Effects of maslinic acid on cardiac function in ischemia-reperfusion injury rats.

Maslinic acid (MA), a pentacyclic triterpenoid, has been reported to exert broad pharmacological properties. However, it is still unclear whether MA exhibits protective effects against ischemia/reperfusion (I/R) injury. Herein, we aimed to investigate the effects of MA on I/R injury and its underlying mechanisms. A rat model of I/R injury was established and administrated with MA by intraperitoneal injection. Cardiac function was assessed with a color ultrasound diagnosis system and PowerLab system. The levels of oxidative stress-related and I/R-related biomarkers were evaluated by using commercial kits. Apoptosis-related biomarkers and sirtuin (SIRT)1/AMP-activated protein kinase (AMPK) signaling proteins were determined by using quantitative reverse transcription PCR and western blotting, respectively. Treatment with MA improved cardiac performance and cardiac hemodynamic parameters in the I/R injury rat model. Besides, treatment with MA (20 mg/kg) ameliorated I/R injury-related biomarkers in serum. Interestingly, treatment with MA (20 mg/kg) also regulated myocardial apoptosis and inhibited oxidative-stress in left ventricular tissue. Mechanistic studies demonstrated that MA upregulated SIRT1 and AMPK phosphorylation in the left ventricular tissue. In summary, MA exerted protective effects against the impairments of cardiac function in I/R injury rats by the regulation of SIRT1/AMPK signaling pathways.

Ameliorative effects of fisetin in letrozole-induced rat model of polycystic ovary syndrome.

BACKGROUND: The present study was conducted to investigate the therapeutic effects of a potent polyphenol, fisetin, on the letrozole-induced rat model of polycystic ovary syndrome (PCOS). METHODOLOGY: Twenty-four female Wistar rats (42 days old) were divided into four groups: control group (received carboxy methylcellulose (CMC 0.5 %)), PCOS group treated with letrozole (1 mg/kg), fisetin group received same dose of letrozole + fisetin (10 mg/kg), and metformin group received same dose of letrozole + metformin (300 mg/kg). At the end of the experiment, biochemical (glucose, lipid profile) and hormonal (insulin, testosterone, estradiol, and progesterone) parameters were analyzed. Histological examinations of ovaries were also conducted by hematoxylin and eosin (H&E) staining. Real-time polymerase chain reaction (PCR) and western blotting were carried out for cytochrome P450 17A1 (CYP17A1), sirtuin-1 (SIRT1), and 5' AMP-activated protein kinase (AMPK) gene expression in the ovaries. Furthermore, enzymatic activities of antioxidants including catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in the ovaries were analyzed by colorimetric method. RESULTS: Letrozole administration resulted in a remarkable abnormality in biochemical and hormonal parameters. Fisetin normalized levels of glucose, lipid profile, homeostatic model assessment for insulin resistance (HOMA-IR), testosterone, estradiol, and progesterone. Moreover, fisetin increased expression levels of SIRT1 and AMPK, and decreased expression level of CYP17A1 in the ovaries. Additionally, fisetin showed protective effect by enhancing antioxidant activities of CAT, SOD, and GPx depleted secondary to induction of PCOS. Fisetin effects were comparable to metformin, as the standard drug used for treatment of PCOS. CONCLUSION: Our results showed that, fisetin treatment caused significant alleviating effects by restoring PCOS-induced alterations in the key genes involved in energy homeostasis and antioxidant enzymes, suggesting that it may have a key role in combating with PCOS.

Red Pepper (Capsicum annuum L.) Seed Extract Improves Glycemic Control by Inhibiting Hepatic Gluconeogenesis via Phosphorylation of FOXO1 and AMPK in Obese Diabetic db/db Mice.

