Palatable Diet Research Articles

Sex and age-dependent effects of a maternal junk food diet on the mu-opioid receptor in rat offspring

Perinatal junk food exposure increases the preference for palatable diets in juvenile and adult rat offspring. Previous studies have implicated reduced sensitivity of the opioid pathway in the programming of food preferences; however it is not known when during development these changes in opioid signalling first emerge. This study aimed to determine the impact of a maternal junk food (JF) diet on mu-opioid receptor (MuR) expression and ligand binding in two key regions of the reward pathway, the nucleus accumbens (NAc) and the ventral tegmental area (VTA) in rats during the early suckling (postnatal day (PND) 1 and 7) and late suckling/early post-weaning (PND 21 and 28) periods. Female rats were fed either a JF or a control diet for two weeks prior to mating and throughout pregnancy and lactation. MuR expression in the VTA was significantly reduced in female JF offspring on PND 21 and 28 (by 32% and 57% respectively, P<0.05), but not at earlier time points (PND 1 and 7). MuR ligand binding was also reduced (by 22%, P<0.05) in the VTA of female JF offspring on PND 28. No effects of perinatal junk food exposure on MuR mRNA expression or binding were detected at these time points in male offspring. These findings provide evidence that the opioid signalling system is a target of developmental programming by the end of the third postnatal week in females, but not in males.

Addiction-like Synaptic Impairments in Diet-Induced Obesity

BackgroundThere is increasing evidence that the pathological overeating underlying some forms of obesity is compulsive in nature and therefore contains elements of an addictive disorder. However, direct physiological evidence linking obesity to synaptic plasticity akin to that occurring in addiction is lacking. We sought to establish whether the propensity to diet-induced obesity (DIO) is associated with addictive-like behavior, as well as synaptic impairments in the nucleus accumbens core considered hallmarks of addiction. MethodsSprague Dawley rats were allowed free access to a palatable diet for 8 weeks then separated by weight gain into DIO-prone and DIO-resistant subgroups. Access to palatable food was then restricted to daily operant self-administration sessions using fixed ratio 1, 3, and 5 and progressive ratio schedules. Subsequently, nucleus accumbens brain slices were prepared, and we tested for changes in the ratio between α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and N-methyl-D-aspartate currents and the ability to exhibit long-term depression. ResultsWe found that propensity to develop DIO is linked to deficits in the ability to induce long-term depression in the nucleus accumbens, as well as increased potentiation at these synapses as measured by AMPA/N-methyl-D-aspartate currents. Consistent with these impairments, we observed addictive-like behavior in DIO-prone rats, including 1) heightened motivation for palatable food; 2) excessive intake; and 3) increased food seeking when food was unavailable. ConclusionsOur results show overlap between the propensity for DIO and the synaptic changes associated with facets of addictive behavior, supporting partial coincident neurological underpinnings for compulsive overeating and drug addiction.

Special postoperative diet orders: Irrational, obsolete, and imprudent

There are no indications to prescribed special diets for postoperative patients. Low-sodium and low-fat or low-cholesterol diets are examples of restricted diets, especially in patients with heart disease and atherosclerosis. These restricted diets are unpalatable. Postoperative nausea, paralytic ileus, and vomiting caused by residual anesthetic effects and opioids used for pain control further contribute to the problem. Long-term adherence to these diets is necessary to derive benefits. Prescribing regular and palatable diets in the immediate postoperative period to meet protein and energy goals is important for wound healing and is commensurate with best clinical practices. In the following, we review the pertinent literature and offer clinical evidence that routine special diet orders for postoperative patients are not necessary.

Trait and state binge eating predispose towards cocaine craving.

