The mechanism of curcumin to protect mouse ovaries from oxidative damage by regulating AMPK/mTOR mediated autophagy.

BACKGROUND: Oxidative stress is considered the main cause of granulosa cell apoptosis in ovarian disease. Curcumin has various biological roles, but its potential role in protecting granulosa cells from oxidative damage remains unidentified. PURPOSE: The study revealed the protective effect of curcumin on granulosa cell survival under oxidative stress, and explored its mode of action. STUDY DESIGN: The protective effect of curcumin on oxidative stress-induced ovarian cell apoptosis was evaluated in vivo and in vitro, and the role of autophagy and AMPK/mTOR signaling pathway in this process was also demonstrated. METHODS: First, mice were injected to 3-nitropropionic acid (3-NPA, 20 mg/kg/day) for 14 consecutive days to establish the ovarian oxidative stress model, at same time, curcumin (50, 100, 200 mg/kg/day) was given orally. Thereafter, functional changes, cell apoptosis, and autophagy in ovarian tissue were evaluated by hematoxylin-eosin staining, enzyme-linked immunosorbent assay, western blotting, TUNEL assays, and transmission electron microscopy. Finally, oxidative stress model of granulosa cells was established with H2O2in vitro and treated with curcumin. The underlying mechanisms of curcumin to protect the apoptosis under oxidative stress in vitro were determined using western blotting and TUNEL assays. RESULTS: In our study, after curcumin treatment, the mouse ovarian function disorder under 3-nitropropionic acid-induced oxidative stress recovered significantly, and ovarian cell apoptosis decreased. H2O2 induced granulosa cell apoptosis in vitro, and curcumin antagonized this process. Autophagy contributes to tissue and cell survival under stress. We therefore examined the role of autophagy in this process. According to the in vivo and in vitro results, curcumin restored autophagy under oxidative stress. The autophagy inhibitor (chloroquine) exhibited the same effect as curcumin, whereas the autophagy activator (rapamycin) antagonized the effect of curcumin. In addition, the study found that the AMPK/mTOR pathway plays a crucial role in curcumin- mediated autophagy to protect against oxidative stress-induced apoptosis. CONCLUSION: Our findings for the first time systematically revealed a new mechanism through which curcumin protects ovarian granulosa cells from oxidative stress-induced damage through AMPK/mTOR-mediated autophagy and suggested that it can be a new therapeutic direction for female ovarian diseases.

[Fuyu Decoction improves ventricular remodeling in rats with heart failure by inhibiting AMPK/mTOR pathway-mediated autophagy].

OBJECTIVE: To investigate the effect of Fuyu Decoction on ventricular remodeling and its association with AMPK/mTOR pathway-mediated autophagy in rats with heart failure. METHODS: Thirty male Wistar rat models of heart failure induced by ligation of the left anterior descending coronary artery were divided into model group, Fuyu Decoction treatment group, Fuyu Decoction treatment +AMPK agonist group (n=10), with another 10 rats receiving sham operation as the Sham group. After 8 weeks of drug intervention, the changes of ventricular function and ventricular remodeling indexs of the rats were assessed. TTC staining was used to detect the myocardial infarction area, and HE and Masson staining were used to observe the pathological changes in the myocardial tissue. Western blotting was performed to detect the protein expressions of p-AMPK, p-mTOR, LC3-II, Beclin1 and p62 in the myocardial tissue. RESULTS: Compared with the sham-operated rats, the rat models of heart failure showed significantly increased left ventricular end-diastolic volume (LVEDV), left ventricular endsystolic volume (LVESV), and left ventricular mass index (LVMI) (P < 0.01), reduced left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), and decreased spherical index (SI) were (P < 0.01). The rat models also showed increased myocardial infarction area, obvious myocardial pathologies and fibrosis, increased apoptosis rate of the cardiomyocytes, enhanced myocardial expressions of p-AMPK, LC3-II/LC3-I and Beclin1 (P < 0.01), and reduced expressions of p-mTOR and p62 (P < 0.01). Fuyu Decoction treatment significantly ameliorated these changes in the rat models (all P < 0.01), but its effects were obviously blocked by treatment with EX229. CONCLUSION: Fuyu Decoction can improve ventricular remodeling in rats with heart failure by inhibiting AMPK/mTOR signaling-mediated autophagy in the cardiomyocytes.

Arctium lappa leaves based on network pharmacology and experimental validation attenuate atherosclerosis by targeting the AMPK-mediated PPARG/LXRα pathway.

