Contenido de vitamina A en dieta de cafetería y expresion de receptores nucleares en tejido adiposo de rata

Abstract

The aim of this study was to determine the effects of cafeteria diet containing control or elevated level of vitamin A on the expression of nuclear receptors in adipose tissue. Male Wistar rats were submitted to 3 experimental diets during 8 weeks, a standard diet and two hyper-energetic, hyperlipidic "cafeteria" diets containing normal (Caf) or higher (Caf+) vitamin A level. During the experiment, body weights and energy intakes were measured. At the end of the experimental period, subcutaneous adipose tissue (Swat) and all the fat mass were removed and weighted. Nuclear receptors mRNA levels of RARalpha, RARgamma, RXRalpha, PPARgamma were measured in the Swat by a real-time semi-quantitative RT-PCR method. We observed that energy intake of Caf+ and Caf groups was significantly higher than that of the control group. Despite a higher increase of the energy intake in the Caf group compared to the Caf+ group, no significant difference was observed in the body weight gain of the Caf+ compared to the Caf group. The Caf+ and Caf diets led to a significant increase of adipose tissue in cafeteria groups as observed in the Swat depot. The mRNA levels of PPARgamma and RXRalpha were significantly increased in the Caf+ group as compared to control group, with a significant positive correlation between these two parameters. Expressions of RARalpha and RARgamma were not modified in experimental groups compared to controls. In conclusion, 8-week exposure to cafeteria diets with normal and higher levels of vitamin A led to an increase of adiposity in rats, associated, only in the group fed with the higher vitamin A level cafeteria diet, with an increase of PPARgamma and RXRalpha expressions in subcutaneous adipose tissue.

Down-regulation in muscle and liver lipogenic genes: EPA ethyl ester treatment in lean and overweight (high-fat-fed) rats

“…For this purpose, the aim of the present study was to determine the mechanisms through which EPA ethyl ester improves lipid metabolism in an experimental animal model of obesity induced by high-fat (cafeteria) diet. As previously reported by our group and others [4,27,36,37], this is an accepted model of diet-induced obesity that shares common features with Western diet and drives towards metabolic syndrome conditions. The dose of EPA ethyl ester used in the present study has been previously reported to have beneficial metabolic actions in rodents.…”

Vitamin A and lipid metabolism: relationship between hepatic stellate cells (HSCs) and adipocytes

“…WAT is able to store as much as 20% of the whole body reserve of vitamin A, under retinol ester forms. After its incorporation into WAT, retinyl esters could be transformed into retinoic acid and act on adipose tissue gene expression [4,50], suggesting that WAT possesses all the equipment necessary for vitamin A metabolism (see Table 1), as it has been previously demonstrated for HSCs. This signaling pathway in WAT suggests that vitamin A could directly affect the regulation of energy balance by the control of the fat mass [10,66].…”

Papel de genes adipogénicos y termogénicos en la resistencia o susceptibilidad al desarrollo de obesidad inducida por la dieta en rata

“…Whereas PPARγ is expressed in small amounts in preadipocytes, its synthesis increased during the process of adipogenesis (9). Furthermore, it is well known that retinoids could be involved in the control of adiposity through the activation of retinoid acid receptors (RARs) and retinoid X receptors (RXRs) (2,20), being RARγ and RXRα specifical isoforms of WAT (2,30). Besides, these nuclear receptors had a close relationship with PPARγ: whereas the RARγ/RXRα heterodimer formation leads to recruitment of adipogenesis co-repressors, the creation of coactivators are related with PPARγ/RXRα heterodimer development, which is ultimately translated into an alteration of the activity of the gene from repressed to activated (5).…”

“…Previous to the RT-PCR determination, the RNA quality was estimated by the bioanalyzer Agilent 2100, using the kit RNA 6000 Nano assay (Agilent technologies). All procedures were performed as described by REDONNET et al (31) and BAIRRAS et al (2). β2-microglobulin was used as housekeeping gene.…”