Biomedical subjects

Annie Quignard-Boulangé

Publications and source records attributed to Annie Quignard-Boulangé.

7 recordsLinked to original sources

PubMed2006

Prevention of adipose tissue depletion during food deprivation in angiotensin type 2 receptor-deficient mice.

Angiotensin (Ang) II is produced locally in various tissues, but its role in the regulation of tissue metabolism is still unclear. Recent studies have revealed the role of type 2 Ang II receptor (AT2R) in the control of energy homeostasis and lipid metabolism. The contribution of the AT2R to adaptation to starvation was tested using AT2R-deficient (AT2R (y)(/-)) mice. Fasted AT2R (y)(/-) mice exhibited a lower loss of adipose tissue weight associated to a decreased free fatty acid (FFA) release from stored lipids than the controls. In vitro studies show that Ang II causes an AT1R-mediated antilipolytic effect in isolated adipocytes. AT1R expression is up-regulated by fasting in both genotypes, but the increase is more pronounced in AT2R (y/-) mice. In addition, the increased muscle beta-oxidation displayed in AT2R (y/-) mice on a fed state, persists after fasting compared with wild-type mice. In liver from fed mice, AT2R deficiency did not modify the expression of genes involved in fatty acid oxidation. However, in response to fasting, the large increase of the expression of this subset of genes exhibited by wild-type mice, was impaired in AT2R (y/-) mice. Taken together, decreased lipolytic capacity and increased muscle fatty acid oxidation participate in the decreased plasma FFA observed in fasted AT2R (y/-) mice and could account for the lower FFA metabolism in the liver. These data reveal an important physiological role of AT2R in metabolic adaptations to fasting.

Adipocytes↗

PubMed2006

Gender-related response of lipid metabolism to dietary fatty acids in the hamster.

Gender and dietary fatty acids are involved in the regulation of lipid metabolism, disturbances of which can lead to pathologies such as metabolic syndrome or CVD. Possible interactions between these factors were investigated in male and female hamsters fed diets rich in either saturated fatty acids ( "butter" diet) or in alpha-linolenic acid ( "linseed oil" diet). Gender effect predominated over the diet effect on cholesterol (CH) metabolism; compared to males, females exhibited lower concentrations of plasma total CH (-20 %, P<0.001), LDL-CH (-40 %, P<0.001) and HDL-CH (-16 %, P<0.001), together with higher LDL receptor (+40 %) and lower HDL receptor (-60 %) hepatic content. Triacylglycerol (TG) metabolism was affected by diet above all: compared to animals fed the "butter" diet, those fed the "linseed oil" diet exhibited lower plasma (-23 %, P=0.046) and liver TG (-20 %, P=0.026) concentration which may result from both an increased beta-oxidation (P<0.001), without any change in PPARalpha mRNA, and a decreased hepatic lipogenesis (P=0.023), without increased sterol response element binding protein 1c (SREBP1c) mRNA. The response to diet was much more pronounced in males than in females, without gender effect on the transcription level of PPARalpha and SREBP1c. Finally, the "linseed oil" diet decreased the insulin resistance index (-80 %, P<0.001) with a more marked effect in males, in relation to their higher hepatic PPARgamma expression (+90 %, P=0.012). In conclusion, in our model, the response of either TG or CH to dietary fatty acids is modulated differently by gender. The possible relevance of these interactions to dietary practice should be taken into account in man.

Adipose Tissue↗

PubMed2006

The natural concentration of the conjugated linoleic acid, cis-9,trans-11, in milk fat has antiatherogenic effects in hyperlipidemic hamsters.

Milk fat is usually considered to be proatherogenic, although its fatty acid composition can vary, due mainly to farming conditions. No study has evaluated whether such variation can modify the atherogenic properties of dairy fat. Aortic lipid deposition and related risk factors were examined in Syrian hamsters fed diets for 12 wk containing 200 g/kg of 2 commercial milk fats [high content of saturated fatty acids (HSF) and low content of saturated fatty acids (LSF)] contrasting, respectively, in total saturated fatty acids (72 vs. 67 g/100 g), 18:1, trans (4.24 vs. 7.26 g/100g), and conjugated linoleic acid (mainly cis-9,trans-11 or rumenic acid; 0.39 vs. 2.59 g/100 g). Hamsters fed the LSF-diet had 25% less aortic cholesteryl-ester deposition than those fed the HSF-diet; this was accompanied by an improved plasma cholesterol profile (lower LDL cholesterol and LDL:HDL cholesterol ratio), a lower local inflammatory status (aortic gene expression of cyclooxygenase-2), and lower aortic gene expression of vascular cell adhesion molecule-1 (all P < 0.05). Supplementation of the LSF-diet with rumenic acid (up to 9 g/kg) amplified the antiatherogenic effect of the original LSF-diet compared with the HSF-diet, i.e., less aortic cholesterol loading, increased reverse cholesterol transport potential (higher plasma HDL cholesterol concentration and ATP-binding cassette, subfamily A, transporter 1 gene expression in aorta), and decreased LDL-peroxidability index and gene expression of proinflammatory IL-1beta in the aorta (all P < 0.05). In conclusion, our results suggest that the atherogenic potential of milk fat can be greatly reduced in products with a naturally high abundance of rumenic acid, and argue for increasing this fatty acid in milk.

Adipose Tissue↗

PubMed2005

A cis-9,trans-11-conjugated linoleic acid-rich oil reduces the outcome of atherogenic process in hyperlipidemic hamster.