Arctium lappa (A. lappa) leaves are widely used in various traditional Chinese herbal formulae to ameliorate atherosclerosis (AS) and its complications such as stroke; however, there is no literature reporting the anti-atherosclerotic effect and mechanism of A. lappa leaves thus far. In the present study, we used network pharmacology and molecular docking approaches to examine the protective effect and potential mechanism of A. lappa leaves against AS in vivo and in vitro. From the network pharmacology, PPARG, HMGCR and SREBF2 were identified as the core targets of A. lappa leaves against AS. Further enrichment analyses of GO and KEGG pathways suggested that A. lappa leaves might play an anti-AS role by regulating metabolic processes and PPAR signalling pathways. The results of molecular docking experiment revealed that the major components of A. lappa leaves interacted with cholesterol efflux-regulating core proteins (PPARG, LXRα, ABCA1, and ABCG1), AMPK and SIRT1. Both in vivo and in vitro experimental results demonstrated that treatment with A. lappa leaves significantly lowered TC and LDL-C, increased HDL-C, and reduced cholesterol accumulation in the liver and aorta of the AS rat model and the foam cell model. Importantly, both in vivo and in vitro experimental results demonstrated that A. lappa leaves regulate the activity of the PPARG/LXRα signalling and AMPK/SIRT1 signalling pathways. Moreover, after treatment with the AMPK inhibitor Compound C in vitro, the improvement induced by A. lappa leaves was significantly reversed. In conclusion, A. lappa leaves attenuated AS-induced cholesterol accumulation by targeting the AMPK-mediated PPARG/LXRα pathway and promoting cholesterol efflux.

Quercetin for managing type 2 diabetes and its complications, an insight into multitarget therapy.

BACKGROUND: Quercetin, a bioflavonoid abundant in grapefruit, onion, berries, etc., has vast therapeutic potential, especially against Type 2 diabetes and its complications. Quercetin showed similar effects as that of metformin, (widely prescribed antidiabetic drug) in cell lines models (Sajan et al., 2010; Dhanya et al., 2017). In vivo findings also showcase it as a promising agent against diabetes and its pathophysiological complications. SCOPE AND APPROACH: Quercetin can be produced on a large scale through a novel fermentation-based glycosylation strategy from cheap substrates and can be utilized as a dietary supplement. The review focuses on the mounting evidence pointing to Quercetin as a promising candidate for managing type 2 diabetes and its oxidative stress mediated pathophysiological complications. CONCLUSION: Quercetin acts on multiple targets of diabetes and regulates key signalling pathways which improve the symptoms as well as the complications of Type 2 diabetes. However further studies are needed to improve the bioavailability and to establish a dosing regimen for Quercetin.

Orally Induced Hyperthyroidism Regulates Hypothalamic AMP-Activated Protein Kinase.

Besides their direct effects on peripheral metabolic tissues, thyroid hormones (TH) act on the hypothalamus to modulate energy homeostasis. However, since most of the hypothalamic actions of TH have been addressed in studies with direct central administration, the estimation of the relative contribution of the central vs. peripheral effects in physiologic conditions of peripheral release (or administration) of TH remains unclear. In this study we used two different models of peripherally induced hyperthyroidism (i.e., T4 and T3 oral administration) to assess and compare the serum and hypothalamic TH status and relate them to the metabolic effects of the treatment. Peripheral TH treatment affected feeding behavior, overall growth, core body temperature, body composition, brown adipose tissue (BAT) morphology and uncoupling protein 1 (UCP1) levels and metabolic activity, white adipose tissue (WAT) browning and liver metabolism. This resulted in an increased overall uncoupling capacity and a shift of the lipid metabolism from WAT accumulation to BAT fueling. Both peripheral treatment protocols induced significant changes in TH concentrations within the hypothalamus, with T3 eliciting a downregulation of hypothalamic AMP-activated protein kinase (AMPK), supporting the existence of a central action of peripheral TH. Altogether, these data suggest that peripherally administered TH modulate energy balance by various mechanisms; they also provide a unifying vision of the centrally mediated and the direct local metabolic effect of TH in the context of hyperthyroidism.

Graptopetalum paraguayense Extract Ameliorates Proteotoxicity in Aging and Age-Related Diseases in Model Systems.