Binge eating (BE) and drug seeking share similar behavioral features, including loss of control over consumption and compulsive seeking of the craved substance. Previous studies in animal models have demonstrated a complex interaction between 'state' BE, produced by intermittent access to a palatable diet, and 'trait' BE, a phenotypical proneness towards overeating. In the present study, we examined the relationship between state and trait BE and cocaine seeking. We used Otsuka Long Evans Tokushima Fatty rats, a genetic model for obesity that demonstrates BE-like behavior, and Long Evans Tokushima Otsuka controls. They received a schedule of limited access to a palatable diet (3 days/week or 5 days/week access to Ensure for a month). Next, they underwent cocaine self-administration training (1 mg/kg, 1 hour/day for 10 days) followed by extinction sessions (7 days). We found that the degree of BE-like behavior and the state and trait BE combination predicted cocaine craving patterns. Lower levels of dopamine D2 receptors in the prefrontal cortex were correlated with increased drug craving. Moreover, restricted access to an attractive diet was found to be a risk factor for heightened cocaine craving, particularly in trait binge eaters, as rats on the 3 days/week access schedule persistently failed to cease cocaine seeking throughout extinction. Hence, we postulate a joint role of state and trait BE as risk factors for heightened cocaine craving.

Exercise training and taurine supplementation reduce oxidative stress and prevent endothelium dysfunction in rats fed a highly palatable diet.

Abstract Aim Few studies have analysed, from a nutritional point of view, the influence of exercise in minimizing detrimental diet-related health effects. This study evaluated the effectiveness of exercise and taurine supplementation in preventing vascular and metabolic disorders caused by highly palatable diet intake. Main methods Thirty-two male Wistar rats (255–265 g) were divided into 4 groups: Sedentary (SD); Sedentary + 2% taurine (SDTAU), Trained (TR) and Trained + 2% taurine (TRTAU). Exercise (treadmill, 60% maximum speed, 60 min, 5 days/week) started after 4 weeks of highly palatable diet feeding and was carried out for 7 weeks. Key findings Exercise effectively reduced insulin (61% and 68%), glucose (30% and 7%) and leptin levels (75% and 67%) in TR and TRTAU groups, respectively. All groups showed a reduction in hepatic triglyceride infiltration (74% for SDTAU, 82% for TR and 85% for TRTAU) but only exercise reduced TBARS (50% for TR and 41% for TRTAU). Impaired relaxation was seen in SD (E max = 67%) and improved with taurine (E max = 86%) and exercise (E max = 90% for TR and TRTAU). Increased expression of EC-SOD (32%) was seen in the aortas from all treated groups. Exercise, in the absence of taurine, increased Cu–Zn SOD (44%) and reduced gp91 phox (34%). Superoxide formation in the aorta was reduced in supplemented (75% in SDTAU) and in trained groups (64% and 77% for TR and TRTAU, respectively). Significance Exercise and taurine supplementation were effective in preventing endothelial dysfunction induced by highly palatable diet intake, through a decrease in vascular oxidative stress.

Changes in mu-opioid receptor expression and function in the mesolimbic system after long-term access to a palatable diet.

The incidence of obesity in both adults and children is rising. In order to develop effective treatments for obesity, it is important to understand how diet can induce changes in the brain that could promote excessive intake of high-calorie foods and alter the efficacy of therapeutic targets. The mu-opioid receptor is involved in regulating the motivation for and hedonic reaction to food. Here, we review the literature examining changes in the expression and function of mu-opioid receptors in the mesolimbic system of rodents after extended access to a high-fat diet. We also review how maternal diet can induce long-term changes in the expression or function of mu-opioid receptors in the mesolimbic system of offspring. Understanding the behavioural and therapeutic implications of these changes requires further study.

Development of a water-stable agar-based diet for the supplementary feeding of cleaner fish ballan wrasse (Labrus bergylta) deployed within commercial Atlantic salmon (Salmon salar) net-pens