Obesity is a notable risk factor for developing type 2 diabetes, augmenting the concern of obese diabetes (ObD). Anti-obesity and antioxidant effects of red pepper seeds extract (RPSE) have increased our expectations that RPSE would also improve the pathological phenotypes of obese diabetes. Therefore, we hypothesized that RPSE would have an anti-diabetic effect in ObD mice. Animals were assigned either as follows: (1) db/+, (2) db/db control, (3) RPSE (200 mg/kg bw), or (4) a comparative control (metformin 150 mg/kg bw). RPSE was orally administered daily for 8 weeks. As a result, RPSE supplementation improved diabetic phenotypes, including fasting glucose, hemoglobin (HbA1c), and insulin levels. Pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6), and triglycerides were reduced in RPSE-treated mice. RPSE supplementation also diminished the rate-limiting enzymes of gluconeogenesis, including glucose 6-phosphatas (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK), in the liver. RPSE supplementation increased the phosphorylation of forkhead box protein O1 (FOXO1) and AMP-activated protein kinase (AMPK), which underlined the mechanism of the anti-diabetic effects of RPSE. Taken together, RPSE has the potential to improve glycemic control by repressing hepatic gluconeogenesis via the phosphorylation of FOXO1 and AMPK in ObD mice.

Decreased Levels of Blood AMPKα1 but not AMPKα2 Isoform in Patients with Mild Cognitive Impairment and Alzheimer's Disease: A Pilot Study.

BACKGROUND: There is an urgent need to develop feasible biomarkers for diagnosis and prognosis of Alzheimer's disease (AD). Mounting evidence implicates that dysregulation of energy metabolism is a key and early event in AD pathogenesis. AMP-activated protein kinase (AMPK) is a central molecular sensor that plays a critical role in maintaining cellular energy homeostasis, and aberrant brain AMPK activities are linked to AD pathophysiology. OBJECTIVE: We aimed to investigated protein levels of AMPKα isoforms, AMPKα1 and AMPKα2, in plasma samples from patients clinically diagnosed with mild cognitive impairment (MCI) or AD, along with age-matched healthy controls. METHODS: 30 participants (10 MCI, 10 AD, and 10 controls) were included in our pilot study. Plasma levels of AMPKα1 and AMPKα2 were determined by ELISA. Receiver operating characteristic (ROC) analysis was used to assess sensitivity and specificity. Linear regression was used to assess the correlation between levels of AMPKα isoforms and other biomarkers. RESULTS: Plasma levels of AMPKα1 were decreased in MCI and AD patients, while levels of AMPKα2 were unaltered as compared to controls. ROC analysis showed relatively high sensitivity and specificity for AMPKα1 to distinguish MCI and AD from controls. Linear regression analysis showed that plasma levels of AMPKα1 were correlated with a brain imaging biomarker (AD signature cortical thicknesses). CONCLUSION: Plasma levels of AMPKα1 were decreased in MCI and AD patients. Future endeavor to explore whether blood AMPKα1 protein expression has the value as a potential biomarker for AD and MCI diagnosis shall be encouraged.

Maternal serum AMP-activated protein kinase levels in mild and severe preeclampsia.

OBJECTIVE: To investigate Phosphorylated adenosine monophosphate activated protein kinase (AMPK) levels in healthy pregnant women and pregnant women with preeclampsia (PE). METHODS: Twenty-eight women with mild-PE, 22 with severe-PE, and 30 normotensive controls were included in this cross-sectional study. The serum AMPK levels of these patients were analyzed. The patients were followed up to delivery. RESULTS: No statistically significant difference was found between the groups for age, gravida, parity, and gestational age at the time the blood samples were obtained (p > .05). No significant difference between the group with mild-PE and the control group was found, while in the severe-PE group, serum AMPK levels were significantly higher relative to both the mild-PE and control groups (p < .001 and p < .001, respectively). No correlation was detected between serum AMPK levels and age, body mass index (BMI), and gestational age at the time the blood samples were collected. A negative correlation was found between AMPK levels and gestational week and birthweight at delivery, while a positive correlation was detected between systolic and diastolic blood pressures and AMPK levels. CONCLUSIONS: Serum AMPK was higher in patients with severe-PE compared with healthy pregnant women and patients with PE without severe features so it might be a new biomarker for the prediction of disease and its severity.

Maternal selenium status is profoundly involved in metabolic fetal programming by modulating insulin resistance, oxidative balance and energy homeostasis.