Declines in physiological functions are the predominant risk factors for age-related diseases, such as cancers and neurodegenerative diseases. Therefore, delaying the aging process is believed to be beneficial in preventing the onset of age-related diseases. Previous studies have demonstrated that Graptopetalum paraguayense (GP) extract inhibits liver cancer cell growth and reduces the pathological phenotypes of Alzheimer's disease (AD) in patient IPS-derived neurons. Here, we show that GP extract suppresses ß-amyloid pathology in SH-SYS5Y-APP695 cells and APP/PS1 mice. Moreover, AMP-activated protein kinase (AMPK) activity is enhanced by GP extract in U87 cells and APP/PS1 mice. Intriguingly, GP extract enhances autophagy in SH-SYS5Y-APP695 cells, U87 cells, and the nematode Caenorhabditis elegans, suggesting a conserved molecular mechanism by which GP extract might regulate autophagy. In agreement with its role as an autophagy activator, GP extract markedly diminishes mobility decline in polyglutamine Q35 mutants and aged wild-type N2 animals in C. elegans. Furthermore, GP extract significantly extends lifespan in C. elegans.

Alpha-lipoic acid attenuates silica-induced pulmonary fibrosis by improving mitochondrial function via AMPK/PGC1α pathway activation in C57BL/6J mice.

Silicosis is characterized by pulmonary interstitial fibrosis that arises as a result of chronic exposure to silica. The few available treatments only delay its progression. As α-lipoic acid (ALA) has been shown to have various beneficial effects, including mitoprotective, antioxidant, and anti-inflammatory effects, we hypothesized that it may exhibit therapeutic effects in pulmonary fibrosis. Therefore, in the present study, we used a murine model of silicosis to investigate whether supplementation with exogenous ALA could attenuate silica-induced pulmonary fibrosis by improving mitochondrial function. ALA was administered to the model mice via continuous intragastric administration for 28 days, and then the antioxidant and mitoprotective effects of ALA were evaluated. The results showed that ALA decreased the production of reactive oxygen species, protected mitochondria from silica-induced dysfunction, and inhibited extracellular matrix deposition. ALA also decreased hyperglycemia and hyperlipidemia. Activation of the mitochondrial AMPK/PGC1α pathway might be responsible for these ALA-mediated anti-fibrotic effects. Exogenous ALA blocked oxidative stress by activating NRF2. Taken together, these findings demonstrate that exogenous ALA effectively prevents the progression of silicosis in a murine model, likely by stimulating mitochondrial biogenesis and endogenous antioxidant responses. Therefore, ALA can potentially delay the progression of silica-induced pulmonary fibrosis.

Protective Effect of Jiang Tang Xiao Ke Granules against Skeletal Muscle IR via Activation of the AMPK/SIRT1/PGC-1α Signaling Pathway.

The Jiang Tang Xiao Ke (JTXK) granule is a classic Chinese herbal formula that has been put into clinical use in the treatment of type 2 diabetes mellitus for decades. However, whether its ability to ameliorate skeletal muscle insulin resistance (IR) is through modulation of the AMPK/SIRT1/PGC-1α signaling pathway remains unknown. Therefore, we aimed to investigate the effects of JTXK granules on IR in skeletal muscle of high-fat diet-induced diabetic mice and C2C12 cells and analyze the underlying mechanisms. In the present study, we showed that JTXK granules attenuated body weight gain, reduced body fat mass, improved body lean mass, and enhanced muscle performance of diabetic mice. JTXK granules also improved glucose metabolism and skeletal muscle insulin sensitivity and partially reversed abnormal serum lipid levels, which might be related to the regulation of the AMPK/SIRT1/PGC-1α pathway, both in skeletal muscle tissue of diabetic mice and in C2C12 cells. Furthermore, drug-containing serum of JTXK granules was capable of enhancing glucose uptake and mitochondrial respiration in C2C12 cells, and AMPKα was proven to be closely involved in this process. Taken together, these results suggest that the JTXK granule ameliorates skeletal muscle IR through activation of the AMPK/SIRT1/PGC-1α signaling pathway, which offers a novel perspective of this formula to combat IR-related metabolic diseases.

Selenite supplementation modulates the hepatic metabolic sensors AMPK and SIRT1 in binge drinking exposed adolescent rats by avoiding oxidative stress.