Abstract The aim of this project was to develop a water-stable and palatable diet for the supplementary feeding of wrasse deployed in salmon sea-pens using a gelling agent mixed with a manufactured dry-feed component. Three binders (gelatine from cold water fish skin, beef gelatin and agar-agar) were compared for water-gel strength over a range of concentrations. Gel formed using agar was found to be significantly stronger than the other binders tested. An experimental aqua-feed made using a grinded, dry ingredient mix binded with 20 g/L agar solution at 1/1.6 (w/v) ratio and offered as blocks within individual feeders was water-stable for 7 days when deployed fresh or following a week of preservation at -20 °C. Farmed ballan wrasse in tanks fed on the agar-based diet within 2 days of deployment. Wild wrasse stocked in salmon sea-pens at low density (1.2–2.1%), up to 4 weeks prior the start of the trial and not previously fed a manufactured diet first ingested the agar feed within 2 weeks and total feed intake significantly increased afterwards. Feed intake was significantly higher from feeders placed within a small feeding shelter made of artificial kelp than within the large wrasse shelter. No nutrient leaching after water immersion and no alterations in the fatty acid profile after preparation of the experimental feed was found. A manufactured grinded ingredient mix binded with 20 g/L agar solution at a 1/1.6 (w/v) ratio and offered within static feeders is proposed as the basis of a novel supplementary feeding methodology for cleaner fish wrasse deployed in salmon sea-pens. This methodology has the potential to facilitate wrasse feeding and to allow the monitoring of feed intake to safeguard the health, welfare and delousing activity of the biological stock over the salmon rearing cycle.

The Orphan G Protein-Coupled Receptor Gene GPR178 Is Evolutionary Conserved and Altered in Response to Acute Changes in Food Intake.

G protein-coupled receptors (GPCRs) are a class of integral membrane proteins mediating physiological functions fundamental for survival, including energy homeostasis. A few years ago, an amino acid sequence of a novel GPCR gene was identified and named GPR178. In this study, we provide new insights regarding the biological significance of Gpr178 protein, investigating its evolutionary history and tissue distribution as well as examining the relationship between its expression level and feeding status. Our phylogenetic analysis indicated that GPR178 is highly conserved among all animal species investigated, and that GPR178 is not a member of a protein family. Real-time PCR and in situ hybridization revealed wide expression of Gpr178 mRNA in both the brain and periphery, with high expression density in the hypothalamus and brainstem, areas involved in the regulation of food intake. Hence, changes in receptor expression were assessed following several feeding paradigms including starvation and overfeeding. Short-term starvation (12–48h) or food restriction resulted in upregulation of Gpr178 mRNA expression in the brainstem, hypothalamus and prefrontal cortex. Conversely, short-term (48h) exposure to sucrose or Intralipid solutions downregulated Gpr178 mRNA in the brainstem; long-term exposure (10 days) to a palatable high-fat and high-sugar diet resulted in a downregulation of Gpr178 in the amygdala but not in the hypothalamus. Our results indicate that hypothalamic Gpr178 gene expression is altered during acute exposure to starvation or acute exposure to palatable food. Changes in gene expression following palatable diet consumption suggest a possible involvement of Gpr178 in the complex mechanisms of feeding reward.

Differential expression of CART in feeding and reward circuits in binge eating rat model

Binge eating (BE) disrupts feeding and subverts reward mechanism. Since cocaine- and amphetamine-regulated transcript peptide (CART) mediates satiety as well as reward, its role in BE justifies investigation. To induce BE, rats were provided restricted access to high fat sweet palatable diet (HFSPD) for a period of 4 weeks. Immunoreactivity profile of the CART elements, and accompanying neuroplastic changes were studied in satiety- and reward-regulating brain nuclei. Further, we investigated the effects of CART, CART-antibody or rimonabant on the intake of normal chow or HFSPD. Rats fed on HFSPD showed development of BE-like phenotype as reflected by significant consumption of HFSPD in short time frame, suggestive of dysregulated satiety mechanisms. At the mid-point during BE, CART-immunoreactivity was significantly increased in hypothalamic arcuate (ARC), lateral (LH), nucleus accumbens shell (AcbSh) and paraventricular nucleus of thalamus (PVT). However, for next 22-h post-binge time-period, the animals showed no interest in food, and low CART expression. Pre-binge treatment with rimonabant, a drug recommended for the treatment of BE, produced anorexia, increased CART expression in ARC and LH, but not in AcbSh and PVT. Higher dose of CART was required to produce anorexia in binged rats. While neuronal tracing studies confirmed CART fiber connectivity from ARC and LH to AcbSh, increase in CART and synaptophysin immunostaining in this pathway in BE rats suggested strengthening of the CART connectivity. We conclude that CART bearing ARC-LH-PVT-AcbSh reward circuit may override the satiety signaling in ARC-PVN pathway in BE rats.

