Low-level arsenite activates the transcription of genes involved in adipose differentiation

In this study we analyzed gene expression in 3T3-F442A pre-adipocyte cells that differentiate in the presence of micro-molar arsenate concentration. Two concentrations of arsenite (As2O3, 0.25 micromol/L and 0.5 micromol/L) were applied for three days with and without insulin (170 nmol/L) and gene expressions were evaluated by quantitative RT-PCR. The genes included genes of oxidative-stress responses: heme-oxygenase-1 (HO1) and the hypoxia inducible factor 1a (HIF1alpha), genes of cell-cycle: c-jun and Kruppel like factor 5 (KLF5), and genes that play important roles in adipose determination: a peroxisome proliferator-activated receptor (PPARgamma) and a CCAAT/ enhancer binding protein (C/EBPalpha). Arsenite induced the expression of HO1, HIF1alpha, KLF5, PPARgamma and C/EBPalpha. These results suggest that under condition of oxidative stress arsenite induces genes that are required for adipose differentiation.     

Key regulators of mitochondrial biogenesis are increased in kidneys of growth hormone receptor knockout (GHRKO) mice

The growth hormone receptor knockout (GHRKO) mice are remarkably long-lived and highly insulin sensitive. Alterations in mitochondrial biogenesis are associated with aging and various metabolic derangements. We have previously demonstrated increased gene expression of key regulators of mitochondriogenesis in kidneys, hearts and skeletal muscles of GHRKO mice. The aim of the present study was to quantify the protein levels of the following regulators of mitochondriogenesis: peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α), AMP-activated protein kinase α (AMPKα), phospho-AMPKα (p-AMPKα), sirtuin-3 (SIRT-3), endothelial nitric oxide synthase (eNOS), phospho-eNOS (p-eNOS), nuclear respiratory factor-1 (NRF-1) and mitofusin-2 (MFN-2) in skeletal muscles and kidneys of GHRKOs in comparison to normal mice. We also were interested in the effects of calorie restriction (CR) and visceral fat removal (VFR) on these parameters. Both CR and VFR improve insulin sensitivity and can extend life span. Results: The renal levels of PGC-1α, AMPKα, p-AMPKα, SIRT-3, eNOS, p-eNOS and MFN-2 were increased in GHRKOs. In the GHRKO skeletal muscles, only MFN-2 was increased. Levels of the examined proteins were not affected by CR (except for PGC-1α and p-eNOS in skeletal muscles) or VFR. Conclusion: GHRKO mice have increased renal protein levels of key regulators of mitochondriogenesis, and this may contribute to increased longevity of these knockouts.     

Effect of unilateral surgical denervation of brown adipose tissue on uncoupling protein mRNA level and cytochrom-c-oxidase activity in the Djungarian hamster

The bilateral lobe of interscapular brown adipose tissue of the Djungarian hamster was unilaterally denervated in order to study the role of the sympathetic innervation for maintenance and cold-induced increase of non-shivering thermogenesis. Denervation decreased the noradrenaline content of brown adipose tissue to less than 9% of the intact contralateral pad. This low noradrenaline level was maintained for 1–14 days after denervation. First, to study the role of the sympathetic innervation of brown adipose tissue in the maintenance of the high thermogenic capacity characteristic of the cold acclimated state, brown adipose tissue was denervated in hamsters either kept at thermoneutrality or acclimated to 5°C ambient temperature for 4 weeks. Cold-acclimated hamsters had elevated levels of uncoupling protein messenger ribonucleic acid (8.1-fold) and cytochrom-c oxidase-activity (3-fold). Denervation of brown adipose tissue decreased uncoupling protein-messenger ribonucleic acid level and cytochrom-c-oxidase-activity as compared to the intact pad in thermoneutral and in cold-acclimated hamsters. However, in cold-acclimated hamsters uncoupling protein-messenger ribonucleic acid level and cytochrom-c-oxidase-activity in denervated brown adipose tissue both were maintained on an elevated 6-fold higher levels as compared to thermoneutral controls. Second, to study the role of the sympathetic innervation of brown adipose tissue in the cold-induced increase in thermogenic capacity, hamsters were denervated prior to cold acclimation and responses were measured after 3 and 14 days of cold exposure. Uncoupling protein-messenger ribonucleic acid level and cytochrom-c-oxidase-activity of intact brown adipose tissue increased after 14 days cold acclimation. Denervation did not completely prevent a cold-induced 1.5-fold increase of cytochrom-c-oxidase-activity and a 3.2-fold increase of the uncoupling protein-messenger ribonucleic acid level in denervated brown adipose tissue after 14 days of cold acclimation. In conclusion, high levels of uncoupling protein-messenger ribonucleic acid and cytochrom-c-oxidase activity in brown adipose tissue of cold-acclimated hamsters can partially be maintained without intact sympathetic innervation, suggesting a considerable contribution of trophic factors not requiring sympathetic innervation for maintenance. The cold-induced increase of cytochrom-c-oxidase activity and expression of uncoupling protein-messenger ribonucleic acid largely depends upon sympathetic innervation of brown adipose tissue.Abbreviations ANOVA analysis of variance - BAT brown adipose tissue - COX cytochrom-c-oxidase - HPLC high performance liquid chromatography - mRNA messenger ribonucleie acid - NA noradrenaline - T _a ambient temperature - UCP uncoupling protein     