Binge drinking (BD) is the main alcohol consumption pattern among teenagers. Recently, oxidative stress (OS) generated by BD exposure has been related to hepatic metabolic deregulation and cardiovascular dysfunction. This study analyzed if BD by generating oxidative stress modulates the alteration in hepatic energy homeostasis through two important regulators of energy metabolism: the NAD+-dependent sirtuin deacetylase (SIRT1) and AMP-activated protein kinase (AMPK) and if supplementation with the antioxidant selenium (Se) improves these metabolic disorders. Four groups of adolescent rats supplemented or not with Se (0.4 ppm) and exposed to intermittent i.p. BD were used. BD rats showed an increased AST/ALT ratio, total bilirubin in serum and lipid peroxidation in the liver. The BD rats also showed a higher abdominal/thoracic ratio and increased levels of TG, gluc, and chol compared to the control group, provoking an increase in mean blood pressure (MBP). This alcohol consumption pattern decreased hepatic Se deposits, cytoplasmic GPx activity, and GSH levels as well as the expressions of two metabolic sensors and the pAMPK/AMPK ratio. Se supplementation restored antioxidant parameters and decreased lipid oxidation, avoiding OS and improving the hepatic expression of pAMPK and SIRT1, contributing to the improvement of metabolic (better lipid profile and IRS-1 expression) and vascular function (lower MBP), and to the increase of hepatic functionality (lower AST/ALT ratio). All these actions decrease cardiometabolic risk factor development in the short and long term and could disrupt the relationship between BD and MS, two problems which are currently affecting adolescents.

p-Coumaric Acid Enhances Hypothalamic Leptin Signaling and Glucose Homeostasis in Mice via Differential Effects on AMPK Activation.

AMP-activated protein kinase (AMPK) plays a crucial role in the regulation of energy homeostasis in both peripheral metabolic organs and the central nervous system. Recent studies indicated that p-Coumaric acid (CA), a hydroxycinnamic phenolic acid, potentially activated the peripheral AMPK pathway to exert beneficial effects on glucose metabolism in vitro. However, CA's actions on central AMPK activity and whole-body glucose homeostasis have not yet been investigated. Here, we reported that CA exhibited different effects on peripheral and central AMPK activation both in vitro and in vivo. Specifically, while CA treatment promoted hepatic AMPK activation, it showed an inhibitory effect on hypothalamic AMPK activity possibly by activating the S6 kinase. Furthermore, CA treatment enhanced hypothalamic leptin sensitivity, resulting in increased proopiomelanocortin (POMC) expression, decreased agouti-related peptide (AgRP) expression, and reduced daily food intake. Overall, CA treatment improved blood glucose control, glucose tolerance, and insulin sensitivity. Together, these results suggested that CA treatment enhanced hypothalamic leptin signaling and whole-body glucose homeostasis, possibly via its differential effects on AMPK activation.

Brain Permeable AMP-Activated Protein Kinase Activator R481 Raises Glycaemia by Autonomic Nervous System Activation and Amplifies the Counterregulatory Response to Hypoglycaemia in Rats.

Aim: We evaluated the efficacy of a novel brain permeable "metformin-like" AMP-activated protein kinase activator, R481, in regulating glucose homeostasis. Materials and Methods: We used glucose sensing hypothalamic GT1-7 neuronal cells and pancreatic αTC1.9 α-cells to examine the effect of R481 on AMPK pathway activation and cellular metabolism. Glucose tolerance tests and hyperinsulinemic-euglycemic and hypoglycemic clamps were used in Sprague-Dawley rats to assess insulin sensitivity and hypoglycemia counterregulation, respectively. Results: In vitro, we demonstrate that R481 increased AMPK phosphorylation in GT1-7 and αTC1.9 cells. In Sprague-Dawley rats, R481 increased peak glucose levels during a glucose tolerance test, without altering insulin levels or glucose clearance. The effect of R481 to raise peak glucose levels was attenuated by allosteric brain permeable AMPK inhibitor SBI-0206965. This effect was also completely abolished by blockade of the autonomic nervous system using hexamethonium. During hypoglycemic clamp studies, R481 treated animals had a significantly lower glucose infusion rate compared to vehicle treated controls. Peak plasma glucagon levels were significantly higher in R481 treated rats with no change to plasma adrenaline levels. In vitro, R481 did not alter glucagon release from αTC1.9 cells, but increased glycolysis. Non brain permeable AMPK activator R419 enhanced AMPK activity in vitro in neuronal cells but did not alter glucose excursion in vivo. Conclusions: These data demonstrate that peripheral administration of the brain permeable "metformin-like" AMPK activator R481 increases blood glucose by activation of the autonomic nervous system and amplifies the glucagon response to hypoglycemia in rats. Taken together, our data suggest that R481 amplifies the counterregulatory response to hypoglycemia by a central rather than a direct effect on the pancreatic α-cell. These data provide proof-of-concept that central AMPK could be a target for future drug development for prevention of hypoglycemia in diabetes.

