It has been suggested that a low grade inflammatory state could predispose for developing insulin resistance and contribute to the development of obesity and type 2 diabetes. Corticosteroid-binding globulin (CBG), the main plasma protein transport for cortisol, has been shown to be negatively regulated by insulin and IL-6, at least in vitro, suggesting that insulin resistance and inflammation may both contribute to decreasing CBG levels. In the present study we measured CBG concentrations in a human healthy population and investigated the relationships of CBG with anthropometric and biochemical markers for inflammation and/or insulin resistance. The data showed that the mean serum CBG level was significantly lower in males (n = 151) than in females (n = 113; 32.5 +/- 9.1 vs. 39.2 +/- 13.9 mg/liter; P < 0.0001). In both sexes serum CBG levels were correlated negatively with age (r = -0.12; P = 0.04), body mass index (r = -0.31; P < 0.0001), waist to hip ratio (WHR; r = -0.39; P < 0.0001), systolic (r = -0.15; P < 0.01) and diastolic (r = -0.15; P = 0.01) blood pressures, and HOMA, an index of insulin resistance (r = -0.12; P = 0.04). In addition, the CBG concentration was negatively associated with serum IL-6 concentrations (r = -0.23; P = 0.017) and with the soluble fraction of TNFalpha receptors, soluble TNF receptor 1 (sTNFR1; r = -0.35; P < 0.0001), and sTNFR2 (r = -0.56; P < 0.0001) in women. A stepwise regression analysis using CBG as an independent variable showed that sex (P < 0.00001), body mass index (P = 0.0002), and HOMA (P = 0.0005), but not systolic blood pressure, diastolic blood pressure, IL-6, sTNFR1, or sTNFR2, constituted significant independent factors that explained 21% of the CBG variance (14%, 2%, and 5%, respectively). In a subsample of 120 men and 68 women, fasting serum free cortisol (calculated as the ratio fasting cortisol/CBG) was significantly associated with WHR (r = 0.24; P = 0.001), systolic (r = 0.18; P = 0.01) and diastolic (r = 0.19; P = 0.007) blood pressures, and HOMA value (r = 0.20; P = 0.005), but not with BMI or age. BMI (P < 0.0001), free cortisol (P = 0.003), and CBG (P = 0.009), but not WHR and age, contributed to 20%, 6%, and 8%, respectively, of HOMA variance in women in a multiple regression analysis. In this model only BMI (P < 0.0001) independently contributed to HOMA variance in men. These findings support the hypothesis that the CBG level is an interesting indicator for both insulin resistance and low grade inflammation. Whether the decrease in CBG levels is genetic by nature or directly associated to increased insulin and/or IL-6 merits further investigation. Nevertheless, because CBG has been shown to be expressed by the adipose tissue, decreased CBG could create locally increased cortisol disposal, with no change in circulating cortisol, and facilitate fat accumulation, insulin resistance, and type 2 diabetes.

Background: Current methodology of gene expression analysis limits the possibilities of comparison between cells/tissues of organs in which cell size and/or number changes as a consequence of the study (e.g. starvation). A method relating the abundance of specific mRNA copies per cell may allow direct comparison or different organs and/or changing physiological conditions. Methods: With a number of selected genes, we analysed the relationship of the number of bases and the fluorescence recorded at a present level using cDNA standards. A lineal relationship was found between the final number of bases and the length of the transcript. The constants of this equation and those of the relationship between fluorescence and number of bases in cDNA were determined and a general equation linking the length of the transcript and the initial number of copies of mRNA was deduced for a given pre-established fluorescence setting. This allowed the calculation of the concentration of the corresponding mRNAs per g of tissue. The inclusion of tissue RNA and the DNA content per cell, allowed the calculation of the mRNA copies per cell. Results: The application of this procedure to six genes: Arbp, cyclophilin, ChREBP, T4 deiodinase 2, acetyl-CoA carboxylase 1 and IRS-1, in liver and retroperitoneal adipose tissue of food-restricted rats allowed precise measures of their changes irrespective of the shrinking of the tissue, the loss of cells or changes in cell size, factors that deeply complicate the comparison between changing tissue conditions. The percentage results obtained with the present methods were essentially the same obtained with the delta-delta procedure and with individual cDNA standard curve quantitative RT-PCR estimation. Conclusion: The method presented allows the comparison (i.e. as copies of mRNA per cell) between different genes and tissues, establishing the degree of abundance of the different molecular species tested.

