Heterogeneous metabolic adaptation of C57BL/6J mice to high-fat diet.

C57BL/6J mice were fed a high-fat, carbohydrate-free diet (HFD) for 9 mo. Approximately 50% of the mice became obese and diabetic (ObD), approximately 10% lean and diabetic (LD), approximately 10% lean and nondiabetic (LnD), and approximately 30% displayed intermediate phenotype. All of the HFD mice were insulin resistant. In the fasted state, whole body glucose clearance was reduced in ObD mice, unchanged in the LD mice, and increased in the LnD mice compared with the normal-chow mice. Because fasted ObD mice were hyperinsulinemic and the lean mice slightly insulinopenic, there was no correlation between insulin levels and increased glucose utilization. In vivo, tissue glucose uptake assessed by 2-[(14)C]deoxyglucose accumulation was reduced in most muscles in the ObD mice but increased in the LnD mice compared with the values of the control mice. In the LD mice, the glucose uptake rates were reduced in extensor digitorum longus (EDL) and total hindlimb but increased in soleus, diaphragm, and heart. When assessed in vitro, glucose utilization rates in the absence and presence of insulin were similar in diaphragm, soleus, and EDL muscles isolated from all groups of mice. Thus, in genetically homogenous mice, HFD feeding lead to different metabolic adaptations. Whereas all of the mice became insulin resistant, this was associated, in obese mice, with decreased glucose clearance and hyperinsulinemia and, in lean mice, with increased glucose clearance in the presence of mild insulinopenia. Therefore, increased glucose clearance in lean mice could not be explained by increased insulin level, indicating that other in vivo mechanisms are triggered to control muscle glucose utilization. These adaptive mechanisms could participate in the protection against development of obesity.

Inconspicuous assessment of diet-induced thermogenesis using whole-body indirect calorimetry.

We report a novel technique for computing diet-induced thermogenesis using data from 24-h respiration chamber measurements of 76 subjects. Physical activity (PA) was determined using a radar system to assess its duration and an accelerometer to evaluate its intensity. The regression line relating PA and energy expenditure facilitated calculation of the integrated thermogenic response to the total energy ingested (11.4% ± 3.8%), which is consistent with the values classically reported in the literature (10%) at the group level.

CB1 blockade potentiates down-regulation of lipogenic gene expression in perirenal adipose tissue in high carbohydrate diet-induced obesity.

De novo lipogenesis and hypercaloric diets are thought to contribute to increased fat mass, particularly in abdominal fat depots. CB1 is highly expressed in adipose tissue, and CB1-mediated signalling is associated with stimulation of lipogenesis and diet-induced obesity, though its contribution to increasing fat deposition in adipose tissue is controversial. Lipogenesis is regulated by transcription factors such as liver X receptor (LXR), sterol-response element binding protein (SREBP) and carbohydrate-responsive-element-binding protein (ChREBP). We evaluated the role of CB1 in the gene expression of these factors and their target genes in relation to lipogenesis in the perirenal adipose tissue (PrAT) of rats fed a high-carbohydrate diet (HCHD) or a high-fat diet (HFD). Both obesity models showed an up-regulated gene expression of CB1 and Lxrα in this adipose pad. The Srebf-1 and ChREBP gene expressions were down-regulated in HFD but not in HCHD. The expression of their target genes encoding for lipogenic enzymes showed a decrease in diet-induced obesity and was particularly dramatic in HFD. In HCHD, CB1 blockade by AM251 reduced the Srebf-1 and ChREBP expression and totally abrogated the remnant gene expression of their target lipogenic enzymes. The phosphorylated form of the extracellular signal-regulated kinase (ERK-p), which participates in the CB1-mediated signalling pathway, was markedly present in the PrAT of obese rats. ERK-p was drastically repressed by AM251 indicating that CB1 is actually functional in PrAT of obese animals, though its activation loses the ability to stimulate lipogenesis in PrAT of obese rats. Even so, the remnant expression levels of lipogenic transcription factors found in HCHD-fed rats are still dependent on CB1 activity. Hence, in HCHD-induced obesity, CB1 blockade may help to further potentiate the reduction of lipogenesis in PrAT by means of inducing down-regulation of the ChREBP and Srebf-1 gene expression, and consequently in the expression of lipogenic enzymes.