POCU1b, the n-Butanol Soluble Fraction of Polygoni Cuspidati Rhizoma et Radix, Attenuates Obesity, Non-Alcoholic Fatty Liver, and Insulin Resistance via Inhibitions of Pancreatic Lipase, cAMP-Dependent PDE Activity, AMPK Activation, and SOCS-3 Suppression.

This study investigated the effects of the n-BuOH soluble fraction of Polygoni Cuspidati 80% ethanol extract (POCU1b) on high-fat diet (HFD)-induced obesity, non-alcoholic fatty liver (NAFL), and insulin resistance (IR) to find a safe and more effective agent. HPLC profiling of POCU1b identified seven marker compounds. POCU1b increased glycerol release, cyclic adenosine monophosphate (cAMP) level, and inhibited phosphodiesterase (PDE) activity. Seven weeks of POCU1b treatment decreased body weight gain, weight and adipocyte size in fat tissues, serum lipids, and triglyceride and lipid droplets in the livers of HFD-fed rats. POCU1b improved blood glucose, insulin sensitivity, and impaired insulin secretion in the pancreas. Further, POCU1b ameliorated adiponectin, leptin, IL-6 and TNF-α levels, increased AMPK and p-ACC expression, activated CPT-1 activity, and suppressed FAS mRNA, SOCS-3 protein expression, and NF-κB DNA-binding activity. When compared with the Xenical®-treated group, a positive group, the action of POCU1b on body weight was more effective than that of Xenical. POCU1b did not show side effects, such as oily spotting and loss of appetite. These results suggest that POCU1b possesses therapeutic or preventive potential for obesity, NAFL and IR via inhibitions of pancreatic lipase and cAMP-dependent PDE activity, AMPK activation, and SOCS-3 suppression, without oily spotting and loss of appetite.

Coumestrol ameliorates doxorubicin-induced cardiotoxicity via activating AMPKα.

Doxorubicin (DOX) acts as the cornerstone in multiple tumour chemotherapy regimens, however, its clinical application is often impeded due to the induction of a severe cardiotoxicity that eventually provokes left ventricular dysfunction and congestive heart failure. Coumestrol (CMT) is a common dietary phytoestrogen with pleiotropic pharmacological effects. The present study aims to investigate the role and mechanism of CMT on DOX-induced cardiotoxicity. Mice were intragastrically administrated with CMT (5 mg/kg/day) for consecutive 2 weeks and then received a single intraperitoneal injection of DOX (15 mg/kg) to mimic the clinical toxic effects after 8-day additional feeding. To verify the role of 5' AMP-activated protein kinase alpha (AMPKα), AMPKα2 global knockout mice were used. H9C2 cells were cultured to further validate the beneficial role of CMT in vitro. CMT administration notably ameliorated oxidative damage, cell apoptosis and cardiac dysfunction in DOX-treated mice. Besides, we observed that DOX-induced reactive oxygen species overproduction and cardiomyocyte apoptosis were also reduced by CMT incubation in H9C2 cells. Mechanistically, CMT activated AMPKα and Ampkα deficiency abolished the beneficial effects of CMT in vivo and in vitro. Finally, we proved that protein kinase A (PKA) was required for CMT-mediated AMPKα activation and cardioprotective effects. CMT activated PKA/AMPKα pathway to alleviate DOX-induced oxidative damage, cell apoptosis and cardiac dysfunction. Our findings provide a promising therapeutic agent for cancer patients receiving anthracycline chemotherapy.

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.

Superior hypoglycemic activity of mulberry lacking monosaccharides is accompanied by better activation of the PI3K/Akt and AMPK signaling pathways.

