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Involvement of intracellular Ca(2+) and ERK1/2 phosphorylation in the fast nongenomic effects of androgens in myotubes was investigated. Testosterone or nandrolone produced fast (<1 min) and transient increases in intracellular Ca(2+) with an oscillatory pattern. Calcium signals were slightly reduced in Ca(2+)-free medium, but lack of oscillations was evident. Signals were blocked by U-73122 and xestospongin B, inhibitors of inositol 1,4,5-trisphosphate (IP(3)) pathway. Furthermore, IP(3) increased transiently 2- to 3-fold 45 sec after hormone addition. Cyproterone neither affected the fast Ca(2+) signal nor the increase in IP(3). Calcium increases could also be induced by the impermeant testosterone conjugated to BSA, and the effect of testosterone was abolished in cells incubated with guanosine 5'-O-(2-thiodiphosphate) or pertussis toxin. Stimulation of myotubes with testosterone, nandrolone, or testosterone conjugated to BSA increased immunodetectable phosphorylation of ERK1/2 within 5 min, and this effect was not inhibited by cyproterone. Phosphorylation was blocked by the use of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethylester, U-73122, and xestospongin B as well as by dominant negative Ras, MAPK kinase (MEK), or the MEK inhibitor PD-98059. In addition, guanosine 5'-O-(2-thiodiphosphate) or pertussis toxin blocked ERK1/2 phosphorylation. These results are consistent with a fast effect of testosterone, involving a G protein-linked receptor at the plasma membrane, IP(3)-mediated Ca(2+) signal, and the Ras/MEK/ERK pathway in muscle cells.

Based on a deductive, culturally decentered approach, new items were generated to improve the reliability of the original Social Axioms Survey, which measures individuals’ general beliefs about the world. In Study 1, results from 11 countries support the original five-factor structure and achieve higher reliability for the axiom dimensions as measured by the new scale. Moreover, moderate but meaningful associations between axiom and Big-Five personality dimensions were found. Temporal change of social axioms at the culture level was examined and found to be moderate. In Study 2, additional new items were generated for social complexity and fate control, then assessed in Hong Kong and the United States. Reliability was further improved for both dimensions. Additionally, two subfactors of fate control were identified: fate determinism and fate alterability. Fate determinism, but not fate alterability, related positively to neuroticism. Other relationships between axiom and personality dimensions were similar to those reported in Study 1. The short forms of the axiom dimensions were generally reliable and correlated highly with the long forms. This research thus provides a stronger foundation for applying the construct of social axioms around the world.

Controlled generation of reactive oxygen species (ROS) may contribute to physiological intracellular signaling events. We determined ROS generation in primary cultures of rat skeletal muscle after field stimulation (400 1-ms pulses at a frequency of 45 Hz) or after depolarization with 65 mM K þ for 1 min. Both protocols induced a long lasting increase in dichlorofluorescein fluorescence used as ROS indicator. Addition of diphenyleneiodonium (DPI), an inhibitor of NAD(P)H oxidase, PEG-catalase, a ROS scavenger, or nifedipine, an inhibitor of the skeletal muscle voltage sensor, significantly reduced this increase. Myotubes contained both the p47 phox and gp91 phox phagocytic NAD(P)H oxidase subunits, as revealed by immunodetection. To study the effects of ROS, myotubes were exposed to hydrogen peroxide (H 2 O 2 ) at concentrations (100-200 mM) that did not alter cell viability; H 2 O 2 induced a transient intracellular Ca 2þ rise, measured as fluo-3 fluorescence. Minutes after Ca 2þ signal initiation, an increase in ERK1/2 and CREB phosphorylation and of mRNA for the early genes c-fos and c-jun was detected. Inhibition of ryanodine receptor (RyR) decreased all effects induced by H 2 O 2 and NAD(P)H oxidase inhibitors DPI and apocynin decreased ryanodine-sensitive calcium signals. Activity-dependent ROS generation is likely to be involved in regulation of calcium-controlled intracellular signaling pathways in muscle cells.