PURPOSE: High and low levels of selenium (Se) have been related to metabolic disorders in dams and in their offspring. Their relationship to oxidative balance and to AMP-activated protein kinase (AMPK) is some of the mechanisms proposed. The aim of this study is to acquire information about how Se is involved in metabolic programming. METHODS: Three experimental groups of dam rats were used: control (Se: 0.1 ppm), Se supplemented (Se: 0.5 ppm) and Se deficient (Se: 0.01 ppm). At the end of lactation, the pups' metabolic profile, oxidative balance, Se levels, selenoproteins and IRS-1 hepatic expression, as well as hepatic AMPK activation were measured. RESULTS: The experimental groups present deep changes in Se homeostasis, selenoproteins and IRS-1 hepatic expression, oxidative balance, AMPK activation ratio and insulin levels. They do, however, have different metabolic profiles. CONCLUSIONS: High- and low-Se diets are linked to insulin resistance, yet the mechanisms involved are completely opposite.

The Chinese medicine Chai Hu Li Zhong Tang protects against non-alcoholic fatty liver disease by activating AMPKα.

An effective treatment for non-alcoholic fatty liver disease (NAFLD) is urgently needed. In the present study, we investigated whether the Chinese medicine Chai Hu Li Zhong Tang (CHLZT) could protect against the development of NAFLD. Rats in an animal model of NAFLD were treated with CHLZT, and their serum levels of cholesterol (TC), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were detected with an automatic biochemical analyzer. A cellular model of NAFLD was also established by culturing HepG2 cells in a medium that contained a long chain fat emulsion. Those cells were treated with CHLZT that contained serum from rats. After treatment, the levels of adenylate-activated protein kinase (AMPK) α (AMPKα), p-AMPKα, acetyl coenzyme A carboxylase (ACC) α (ACCα), pACCα, PPARγ, and SREBP-2 were detected. The AMPK agonist, acadesine (AICAR), was used as a positive control compound. Our results showed that CHLZT or AICAR significantly decreased the serum levels of TG, TC, LDL-C, AST, ALT, and insulin in NAFLD rats, and significantly increased their serum HDL-C levels. Treatments with CHLZT or AICAR significantly decreased the numbers of lipid droplets in NAFLD liver tissues and HepG2 cells. CHLZT and AICAR increased the levels of p-AMPKα and PPARγ in the NAFLD liver tissues and HepG2 cells, but decreased the levels of ACC-α, p-ACC-α, SREBP-2, and 3-hydroxyl-3-methylglutaryl-coenzyme A reductase (HMGR). CHLZT protects against NAFLD by activating AMPKα, and also by inhibiting ACC activity, down-regulating SREBP2 and HMGR, and up-regulating PPAR-γ. Our results suggest that CHLZT might be useful for treating NAFLD in the clinic.

Effects of Fish Oil on Lipid Metabolism and Its Molecular Biological Regulators in Chronic Ethanol-Fed Rats.

The purpose of this study was to clarify the hepatoprotective mechanisms of fish oil in ethanol-fed rats based on lipid metabolism. Thirty eight-week-old male Wistar rats were divided into six groups: C (control), CF25 (control diet with 25% fish oil substitution), CF57 (control diet with 57% fish oil substitution), E (ethanol-containing diet) group, EF25 (ethanol-containing diet with 25% fish oil substitution), and EF57 (ethanol-containing diet with 57% fish oil substitution) groups. All of the groups were pair-fed an isoenergetic diet based on E group. Rats were sacrificed after eight weeks. When compared with C group, the plasma aspartate transaminase (AST) activity and hepatic steatosis and inflammatory cell infiltration were significantly higher, while plasma adiponectin level and hepatic AMP-activated protein kinase α (AMPKα) protein expression was significantly lower in the E group. However, the hepatic damage, including steatosis and inflammation were ameliorated in the EF25 and EF57 groups. Moreover, mRNA levels of fatty acid-oxidative enzymes, such as medium-chain acyl-coenzyme A dehydrogenase (MCAD) and carnitine palmitoyltransferase I (CPT-1) were significantly elevated in the EF57 group than those in E group. Partial replacement with fish oil might improve the fatty acid oxidation by raising mRNA levels of downstream transcription factors, finally inhibit the ethanol-induced hepatic steatosis in rats.

