Resistance training may concomitantly benefit body composition, blood pressure and muscle MMP-2 activity on the left ventricle of high-fat fed diet rats

OBJECTIVE

The purpose of this study was to evaluate the effect of resistance training (RT) on body composition, systolic and diastolic blood pressures (BP), and activity of muscle MMP-2 in the left ventricle of high-fat fed rats.

MATERIALS/METHODS

We have evaluated 32 male Wistar rats divided into four experimental groups (n=8/each) according to diet and exercise status: sedentary (SED; standard diet), sedentary obese (SED-OB; diet: 30% of fat), RT (RT; standard diet) and RT obese (RT-OB; diet: 30% of fat). After weaning (day 21), animals were subjected to the experimental diet according to their groups during 24 weeks. A 12-week strength-training period was used, during which the rats climbed a 1.1-m vertical ladder with weights attached to their tails. Sessions were performed three times/week (Mondays, Wednesdays and Fridays), with 4-9 climbs/session and 8-12 dynamic movements/climb.

RESULTS

RT induced higher muscle MMP-2 activity in the left ventricle in RT and RT-OB groups. Moreover, this study demonstrated that RT promoted lower body and fat masses, fat percentage, systolic and diastolic BPs and higher fat free mass in both trained groups.

CONCLUSION

RT increased muscle MMP-2 activity in the left ventricle, induced positive changes on body composition and lowered BPs in high-fat diet fed rats, suggesting that it may be a useful tool to prevent alterations induced by high-fat diet consumption.

Exercise does not counteract the effects of a "westernized" diet on prostate cancer xenografts

BACKGROUND

The relationships between diet, exercise, and prostate cancer (PCa) remain unclear. We have previously reported that a "Western" diet promotes PCa tumor growth in vivo. Presently, we report the effects of sustained aerobic exercise on PCa progression in animals fed a high-fat diet versus a standard diet.

METHODS

Athymic mice (n = 43) were inoculated subcutaneously with human PCa (LNCaP) cells, fed ad libitum with either a high-fat or a standard diet, and randomized into forced exercising and non-exercising groups. Body weight, tumor volume, and food consumption were recorded tri-weekly. Terminal serum samples and tumor biopsies were obtained for analysis.

RESULTS

Body weight differences were not observed between the groups over time. The high-fat diet with exercise (HF-Ex) group showed significantly increased tumor growth rate compared to all other groups (P < 0.0007). Tumor growth rate of the standard diet with exercise (Std-Ex) group was reduced significantly compared to the high-fat diet without exercise (HF-No Ex) group (P = 0.0008). Significant differences (P ≤ 0.012) were observed in energy consumption (kcal) between the groups over time. Exercising mice consumed significantly more kcal than non-exercising mice, and the HF-Ex group consumed significantly more than each of the other three groups (P < 0.0007). The expression levels of p27 and p21 were increased in exercising animals, while AR expression was elevated in the HF-Ex group versus the Std-Ex and HF-No Ex groups.

CONCLUSIONS

Sustained aerobic exercise did not counteract the tumor-promotional effect of increased consumption of a high-fat diet, suggesting that diet is more influential in PCa progression than exercise. Combining exercise with a healthy diet reduced the rate of PCa progression in this model. This study may have implications for PCa risk reduction in humans.

High beta-palmitate fat controls the intestinal inflammatory response and limits intestinal damage in mucin Muc2 deficient mice

BACKGROUND

Palmitic-acid esterified to the sn-1,3 positions of the glycerol backbone (alpha, alpha'-palmitate), the predominant palmitate conformation in regular infant formula fat, is poorly absorbed and might cause abdominal discomfort. In contrast, palmitic-acid esterified to the sn-2 position (beta-palmitate), the main palmitate conformation in human milk fat, is well absorbed. The aim of the present study was to examine the influence of high alpha, alpha'-palmitate fat (HAPF) diet and high beta-palmitate fat (HBPF) diet on colitis development in Muc2 deficient (Muc2(-/-)) mice, a well-described animal model for spontaneous enterocolitis due to the lack of a protective mucus layer.

METHODS

Muc2(-/-) mice received AIN-93G reference diet, HAPF diet or HBPF diet for 5 weeks after weaning. Clinical symptoms, intestinal morphology and inflammation in the distal colon were analyzed.

