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Food Delivery (food + delivery)
Selected AbstractsRESEARCH FOCUS ON COMPULSIVE BEHAVIOUR IN ANIMALS: Pre-exposure to environmental cues predictive of food availability elicits hypothalamic,pituitary,adrenal axis activation and increases operant responding for food in female ratsADDICTION BIOLOGY, Issue 4 2009Carlo Cifani ABSTRACT The present study was undertaken to develop an animal model exploiting food cue-induced increased motivation to obtain food under operant self-administration conditions. To demonstrate the predictive validity of the model, rimonabant, fluoxetine, sibutramine and topiramate, administered 1 hour before the experiment, were tested. For 5 days, female Wistar rats were trained to self-administer standard 45 mg food pellets in one daily session (30 minutes) under FR1 (fixed ratio 1) schedule of reinforcement. Rats were then trained to an FR3 schedule and finally divided into two groups. The first group (control) was subjected to a standard 30 minutes FR3 food self-administration session. The second group was exposed to five presentations of levers and light for 10 seconds each (every 3 minutes in 15 minutes total). At the completion of this pre-session phase, a normal 30-minute session (as in the control group) started. Results showed that pre-exposure to environmental stimuli associated to food deliveries increased response for food when the session started. Corticosterone and adrenocorticotropic hormone plasma levels, measured after the 15-minute pre-exposure, were also significantly increased. No changes were observed for the other measured hormones (growth hormone, prolactin, thyroid-stimulating hormone, luteinizing hormone, insulin, amylin, gastric inhibitor polypeptide, ghrelin, leptin, peptide YY and pancreatic polypeptide). Rimonabant, sibutramine and fluoxetine significantly reduced food intake in both animals pre-exposed and in those not pre-exposed to food-associated cues. Topiramate selectively reduced feeding only in pre-exposed rats. The present study describes the development of a new animal model to investigate cue-induced increased motivation to obtain food. This model shows face and predictive validity, thus, supporting its usefulness in the investigation of new potential treatments of binge-related eating disorders. In addition, the present findings confirm that topiramate may represent an important pharmacotherapeutic approach to binge-related eating. [source] Evolution of single-chick broods in the Swallow-tailed Gull Creagrus furcatusIBIS, Issue 2 2003ANA Agreda Swallow-tailed Gulls lay single-egg clutches, and so raise single-chick broods. As they are pelagic seabirds, this small brood size is expected to relate to proximate food limitation owing to infrequent food deliveries. However, a previous brood doubling experiment detected an 82% increase in fledging success from experimentally doubled broods compared to controls. We repeated the brood doubling experiment, and found that none of 50 enlarged broods produced more than one independent offspring. Control and experimental parents produced fledglings of similar body size, which also had indistinguishable rates of fledging and subsequent survival and reproduction. A variety of parameters estimating survival and breeding costs of reproduction showed no treatment effect. Since two-chick broods yield dramatically higher fledging rates at some times, apparently without excess costs of reproduction, selection on brood size appears to favour a two-chick brood. However, selection may not favour a two-egg clutch if egg production is very costly. Additionally, our estimates of reproductive success do not incorporate the performance of experimental and control offspring as adults, which could differ, since growth of chicks differed slightly by treatment. [source] The Process and Causes of Fledging in a Cavity-Nesting Passerine Bird, the House Wren (Troglodytes aedon)ETHOLOGY, Issue 9 2004L. Scott Johnson Little is known about the process or causes of fledging or nest-leaving in passerine birds because researchers can rarely predict when fledging will occur in a given nest. We used continuous videotaping of nests to both document the process of fledging in the house wren, Troglodytes aedon, a small, cavity-nesting songbird, and test hypotheses as to what might cause fledging to begin. Fledging began any time from 14 to 19 d after hatching commenced. Slower-developing broods fledged later than faster-developing broods. Fledging typically