Aged garlic extract suppresses inflammation in apolipoprotein E-knockout mice.

SCOPE: Chronic inflammation plays a major role in the formation and progression of atherosclerotic plaques. To clarify the mode of action of aged garlic extract (AGE) to retard atherosclerosis, we investigated whether AGE suppresses the inflammation in apolipoprotein E-knockout (ApoE-KO) mice. METHODS AND RESULTS: ApoE-KO mice were fed standard diet with or without 3% AGE for 12 wk. AGE feeding inhibited the progression of atherosclerotic lesion by 27% and reduced the level of C-reactive protein (CRP) and thromboxane B2 (TXB2 ), a marker of platelet activation, in serum by 39 and 33%, respectively, compared to ApoE-KO mice without AGE treatment. AGE treatment also decreased the level of tumor necrosis factor alpha (TNF-α), a major stimulus inducing CRP production, in the liver by 35%. AGE decreased the level of interleukin-1 receptor-associated kinase 4 (IRAK4) by 60% and almost doubled the level of phospho-AMP-activated protein kinase (p-AMPK) in the liver. CONCLUSION: The anti-atherosclerotic effect of AGE involves the suppression of inflammation by reducing the serum level of CRP and TXB2 , and the protein level of TNF-α and IRAK4, and increasing AMPK activity in liver.

Effect of a single bout of aerobic exercise on high-fat meal-induced inflammation.

BACKGROUND AND AIMS: Chronic low-grade inflammation is involved in the development of metabolic disorders including atherosclerosis, type 2 diabetes (T2D) and metabolic syndrome. Aerobic exercise has been shown to be anti-inflammatory and attenuate postprandial blood lipids, however, the effect of exercise on postprandial inflammation remains unclear. The aim of this study was to determine the protective effect of a single bout of aerobic exercise against postprandial lipemia and peripheral blood mononuclear cell (PBMC) inflammation and to evaluate associations with changes in the energy-sensing enzyme, AMP-activated protein kinase (AMPK). MATERIALS AND METHODS: Healthy male subjects (n=12, age=23±2, %Fat=19±2) reported to the laboratory following an overnight fast (12-14h) on two separate occasions for consumption of a high-fat meal (HFM). Participants completed an acute bout of aerobic exercise the afternoon prior to one of the HFM visits. RESULTS AND CONCLUSION: Results indicate that the single bout of moderate aerobic exercise increased AMPK signaling in PBMCs, as shown by increased phosphorylated acetyl-CoA carboxylase (p-ACC). This may be due to decreases in the AMPK inhibitory kinases PKD and GSK3ß. Additionally, prior moderate intensity exercise decreased postprandial lipemia (PPL) and some mediators of the inflammatory pathway, such as p-NF-κB. These findings that acute aerobic exercise improves AMPK and NF-κB signaling in human PBMCs contribute support to the anti-inflammatory roles of exercise.

Beneficial Role of Erythrocyte Adenosine A2B Receptor-Mediated AMP-Activated Protein Kinase Activation in High-Altitude Hypoxia.

BACKGROUND: High altitude is a challenging condition caused by insufficient oxygen supply. Inability to adjust to hypoxia may lead to pulmonary edema, stroke, cardiovascular dysfunction, and even death. Thus, understanding the molecular basis of adaptation to high altitude may reveal novel therapeutics to counteract the detrimental consequences of hypoxia. METHODS: Using high-throughput, unbiased metabolomic profiling, we report that the metabolic pathway responsible for production of erythrocyte 2,3-bisphosphoglycerate (2,3-BPG), a negative allosteric regulator of hemoglobin-O2 binding affinity, was significantly induced in 21 healthy humans within 2 hours of arrival at 5260 m and further increased after 16 days at 5260 m. RESULTS: This finding led us to discover that plasma adenosine concentrations and soluble CD73 activity rapidly increased at high altitude and were associated with elevated erythrocyte 2,3-BPG levels and O2 releasing capacity. Mouse genetic studies demonstrated that elevated CD73 contributed to hypoxia-induced adenosine accumulation and that elevated adenosine-mediated erythrocyte A2B adenosine receptor activation was beneficial by inducing 2,3-BPG production and triggering O2 release to prevent multiple tissue hypoxia, inflammation, and pulmonary vascular leakage. Mechanistically, we demonstrated that erythrocyte AMP-activated protein kinase was activated in humans at high altitude and that AMP-activated protein kinase is a key protein functioning downstream of the A2B adenosine receptor, phosphorylating and activating BPG mutase and thus inducing 2,3-BPG production and O2 release from erythrocytes. Significantly, preclinical studies demonstrated that activation of AMP-activated protein kinase enhanced BPG mutase activation, 2,3-BPG production, and O2 release capacity in CD73-deficient mice, in erythrocyte-specific A2B adenosine receptor knockouts, and in wild-type mice and in turn reduced tissue hypoxia and inflammation. CONCLUSIONS: Together, human and mouse studies reveal novel mechanisms of hypoxia adaptation and potential therapeutic approaches for counteracting hypoxia-induced tissue damage.