RESULTS

Both HBPF diet and AIN-93G diet limited the extent of intestinal erosions and morphological damage in Muc2(-/-) mice compared with HAPF diet. In addition, the immunosuppressive regulatory T (Treg) cell response as demonstrated by the up-regulation of Foxp3, Tgfb1 and Ebi3 gene expression levels was enhanced by HBPF diet compared with AIN-93G and HAPF diets. HBPF diet also increased the gene expression of Pparg and enzymatic antioxidants (Sod1, Sod3 and Gpx1), genes all reported to be involved in promoting an immunosuppressive Treg cell response and to protect against colitis.

CONCLUSIONS

This study shows for the first time that HBPF diet limits the intestinal mucosal damage and controls the inflammatory response in Muc2(-/-) mice by inducing an immunosuppressive Treg cell response.

Vascular and inflammatory high fat meal responses in young healthy men; a discriminative role of IL-8 observed in a randomized trial

Background

High fat meal challenges are known to induce postprandial low-grade inflammation and endothelial dysfunction. This assumption is largely based on studies performed in older populations or in populations with a progressed disease state and an appropriate control meal is often lacking. Young healthy individuals might be more resilient to such challenges. We therefore aimed to characterize the vascular and inflammatory response after a high fat meal in young healthy individuals.

Methods

In a double-blind randomized cross-over intervention study, we used a comprehensive phenotyping approach to determine the vascular and inflammatory response after consumption of a high fat shake and after an average breakfast shake in 20 young healthy subjects. Both interventions were performed three times.

Results

Many features of the vascular postprandial response, such as FMD, arterial stiffness and micro-vascular skin blood flow were not different between shakes. High fat/high energy shake consumption was associated with a more pronounced increase in blood pressure, heart rate, plasma concentrations of IL-8 and PBMCs gene expression of IL-8 and CD54 (ICAM-1), whereas plasma concentrations of sVCAM1 were decreased compared to an average breakfast.

Conclusion

Whereas no difference in postprandial response were observed on classical markers of endothelial function, we did observe differences between consumption of a HF/HE and an average breakfast meal on blood pressure and IL-8 in young healthy volunteers. IL-8 might play an important role in dealing with high fat challenges and might be an early marker for endothelial stress, a stage preceding endothelial dysfunction.

Trial Registration

ClinicalTrials.gov NCT00766623

Leptin overexpression in VTA trans-activates the hypothalamus whereas prolonged leptin action in either region cross-desensitizes

High-fat feeding or CNS leptin overexpression in chow-fed rats results in a region-specific cellular leptin resistance in medial basal hypothalamic regions and the ventral tegmental area (VTA). The present investigation examined the effects of targeted chronic leptin overexpression in the VTA as compared with the medial basal hypothalamus on long-term body weight homeostasis. The study also examined if this targeted intervention conserves regional leptin sensitivity or results in localized leptin resistance. Cellular leptin resistance was assessed by leptin-stimulated phosphorylation of signal transducers and activators of transcription 3 (STAT3). Tyrosine hydroxylase was measured in hypothalamus and VTA along with brown adipose tissue uncoupling protein 1. Leptin overexpression in VTA tempered HF-induced obesity, but to a slightly lesser extent than that with leptin overexpression in the hypothalamus. Moreover, the overexpression of leptin in the VTA stimulated cellular STAT3 phosphorylation in several regions of the medial basal hypothalamus, whereas verexpression in the hypothalamus did not activate STAT3 signaling in the VTA. This unidirectional trans-stimulation did not appear to involve migration of either the vector or the gene product. Long-term leptin overexpression in either the medial basal hypothalamus or VTA caused desensitization of leptin signaling in the treated region and cross-desensitization of leptin signaling in the untreated region. These results demonstrate a role of leptin receptors in the VTA in long-term body weight regulation, but the trans-activation of the hypothalamus following VTA leptin stimulation suggests that an integrative response involving both brain regions may account for the observed physiological outcomes.

Alternate day fasting (ADF) with a high-fat diet produces similar weight loss and cardio-protection as ADF with a low-fat diet

Alternate day fasting (ADF) with a low-fat (LF) diet is effective for weight loss and cardio-protection. However, the applicability of these findings is questionable as the majority of Americans consume a high-fat (HF) diet.

OBJECTIVE

The goal of this study was to determine if these beneficial changes in body weight and coronary heart disease (CHD) risk can be reproduced if an HF background diet is used in place of an LF diet during ADF.

METHODS

Thirty-two obese subjects were randomized to an ADF-HF (45% fat) or ADF-LF diet (25% fat), which consisted of two phases: 1) a 2-week baseline weight maintenance period, and 2) an 8-week ADF weight loss period. All food was provided during the study.