began within 5 h of sunrise and over 80% of all nestlings fledged before noon. All nestlings fledged on the same day at 65% of nests and over two consecutive days in most other nests. We found no evidence that fledging was triggered by changes in parental behaviour. Parental rate of food delivery to nestlings did not decline during a 3-h period leading up to the first fledging, nor was the rate of feeding just prior to the first fledging lower than the rate at the same time the day before. Moreover, parents did not slow the rate of food delivery to nests after part of the brood had fledged. Hatching is asynchronous in our study population which creates a marked age/size hierarchy within broods. At most nests, the first nestling to fledge was the most well-developed nestling in the brood or nearly so (as measured by feather length). This suggests that fledging typically begins when the most well-developed nestlings in the brood reach some threshold size. However, at about one-fifth of nests, the first nestling to fledge was only moderate in size. At these nests, severe competition for food may have caused smaller, less competitive nestlings to fledge first to increase their access to food. We found no strong support for the suggestion that the oldest nestlings delay fledging until their least-developed nestmate reaches some minimum size, although further experimental work on this question is warranted. [source] Foraging effort in relation to the constraints of reproduction in free-ranging albatrossesFUNCTIONAL ECOLOGY, Issue 1 2003S. A. Shaffer Summary 1Theoretical models predict that animals will vary their effort to maximize different currencies such as time and energy when the constraints of reproduction change during breeding, but this has been poorly studied in free-ranging animals. 2Foraging effort (energy per unit time) was examined by comparing mass changes, foraging costs and activity-specific behaviours of Wandering Albatrosses (Diomedea exulans Linnaeus) during the incubation and chick-brooding stages. In 1998, 38 albatrosses (20 during incubation and 18 during brooding) were injected with doubly labelled water and equipped with satellite transmitters and activity data loggers. 3During incubation, albatrosses travelled 3·7 times farther and were at sea 3·2 times longer, yet foraging costs were significantly lower than trips made during brooding (incubation 4·52 ± 0·50 SD W kg,1vs brooding 4·98 ± 0·55 SD W kg,1). 4The rate of daily mass gain decreased significantly with time at sea during incubation whereas the rate of daily mass gain increased significantly with time at sea during brooding. 5Foraging effort was higher during brooding, suggesting that birds were minimizing time at sea to maximize the rate of food delivery to chicks. In contrast, foraging effort was lower during incubation, suggesting that birds were maximizing time at sea and minimizing the energy costs of foraging. 6Foraging costs were also different between sexes. However, this was related to body size differences and not to differences in foraging effort as suggested in previous studies. [source] Brood reduction in the Red-necked Grebe Podiceps grisegenaIBIS, Issue 2 2003Janusz Kloskowski Brood reduction in Red-necked Grebes Podiceps grisegena breeding on fish ponds in south-eastern Poland occurred either through the desertion of the last-laid eggs after partial hatching of the clutch and/or the selective starvation of the smallest chicks. Abandonment of unhatched eggs was not influenced by the number of young already hatched or by the breeding date, but it was more likely in larger clutches and in families suffering chick starvation. Chicks from the largest broods had a higher probability of survival until fledging than those from single-chick broods. Larger chicks obtained food more successfully through better positioning during food delivery. In families that did not suffer brood reduction, chicks were better provisioned with food than in reduced broods. Although allocation of food among chicks in reduced broods was more skewed to the disadvantage of the younger siblings, dominant chicks obtained less food prior to brood reduction than dominant siblings in unreduced broods. Sibling aggression did not differ between unreduced and reduced broods before death of the weakest chicks. Post-laying adjustment of the number of offspring to prevailing feeding conditions occurred at two stages: by parental manipulation of the number of hatched eggs at the time when parents and chicks leave the nest and