Restricting access to palatable foods affects children's behavioral response, food selection, and intake.
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BACKGROUND: Restricting children's access to palatable foods may appeal to parents as a straightforward means of promoting moderate intakes of foods high in fat and sugar; however, restricting access to palatable foods may have unintended effects on children's eating. The efficacy of restricting children's access to palatable foods as a means of promoting patterns of moderate intake of those foods is unknown. OBJECTIVE: Two experiments were conducted to test the hypothesis that restricting access to a palatable food enhances children's subsequent behavioral responses to, selection of, and intake of that restricted food. DESIGN: Both experiments used a within-subjects design to examine the effects of restricting access to a palatable food on children's subsequent behavior, food selection, and food intake. The first experiment examined the effects of restriction within and outside the restricted context and the second experiment focused on the effects within the restricted context. RESULTS: In both experiments, restricting access to a palatable food increased children's behavioral response to that food. Experiment 2 showed that restricting access increased children's subsequent selection and intake of that food within the restricted context. CONCLUSIONS: Restricting access focuses children's attention on restricted foods, while increasing their desire to obtain and consume those foods. Restricting children's access to palatable foods is not an effective means of promoting moderate intake of palatable foods and may encourage the intake of foods that should be limited in the diet. (+info)
Gut vagal afferent lesions increase meal size but do not block gastric preload-induced feeding suppression.
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Subdiaphragmatic vagal afferent (SVA) signals arising from gut sites may provide critical feedback for the control of food intake within a meal. To evaluate the role of SVAs in both spontaneous and scheduled meals, food intake was assessed in two paradigms in male Sprague-Dawley rats. In the first study, control (Con) rats (n = 6) and rats with subdiaphragmatic vagal deafferentation (SDA) (n = 7) had 12-h nightly access to Ensure liquid diet (1 kcal/ml). SDA rats had larger and fewer meals and maintained initial rapid rates of licking, yet total numbers of licks were unaffected. In the second study, Con (n = 8) and SDA (n = 7) rats had scheduled access to 12. 5% liquid glucose after overnight food deprivation. Glucose intake was assessed after 5-ml gastric preloads of 0.9% saline or glucose, peptone, and Intralipid solutions at three concentrations (0.5, 1, and 2 kcal/ml). Glucose and peptone preloads suppressed intake similarly in Con and SDA rats, whereas Intralipid was ineffective. These results suggest that meal-related SVA signals 1) are not critical in determining preload-induced feeding suppression after deprivation, yet 2) contribute to satiety during spontaneous meals. (+info)
The effect of moxonidine on feeding and body fat in obese Zucker rats: role of hypothalamic NPY neurones.
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The antihypertensive agent moxonidine, an imidazoline Ii-receptor agonist, also induces hypophagia and lowers body weight in the obese spontaneously hypertensive rat, but the central mediation of this action and the neuronal pathways that moxonidine may interact with are not known. We studied whether moxonidine has anti-obesity effects in the genetically-obese and insulin-resistant fa/fa Zucker rat, and whether these are mediated through inhibition of the hypothalamic neuropeptide Y (NPY) neurones. Lean and obese Zucker rats were given moxonidine (3 mg kg(-1) day(-1)) or saline by gavage for 21 days. Moxonidine decreased food intake throughout by 20% in obese rats (P<0.001) and by 8% in lean rats (P<0.001), and reduced weight gain that final body weight was 15% lower in obese (P<0.001) and 7% lower in lean (P<0.01) rats than their untreated controls. Plasma insulin and leptin levels were decreased in moxonidine-treated obese rats (P<0.01 and P<0.05), but unchanged in treated lean rats. Uncoupling protein-1 gene expression in brown adipose tissue was stimulated by 40-50% (P< or =0.05) in both obese and lean animals given moxonidine. Obese animals given moxonidine showed a 37% reduction in hypothalamic NPY mRNA levels (P = 0.01), together with significantly increased NPY concentrations in the paraventricular nucleus (P<0.05), but no changes in the arcuate nucleus or other nuclei; this is consistent with reduced NPY synthesis in the arcuate nucleus and blocked release of NPY in the paraventricular nucleus. In lean animals, moxonidine did not affect NPY levels or NPY mRNA. The hypophagic, thermogenic and anti-obesity effects of moxonidine in obese Zucker rats may be partly due to inhibition of the NPY neurones, whose inappropriate overactivity may underlie obesity in this model. (+info)
Protective effects of dietary nasunin on paraquat-induced oxidative stress in rats.
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The preventive effects of nasunin (delphinidin-3-[4-p-coumaroyl-rhamnosyl(1-->6)glucosid e]-5-glucoside) on paraquat-induced oxidative stress were determined in rats. Decreased food intake and body weight gain and increased lung weight by feeding the rats a diet containing paraquat were clearly suppressed by supplementing nasunin to the paraquat diet. Paraquat feeding increased the concentration of thiobarbituric acid-reactive substances (TBARS) in liver lipids and the atherogenic index, and decreased the liver triacylglycerol level. These effects were also suppressed by supplementing nasunin to the paraquat diet. In addition, catalase activity in the liver mitochondrial fraction was markedly decreased by feeding the paraquat diet, this decrease being partially suppressed by supplementing the paraquat diet with nasunin. These results suggest that nasunin acted preventively against the oxidative stress in vivo that may have been due to active oxygen species formed through the action of paraquat. (+info)
Enhancing effect of dietary vinegar on the intestinal absorption of calcium in ovariectomized rats.