Omega-3 (n-3) long-chain polyunsaturated fatty acids (n-3 LCPUFA) are associated with several physiological functions, suggesting that their administration may prevent non transmissible chronic diseases. Therefore, we investigate whether dietary n-3 LCPUFA supplementation triggers an antioxidant response preventing liver steatosis in mice fed a high fat diet (HFD) in relation to n-3 LCPUFA levels. Male C57BL/6J mice received (a) control diet (10% fat, 20% protein, 70% carbohydrate), (b) control diet plus n-3 LCPUFA (108 mg/kg/day eicosapentaenoic acid plus 92 mg/kg/day docosahexaenoic acid), (c) HFD (60% fat, 20% protein, 20% carbohydrate), or (d) HFD plus n-3 LCPUFA for 12 weeks. Parameters of liver steatosis, glutathione status, protein carbonylation, and fatty acid analysis were determined, concomitantly with insulin resistance and serum tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 levels. HFD significantly increased total fat and triacylglyceride contents with macrovesicular steatosis, concomitantly with higher fasting serum glucose and insulin levels, HOMA, and serum TNF-α, IL-1β, and IL-6. Reduced and total liver glutathione contents were diminished by HFD, with higher GSSG/GSH ratio and protein carbonylation, n-3 LCPUFA depletion and elevated n-6/n-3 ratio over control values. These changes were either reduced or normalized to control values in animals subjected to HFD and n-3 LCPUFA, with significant increased hepatic total n-3 LCPUFA content and reduced n-6/n-3 ratio being observed after n-3 LCPUFA supplementation alone. So, repletion of liver n-3 LCPUFA levels by n-3 LCPUFA dietary supplementation in HFD obese mice reduces hepatic lipid content, with concomitant antioxidant and anti-inflammatory responses favouring insulin sensitivity.

Skeletal muscle is one of the main regulators of carbohydrate and lipid metabolism in our organism, and therefore, it is highly susceptible to changes in glucose and fatty acid (FA) availability. Skeletal muscle is an extremely complex tissue: its metabolic capacity depends on the type of fibers it is made up of and the level of stimulation it undergoes, such as acute or chronic contraction. Obesity is often associated with increased FA levels, which leads to the accumulation of toxic lipid intermediates, oxidative stress, and autophagy in skeletal fibers. This lipotoxicity is one of the most common causes of insulin resistance (IR). In this scenario, the “isolation” of certain lipids in specific cell compartments, through the action of the specific lipid droplet, perilipin (PLIN) family of proteins, is conceived as a lifeguard compensatory strategy. In this review, we summarize the cellular mechanism underlying lipid mobilization and metabolism inside skeletal muscle, focusing on the function of lipid droplets, the PLIN family of proteins, and how these entities are modified in exercise, obesity, and IR conditions.

Synergistic beneficial effects of DHA + EVOO supplementation are associated with the activation/inactivation of key transcription factors involved in the above-mentioned processes. Data presented indicate that dietary supplementation with DHA + EVOO drastically reduces the development of nonalcoholic fatty liver disease.

Skeletal muscle glucose uptake in response to exercise is preserved in insulin-resistant conditions, but the signals involved are debated. ATP is released from skeletal muscle by contractile activity and can autocrinely signal through purinergic receptors, and we hypothesized it may influence glucose uptake. Electrical stimulation, ATP, and insulin each increased fluorescent 2-NBD-Glucose (2-NBDG) uptake in primary myotubes, but only electrical stimulation and ATP-dependent 2-NBDG uptake were inhibited by adenosine-phosphate phosphatase and by purinergic receptor blockade (suramin). Electrical stimulation transiently elevated extracellular ATP and caused Akt phosphorylation that was additive to insulin and inhibited by suramin. Exogenous ATP transiently activated Akt and, inhibiting phosphatidylinositol 3-kinase (PI3K) or Akt as well as dominant-negative Akt mutant, reduced ATP-dependent 2-NBDG uptake and Akt phosphorylation. ATP-dependent 2-NBDG uptake was also inhibited by the G protein βγ subunit-interacting peptide βark-ct and by the phosphatidylinositol 3-kinase-γ (PI3Kγ) inhibitor AS605240. ATP caused translocation of GLUT4myc-eGFP to the cell surface, mechanistically mediated by increased exocytosis involving AS160/Rab8A reduced by dominant-negative Akt or PI3Kγ kinase-dead mutants, and potentiated by myristoylated PI3Kγ. ATP stimulated 2-NBDG uptake in normal and insulin-resistant adult muscle fibers, resembling the reported effect of exercise. Hence, the ATP-induced pathway may be tapped to bypass insulin resistance.