RESULTS

Body weight was reduced (P<0.0001) by ADF-HF (4.8%±1.1%) and by ADF-LF (4.2%±0.8%). Fat mass decreased (P<0.0001) by ADF-HF (5.4±1.5 kg) and ADF-LF (4.2±0.6 kg). Fat free mass remained unchanged. Waist circumference decreased (P<0.001) by ADF-HF (7.2±1.5 cm) and ADF-LF (7.3±0.9 cm). LDL cholesterol and triacylglycerol concentrations were reduced (P<0.001) by both interventions (ADF-HF: 18.3%±4.6%, 13.7%±4.8%; and ADF-LF: 24.8%±2.6%, 14.3%±4.4%). HDL cholesterol, blood pressure, and heart rate remained unchanged. There were no between-group differences for any parameter.

CONCLUSION

These findings suggest that an ADF-HF diet is equally as effective as an ADF-LF diet in helping obese subjects lose weight and improve CHD risk factors.

Lipidomic profiling of chylomicron triacylglycerols in response to high fat meals

Using lipidomic methodologies the impact that meal lipid composition and metabolic syndrome (MetS) exerts on the postprandial chylomicron triacylglycerol (TAG) response was examined. Males (9 control; 11 MetS) participated in a randomised crossover trial ingesting two high fat breakfast meals composed of either dairy-based foods or vegetable oil-based foods. The postprandial lipidomic molecular composition of the TAG in the chylomicron-rich (CM) fraction was analysed with tandem mass spectrometry coupled with liquid chromatography to profile CM TAG species and targeted TAG regioisomers. Postprandial CM TAG concentrations were significantly lower after the dairy-based foods compared with the vegetable oil-based foods for both control and MetS subjects. The CM TAG response to the ingested meals involved both significant and differential depletion of TAG species containing shorter- and medium-chain fatty acids (FA) and enrichment of TAG molecular species containing C16 and C18 saturated, monounsaturated and diunsaturated FA. Furthermore, there were significant changes in the TAG species between the food TAG and CM TAG and between the 3- and 5-h postprandial samples for the CM TAG regioisomers. Unexpectedly, the postprandial CM TAG concentration and CM TAG lipidomic responses did not differ between the control and MetS subjects. Lipidomic analysing of CM TAG molecular species revealed dynamic changes in the molecular species of CM TAG during the postprandial phase suggesting either preferential CM TAG species formation and/or clearance.

RAGE influences obesity in mice. Effects of the presence of RAGE on weight gain, AGE accumulation, and insulin levels in mice on a high fat diet

BACKGROUND

The metabolic syndrome is defined by the presence of obesity, insulin resistance, dyslipidemia, and hypertension. Advanced glycation end products (AGEs) are stable end products of the Maillard reaction, whereby AGE accumulation is considered not only a biomarker of aging but is also associated with several degenerative diseases. AGEs are recognized by several receptor molecules of which the receptor of AGEs (RAGE) is currently the most intensively studied receptor. Activation of RAGE causes an unfavorable proinflammatory state and deletion of RAGE in diabetic animals has been reported to protect against atherosclerosis. AGEs and a high fat diet are associated with cardiovascular diseases, whereas is still not clear whether a direct link between high fat nutrition and AGEs exists in vivo.

MATERIALS AND METHODS

C57BL/6 and C57BL/6 RAGE -/- mice were fed a high fat diet to induce obesity. Weight, insulin, lipid levels, AGE modifications, and cardiac gene expression were analyzed.

RESULTS

The absence of RAGE resulted in accelerated weight gain, increased plasma cholesterol, and higher insulin levels in obese mice. The hearts of normal and obese RAGE -/- mice contained lower levels of the AGE arginine-pyrimidine and 3DG-imidazolone than RAGE + / + animals. RAGE -/- mice also exhibited lower expression of the genes encoding the antioxidative enzymes MnSOD, Cu/ZnSOD, and ceruloplasmin in cardiac tissue, whereas the AGE receptors AGER-1, -2, and -3 were equally expressed in both genotypes. Obese mice of both strains expressed increased amounts of AGER-2. Only obese RAGE + / + mice exhibited a reduced mRNA accumulation of Cu/Zn SOD.

CONCLUSION

These data suggest that RAGE is involved in the development of obesity and insulin resistance.