Description of a new artificial diet for rearing ant colonies as Iridomyrmex humilis, Monomorium pharaonis and Wasmannia auropunctata (Hymenoptera, Formicidae)

A diet which does not desiccate was developed for rearing various ant species. this diet was found to be very attractive forIridomyrmex humilis. Monomorium pharaonis andWasmannia auropunctata in which species it permitted the rearing of colonies for long periods and the regular production of sexuals. Nous présentons la recette d'une nourriture artificielle élaborée pour élever des fourmis en laboratoire. Cette nourriture ne se dessèche pas et s'est avérée adéquate pour l'élevage de plusieur espèces telles queIridomyrmex humilis, Monomorium pharaonis etWasmannia auropunctata. Des sexués mâles et femelles ont été régulièrement produits dans ces sociétés.

Morphologic and electroretinographic phenotype of SR-BI knockout mice after a long-term atherogenic diet.

PURPOSE: To evaluate functional and ultrastructural changes in the retina of scavenger receptor B1 (SR-BI) knockout (KO) mice consuming a high fat cholate (HFC) diet. METHODS: Three-month-old male KO and wild-type (WT) mice were fed an HFC diet for 30 weeks. After diet supplementation, plasma cholesterol levels and electroretinograms were analyzed. Neutral lipids were detected with oil red O, and immunohistochemistry was performed on cryostat ocular tissue sections. The retina, Bruch's membrane (BM), retinal pigment epithelium (RPE), and choriocapillaris (CC) were analyzed by transmission electron microscopy. RESULTS: Using the WT for reference, ultrastructural changes were recorded in HFC-fed SR-BI KO mice, including lipid inclusions, a patchy disorganization of the photoreceptor outer segment (POS) and the outer nuclear layer (ONL), and BM thickening with sparse sub-RPE deposits. Within the CC, there was abnormal disorganization of collagen fibers localized in ectopic sites with sparse and large vacuolization associated with infiltration of macrophages in the subretinal space, reflecting local inflammation. These lesions were associated with electroretinographic abnormalities, particularly increasing implicit time in a- and b-wave scotopic responses. Abnormal vascular endothelial growth factor (VEGF) staining was detected in the outer nuclear layer. CONCLUSIONS: HFC-fed SR-BI KO mice thus presented sub-RPE lipid-rich deposits and functional and morphologic alterations similar to some features observed in dry AMD. The findings lend further support to the hypothesis that atherosclerosis causes retinal and subretinal damage that increases susceptibility to some forms of AMD.

Ad libitum intake of a high-carbohydrate or high-fat diet in young men: effects on nutrient balances.

The effect of diet composition [high-carbohydrate, low-fat (HC) and high-fat, low-carbohydrate (HF) diets] on macronutrient intakes and nutrient balances was investigated in young men of normal body weight. Eleven subjects were studied on two occasions for 48 h in a whole-body indirect calorimeter in a crossover design. Subjects selected their meals from a list containing a large variety of common food, which had a food quotient > 0.85 for the HC diet and < 0.85 for the HF diet. The average ad libitum intake was 14.41 +/- 0.85 MJ/d (67%, 18%, and 15% of energy as carbohydrate, fat, and protein, respectively) with the HC diet and 18.25 +/- 0.90 MJ/d (26%, 61%, and 13% of energy as carbohydrate, fat, and protein, respectively) with the HF diet. Total energy expenditure was not significantly influenced by diet composition: 10.46 +/- 0.27 and 10.97 +/- 0.22 MJ/d for the HC and HF diets, respectively. During the 2 test days, cumulative carbohydrate storage was 418 +/- 72 and 205 +/- 47 g, and fat balance was 29 +/- 17 and 291 +/- 29 g with the HC and HF diets, respectively. Only the HF diet induced a significantly positive fat balance. These results emphasize the important role of the dietary fat content in body fat storage.

Fructose-rich diet-induced abdominal adipose tissue endocrine dysfunction in normal male rats.