Intrauterine growth restriction increases the preference for palatable foods and affects sensitivity to food rewards in male and female adult rats

Clinical evidence suggests that intrauterine growth restriction (IUGR) can cause persistent changes in the preference for palatable foods. In this study, we compared food preferences, the response to food rewards, and the role of the mesolimbic dopaminergic system in feeding behavior, between IUGR and control rats. Time-mated pregnant Sprague–Dawley rats were randomly allocated to a control group (standard chow ad libitum) or a 50% food restriction (FR) group, which received 50% of the control dams׳ habitual intake. These diets were provided from gestation day 10 to the 21st day of lactation. Within 24h of birth, pups were cross-fostered and divided into four groups: Adlib/Adlib, FR/Adlib, FR/FR, Adlib/FR. Standard chow consumption was compared between all groups. Food preferences, conditioned place preference to a palatable diet, and the levels of tyrosine hydroxylase (TH) phosphorylation and D2 receptors in the nucleus accumbens were analyzed and compared between the two groups of interest: Adlib/Adlib (control) and FR/Adlib (exposed to growth restriction during the fetal period only). IUGR adult rats had a stronger preference for palatable foods, but showed less conditioned place preference to a palatable diet than controls. D2 receptors levels were lower in IUGR rats. At baseline, TH and pTH levels were higher in FR/Adlib than control males. Measurements taken after exposure to sweet foods revealed higher levels of TH and pTH in FR/Adlib than control females. These data showed that IUGR rats exhibited a preference for palatable foods, potentially due to alterations in their mesolimbic reward pathway. Additionally, the changes observed in the mesolimbic dopaminergic system of IUGR rats proved to be sex-specific.This article is part of a Special Issue entitled 1618.

Alterations in sucrose sham-feeding intake as a function of diet-exposure in rats maintained on calorically dense diets

We previously reported that rats increase meal size upon initial presentation of a calorically dense diet. The increase may be attributed to increased orosensory stimulation and/or reduced sensitivity to post-ingestive inhibitory signals. During feeding both types of signals are simultaneously in play; thus here, we compare responses in rats presented a high-energy diet (HE) or 45% high-fat diet (HF) with those of chow-fed controls (CHOW) in a sham-feeding procedure in which post-ingestive feedback is minimized. Measures of sham-feeding to sucrose were taken before diet manipulation (baseline), ~5 days (dynamic phase) and ~6 weeks (static phase) following introduction of the palatable diet, as well as after animals were switched back to standard chow (recovery phase). Some but not all the hypotheses based on our previous findings were confirmed by the outcomes here. Consistent with our hypothesis that enhanced orosensory stimulation during the dynamic phase compared with the static phase would generalize to increased intake of other palatable stimuli, HE rats showed higher sucrose intake during the dynamic phase compared with the static phase. Contrary to what we hypothesized, HE and HF rats did not increase responses to sucrose compared to CHOW rats. In fact, HE rats showed decreased responses compared to CHOW controls. Thus changes in orosensory stimulation do not necessarily generalize to increased intake of other palatable stimuli.

Perinatal malnutrition stimulates motivation through reward and enhances drd1a receptor expression in the ventral striatum of adult mice

AimThe aim of this study was to analyze the effects of protein perinatal malnutrition on the function of dopamine DRD1 and DRD2 receptors in regards to motivation and food consumption in adult mice. The study also analyzed the effect of protein perinatal malnutrition on the gene expression of these receptors in the ventral striatum. MethodsWistar lineage mice were divided into two groups according to maternal diet: control (17% casein), n=30 and low protein (8% casein), n=30. Between 30 and 120days of life, the following factors were measured: body weight; the effect of dopamine D1 and D2 agonists on the ingestion of palatable food; the motivational aspect under the action of the D1 (SKF 38393) and D2 Quinpirole dopaminergic agonists; and the gene expression of DRD1 and DRD2 receptors in the ventral striatum. ResultsThe body weights of the malnourished animals remained significantly lower than those of the control group from 30 to 120days of life. Malnourished animals ingested a greater quantity of palatable food. There was a decrease in palatable diet consumption in both the control and malnourished groups after the application of D1 and D2 agonists; however, the anorexic effect of the D1 agonist was understated in malnourished animals. Perinatal malnutrition increases the motivational behavior of the animal when food reward is used. There was an increase in gene expression of the DRD1a receptor in the ventral striatum of malnourished animals, and there were no significant changes concerning the DRD2 receptor. ConclusionsPerinatal protein malnutrition stimulates hedonic control of eating behavior by promoting increased intake of palatable foods, possibly due to increased expression of dopamine receptor DRD1a in the ventral striatum.