Reduction Levels and the Effects of High-Molecular-Weight Adiponectin via AMPK/eNOS in Chinese Type 2 Diabetes.

Aim: This study was to investigate the change of high-molecula-weight (HMW) adiponectin (APN) isoform, the association between type 2 diabetes mellitus (T2DM) and HMW APN isoform, the variation of Disulfide-bond A oxidoreductase-like protein (DsbA-L), the effect of HMW APN isoform on AMP-dependent protein kinase (AMPK) and endothelial nitric oxide synthase (eNOS) in Chinese T2DM. Method: 169 patients aged at (48.7±9.4) years and 107 healthy control subjects aged at (42.6±7.8) years took part in this study. Anthropometric measures of the characters were assayed and different APN isoforms, DsbA-L, AMPK and eNOS levels were determined. Results: Ln(sRAGE) and Ln(Adiponectin) were significantly lower and significantly higher for the other characteristics in T2DM. Ln(Adiponectin) was negatively and significantly correlated with WHR, Ln(triglycerides), fasting plasma glucose, HbA1c (%) in control subjects and T2DM patients. Plasma and adipose tissue total APN and HMW APN were significantly reduced in newly diagnosed T2DM patients. DsbA-L was markedly down-regulated in diabetic adipose tissue. HMW APN caused significant decreases in AMPK and eNOS phosphorylation levels of human umbilical vein endothelial cells (HUVECs). Conclusions: Our results demonstrated that total APN levels was closely related to the risk of T2DM and HMW APN reduction was involved in the diabetic vascular AMPK/eNOS signal pathway. The findings will provide insight into novel therapeutic approaches for reducing the elevated cardiovascular risk associated with T2DM.

The impact of endurance exercise on global and AMPK gene-specific DNA methylation.

Alterations in gene expression as a consequence of physical exercise are frequently described. The mechanism of these regulations might depend on epigenetic changes in global or gene-specific DNA methylation levels. The AMP-activated protein kinase (AMPK) plays a key role in maintenance of energy homeostasis and is activated by increases in the AMP/ATP ratio as occurring in skeletal muscles after sporting activity. To analyze whether exercise has an impact on the methylation status of the AMPK promoter, we determined the AMPK methylation status in human blood samples from patients before and after sporting activity in the context of rehabilitation as well as in skeletal muscles of trained and untrained mice. Further, we examined long interspersed nuclear element 1 (LINE-1) as indicator of global DNA methylation changes. Our results revealed that light sporting activity in mice and humans does not alter global DNA methylation but has an effect on methylation of specific CpG sites in the AMPKα2 gene. These regulations were associated with a reduced AMPKα2 mRNA and protein expression in muscle tissue, pointing at a contribution of the methylation status to AMPK expression. Taken together, these results suggest that exercise influences AMPKα2 gene methylation in human blood and eminently in the skeletal muscle of mice and therefore might repress AMPKα2 gene expression.

Comparative Study on the Cytoprotective Effects of Activated Protein C Treatment in Nonsteatotic and Steatotic Livers under Ischemia-Reperfusion Injury.

