lying, position (586 +/- 170 vs. 177 +/- 65 [cm/sec] x sec; P < 0.05). Posture affected intragastric distribution; more of the drink was retained in the distal stomach in the sitting position (e.g., at 30 min: sitting, 29 +/- 3%, vs. lying, 12 +/- 3%; P < 0.0001) but had no effect on the overall rate of GE or the blood glucose response. AA at t = 30 min (P < 0.005) was greater in the sitting position; there was an inverse relationship between hunger and AA at 30 min (r = -0.53, P < 0.05). We conclude that posture influences initial TF and intragastric distribution, but not the overall rate of GE of, or the glycemic response to, a large-volume nutrient liquid. The increases in AA and content in the sitting position are associated with a reduction in hunger.

Administration, Oral↗
PubMed1990

Cognitive restraint and sensitivity to cues for hunger and satiety.

The present study provides experimental evidence for the effects of cognitive restraint on sensitivity to internal and external cues of hunger. The design involved four experimental conditions. In each condition the subjects were given either a high calorie or a low calorie early morning drink, and either correctly or incorrectly told its calorie content. The subjects, 10 restrained and 10 nonrestrained normal weight women, then rated their subjective hunger and satiety responses and had a test meal. All subjects reported lower sensations of hunger and higher sensations of fullness after the high calorie drink than the low calorie drink, indicating sensitivity to internal cues. However, the restrained eaters' ratings of hunger were also influenced by the believed content of the drink, indicating sensitivity to external cues. The implications of the results are analysed in terms of current theories of restrained eating and their relevance to further research into pathological eating regulation is discussed.

Adult↗
PubMed1991

Soft drinks with aspartame: effect on subjective hunger, food selection, and food intake of young adult males.

Ingestion of aspartame-sweetened beverages has been reported to increase subjective measures of appetite. This study examined the effects of familiar carbonated soft drinks sweetened with aspartame on subjective hunger, energy intake and macronutrient selection at a lunch-time meal. Subjects were 20 normal weight young adult males, classified as either restrained or nonrestrained eaters. Four treatments of carbonated beverages included 280 ml of mineral water, one can of a soft drink (280 ml) consumed in either 2 or 10 minutes, or two cans of a soft drink (560 ml) consumed in 10 minutes, administered at 11:00 a.m. Subjective hunger and food appeal were measured from 9:30 a.m. to 12:30 p.m., and food intake data were obtained from a buffet lunch given at 12:00 noon. There were no treatment effects on energy intake, macronutrient selection or food choice at the lunch-time meal, or food appeal, though restrained eaters consumed more than nonrestrained eaters in all four treatment conditions. Consumption of two soft drinks (560 ml, 320 mg aspartame) significantly reduced subjective hunger from 11:05 a.m. to 11:30 a.m. compared to one soft drink (280 ml, 160 mg aspartame) or 280 ml of mineral water. Thus ingestion of soft drinks containing aspartame did not increase short-term subjective hunger or food intake.

Adult↗
PubMed1988

Benzodiazepine-induced hyperphagia: a test of the hunger-mimetic model.

The 'hunger-mimetic' model is a prominent explanatory account of benzodiazepine-induced hyperphagia. A salient feature of food deprivation (hunger) in laboratory animals is 'finicky' eating, or an enhanced reactivity to the palatability of food. If the hunger-mimetic model is correct, a similar finicky pattern of increased eating should be observed both in hungry (food-deprived) rats and in benzodiazepine-treated, hyperphagic rats. Two groups of rats were matched on measures of ad lib baseline intake of both a highly palatable food (sweetened condensed milk) and a food low in palatability (milk adulterated with 37.5 mg% quinine). Subsequently one group was placed on a moderate food deprivation schedule while the second group was maintained on ad lib food but was injected (IP) with 5 mg/kg chlordiazepoxide (CDP) 30 min prior to food presentation tests. Single-bottle tests indicated that while the food deprived animals exhibited a greater augmentation of eating when given the high-palatability food, the animals pretreated with CDP exhibited an indiscriminate elevation of eating across both foods. Similarly, on two-bottle choice tests the food-deprived rats exhibited an enhanced preference for the high-palatability food, whereas the CDP-treated animals did not change from baseline food preference. These results fail to support the hunger-mimetic model of benzodiazepine-induced hyperphagia. Alternative models based on a perseverative, disinhibitory action of benzodiazepines are discussed.

Animals↗