Age-related autocrine diabetogenic effects of transgenic resistin in spontaneously hypertensive rats: gene expression profile analysis.

Increased circulating levels of resistin have been proposed as a possible link between obesity and insulin resistance; however, many of the potential metabolic effects of resistin remain to be investigated, including systemic versus local resistin action. We investigated potential autocrine effects of resistin on lipid and glucose metabolism in 2- and 16-mo-old transgenic spontaneously hypertensive rats (SHR) expressing a nonsecreted form of mouse resistin under control of the aP2 promoter. To search for possible molecular mechanisms, we compared gene expression profiles in adipose tissue in 6-wk-old transgenic SHR versus control rats, before development of insulin resistance, by digital transcriptional profiling using high-throughput sequencing. Both young and old transgenic rats showed moderate expression of the resistin transgene in adipose tissue but had serum resistin levels similar to control SHR and undetectable levels of transgenic resistin in the circulation. Young transgenic rats exhibited mild glucose intolerance. In contrast, older transgenic rats displayed marked glucose intolerance in association with near total resistance of adipose tissue to insulin-stimulated glucose incorporation into lipids (6 ± 2 vs. 77 ± 19 nmol glucose·g(-1)·2 h(-1), P < 0.00001). Ingenuity Pathway Analysis of differentially expressed genes revealed calcium signaling, Nuclear factor-erythroid 2-related factor-2 (NRF2)-mediated oxidative stress response, and actin cytoskeletal signaling canonical pathways as those most significantly affected. Analysis using DAVID software revealed oxidative phosphorylation, glutathione metabolism, pyruvate metabolism, and peroxisome proliferator-activated receptor (PPAR) signaling as top Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. These results suggest that with increasing age autocrine effects of resistin in fat tissue may predispose to diabetes in part by impairing insulin action in adipose tissue.

Microdispersed Oxidized Cellulose as a novel potential substance with hypolipidemic properties.

OBJECTIVE: The aim of this study was to determine whether Microdispersed Oxidized Cellulose (MDOC) possesses a hypolipidemic effect in apolipoprotein-E/low-density lipoprotein receptor double-knockout (ApoE/LDLR-deficient) mice and the possible mechanism of this effect in mice. METHODS: Female ApoE/LDLR-deficient mice subdivided into two groups were fed with a Western-type diet for 8 wk, and the experimental group was supplemented with 5% MDOC for 8 wk. Female C57BL/6J mice were fed an atherogenic diet containing 5% MDOC or pectin for the determination of a possible hypolipidemic mechanism of MDOC action. RESULTS: Biochemical analysis showed that 5% MDOC treatment significantly decreased total cholesterol by 20% (P = 0.0338) and very-LDL cholesterol by 21% (P = 0.0110) and significantly increased the level of high-density lipoprotein cholesterol by 62% (P = 0.0172) when compared with non-treated ApoE/LDLR-deficient mice. The results Association of Official Analytical Chemists method 991.43 revealed that MDOC contains 59.78 +/- 5.0% of fiber. Furthermore, it was demonstrated that administration of MDOC did not affect cholesterol absorption in the small intestine. Using C57BL/6J mice, MDOC and pectin treatments decreased cholesterol content in liver and increased fermentation in the gut in vivo. In vitro experiments confirmed that MDOC is fermentable under conditions mimicking those in the large intestine. CONCLUSION: We demonstrated hypolipidemic effects of MDOC in ApoE/LDLR-deficient mice. Moreover, we propose that MDOC is a hypolipidemic soluble fiber acting probably by increased fermentation and production of short-chain fatty acids in the large intestine in mice. We propose that MDOC might be a possible source of soluble fiber for use in dietary supplements.

Identification of renal Cd36 as a determinant of blood pressure and risk for hypertension.

To identify renally expressed genes that influence risk for hypertension, we integrated expression quantitative trait locus (QTL) analysis of the kidney with genome-wide correlation analysis of renal expression profiles and blood pressure in recombinant inbred strains derived from the spontaneously hypertensive rat (SHR). This strategy, together with renal transplantation studies in SHR progenitor, transgenic and congenic strains, identified deficient renal expression of Cd36 encoding fatty acid translocase as a genetically determined risk factor for spontaneous hypertension.