Satiety and Reward: Dichotomy of Cocaine‐ and Amphetamine‐Regulated Transcript Peptide's Function During Binge Eating

Since cocaine‐ and amphetamine‐regulated transcript peptide (CART) mediates feeding as well as reward, we investigated its role in binge eating (BE), a clinical condition which disrupts satiety. BE was induced in rats by providing 2‐h access to high fat‐sweet palatable diet (HFSPD) on alternate days for 4 weeks. Effect of drug treatments on HFSPD intake and CART immunoreactive profile in reward and satiety regulating nuclei was studied. Rats fed on HFSPDshowed explosive BE. Higher doses of CART or rimonabant was required to reduce BE, as compared to that of normal chow intake in naïve rats. At the mid‐point during BE, CART immunoreactivity was significantly up‐regulated in the arcuate (ARC), lateral (LH) nucleus, paraventricular nucleus of thalamus (PVT), and nucleus accumbens shell (AcbSh) but not in the paraventricular (PVN) nucleus. At mid‐binge time‐point, the rimonabant treated rats showed increased CART expression in ARC and LH, while that in PVT and AcbSh was decreased. Increase in co‐expression of CART and synaptophysin in LH and cornu ammonis 1 of hippocampus suggested neuroplastic changes in CART system in BE rats. We suggests that BE enhanced the CARTergic signaling in the ARC/LH‐PVT‐AcbSh axis and suppressed the ARC‐PVN pathway. The net result may be the reward pathway overriding the satiety circuit. Opposite may happen following treatment with rimonabant. Further, CART seems to participate in the memory formation pertaining to HFSPD‐related reward.

High Trait Impulsivity Predicts Food Addiction‐Like Behavior in the Rat

Impulsivity is a behavioral trait frequently seen in drug addicted individuals and individuals who pathologically overeat. In this study, we hypothesized that high impulsivity precedes and confers vulnerability for food addiction-like behavior. For this purpose we trained rats in a differential reinforcement of low rates of responding (DRL) task to select high- and low-impulsive rats. These rats then self-administered a highly palatable diet (Palatable group) or a regular chow diet (Chow group) in 1h daily sessions, under increasing fixed ratio (FR) and a progressive ratio (PR) schedule of reinforcement. In addition, we tested the compulsiveness for food by measuring the food eaten in the aversive, open compartment of a light/dark conflict test. Finally, we measured the expression of the transcription factor ΔFosB in the shell and the core of the nucleus accumbens which is a marker for neuroadaptive changes following addictive drug exposure. The data we obtained demonstrate that impulsivity is a trait which predicts the development of food addiction-like behaviors, including: i) excessive intake, ii) heightened motivation for food, and iii) compulsive-like eating, when rats are given access to highly palatable food. In addition, we show that the food addiction phenotype in high impulsive subjects is characterized by an increased expression of the transcription factor ΔFosB in the nucleus accumbens shell. These results prove that impulsivity confers an increased propensity to develop uncontrollable overeating of palatable food.

Seeking behavior, place conditioning, and resistance to conditioned suppression of feeding in rats intermittently exposed to palatable food.

