Feeding Behavior In Response Research Articles

Feeding behavior responses of Zucker rats to naloxone

The effects of naloxone on feeding patterns were studied in both obese and lean Zucker rats during both light and dark phases of the diurnal cycle. Eight female obese (471±9 g) and lean (225±6 g) Zucker rats were trained to bar press for food. They were administered 0, 0.5, 1.0 or 2.0 mg/kg naloxone at the initiation of the light or dark phase of the diurnal cycle and feeding behavior was recorded for the subsequent 12 hr using an automated real-time data collection system. First meal size and duration were decreased and first postmeal interval was increased by naloxone and responses did not vary with phenotype or phase of the diurnal cycle. Naloxone decreased food intake during the 12-hr period by decreasing average meal size but meal frequency was not affected. Overall, the feeding behavior responses of obese rats to naloxone were greater than those of lean rats, supporting the hypothesis of an association between opioid peptides and obesity. Opioid involvement in diurnal control of food intake is also supported by the greater responses generally demonstrated in the light compared with dark phases.

Control of Feeding Behavior in Response to Changes in Short-chain Polyhydroxymonocarboxylic Acids

Control of Feeding Behavior in Response to Changes in Short-chain Polyhydroxymonocarboxylic Acids

Feeding behavior response of zucker rats to proglumide, a CCK receptor antagonist

Proglumide not only antagonizes the gastric secretion induced by histamine, tetragastrin and ligation of the pylorus, but also antagonizes the effects of cholecystokinin (CCK) on contraction of the gallbladder and stimulation of amylase secretion from the pancreas. Since CCK is a putative satiety peptide, it was hypothesized that administration of proglumide would increase food intake by inhibiting the satiety effect of CCK. Zucker obese (638±26 g) and lean (462±24 g) rats, trained to bar press for food pellets, were administered intragastrically 0.25, 0.42 or 0.59 g/kg proglumide 15 min before the end of a 3- or 6-hr fast. Feeding behavior was analyzed during the subsequent 18 hr using an automated data collection system. Food intakes, while not affected by proglumide treatment during the first meal (4.30 vs. 4.30 g) were increased 3 (5.60 vs. 4.92 g, p<0.02) and 18 (34.0 vs. 32.5 g. p<0.008) hr after treatment. In addition, water intake 18 hr after proglumide treatment was increased (46.8 vs. 41.5 ml, p<0.001) and food intake to water intake ratio was decreased (0.74 vs. 0.80 g/ml, p<0.004). These responses were not different in obese compared with lean rats or in 3-hrs vs. 6-hr fasted rats. Daily feeding patterns in 6-hr fasted obese rats treated with 0.59 g/kg proglumide were characterized by increased meal frequency (12.4±1.0 vs. 9.6±1.1, p<0.001) and decreased average meal size (3.1±0.2 vs. 3.6±0.3 g, p<0.03). In 3-hr fasted obese and lean rats serum concentrations of proglumide were 7.1±2.1 mg/dl 20 min and 6.6±1.5 mg/dl 120 min after administration of 0.59 g/kg proglumide, indicating levels remained significantly elevated after 120 min. Since proglumide has been shown previously to be an antagonist to the effects of CCK on gallbladder, gastric and pancreatic function, it is postulated that increased food intake in Zucker obese and lean rats after proglumide administration is a result of antagonism of the receptor for the effect of CCK on satiety.

Effects of CCK on gastrointestinal function in lean and obese Zucker rats

Cholecystokinin (CCK), a hormone affecting several gastrointestinal functions, has also been shown to elicit satiety and affect daily meal patterns. Since Zucker obese rats are less sensitive to the satiety effects of CCK, two experiments were designed to determine if they are also less sensitive to the gastric emptying and intestinal transit rate effects of CCK. In the first experiment phenol red was administered to 5.5 hr fasted rats 15 minutes after intraperitoneal injection of CCK-8 or saline. Rats were sacrificed after 30 minutes, the stomach and small intestine were removed, and phenol red content was measured. More phenol red was in the stomach of obese but not lean rats treated with CCK-8. The rate of transit of the contents of the small intestine was increased by CCK-8 and the percent of phenol red in the fourth quarter of the small intestine was greater in obese than lean rats (91 vs 37%, p<0.05). In the second experiment gastrointestinal transit of ferric oxide was measured during the light and dark phases of the diurnal cycle, and when obese rats were ad lib or yoke-fed to lean pair-mates. Total gastrointestinal transit time of the ferric oxide was decreased 15% when CCK-8 was administered to yoke-fed obese rats in either the light or dark portions of the diurnal cycle but was not affected in ad lib-fed obese rats or lean rats. Thus, while Zucker obese rats are less sensitive to satiety effects of CCK, they appear to be more sensitive to the gastrointestinal effects of CCK, and therefore it is not clear what role these gastrointestinal responses have on the feeding behavior responses.