ROS generation and multiple forms of mammalian mitochondrial glycerol-3-phosphate dehydrogenase

Overproduction of reactive oxygen species (ROS) has been implicated in a range of pathologies. Mitochondrial flavin dehydrogenases glycerol-3-phosphate dehydrogenase (mGPDH) and succinate dehydrogenase (SDH) represent important ROS source, but the mechanism of electron leak is still poorly understood. To investigate the ROS production by the isolated dehydrogenases, we used brown adipose tissue mitochondria solubilized by digitonin as a model. Enzyme activity measurements and hydrogen peroxide production studies by Amplex Red fluorescence, and luminol luminescence in combination with oxygraphy revealed flavin as the most likely source of electron leak in SDH under in vivo conditions, while we propose coenzyme Q as the site of ROS production in the case of mGPDH. Distinct mechanism of ROS production by the two dehydrogenases is also apparent from induction of ROS generation by ferricyanide which is unique for mGPDH. Furthermore, using native electrophoretic systems, we demonstrated that mGPDH associates into homooligomers as well as high molecular weight supercomplexes, which represent native forms of mGPDH in the membrane. By this approach, we also directly demonstrated that isolated mGPDH itself as well as its supramolecular assemblies are all capable of ROS production.     

Tonsil-derived mesenchymal stem cells alleviate concanavalin A-induced acute liver injury

Acute liver failure, the fatal deterioration of liver function, is the most common indication for emergency liver transplantation, and drug-induced liver injury and viral hepatitis are frequent in young adults. Stem cell therapy has come into the limelight as a potential therapeutic approach for various diseases, including liver failure and cirrhosis. In this study, we investigated therapeutic effects of tonsil-derived mesenchymal stem cells (T-MSCs) in concanavalin A (ConA)- and acetaminophen-induced acute liver injury. ConA-induced hepatitis resembles viral and immune-mediated hepatic injury, and acetaminophen overdose is the most frequent cause of acute liver failure in the United States and Europe. Intravenous administration of T-MSCs significantly reduced ConA-induced hepatic toxicity, but not acetaminophen-induced liver injury, affirming the immunoregulatory capacity of T-MSCs. T-MSCs were successfully recruited to damaged liver and suppressed inflammatory cytokine secretion. T-MSCs expressed high levels of galectin-1 and -3, and galectin-1 knockdown which partially diminished interleukin-2 and tumor necrosis factor α secretion from cultured T-cells. Galectin-1 knockdown in T-MSCs also reversed the protective effect of T-MSCs on ConA-induced hepatitis. These results suggest that galectin-1 plays an important role in immunoregulation of T-MSCs, which contributes to their protective effect in immune-mediated hepatitis. Further, suppression of T-cell activation by frozen and thawed T-MSCs implies great potential of T-MSC banking for clinical utilization in immune-mediated disease.     

Uncoupling Protein 3: Its Possible Biological Role and Mode of Regulation in Rodents and Humans

The recently discovered uncoupling protein 3 (UCP3) is highly homologous to the mitochondrialinner membrane protein UCP1, which generates heat by uncoupling the respiratory chainfrom oxidative phosphorylation. The thermogenic function of UCP1 protects against cold andregulates the energy balance in rodents. We review in vitro studies investigating the uncouplingactivity of UCP3 and in vivo studies, which address UCP3 gene expression in brown adiposetissue and skeletal muscle under various metabolic conditions. The data presented are, for themost, consistent with an uncoupling role for UCP3 in regulatory thermogenesis. We alsodiscuss mediators of UCP3 regulation and propose a potential role for intracellular fatty acidsin the mechanism of UCP3 modulation. Finally, we hypothesize a role for UCP3 in themetabolic adaptation of the mitochondria to the degradation of fatty acids.     