UNLABELLED: Activated protein C (APC) has cytoprotective effects on liver ischemia-reperfusion injury (IRI). However, it is unclear whether APC is beneficial in steatotic liver IRI. We compared the cytoprotective effects of APC in nonsteatotic and steatotic liver IRI. METHODS: Mice fed either normal diets (ND mice) or high fat diets (HF mice), were treated with APC or saline (control) and were performed 60 min partial IRI. Moreover, primary steatotic hepatocytes were either untreated or treated with APC and then incubated with H2O2. RESULTS: APC significantly reduced serum transaminase levels and the inflammatory cells infiltration compared with control at 4 h in ND mice and at 24 h in HF mice. APC inhibited sinusoidal endothelial injury in ND mice, but not in HF mice. In contrast, APC activated adenosine monophosphate-activated protein kinase (AMPK) phosphorylation in HF mice, but not in ND mice. In the in vitro study, APC significantly increased AMPK phosphorylation, ATP concentration, and survival rates of hepatocytes compared with control. CONCLUSION: During IRI in normal liver, APC attenuated initial damage by inhibiting inflammatory cell infiltration and sinusoidal endothelial injury, but not in steatotic liver. However, in steatotic liver, APC might attenuate late damage via activation of AMPK.

Effects of heat stress on serum insulin, adipokines, AMP-activated protein kinase, and heat shock signal molecules in dairy cows.

Heat stress affects feed intake, milk production, and endocrine status in dairy cows. The temperature-humidity index (THI) is employed as an index to evaluate the degree of heat stress in dairy cows. However, it is difficult to ascertain whether THI is the most appropriate measurement of heat stress in dairy cows. This experiment was conducted to investigate the effects of heat stress on serum insulin, adipokines (leptin and adiponectin), AMP-activated protein kinase (AMPK), and heat shock signal molecules (heat shock transcription factor (HSF) and heat shock proteins (HSP)) in dairy cows and to research biomarkers to be used for better understanding the meaning of THI as a bioclimatic index. To achieve these objectives, two experiments were performed. The first experiment: eighteen lactating Holstein dairy cows were used. The treatments were: heat stress (HS, THI average=81.7, n=9) and cooling (CL, THI average=53.4, n=9). Samples of HS were obtained on August 16, 2013, and samples of CL were collected on April 7, 2014 in natural conditions. The second experiment: HS treatment cows (n=9) from the first experiment were fed for 8 weeks from August 16, 2013 to October 12, 2013. Samples for moderate heat stress, mild heat stress, and no heat stress were obtained, respectively, according to the physical alterations of the THI. Results showed that heat stress significantly increased the serum adiponectin, AMPK, HSF, HSP27, HSP70, and HSP90 (P<0.05). Adiponectin is strongly associated with AMPK. The increases of adiponectin and AMPK may be one of the mechanisms to maintain homeostasis in heat-stressed dairy cows. When heat stress treatment lasted 8 weeks, a higher expression of HSF and HSP70 was observed under moderate heat stress. Serum HSF and HSP70 are sensitive and accurate in heat stress and they could be potential indicators of animal response to heat stress. We recommend serum HSF and HSP70 as meaningful biomarkers to supplement the THI and evaluate moderate heat stress in dairy cows in the future.

Metformin reduces hyper-reactivity of platelets from patients with polycystic ovary syndrome by improving mitochondrial integrity.

Polycystic ovary syndrome (PCOS) is associated with decreased fertility, insulin resistance and an increased risk of developing cardiovascular disease. Treating PCOS patients with metformin improves fertility and decreases cardiovascular complications. Given that platelet activation contributes to both infertility and cardiovascular disease development, we assessed platelet reactivity in PCOS patients and the consequences of metformin treatment. Compared to washed platelets from healthy donors, platelets from PCOS patients demonstrated enhanced reactivity and impaired activation of the AMP-activated kinase (AMPK). PCOS platelets also demonstrated enhanced expression of mitochondrial proteins such as the cytochrome c reductase, ATP synthase and the voltage-dependent anion channel-1. However, mitochondrial function was impaired as demonstrated by a decreased respiration rate. In parallel, the phosphorylation of dynamin-related protein-1 (Drp-1) on Ser616 was increased while that on Ser637 decreased. The latter changes were accompanied by decreased mitochondrial size. In insulin-resistant PCOS patients (HOMA-IR> 2) metformin treatment (1.7 g per day for 4 weeks to 6 months) improved insulin sensitivity, restored mitochondrial integrity and function and normalised platelet aggregation. Treatment was without effect in PCOS patients with HOMA-IR< 2. Moreover, treatment of megakaryocytes with metformin enhanced mitochondrial content and in the same cells metformin enhanced the phosphorylation of the Drp-1 on Ser637 via an AMPKα1-dependent mechanism. In conclusion, the improvement of mitochondrial integrity and platelet reactivity may contribute to the beneficial effects of metformin on cardiovascular disease.