Binge eating disorder is characterized by excessive consumption of highly palatable food within short periods of time accompanied by loss of control over eating. Extensive evidence provides support for the consideration of binge eating disorder as an addiction-like disorder. In this study, we wanted to determine whether rats undergoing an operant binge-like eating procedure could develop maladaptive forms of conditioned feeding behaviors. For this purpose, we trained male rats to self-administer either a sugary, highly palatable diet ("Palatable" rats) or a chow diet ("Chow" rats) for 1 hour a day. After escalation and stabilization of palatable food intake, we tested Chow and Palatable rats in (a) a conditioned place preference test, (b) a second-order schedule of reinforcement, (c) a cue-induced suppression of feeding test. In the conditioned place preference task, Palatable rats spent significantly more time in the compartment that was previously paired with the palatable food, compared to Chow controls. Furthermore, in the second-order schedule of reinforcement task, Palatable rats exhibited active lever responding 4- to 6-fold higher than Chow control rats. Finally, in the cue-induced suppression of feeding test, although Chow control subjects reduced responding by 32% in the presence of the conditioned punishment, Palatable rats persevered in responding despite the aversive cue. These results further characterize this animal model of binge-like eating and provide additional evidence for the addictive properties of highly palatable food.

Wheel running decreases palatable diet preference in Sprague–Dawley rats

Physical activity has beneficial effects on not only improving some disease conditions but also by preventing the development of multiple disorders. Experiments in this study examined the effects of wheel running on intakes of chow and palatable diet e.g. high fat (HF) or high sucrose (HS) diet in male and female Sprague–Dawley rats. Experiment 1 demonstrated that acute wheel running results in robust HF or HS diet avoidance in male rats. Although female rats with running wheel access initially showed complete avoidance of the two palatable diets, the avoidance of the HS diet was transient. Experiment 2 demonstrated that male rats developed decreased HF diet preferences regardless of the order of diet and wheel running access presentation. Running associated changes in HF diet preference in females, on the other hand, depended on the testing schedule. In female rats, simultaneous presentation of the HF diet and running access resulted in transient complete HF diet avoidance whereas running experience prior to HF diet access did not affect the high preference for the HF diet. Ovariectomy in females resulted in HF diet preference patterns that were similar to those in male rats during simultaneous exposure of HF and wheel running access but similar to intact females when running occurred before HF exposure. Overall, the results demonstrated wheel running associated changes in palatable diet preferences that were in part sex dependent. Furthermore, ovarian hormones play a role in some of the sex differences. These data reveal complexity in the mechanisms underlying exercise associated changes in palatable diet preference.

Metabolic consequences of chronic intermittent mild stress exposure

Chronic stress in humans has divergent effects on food intake, with some individuals reporting increased vs. decreased food intake during stress. This divergence may depend in part on stress intensity, with higher-intensity stressors preferentially promoting anorexia. Consistent with this idea, rodents given a high-intensity chronic variable stress paradigm have robustly decreased food intake and body weight gain. However, the metabolic effects of a less intense chronic stress paradigm are not clear. Thus in the present study, adult male rats were given chronic intermittent mild stress (CIMS) exposure (3cycles, in which each cycle consists of once daily mild stress for 5days/week for 2weeks, followed by 2weeks of no stress) vs. non-stress controls, combined with ongoing access to a palatable diet (PD; choice of chow, high-fat diet, 30% sucrose drink, and water) vs. control diet (chow and water). As expected, access to PD increased caloric intake, body weight gain, and adiposity, and impaired glucose tolerance. CIMS decreased body weight gain only during the first cycle of stress and did not affect body weight gain thereafter, regardless of diet. Moreover, CIMS did not alter total food intake, adiposity or glucose tolerance regardless of diet. Lastly, CIMS transiently increased high-fat diet preference in PD-fed rats during the first stress cycle. Collectively, these results suggest that CIMS has relatively modest metabolic effects that occur primarily during initial stress exposure. These results support the hypothesis that the metabolic consequences of chronic stress vary with stress intensity and/or frequency.