Oleoyl-estrone given i.v. – incorporated in liposomes to mimic lipoprotein delivery – (Merlin-2) to normal weight rats, induces a dose-dependent weight loss. Analysis of body composition showed that body protein concentration was preserved and fat stores wasted. The respiratory quotient was consistent with the massive oxidation of body fat, since the diet contained practically no lipid. Appetite was affected by Merlin-2, and thus food intake showed a transient decrease. But oxygen consumption (and basal metabolic rates) was kept practically unchanged at the levels of the controls, i. e. higher than needed to oxidize the food ingested during the weight loss period. Brown adipose tissue uncoupling protein levels were proportionally preserved with a 2-week treatment, but it lost a substantial amount of lipid. In conclusion, Merlin-2 is a slimming agent with considerable potential given its powerful fat-wasting action, since it maintains thermogenesis despite lowered energy intake.

Adipose tissue (AT) is distributed as large differentiated masses, and smaller depots covering vessels, and organs, as well as interspersed within them. The differences between types and size of cells makes AT one of the most disperse and complex organs. Lipid storage is partly shared by other tissues such as muscle and liver. We intended to obtain an approximate estimation of the size of lipid reserves stored outside the main fat depots. Both male and female rats were made overweight by 4-weeks feeding of a cafeteria diet. Total lipid content was analyzed in brain, liver, gastrocnemius muscle, four white AT sites: subcutaneous, perigonadal, retroperitoneal and mesenteric, two brown AT sites (interscapular and perirenal) and in a pool of the rest of organs and tissues (after discarding gut contents). Organ lipid content was estimated and tabulated for each individual rat. Food intake was measured daily. There was a surprisingly high proportion of lipid not accounted for by the main macroscopic AT sites, even when brain, liver and BAT main sites were discounted. Muscle contained about 8% of body lipids, liver 1–1.4%, four white AT sites lipid 28–63% of body lipid, and the rest of the body (including muscle) 38–44%. There was a good correlation between AT lipid and body lipid, but lipid in “other organs” was highly correlated too with body lipid. Brain lipid was not. Irrespective of dietary intake, accumulation of body fat was uniform both for the main lipid storage and handling organs: large masses of AT (but also liver, muscle), as well as in the ”rest” of tissues. These storage sites, in specialized (adipose) or not-specialized (liver, muscle) tissues reacted in parallel against a hyperlipidic diet challenge. We postulate that body lipid stores are handled and regulated coordinately, with a more centralized and overall mechanisms than usually assumed.

Corticosteroid-binding globulin (CBG) is synthesized by the liver and secreted into the bloodstream where binds to glucocorticoids. Thus CBG has the role of glucocorticoid transport and free hormone control. In addition, CBG has been detected in some extrahepatic tissues without a known role. CBG-deficient mice show decreased total corticosterone levels with missing of classical sexual dimorphism, increased free corticosterone, higher adrenal gland size and altered HPA axis response to stress. Our aim was to ascertain whether CBG deficiency could affect the endocrine synthetic activity of adrenal gland and if the adrenal gland produces CBG. We determined the expression in adrenal gland of proteins involved in the cholesterol uptake and its transport to mitochondria and the main enzymes involved in the corticosterone, aldosterone and catecholamine synthesis. The results showed that CBG is synthesized in the adrenal gland. CBG-deficiency reduced the expression of ACTH receptor, SRB1 and the main genes involved in the adrenal hormones synthesis, stronger in females resulting in the loss of sexual dimorphism in corticosteroid adrenal synthesis, despite corticosterone content in adrenal glands from CBG-deficient females was similar to wildtype ones. In conclusion, these results point to an unexplored and relevant role of CBG in the adrenal gland functionality related to corticosterone production and release.