Feeding behaviour in response to blood fractions and chemical phagostimulants in the black‐fly, Simulium venustum

ABSTRACT. Wild‐caught black‐flies (Simulium venustum Say complex) were presented with diets at 37°C in an artificial feeding apparatus. Washed human red cells resuspended 1:1 in Ringer solution were potent phagostimulants, causing 89% of flies to gorge. Whole plasma was more potent (32% gorging) than platelet‐poor plasma (2%). The ED50 for red cells was 3.5%. Although ADP, contained in high‐concentration in platelets, was confirmed as a more potent phagostimulant than ATP (ED50 of 5πM V. 12μM), red cells were clearly more phagostimulatory than platelets, and with a potency more than adequate to trigger gorging in vivo. A high response to the ATP analogues, β, γ‐methylene ATP and adenine phosphosulphate, supports the view that the phosphate chain is relatively unimportant in determining nucleotide potency to simuliids. The compounds phytic acid and 2,3‐disphosphoglycerate, potent stimulants to Rhodnius prolixus, produced only moderate and no response, respectively at 1 mM; 5‐hydroxytryptamine, another major constituent of platelets, also produced only a moderate response. Only flies caught while showing a characteristic probing behaviour would subsequently probe and feed in vitro; this ‘blood‐feeding mode’ rapidly disappeared in the absence of stimuli eliciting actual probing, but for flies in this state a small temperature rise was sufficient stimulus for probing.

Size‐Selective Predation on Daphnia by Neomysis Mercedis

Predation on different—sized Daphnia by the crustacean Neomysis mercedis was examined in the laboratory and the field. Small mysids select the smallest prey available, while adult mysids can consume Daphnia as large as 3.0 mm. Laboratory observations and frequencies of injured Daphnia in the lake indicate that difficulty in handling prey sets the upper limit to the size of Daphnia ingested. The pattern of electivity over the manageable size range of prey is variable for large Neomysis, suggesting that the mysids may alter their feeding behavior in response to changing availability of prey. Freshwater mysids apparently consume prey of a broader size range than most other invertebrate planktivores. The opportunities for evolutionary adjustment of body size and morphology in response to mysid predation are relatively limited for zooplankton prey, especially in lakes where visual predators restrict the sizes that can be attained. This limitation may help to explain the apparent effectiveness of mysids in controlling Daphnia populations.

Decreased sensitivity of Zucker obese rats to the putative satiety agent cholecystokinin

In obese rodents increased daily food intake leading to accumulation of adipose tissue is frequently accompanied by increased meal size and loss of the normal diurnal variations in feeding pattern. Increased meal size of obese rats may be due to decreased sensitivity to factors which elicit satiety. We compared Zucker obese and lean rat feeding behavior responses to octapeptide of cholecystokinin (OP-CCK), a peptide shown to decrease meal size in several species. Obese rats were less sensitive than lean rats to OP-CCK (.06, .25 and 1.0 μg/kg/meal) injected before each of four consecutive scheduled meals in the light portion of the diurnal cycle, when obese meal size was larger than lean. However, neither obese nor lean rats responded to injection of the same doses of OP-CCK during meals in the dark, when average meal size was larger than during the light and when average meal size of the obese rats was similar to that of lean rats. In both obese and lean rats injection of OP-CCK affected daily feeding pattern. Obese and lean Zucker rats are less sensitive to OP-CCK when meal size is larger, whether this is due to phase of the diurnal cycle (dark vs. light in both obese and lean rats) or phenotype (obese vs. lean rats in the light).

Feeding and drinking behavior responses of adult Zucker obese rats to cholecystokinin

Increased meal size in obese animals may occur because of decreased sensitivity to satiety factors. Feeding and drinking behavior responses of Zucker obese and lean rats to two forms of cholecystokinin (CCK), a putative satiety factor, were compared in these experiments. Octapeptide of CCK (CCK-8) in both obese and lean rats decreased meal size (47 and 65%) and rate of eating but not meal duration, and increased satiety ratio but not postmeal interval. Impure CCK decreased first meal size after a 6-hr fast similarly in obese and lean rats (33 and 40%, respectively); however, meal duration was decreased only in lean rats, and rate of eating was decreased only in obese rats. Postmeal interval was decreased in lean rats, while satiety ratio was increased only in obese rats. In spite of decreased first meal size daily food intakes were increased by both impure CCK and CCK-8 in lean rats. In 6-hr water-deprived rats injected with CCK-8, decreased water intake was associated with decreased food intake. However, while impure CCK in lean rats elicited similar responses as CCK-8, impure CCK in obese rats decreased food but not water intake. Feeding behavior response to the putative satiety agent, cholecystokinin, depended on form of the peptide administered and phenotype.

Effects of Synthetic Pyrethroids on Major Insect and Mite Pests of Apple1

Seasonal applications of synthetic pyrethroids for major apple insects were generally effective in the range of 1.5–12 g AI/100 liters. Pyrethroids gave better control of plum curculio, Conotrachelus nenuphar (Herbst), in the field than expected from mortality evaluations in the laboratory. Observed behavioral effects such as reduction in curculio feeding, adult lethargy, and avoidance reactions can contribute to total effect of crop protection. Seasonal applications of pyrethroids led to general resurgence of European red mite, Panonychus ulmi (Koch), in each year of use. Laboratory tests with the twospotted spider mite, Tetranychus urticae Koch, showed changes in feeding behavior in response to fenvalerate.