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We studied the effect of dietary vinegar on calcium absorption by using ovariectomized rats fed on a low-calcium diet. The apparent absorption of calcium was higher when the rats were fed on a diet containing 1.6% vinegar for 32 days than when fed on a diet without vinegar (P < 0.05). The calcium content in the femur of the rats given diets containing 0.4% and 1.6% vinegar were also higher (P < 0.05). The serum parathyroid hormone level was lower and the crypt depth of the duodenum thicker in the rats fed on a diet containing 1.6% vinegar (P < 0.05). These results suggest that dietary vinegar enhanced intestinal calcium absorption by improving calcium solubility and by the trophic effect of the acetic acid contained in vinegar, which would reduce the bone turnover caused by ovariectomy and be helpful in preventing osteoporosis. (+info)
Flight performance during hunting excursions in Eleonora's falcon Falco eleonorae.
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Among birds, falcons are high-performance flyers, in many cases adapted for aerial hunting and hence suitable targets for investigating limits to flight performance. Using an optical range finder, we measured flight tracks of Eleonora's falcon (Falco eleonorae), a species breeding in the Mediterranean region and specialised for hunting autumn passage bird migrants, when commuting between their nesting colony and offshore hunting areas (straight transportation flight) and when searching for prey (transecting and searching flight). Airspeed during searching flight was significantly slower than during straight transportation and transecting flight, but there was no significant difference in airspeed between the latter two flight modes. Straight transportation flight was significantly faster than predicted minimum power speed. Also, during straight transportation flight, the falcons responded to head- and tailwinds by increasing their airspeed when flying into the wind. However, they did not show any significant airspeed adjustments with respect to the angle between the track and the heading, as would be expected in birds trying to maintain a constant track direction. Mean sustainable climb rate (during (greater than or equal to) 240 s) was 1.4+/-0.31 m s-1 (mean +/- s.d., N=13), which is rather a high rate for a bird the size of an Eleonora's falcon. The climb rate was used to calculate maximum load-carrying capacity and maximum sustained horizontal flapping flight speed. The mean wingbeat frequency during powered climbing flight was 4.68 Hz, which was used to estimate the mass-specific muscle work. When falcons were leaving the colony for offshore hunting, they gained altitude by slope-soaring when there was an onshore wind. We formulated a simple criterion for the required gliding-flight rate of climb during an initial slope-soaring episode when minimizing the energy cost of reaching a certain altitude far out over the sea (which is where the prey is to be found). This climb rate was 0.36 m s-1, and our observations indicated that the falcons experienced climb rates above this value when soaring in slope-lift. (+info)
Reduction of unsafe eating in a patient with esophageal stricture.
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Previous research has demonstrated the efficacy of behavioral interventions in teaching self-feeding skills as well as in reducing inappropriate self-feeding behavior. The purpose of this study was to extend previous research on the use of prompting and reinforcement in reducing unsafe eating behaviors to the treatment of an adolescent with developmental disabilities and esophageal stricture. A behavioral assessment and treatment using prompting and reinforcement were shown to be effective in decreasing bite rate, decreasing bite size, and increasing the number of chews per bite. (+info)
Orbitofrontal cortex and representation of incentive value in associative learning.
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Clinical evidence indicates that damage to ventromedial prefrontal cortex disrupts goal-directed actions that are guided by motivational and emotional factors. As a consequence, patients with such damage characteristically engage in maladaptive behaviors. Other research has shown that neurons in the corresponding orbital region of prefrontal cortex in laboratory animals encode information regarding the incentive properties of goals or expected events. The present study investigates the effect of neurotoxic orbitofrontal cortex (OFC) lesions in the rat on responses that are normally influenced by associations between a conditioned stimulus (CS) and the incentive value of reinforcement. Rats were first trained to associate a visual CS with delivery of food pellets to a food cup. As a consequence of learning, rats approached the food cup during the CS in anticipation of reinforcement. In a second training phase, injection of LiCl followed consumption of the food unconditioned stimulus (US) in the home cage, a procedure used to alter the incentive value of the US. Subsequently, rats were returned to the conditioning chamber, and their responding to the CS in the absence of the food US was tested. Lesions of OFC did not affect either the initial acquisition of a conditioned response to the light CS in the first training phase or taste aversion learning in the second training phase. In the test for devaluation, however, OFC rats exhibited no change in conditioned responding to the visual CS. This outcome contrasts with the behavior of control rats; after devaluation of the US a significant decrease occurred in approach to the food cup during presentation of the CS. The results reveal an inability of a cue to access representational information about the incentive value of associated reinforcement after OFC damage. (+info)