Interim Diets for Specialist Predators of Hemlock Woolly Adelgids

We provide a rationale for diets that temporarily support populations of insects but not sustained rearing of target insects. We call such sustaining media, “interim diets”. We present formulation and performance details of such a diet, which sustains specialist adult predators of hemlock woolly adelgids (HWA) for several months. The diet base is ground, freeze-dried, cooked chicken breast, heat-treated chicken egg yolk with several nutritional and functional supplements. This diet has been tested in our laboratories for five years and has been validated in several mass-rearing laboratories where HWA predators are routinely produced. Although the current diet does not support complete development of HWA predators from egg to adult, it is useful as an economical and convenient means of keeping predators alive and healthy during periods when natural prey are not available. Unlike generalist predators, HWA predators would not accept factitious hosts such as scale, aphids, lepidopteran eggs or other foods that might have sustained them during “feeding droughts”. The predators studied here were beetles, Sasajiscymnus tsugae (Coccinellidae) and Laricobius nigrinus (Derodontidae). We experimented with several diet-presentation systems designed to fulfill the feeding requirements of the beetles and to preserve the diets by preventing desiccation and deterioration. We developed several forms of a hen’s egg-based diet and a diet-presentation system that included alginate gels and slurry diets that were made from adhering liquid materials to a solid/capture medium (freeze dried, powdered chicken breast). Some diets and diet-presentation systems induced strong feeding responses and allowed adult predators to stay alive and active for several months and to return to egg production days after being returned to HWA. The paper describes a stable, palatable diet and dietpresentation techniques that allow researchers and mass-rearing facilities to sustain healthy populations of predators during regular periods of prey scarcity.

An assessment of the test–retest reliability of the New Nordic Diet score

BackgroundThere is a growing interest in the New Nordic Diet (NND) as a potentially health promoting, environmentally friendly, and palatable regional diet. Also, dietary scores are gaining ground as a complementary approach for examining relations between dietary patterns and various health outcomes. A score assessing adherence to the NND has earlier been published, yet not tested for reliability.ObjectiveTo assess the test–retest reliability of the NND score in a sample of parents of toddlers, residing in Southern Norway.DesignA questionnaire survey was completed on two occasions, approximately 14 days apart, by 67 parents of toddlers [85% females, mean age 34 years (SD=5.3 years)]. The NND score was constructed from 24 items and comprised 10 subscales that summarize meal pattern and intake of typical Nordic foods. Each subscale was dichotomized by the median and assigned values of ‘0’ or ‘1’. Adding the subscales yielded a score ranging from 0 to 10, which was further trichotomized. Test–retest reliability of the final NND score and individual subscales was assessed by Pearson's correlation coefficient and Spearman's rank correlation coefficient, respectively. Additionally, cross tabulation and kappa measure of agreement (k) were used to assess the test–retest agreement of classification into the NND score, and the subscales.ResultsTest–retest correlations of the NND score and subscales were r=0.80 (Pearson) and r=0.54–0.84 (Spearman), respectively, all p<0.001. There were 69% (k=0.52) and 67–88% (k=0.32–0.76) test–retest correct classification of the trichotomized score and the dichotomized subscales, respectively.ConclusionThe NND score and the 10 subscales appear to have acceptable test–retest reliability when tested in a sample of parents of toddlers.

Antagonism of corticotrophin-releasing factor type 1 receptors attenuates caloric intake of free feeding subordinate female rhesus monkeys in a rich dietary environment.

Social subordination in macaque females is a known chronic stressor and previous studies have shown that socially subordinate female rhesus monkeys consume fewer kilocalories than dominant animals when a typical laboratory chow diet is available. However, in a rich dietary environment that provides access to chow in combination with a more palatable diet (i.e. high in fat and refined sugar), subordinate animals consume significantly more daily kilocalories than dominant conspecifics. Substantial literature is available supporting the role of stress hormone signals in shaping dietary preferences and promoting the consumption of palatable, energy-dense foods. The present study was conducted using stable groups of adult female rhesus monkeys to test the hypothesis that pharmacological treatment with a brain penetrable corticotrophin-releasing factor type 1 receptor (CRF1) antagonist would attenuate the stress-induced consumption of a palatable diet among subordinate animals in a rich dietary environment but would be without effect in dominant females. The results show that administration of the CRF1 receptor antagonist significantly reduced daily caloric intake of both available diets among subordinate females compared to dominant females. Importantly, multiple regression analyses showed that the attenuation in caloric intake in response to Antalarmin (Sigma-Aldrich, St Louis, MO, USA) was significantly predicted by the frequency of submissive and aggressive behaviour emitted by females, independent of social status. Taken together, the findings support the involvement of activation of CRF1 receptors in the stress-induced consumption of excess calories in a rich dietary environment and also support the growing literature concerning the importance of CRF for sustaining emotional feeding.