We have currently studied the changes induced by administration of a fructose-rich diet (FRD) to normal rats in the mass and the endocrine function of abdominal (omental) adipose tissue (AAT). Rats were fed ad libitum a standard commercial chow and tap water, either alone (control diet, CD) or containing fructose (10%, w/vol) (FRD). Three weeks after treatment, circulating metabolic markers and leptin release from adipocytes of AAT were measured. Plasma free fatty acids (FFAs), leptin, adiponectin, and plasminogen activator inhibitor-1 (PAI-1) levels were significantly higher in FRD than in CD rats. AAT mass was greater in FRD than in CD rats and their adipocytes were larger, they secreted more leptin and showed impaired insulin sensitivity. While leptin mRNA expression increased in AAT from FRD rats, gene expression of insulin receptor substrate, IRS1 and IRS2 was significantly reduced. Our study demonstrates that administration of a FRD significantly affects insulin sensitivity and several AAT endocrine/metabolic functions. These alterations could be part of a network of interacting abnormalities triggered by FRD-induced oxidative stress at the AAT level. In view of the impaired glucose tolerance observed in FRD rats, these alterations could play a key role in both the development of metabolic syndrome (MS) and beta-cell failure.

Differential effects of high-fat diet on myocardial lipid metabolism in failing and nonfailing hearts with angiotensin II-mediated cardiac remodeling in mice.

Normal myocardium adapts to increase of nutritional fatty acid supply by upregulation of regulatory proteins of the fatty acid oxidation pathway. Because advanced heart failure is associated with reduction of regulatory proteins of fatty acid oxidation, we hypothesized that failing myocardium may not be able to adapt to increased fatty acid intake and therefore undergo lipid accumulation, potentially aggravating myocardial dysfunction. We determined the effect of high-fat diet in transgenic mice with overexpression of angiotensinogen in the myocardium (TG1306/R1). TG1306/R1 mice develop ANG II-mediated left ventricular hypertrophy, and at one year of age approximately half of the mice present heart failure associated with reduced expression of regulatory proteins of fatty acid oxidation and reduced palmitate oxidation during ex vivo working heart perfusion. Hypertrophied hearts from TG1306/R1 mice without heart failure adapted to high-fat feeding, similarly to hearts from wild-type mice, with upregulation of regulatory proteins of fatty acid oxidation and enhancement of palmitate oxidation. There was no myocardial lipid accumulation or contractile dysfunction. In contrast, hearts from TG1306/R1 mice presenting heart failure were unable to respond to high-fat feeding by upregulation of fatty acid oxidation proteins and enhancement of palmitate oxidation. This resulted in accumulation of triglycerides and ceramide in the myocardium, and aggravation of contractile dysfunction. In conclusion, hearts with ANG II-induced contractile failure have lost the ability to enhance fatty acid oxidation in response to increased fatty acid supply. The ensuing accumulation of lipid compounds may play a role in the observed aggravation of contractile dysfunction.

The occurrence of reptiles in Barn Owl diet in Europe

Capsule We present a review of the propensity to eat reptiles in the Barn Owl Tyto alba in Europe. Based on the analysis of 591 published studies reporting 3.07 million prey items identified in pellets, only 2402 reptiles (0.08%) were found. Reptiles were most often captured in southern parts of the European continent and on islands. A large proportion of the 1304 identified reptiles to the species level were nocturnal Gekkonidae (77.1%).

The Effect of occupational sex-composition on earnings: job-specialisation, sex-role attitudes and the division of domestic-labour in Spain

Important theoretical controversies remain unresolved in the literatire on occupational sex-segregation and the gender wage-gap. A useful way of summarising these controversies is viewing them as a debate between - cultural -socialisation. The paper discusses these theories in detail and carries out a preliminary test of the relative explanatory performance of some of their most consequential predictions. This is done by drawing on the Spanish sample of the second wave of the European Social Survey, ESS. The empirical analysis of ESS data illustrates the notable analytical pay-offs that can stem from using rich individual-level indicators, but also exemplifies the statistical llimitations generated by small sample size and high rates of non-response. Empirical results should, therefore, be taken as preliminary. They seem to suggest that the effect of occupational sex-segregation on wages could be explicable by workers' sex-role attitutes, their relative input in domestic production and the job-specific human capital requirements of their jobs. Of these three factors, job-specialisation seeems clearly the most important one.