Abnormal feeding and postprandial behavioral responses to food deprivation in genetically obese mice (C57Bl/6J-ob/ob)

Meal size, intermeal interval (IMI), statiety ratio and postprandial behaviors of obese and lean male mice were measured after 1.5 to 6.0 hr of food deprivation in the dynamic and static phases of weight gain. Obese mice ate the same sized meal as lean mice after food deprivation except after 1.5 hr deprivation in the dynamic phase when obese mice ate more. Obese mice had significantly different satiety ratios than lean mice, but the nature of the difference depended on the phase of weight gain. In the dynamic phase obese mice had a significantly smaller satiety ratio after 1.5 hr deprivation, but in the static phase obese mice had a significantly larger satiety ratio after 1.5 and 3.0 hr deprivation. Thus the differences in meal taking did not persist from the dynamic to the static phase. Differences in postprandial behaviors did. Obese mice groomed less, explored less and rested more than lean mice in the dynamic and static phases of weight gain. This demonstrates that these differences in postprandial behaviors are dissociated from body weight and meal taking responses to deprivation.

Sensory functions of the liver--a review

In this paper we critically review anatomic, electrophysiological, physiological, and behavioral evidence for neural receptors in the liver. Several lines of evidence suggest that the afferent innervation of the liver may be substantial, although few anatomic studies have directly addressed the question of an hepatic sensory supply. On the other hand, there is convincing functional evidence for a variety of hepatic sensory receptors. Hepatic osmo-, ion, and baroreceptors, sensitive to changes in the osmolarity and electrolyte concentrations in blood and to variations in portal venous pressure, modulate diuresis and natriuresis. Metabolic receptors, for which the adequate stimuli have not yet been specified, influence feeding behavior and gastric acid secretion in response to alterations in hepatic metabolism associated with changes in the supply of metabolic fuels. Directions for future research are suggested and general conclusions about the role of hepatic receptors in homeostasis are discussed.

FEEDING BEHAVIOR IN POLYPS OF THE CHESAPEAKE BAY SEA NETTLE,CHRYSAORA QUINQUECIRRHA(DESOR, 1848)

1. Polyps of Chrysaora quinquecirrha exhibit characteristic feeding behavior in response to low concentrations of most common amino acids and to several small peptides.2. Isolated tentacles also respond in characteristic fashion to amino acids and peptides. The data imply the presence of feeding reflex receptors on the tentacles.3. Increasing concentrations of brine shrimp extract or reduced glutathione induce longer feeding response times until a maximum value is reached; further increases in extract or reduced glutathione concentration are inhibitory to the response. Thus maximum stimulation of feeding reflex receptors is inhibitory to the feeding behavior response.4. It was not possible at this time to characterize a specific active site in amino acids or peptides which induces feeding behavior in Chrysaora polyps. The data suggest that Chrysaora possesses more than one type of receptor, and thus can interact with a number of amino acids and peptides to bring about orderly, modulated, feeding behavior.

The ventromedial hypothalamus and metabolic adjustments of feeding behavior

Rats with bilateral lesions in the VMH did not show the usual preference reversal seen in intact rats during free access to concentrated (25 or 50%) vs dilute (5 or 10%) glucose solutions. In addition, unlike intact rats or rats with bilateral lesions of the lateral hypothalamus, rats with medial hypothalamic lesions did not exhibit prolonged depression of food intake following intraperitoneal injection of glucose. Finally, intraperitoneal injections of [ 14 C]-labeled glucose which inhibit food intake more than identical intragastric loads produce larger absolute and relative levels of radioactivity in the medial hypothalamus than lateral hypothalamus. These findings indicate the medial hypothalamus modulates feeding behavior in response to metabolic states, and suggests that these adjustments may be due to differential handling of incoming nutrients by the medial hypothalamus as compared to other parts of the brain.

Larval Behavior of Eupsilia morrisoni1

Feeding behavior, host range, and phototactic responses are described for the 6 larval instars of Eupsilia morrisoni (Grote) (Lepidoptera: Noctuidae). First instars fed within opening leaf buds and later on the inside of open blossoms of fruit and shade trees. Second instars webbed together unfolding leaves and fed within these leaves or consumed the pistils, stamens, and petals of blossoms. Third instars were leaf folders, while the later instars were free feeding. Experimental evidence indicates that the species may have an exceptionally broad host range. First instars were positively phototactic. Third instars exhibited little if any phototactic response. Second and 4th instars were slightly negatively phototactic, while the 5th and 6th instars were negatively phototactic. Sixth instars did not exhibit any definite climbing tendencies in an experimental arena.

Social Cohesion of Steers and Sheep as a Possible Variable in Grazing Studies1

AbstractDuring a 4‐year study on the comparative productivity of pastures grazed by cattle and sheep, we also observed the social behavior of these species when kept together. We observed that a strong social relationship between steers and sheep will develop and that time will add to the strength of this relationship. Changes in feeding behavior in response to established social relationships might affect animal performance.