Stimulation of accumbens shell cannabinoid CB(1) receptors by noladin ether, a putative endocannabinoid, modulates food intake and dietary selection in rats

Stimulation of cannabinoid CB(1) receptors in nucleus accumbens shell has been shown to stimulate feeding and enhance positive 'liking' reactions to intraoral sucrose. This study examined the behavioural effects of noladin ether and 2-arachidonoylglycerol following infusion into accumbens shell, on chow intake and food preference in high-carbohydrate and high-fat preferring rats. Noladin ether, potently and dose-dependently stimulated chow intake as compared with 2-arachidonoylglycerol in free-feeding rats. In the diet preference paradigm, in which rats were given free access to both, high-carbohydrate (HC) and high-fat (HF) diets simultaneously, an intra-accumbens administration of noladin ether as well as 2-arachidonoylglycerol, preferentially enhanced fat consumption over carbohydrate in both HF- and HC-preferring rats. These effects were significantly attenuated by the CB(1) receptor antagonist, AM 251. These results suggesting that, the endocannabinoids through CB(1) receptors, affects appetite for specific dietary components. Both these agents exert a specific action on eating motivation and possibly promoting eating by enhancing the incentive value of food. Altogether these findings reinforce the idea that the endogenous cannabinoid system in the accumbens shell may be important to augment reward-driven feeding via modulation of CB(1) receptor signalling pathways.

Stearoyl-CoA Desaturase 1 (SCD1) is a key factor mediating diabetes in MyD88-deficient mice

Saturated fatty acids, acting as ligands for toll-like receptor 4 (TLR4), induce inflammation and mediate the development of insulin resistance. Myeloid differentiation factor 88 (MyD88) is an adaptor protein for TLR4. Previously, we found MyD88-deficient mice fed a high-fat diet (HFD) exhibited a severe diabetic phenotype. Stearoyl-CoA Desaturase 1 (SCD1) is the rate-limiting enzyme in the biosynthesis of monounsaturated fatty acids and known as a risk factor of diabetes. In the present study, we found SCD1 was dramatically increased in HFD-fed MyD88-deficient mice liver. This finding showed the novel linkage between MyD88 and SCD1 in the development of diabetes mellitus.

Maternal high-fat diet programs for metabolic disturbances in offspring despite leptin sensitivity

A fatty diet during pregnancy in mouse dams causes metabolic abnormalities (similar to metabolic syndrome in humans) in the rodents' offspring. We tested the hypothesis that the offspring of dams fed a high-fat diet during pregnancy and lactation develop metabolic abnormalities and leptin resistance. Pregnant C57BL/6 mice (n = 20) were fed either standard chow (SC; 19% fat) or a high-fat diet (HF; 49% fat). After weaning, male offspring were divided into four groups, according to the diet of dams and offspring: SC(dams)/SC(offspring), SC/HF, HF/SC and HF/HF (n = 30/group). For a metabolic analysis, we evaluated body mass, fat mass depots, blood plasma and adipocyte structure at 12 weeks of age. To analyse leptin sensitivity, each group was divided into two groups (vehicle or leptin) to identify the feeding response and pSTAT3 expression after acute intracerebroventricular (ICV) treatment. The offspring of mothers fed a high-fat diet presented increased body mass and visceral fat, adipocyte hypertrophy and insulin resistance. This phenotype was not associated with central leptin resistance. Thus, maternal programming by HF predisposes offspring to metabolic abnormalities despite leptin sensitivity.

Expression and nutritional regulation of the (pro)renin receptor in rat visceral adipose tissue

BACKGROUND

Early life nutritional environment plays an important role in the development of visceral adipose tissue and interacts with nutritional regulations in adulthood, leading to metabolic dysregulations.

AIM

We hypothesized that the renin-angiotensin system may play a role in the programming-induced development of visceral adipose tissue.

MATERIAL AND METHODS

We studied, using a model of programming of overweight and glucose intolerance, obtained by post-natal overfeeding with consecutive highfat diet, the status of plasma renin activity and mesenteric adipose renin-angiotensin system, including the recently identified (pro)renin receptor, in adult rats.

RESULTS

Post-natal overfeeding or high-fat feeding lead to overweight with increased visceral fat mass and adipocytes surface. When both paradigms were associated, adipocytes surface showed a disproportionate increase. A strong immunoreactivity for (pro)renin receptor was found in stromal cells. Plasma renin activity increased in programmed animals whereas (pro)renin receptor expressing cells density was stimulated by high-fat diet. There was a positive, linear relationship between plasma renin activity and (pro)renin receptor expressing cells density and adipocytes surface.

CONCLUSIONS

Our experiments demonstrate that association of post-natal overfeeding and high-fat diet increased plasma renin activity and adipose (pro)renin receptor expression. Such phenomenon could explain, at least in part, the associated disproportionate adipocyte hypertrophy and its accompanying increased glucose intolerance.