A high-fructose diet impairs basal and stress-mediated lipid metabolism in healthy male subjects

Rapport de synthèse : La consommation de boissons sucrées contenant du fructose a remarquablement augmenté ces dernières décennies et, on pense qu'elle joue un rôle important dans l'épidémie actuelle d'obésité et de troubles métaboliques. Des études faites sur des rats ont montré qu'une alimentation riche en sucre ou fructose induisait une obésité, une résistance à l'insuline, diabète, dyslipidémie et une hypertension artérielle, tandis que chez l'homme, une alimentation riche en fructose conduit, après quelques jours, au développement d'une hypertryglycémie et une résistance hépatique à l'insuline. Nous avons entrepris une étude de 7 jours d'alimentation riche en fructose ou d'une alimentation contrôlée chez six hommes en bonne santé. Les NEFA plasmatiques et la beta-hydroxybutyrate, l'oxydation nette de lipide (calorimétrie indirecte) et l'oxydation exogène de lipide (13 CO2) ont été surveillés dans des conditions basales, et après un chargement en lipide (huile d'olive marqué au 13C-trioléine), puis durant un stress mental standardisé. La clearance de lactate et les effets métaboliques de la perfusion de lactate exogène ont également été évalués. Nos résultats ont montré que l'alimentation riche en fructose diminue la concentration plasmatique de NEFA, de beta-hydroxybutyrate de même que l'oxydation des lipides dans les conditions de bases et après surcharge en lipides. De plus, l'alimentation riche en fructose amortie l'augmentation des NEFA plasmatique et l'oxydation des lipides exogènes durant le stress mental. Elle augmente également la concentration basale de lactate et la production de lactate de respectivement 31.8% et 53.8%, tandis que la clearance du lactate reste inchangée. L'injection de lactate diminue le taux des NEFA lors de l'alimentation de contrôle et l'alimentation de base, et l'oxydation nette de lipide lors de l'alimentation de contrôle et l'alimentation riche en fructose. Ces résultats indiquent que 7 jours d'alimentation riche en fructose inhibent remarquablement la lipolyse et l'oxydation des lipides. L'alimentation riche en fructose augmente aussi la production de lactate, et l'augmentation de l'utilisation de lactate peut contribuer à supprimer l'oxydation des lipides. Abstact : The effects of a 7 d high-fructose diet (HFrD) or control diet on lipid metabolism were studied in a group of six healthy lean males. Plasma NEFA and β-hydroxybutyrate concentrations, net lipid oxidation (indirect calorimetry) and exogenous lipid oxidation (13CO2 production) were monitored in basal conditions, after lipid loading (olive oil labelled with [13C] triolein) and during a standardised mental stress. Lactate clearance and the metabolic effects of an exogenous lactate infusion were also monitored. The HFrD lowered plasma concentrations of NEFA and (β-hydroxybutyrate as well as lipid oxidation in both basal and after lipid-loading conditions. In addition, the HFrD blunted the increase in plasma NEFA and exogenous lipid oxidation during mental stress. The HFrD also increased basal lactate concentrations by 31.8%, and lactate production by 53.8 %, while lactate clearance remained unchanged. Lactate infusion lowered plasma NEFA with the control diet, and net lipid oxidation with both the HFrD and control diet. These results indicate that a 7 d HFrD markedly inhibits lipolysis and lipid oxidation. The HFrD also increases lactate production, and the ensuing increased lactate utilisation may contribute to suppress lipid oxidation.

Covariation between plumage colour polymorphism and diet in the Barn Owl Tyto alba

Several hypotheses might explain the evolution and maintenance of colour morphs within animal populations. The 'alternative foraging strategy' hypothesis states that alternative colour morphs exploit different ecological niches. This hypothesis predicts that morphs differ in diet, either because foraging success on alternative prey species is morph-dependent or because differently coloured individuals exploit alternative habitats. I examined this prediction in the Barn Owl Tyto alba, a bird that varies in plumage coloration continuously from dark reddish-brown to white. On the European continent, Owls are light-coloured (subspecies T. a. alba) in the south and reddish-brown (T. a. guttata) in the north; in central Europe the two subspecies interbreed, generating many colour variants. If plumage coloration indicates alternative foraging strategies, in sympatry dark- and light-coloured owls should consume prey species that are typical of the diets of T. a. guttata and T. a. alba in allopatry, respectively. In line with this prediction, both in allopatry and in sympatry in Switzerland T. a. guttata fed primarily upon Common Voles Microtus arvalis and T. a. alba upon Wood Mice Apodemus spp. Statistical analyses suggest that morph-dependent diet did not arise from a non-random habitat distribution of owls with respect to plumage coloration. This suggests that foraging success upon alternative prey is morph-dependent.

Marijuana use, diet, body mass index, and cardiovascular risk factors (from the CARDIA study).