Tang-Nai-Kang alleviates pre-diabetes and metabolic disorders and induces a gene expression switch toward fatty acid oxidation in SHR.Cg-Leprcp/NDmcr rats.

Increased energy intake and reduced physical activity can lead to obesity, diabetes and metabolic syndrome. Transcriptional modulation of metabolic networks has become a focus of current drug discovery research into the prevention and treatment of metabolic disorders associated with energy surplus and obesity. Tang-Nai-Kang (TNK), a mixture of five herbal plant extracts, has been shown to improve abnormal glucose metabolism in patients with pre-diabetes. Here, we report the metabolic phenotype of SHR.Cg-Leprcp/NDmcr (SHR/cp) rats treated with TNK. Pre-diabetic SHR/cp rats were randomly divided into control, TNK low-dose (1.67 g/kg) and TNK high-dose (3.24 g/kg) groups. After high-dose treatment for 2 weeks, the serum triglycerides and free fatty acids in SHR/cp rats were markedly reduced compared to controls. After 3 weeks of administration, the high dose of TNK significantly reduced the body weight and fat mass of SHR/cp rats without affecting food consumption. Serum fasting glucose and insulin levels in the TNK-treated groups decreased after 6 weeks of treatment. Furthermore, TNK-treated rats exhibited obvious improvements in glucose intolerance and insulin resistance. The improved glucose metabolism may be caused by the substantial reduction in serum lipids and body weight observed in SHR/cp rats starting at 3 weeks of TNK treatment. The mRNA expression of NAD+-dependent deacetylase sirtuin 1 (SIRT1) and genes related to fatty acid oxidation was markedly up-regulated in the muscle, liver and adipose tissue after TNK treatment. Furthermore, TNK promoted the deacetylation of two well-established SIRT1 targets, PPARγ coactivator 1α (PGC1α) and forkhead transcription factor 1 (FOXO1), and induced the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) in different tissues. These observations suggested that TNK may be an alternative treatment for pre-diabetes and metabolic syndrome by inducing a gene expression switch toward fat oxidation through the activation of SIRT1 and AMPK signaling.

Searching for biomarkers of comorbidities in sera of treated HIV-infected patients by isoelectric focusing.

Based on their characteristics, we hypothesized that the following parameters, namely collagen IV, glutathione S-transferase, secretory component (SC), and AMP-activated protein kinase α1α2 may be useful serum markers in the detection of comorbidities in treated HIV-infected patients. These parameters were determined in 204 HIV-infected patients and 35 controls by using IEF and densitometry. Collagen IV was undetectable in controls and the majority of HIV-infected patients. Twenty-two HIV-infected patients presented significantly elevated levels of collagen IV, most of them were coinfected with hepatitis C virus and/or hepatitis B virus. SC was undetectable in controls. SC was significantly increased in 81 HIV-infected patients and significantly correlated with aspartate aminotransferase (r = 0.267, p = 0.0049), alkaline phosphatase (r = 0.309, p = 0.0011), and γ-glutamyl-transferase (r = 0.264, p = 0.0054). Glutathione S-transferase levels of HIV-infected patients were significantly higher than the controls (3779 ± 5860 vs. 785 ± 71 DU, p = 0.0007) and significantly correlated with serum urea (r = 0.204, p = 0.0038), triglycerides (r = 0.209, p = 0.0033), and lipase (r = 0.219, p = 0.0025). AMP-activated protein kinase α1α2 levels of HIV-infected patients were significantly higher than the controls (5676 ± 6248 vs. 1189 ± 6248 DU, p = 0.0009). Further studies are needed to demonstrate the relevance of these results to diagnose non-AIDS-related illnesses in HIV-infected patients.