by competition between chicks. It is suggested that late egg desertion may be an adaptive mechanism of brood-size adjustment, when elimination of the weakest chicks through sibling competition is not very efficient. [source] Experimental addition of greenery reduces flea loads in nests of a non-greenery using species, the tree swallow Tachycineta bicolorJOURNAL OF AVIAN BIOLOGY, Issue 1 2007Dave Shutler Several bird species, including cavity-nesters such as European starlings Sturnus vulgaris, add to their nests green sprigs of plants such as yarrow Achillea millefolium that are rich in volatile compounds. In this field study on another cavity-nester, tree swallows Tachycineta bicolor, we tested whether yarrow reduced ectoparasite loads (the nest protection hypothesis), stimulated nestling immune systems (the drug hypothesis), or had other consequences for nestling growth or parental reproductive success (predicted by both preceding hypotheses). Tree swallows do not naturally add greenery to their nests, and thus offer several advantages in testing for effects of greenery independent of other potentially confounding explanations for the behaviour. We placed fresh yarrow in 23 swallow nests on the day the first egg was laid, replenishing every two days until clutch completion (=three times), and at 44 control nests, nesting material was simply touched. At 12 days of age, we measured nestling body size and mass, and took blood smears to do differential white blood cell counts. We subsequently determined the number and proportion of young fledging from nests and the number of fleas remaining after fledging. Higher humidity was associated with higher flea numbers whereas number of feathers in the nest was not. Our most significant finding was that an average of 773 fleas Ceratophyllus idius was found in control nests, versus 419 in yarrow nests. Possibly, parents compensate for blood that nestlings lose to ectoparasites by increasing food delivery, because we detected no differences between treatments in nestling mass, nestling leukocyte profiles, or proportion of young fledging, or relative to flea numbers. Our results provide no support for the drug hypothesis and strong support for the nest protection hypothesis. [source] How different provisioning strategies result in equal rates of food delivery: an experimental study of blue tits Parus caeruleusJOURNAL OF AVIAN BIOLOGY, Issue 4 2002Fabrizio Grieco Food provisioning in birds requires a considerable amount of time and usually has to be traded-off against other parental and non-parental activities. I investigated experimentally the rate at which blue tit Parus caeruleus parents deliver food to their brood after a change in food availability. The main argument behind this study is that parents enjoying an additional food source may use less time for self-feeding and therefore use more time for food provisioning. This could increase the rate at which food is brought to the nest. However, a prey choice model that takes the energetic needs of the parent into account allows for the possibility that the food-supplemented parents would deliver the same amount of food by increasing prey size (through an increase in prey selectivity) and reducing visit rate. The field data indicate that the parents changed provisioning strategy when food-supplemented: they fed the chicks natural food less frequently, but brought larger larvae. On the whole, delivery rate of natural food was the same or lower than in controls. The results suggest that food-supplemented parents used the time saved to increase their degree of food selectivity. When the gains from an increased delivery rate are not worth the increased costs (mainly resulting from an increased visiting rate), the parent with low energetic need may increase selectivity to provide the same amount of food to the brood as the unmanipulated parent, but at a lower cost. [source] Fast food delivery: the response of nursing astrocytes to an exciting call from neuronsJOURNAL OF NEUROCHEMISTRY, Issue 2003L. Pellerin It was suggested long time ago that astrocytes might play a prominent role in the distribution of energy substrates to neurons but convincing evidence was lacking. More recently, the excitatory neurotransmitter glutamate was shown to enhance aerobic glycolysis in cultured cortical astrocytes by a mechanism involving glial glutamate transporters. Using specific knockout mice for these transporters, it was demonstrated that a classical metabolic response to neuronal activation in the