猫皮层体感Ⅱ区内脏伤害感受神经元的电生理特性及形态特征

应用胞内记录和标记技术,观察了猫皮质第Ⅱ感觉区内脏大神经代表区的神经元对电刺激内脏大神经反应诱发反应及形态特征。结果表明,在２５１个记录单位中,有１０９个为内脏伤害性感受神经元,其诱发反应分为兴奋性、抑制性及混合性三类。在形式上ＩＳＰＳ及ＥＰＳＰ－ＩＰＳＰ序列反应较多。对其中２１个神经元用神经生物素进行细胞内电泳标记,显示细胞的形态特点是胞体较小,分布于皮质Ⅱ、Ⅲ、Ⅴ层,其中兴奋性和神经元形态多为     

Relationship between body condition score loss and mRNA of genes related to fatty acid metabolism and the endocannabinoid system in adipose tissue of periparturient cows

The endocannabinoid system (ECS) controls feed intake and energy balance in nonruminants. Recent studies suggested that dietary management alters the expression of members of the ECS in the liver and endometrium of dairy cows. The aim of this study was to determine the relationship between body condition score (BCS) loss and the mRNA abundance of genes related to fatty acid metabolism and the ECS in the subcutaneous adipose tissue (AT) of dairy cows. The BCS was determined in multiparous (3.2 ± 0.5 lactations) Holstein cows at −21 and 42 days relative to calving (designated as d = 0). Cows were grouped into three categories according to BCS loss between both assessments as follows: (1) lost ≤0.25 unit (n = 8, low BCS loss (LBL)), (2) lost between 0.5 and 0.75 units (n = 8, moderate BCS loss (MBL)) and (3) lost ≥1 unit (n = 8, high BCS loss (HBL)). Concentrations of haptoglobin and non-esterified fatty acids (NEFAs) were determined in plasma. Real-time PCR was used to determine mRNA abundance of key genes related to fatty acid metabolism, inflammation and ECS in AT. Milk yield (kg/day) between week 2 and 6 post-calving was greater in the LBL group (49.4 ± 0.75) compared to MBL (47.9 ± 0.56) and HBL (47.4 ± 0.62) groups (P < 0.05). The overall mean plasma haptoglobin and NEFA concentrations were greater in MBL and HBL groups compared with the LBL group (P < 0.05). The mRNA abundance of TNF-α, Interleukin-6 (IL-6) and IL-1β was greatest at 21 and 42 days post-calving in HBL, intermediate in MBL and lowest in LBL groups, respectively. Cows in the HBL group had the greatest AT gene expression for carnitine palmitoyltransferase 1A, hormone sensitive lipase and adipose triglyceride lipase at 21 and 42 days post-calving (P < 0.05). Overall, mRNA abundance for very long chain acyl-CoA dehydrogenase and peroxisome proliferator-activated receptor gamma, which are related to NEFA oxidation, were greater in MBL and HBL groups compared to the LBL group at 42 days post-calving. However, mRNA abundance of fatty acid amide hydrolase was lower at 21 and 42 days post-calving in HBL cows than in LBL cows (P < 0.05). In summary, results showed a positive association between increased degree of BCS loss, inflammation and activation of the ECS network in AT of dairy cows. Findings suggest that the ECS might play an important role in fatty acid metabolism, development of inflammation and cow’s adaptation to onset of lactation.     

Sympathovagal Balance,Nighttime Blood Pressure,and QT Intervals in Normotensive Obese Women

Objective : We describe associations among the heart‐rate‐corrected QT (QTc) interval, QTc dispersion (QTc‐d), circadian BP variation, and autonomic function in obese normotensive women and the effect of sustained weight loss. Research Methods and Procedures : In 71 obese (BMI = 37.14 ± 2.6 kg/m²) women, 25 to 44 years of age, circadian BP variations (24‐hour ambulatory BP monitoring), autonomic function (power spectral analysis of RR interval oscillations), and cardiac repolarization times (QTc‐d and QTc interval) were recorded at baseline and after 1 year of a multidisciplinary program of weight reduction. Results : Compared with nonobese age‐matched women (n = 28, BMI = 23 ± 2.0 kg/m²), obese women had higher values of QTc‐d (p < 0.05) and QTc (p < 0.05), an altered sympathovagal balance (ratio of low‐frequency/high‐frequency power, p < 0.01), and a blunted nocturnal drop in BP (p < 0.01). In obese women, QTc‐d and the QTc interval correlated with diastolic nighttime BP (p < 0.01) and sympathovagal balance (p < 0.01). Waist‐to‐hip ratio, free fatty acids, and plasma insulin levels correlated with QT intervals and reduced nocturnal drops in both systolic and diastolic BP and sympathovagal balance (p < 0.01). After 1 year, obese women lost at least 10% of their original weight, which was associated with decrements of QTc‐d (p < 0.02), the QTc interval (p < 0.05), nighttime BP (p < 0.01), and sympathovagal balance (p < 0.02). Discussion : Sustained weight loss is a safe method to ameliorate diastolic nighttime BP drop and sympathetic overactivity, which may reduce the cardiovascular risk in obese women.