Conjugated linoleic acid (CLA) mixtures demonstrated antiatherogenic properties in several animal models, including hamsters, but the mechanism of action of the main food-derived CLA isomer is unknown in this species. This study thus focused on cis-9,trans-11-CLA (rumenic acid), and its effect was compared with that of fish oil, which is known to influence several aspects of atherogenesis. Syrian hamsters were fed (for 12 wk) diets containing 20% (wt/wt) butter fat (B diet) or the same diet augmented with either 1% (wt/wt) of a cis-9,trans-11-CLA-rich oil (BR diet) or 1% (wt/wt) fish oil (BF diet). The BR diet induced the lowest aortic lipid deposition (from -30% to -45%) among the butter oil-fed hamsters. In this group, plasma also displayed a reduced non-HDL-to-HDL-cholesterol ratio (21% less than in the butter oil group) and inflammatory serum amyloid A levels (70-80%) and an improvement of anti-oxidized LDL paraoxonase activity (all P < 0.05). Compared with the B group, the beneficial effects of the BR diet could be further explained in part by preventing the high VCAM-1 expression rate, increasing (30%) ATP-binding cassette subfamily A1 expression in the aorta, and downregulating expression of inflammatory-related genes (TNF-alpha, IL-1beta, and cyclooxygenase 2, 2- to 2.8-fold, P < 0.05). This effect was partly associated with an activation of peroxisome proliferator-activating receptor (PPAR)/liver X receptor (LXR)-alpha signaling cascade. Interestingly, activation of PPAR/LXR-alpha signaling was not observed in hamsters fed the BF diet, in which the early signs of atherogenesis were increased. In conclusion, this study demonstrated that milk fat-rich cis-9,trans-11-CLA reduces the atherogenic process in hyperlipidemic hamsters.

Animals↗

PubMed2004

Adipose angiotensinogen secretion, blood pressure, and AGT M235T polymorphism in obese patients.

OBJECTIVE: To investigate AGT secretion in cultured adipocytes from obese patients and its relationship with obesity-related phenotypes, blood pressure, and the M235T polymorphism in the AGT gene. RESEARCH METHODS AND PROCEDURES: Measurements, including anthropometry, body composition (DXA), and blood pressure, were performed in 61 overweight or obese women (BMI: 28 to 68 kg/m(2)). A subcutaneous abdominal adipose tissue biopsy was used for adipocyte size determination and quantification of AGT secretion in the medium of cultured adipocytes. AGT M235T genotype was determined using polymerase chain reaction-restriction fragment length polymorphism. RESULTS: Adipose secretion of the AGT protein (range, 140 to 2575 ng/10(6) cells/24 h) was not significantly correlated with BMI, body fat, or blood pressure and did not vary according to the M235T polymorphism in the AGT gene. However, the AGT M235T polymorphism was associated with adipocyte size (111.6 +/- 2.8, 108.8 +/- 1.9, 118.2 +/- 2.6 micro m in MM, MT, and TT genotypes, respectively; p < 0.01) after adjustment for age and fat mass. An association between the AGT M235T polymorphism and adipocyte size (p < 0.02 adjusted for sex, age, and BMI) was found in another independent sample of 106 obese subjects (sex ratio, M/F 16/90; BMI, 29 to 70 kg/m(2)). DISCUSSION: In cultured adipocytes from obese subjects, AGT secretion was not associated with body fat phenotypes, blood pressure, or fat cell size. However, results from two independent studies suggest an association between the AGT M235T polymorphism and adipocyte size.

Abdomen↗

PubMed2003

Dietary fish oil increases lipid mobilization but does not decrease lipid storage-related enzyme activities in adipose tissue of insulin-resistant, sucrose-fed rats.

Fish oil feeding has been shown to limit visceral fat accumulation in insulin-resistant rats. Our goal was to determine whether this finding is due to increased fat mobilization or decreased lipid storage. Adipocytes were isolated from rats fed for 3 wk a diet containing 57.5 g/100 g sucrose and 14 g/100 g lipids as either fish oil (SF) or a mixture of standard oils (SC); there was also a reference group (R). Substituting fish oil for standard oils protected rats from visceral fat hypertrophy, hypertriglyceridemia and hyperglycemia. The stimulation of lipolysis was greater in adipocytes isolated from SF-fed rats than in those from SC-fed rats. Fatty acid synthase (FAS) activity was markedly lower in the liver but not in the adipose tissues of rats fed SF. Lipoprotein lipase (LPL) activity was 2.2-fold higher in the adipose tissues but not in the muscle in rats fed the SF diet than in those fed the SC diet. The decrease in visceral fat in rats fed fish oil could be attributed to decreased plasma triacylglycerol concentration and/or increased lipid mobilization rather than to reduced lipid storage.

Adipose Tissue↗

PubMed2002

Adipose tissue-specific increase in angiotensinogen expression and secretion in the obese (fa/fa) Zucker rat.

We investigated angiotensinogen (AGT) expression in adipose tissue and liver of Zucker rats during the onset of obesity. The developmental pattern of AGT expression (protein and mRNA) in liver was similar in both genotypes. In inguinal adipose tissue, AGT cell content was similar in suckling and weaned pups in lean rats, whereas it continuously increased with age in obese rats. AGT amount in adipocytes was unaffected by the genotype until weaning. Thereafter, adipocytes from obese rats displayed a significant increase in AGT content that was strengthened with age. Compared with the cell content, the amount of secreted AGT over 24 h was higher, and a genotype effect was observed as early as 14 days of age. Using fat cell populations differing by size, we showed that this AGT oversecretion was not solely related to adipocyte hypertrophy. Our results demonstrate that the fa genotype exerts a control on the production of AGT in a tissue-specific manner, suggesting a local role of AGT in the overdevelopment of adipose tissue.

Adipocytes↗