whisker-to-barrel system, 2-deoxyglucose accumulation, was disrupted in the somatosensory cortex of these animals at postnatal day 10. From these data, it was concluded that a net transfer of some energy substrate, preferentially lactate, must be taking place in order to fulfill increasing neuronal energy needs during periods of enhanced activity. In support of this concept, the presence of specific transporters for lactate, known as monocarboxylate transporters, was recently described both on astrocytes and neurons in vitro as well as in vivo. [source] Induction and Maintenance of Ethanol Self-Administration in Cynomolgus Monkeys (Macaca fascicularis): Long-Term Characterization of Sex and Individual DifferencesALCOHOLISM, Issue 8 2001J. A. Vivian Background: Investigations of oral ethanol self-administration in nonhuman primates have revealed important parallels with human alcohol use and abuse, yet many fundamental questions concerning the individual risk to, and the biological basis of, excessive ethanol consumption remain unanswered. Moreover, many conditions of access to ethanol in nonhuman primate research are largely unexplored. This set of experiments extends within- and across-session exposure to ethanol to more fully characterize individual differences in oral ethanol self-administration. Methods: Eight male and eight female adult cynomolgus monkeys (Macaca fascicularis) were exposed to daily oral ethanol self-administration sessions for approximately 9 months. During the first 3 months, a fixed-time (FT) schedule of food delivery was used to induce the consumption of an allotted dose of ethanol in 16-hr sessions. Subsequently, the FT schedule was suspended, and ethanol was available ad libitum for 6 months in 16- or 22-hr sessions. Results: Cynomolgus monkeys varied greatly in their propensity to self-administer ethanol, with sex and individual differences apparent within 10 days of ethanol exposure. Over the last 3 months of ethanol access, individual average ethanol intakes ranged from 0.6 to 4.0 g/kg/day, resulting in blood ethanol concentrations from 5 to 235 mg/dl. Males drank approximately 1.5-fold more than females. In addition, heavy-, moderate-, and light-drinking phenotypes were identified by using daily ethanol intake and the percentage of daily calories obtained from ethanol as criteria. Conclusions: Cynomolgus monkeys displayed a wide intersubject range of oral ethanol self-administration with a procedure that used a uniform and prolonged induction that restricted early exposure to ethanol and subsequently allowed unlimited access to ethanol. There were sex and stable individual differences in the propensity of monkeys to consume ethanol, indicating that this species will be important in characterizing risk factors associated with heavy-drinking phenotypes. [source] Long-term cisapride treatment improves diabetic gastroparesis but not glycaemic controlALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 7 2002B. Braden Background: In patients with diabetic gastroparesis, delayed food delivery to the intestine may become a major obstacle to post-prandial glycaemic control. Aim: To investigate whether cisapride accelerates gastric emptying in the long term or improves diabetes control in patients with diabetic gastroparesis. Methods: Eighty-five patients with long-standing insulin-dependent diabetes mellitus (glycosylated haemoglobin (HbA1c) > 7.0%), dyspepsia and diabetic neuropathy were tested for impaired gastric emptying of solids by the 13C-octanoate breath test. Nineteen of these patients with severe diabetic gastroparesis (i.e. t1/2 > 170 min) were randomly treated with 10 mg cisapride t.d.s. (n=9) or placebo (n=10) for 12 months. Thereafter, the breath test, dyspeptic symptoms and HbA1c values were reassessed. Results: Half emptying times in nine patients with diabetic gastroparesis were significantly shortened by cisapride (175 ± 46 min vs. 227 ± 40 min; P < 0.03). Half emptying times in the 10 patients taking placebo did not change (205 ± 37 min vs. 211 ± 36 min, P=0.54). Cisapride significantly reduced dyspepsia (score: 4.1 ± 1.6 vs. 2.0 ± 0.5, P=0.002). HbA1c values after 12 months of treatment were not different (cisapride: 7.7 ± 0.4% vs. 7.6 ± 0.9%, P=0.76; placebo: 7.5 ± 0.6% vs. 7.6 ± 1.5%, P=0.89). Conclusions: Prokinetic treatment with cisapride accelerates gastric emptying of solids and improves dyspeptic symptoms in diabetic gastroparesis. Glycaemic control, however, is not affected by cisapride. [source] | |||||||||||||||||||||||||