The contributions of oxidative stress, oxidised lipoproteins and AMPK towards exercise-associated PPARγ signalling within human monocytic cells.

Peroxisome proliferator-activated receptor gamma (PPARγ) is known to be activated via exercise-associated transient increases in oxidative stress. However, the precise mechanism(s) triggering PPARγ activation in monocytes during/following exercise remain to be confirmed. Here, two cohorts of five healthy male individuals undertook exercise bouts (cycling; 70% VO2max; 45 min) in the presence/absence of dietary antioxidant supplementation (vitamins C (1000 mg/day) and E (400IU/day) for four weeks before exercise); monocytic 5' adenosine monophosphate-activated protein kinase (AMPK)/PPARγ co-activator-1alpha (PGC-1α)/PPARγ signalling was investigated in samples obtained before exercise and up to 24 h after exercise, while THP-1 cells were cultured as an in vitro monocyte model. In THP-1 cells, AMPKα1 was phosphorylated within 1h of menadione (15 µM)-triggered increases in [reactive oxygen species (ROS)]cyto, an effect which was followed by upregulation of PPARγ and several of its target genes (PGC-1α, liver X receptor alpha [LXRα] and ATP-binding cassette subfamily A, member 1 [ABCA1]; 24-72 h), with these effects being blunted by co-administration of vitamin C (62.5 µM). Conversely, treatment with oxidised low-density lipoprotein (oxLDL) (1 µg/mL; 24-72 h), but not non-oxidised LDL, upregulated the above PPARγ-regulated genes without affecting AMPKα1 phosphorylation. In vivo, dietary antioxidant supplementation (which is known to prevent exercise-triggered increases in oxLDL levels) blunted exercise-associated upregulation of the above PPARγ-regulated genes, but had no effect on exercise-associated transient [ROS]cyto increases, or on AMPK phosphorylation. These data suggest that exercise-associated PPARγ signalling effects appear, at least in monocytes, to be mediated by increased generation of PPARγ ligands via oxidation of lipoproteins (following exercise-associated transient increases in oxidative stress), rather than via [ROS]cyto-mediated AMPK activation. These findings may be of clinical relevance, as PPARγ activation in monocytes is associated with beneficial effects related to type-2 diabetes and its cardiovascular complications.

Differentiated mTOR but not AMPK signaling after strength vs endurance exercise in training-accustomed individuals.

The influence of adenosine mono phosphate (AMP)-activated protein kinase (AMPK) vs Akt-mammalian target of rapamycin C1 (mTORC1) protein signaling mechanisms on converting differentiated exercise into training specific adaptations is not well-established. To investigate this, human subjects were divided into endurance, strength, and non-exercise control groups. Data were obtained before and during post-exercise recovery from single-bout exercise, conducted with an exercise mode to which the exercise subjects were accustomed through 10 weeks of prior training. Blood and muscle samples were analyzed for plasma substrates and hormones and for muscle markers of AMPK and Akt-mTORC1 protein signaling. Increases in plasma glucose, insulin, growth hormone (GH), and insulin-like growth factor (IGF)-1, and in phosphorylated muscle phospho-Akt substrate (PAS) of 160 kDa, mTOR, 70 kDa ribosomal protein S6 kinase, eukaryotic initiation factor 4E, and glycogen synthase kinase 3a were observed after strength exercise. Increased phosphorylation of AMPK, histone deacetylase5 (HDAC5), cAMP response element-binding protein, and acetyl-CoA carboxylase (ACC) was observed after endurance exercise, but not differently from after strength exercise. No changes in protein phosphorylation were observed in non-exercise controls. Endurance training produced an increase in maximal oxygen uptake and a decrease in submaximal exercise heart rate, while strength training produced increases in muscle cross-sectional area and strength. No changes in basal levels of signaling proteins were observed in response to training. The results support that in training-accustomed individuals, mTORC1 signaling is preferentially activated after hypertrophy-inducing exercise, while AMPK signaling is less specific for differentiated exercise.