Marijuana use has been associated with increased appetite, high caloric diet, acute increase in blood pressure, and decreases in high-density lipoprotein cholesterol and triglycerides. Marijuana is the most commonly used illicit drug in the United States, but its long-term effects on body mass index (BMI) and cardiovascular risk factors are unknown. Using 15 years of longitudinal data from 3,617 black and white young adults participating in the Coronary Artery Risk Development in Young Adults (CARDIA) study, we assessed whether marijuana use was associated with caloric intake, BMI, and cardiovascular risk factors. Of the 3,617 participants, 1,365 (38%) reported ever using marijuana. Marijuana use was associated with male gender, tobacco smoking, and other illicit drug use. More extensive marijuana use was associated with a higher caloric intake (2,746 kcal/day in never users to 3,365 kcal/day in those who used marijuana for > or = 1,800 days over 15 years) and alcohol intake (3.6 to 10.8 drinks/week), systolic blood pressure (112.7 to 116.5 mm Hg), and triglyceride levels (84 to 100 mg/dl or 0.95 to 1.13 mmol/L, all p values for trend < 0.001), but not with higher BMI and lipid and glucose levels. In multivariate analysis, the associations between marijuana use and systolic blood pressure and triglycerides disappeared, having been mainly confounded by greater alcohol use in marijuana users. In conclusion, although marijuana use was not independently associated with cardiovascular risk factors, it was associated with other unhealthy behaviors, such as high caloric diet, tobacco smoking, and other illicit drug use, which all have long-term detrimental effects on health.

Partial gene deletion of endothelial nitric oxide synthase predisposes to exaggerated high-fat diet-induced insulin resistance and arterial hypertension.

Nitric oxide (NO) plays a major role in the regulation of cardiovascular and metabolic homeostasis, as evidenced by insulin resistance and arterial hypertension in endothelial NO synthase (eNOS) null mice. Extrapolation of these findings to humans is difficult, however, because eNOS gene deficiency has not been reported. eNOS gene polymorphism and impaired NO synthesis, however, have been reported in several cardiovascular disease states and could predispose to insulin resistance. High-fat diet induces insulin resistance and arterial hypertension in normal mice. To test whether partial eNOS deficiency facilitates the development of insulin resistance and arterial hypertension during metabolic stress, we examined effects of an 8-week high-fat diet on insulin sensitivity (euglycemic clamp) and arterial pressure in eNOS(+/-) mice. When fed a normal diet, these mice had normal insulin sensitivity and were normotensive. When fed a high-fat diet, however, eNOS(+/-) mice developed exaggerated arterial hypertension and had fasting hyperinsulinemia and a 35% lower insulin-stimulated glucose utilization than control mice. The partial deletion of the eNOS gene does not alter insulin sensitivity or blood pressure in mice. When challenged with nutritional stress, however, partial eNOS deficiency facilitates the development of insulin resistance and arterial hypertension, providing further evidence for the importance of this gene in linking metabolic and cardiovascular disease.

Diet-induced thermogenesis measured over a whole day in obese and nonobese women.

The overall thermogenic response to food intake measured over a whole day in 20 young nondiabetic obese women (body fat mean +/- SEM: 38.6 +/- 0.7%), was compared with that obtained in eight nonobese control women (body fat: 24.7 +/- 0.9%). The energy expenditure of the subjects was continuously measured over 24 h with a respiration chamber, and the spontaneous activity was assessed by a radar system. A new approach was used to obtain the integrated thermogenic response to the three meals ingested over the day (from 8:30 AM to 10:30 PM). This method allows to subtract the energy expended for physical activity from total energy expenditure and to calculate the integrated dietary-induced thermogenesis as the difference between the energy expended without physical activity and basal metabolic rate. The thermogenic response to the three meals (expressed in percentage of the total energy ingested) was found to be blunted in obese women (8.7 +/- 0.8%) as compared with that of controls (14.8 +/- 1.1%). There was an inverse correlation between the percentage body fat and the diet-induced thermogenesis (r = -0.61, p less than 0.001). In addition, the relative increase in diurnal urinary norepinephrine excretion was lower in obese than in the control subjects. It is concluded that a low overall thermogenic response to feeding may be a contributing factor for energy storage in some obese subjects; a blunted response of the sympathetic nervous system could explain this low thermogenic response.