Mulberry has been used as a functional food to treat type 2 diabetes mellitus (T2DM). However, it contains relatively high levels of fructose and glucose, which are not suitable for excess consumption by diabetic patients. In this study we used microbial fermentation to remove fructose and glucose from mulberry fruit, and then determined the effects on glycemia, the phosphatidylinositol 3-hydroxykinase/Akt (PI3K/Akt) and adenosine monophosphate-activated protein kinase (AMPK) signaling pathways and their downstream effectors in T2DM mice. After 5 weeks of administration, fermented mulberry (FM) significantly reduced fasting blood glucose, and also improved insulin sensitivity and glucose tolerance, more effectively than unfermented mulberry (MP). Moreover, compared with MP, FM had a more marked effect on the protein expression of intermediates in the PI3K/Akt and AMPK signaling pathways and their effectors: insulin receptor, phosphorylated Akt (Ser 308), phosphorylated glycogen synthase kinase-3ß (Ser 9), glycogen synthetase, phosphorylated forkhead transcription factor 1 (Ser 256), pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1, 6-bisphosphatase, glucose-6-phosphatase, lipoprotein lipase, and phosphorylated AMPK (Thr 172), glucose transporter 4 and pyruvate kinase. These findings indicate that mulberry fruit modified to remove fructose and glucose may be more promising than whole mulberry as a treatment for diabetes.

A phytoestrogen secoisolariciresinol diglucoside induces browning of white adipose tissue and activates non-shivering thermogenesis through AMPK pathway.

Secoisolariciresinol diglucoside (SDG) is the main phytoestrogen component of flaxseed known as an antioxidant. Current study focused on the effect of SDG in white adipose tissue (WAT) browning. Browning of WAT is considered as a promising treatment strategy for metabolic diseases. To demonstrate the effect of SDG as an inducer of browning, brown adipocyte markers were investigated in inguinal WAT (iWAT) of high fat diet-fed obese mice and genetically obese db/db mice after SDG administration. SDG increased thermogenic factors such as uncoupling protein 1, peroxisome proliferator-activated receptor gamma coactivator 1 alpha and PR domain containing 16 in iWAT and brown adipose tissue (BAT) of mice. Similar results were shown in beige-induced 3T3-L1 adipocytes and primary cultured brown adipocytes. Furthermore, SDG increased factors of mitochondrial biogenesis and activation. We also observed SDG-induced alteration of AMP-activated protein kinase α (AMPKα). As AMPKα is closely related in the regulation of adipogenesis and thermogenesis, we then evaluated the effect of SDG in AMPKα-inhibited conditions. Genetic or chemical inhibition of AMPKα demonstrated that the role of SDG on browning and thermogenesis was dependent on AMPKα signaling. In conclusion, our data suggest SDG as a potential candidate for improvement of obesity and other metabolic disorders.

Berberine induces apoptosis in glioblastoma multiforme U87MG cells via oxidative stress and independent of AMPK activity.

Glioblastoma multiforme (GM) is the most prevalent tumor among gliomas and presents the highest mortality rate among brain tumors. Berberine (BBR) is an alkaloid isoquinoline found in medicinal plants such as Coptis chinensis. Studies have been showed that BBR presents protective activity in mesenchymal cells and neurons, and antitumor properties in breast cancer and hepatocarcinoma. The aim of this study was to investigate the antitumor effects of BBR in GM U87MG cells, as well as to identify, whether such effects are mediated by oxidative stress and canonical apoptotic pathways. After treatment with several concentrations of BBR (10, 25, 100 and 250 µM) for 24, 48 and 72 h of exposure, BBR reduce cell viability of U87MG cells in a concentration- and time-dependent manner. Afterwards, it was observed that BBR, starting at a concentration of 25 µM of 24 h exposure, significantly suppressed proliferation and increased early apoptosis (53.5% ± 11.15 of annexin V+ propidium iodide- cells) compared to untreated cells (7.5% ± 4.6). BBR-induced apoptosis was independent from AMPK activity and did not change total caspase-3 and p-p53 levels. Moreover, BBR (25 µM/24 h) increased oxidative stress in U87MG cells, evidenced by high levels of reactive oxygen species, thiobarbituric acid reactive substance and protein carbonylation. Considering the antitumor effects of BBR in U87MG cells, this compound may be a potential candidate for adjuvant GM treatment.

Olanzapine increases AMPK-NPY orexigenic signaling by disrupting H1R-GHSR1a interaction in the hypothalamic neurons of mice.

Second generation antipsychotics, particularly olanzapine, induce severe obesity, which is associated with their antagonistic effect on the histamine H1 receptor (H1R). We have previously demonstrated that oral administration of olanzapine increases the concentration of neuropeptide Y (NPY) in the hypothalamus of rats, accompanied by hyperphagia and weight gain. However, it is unclear if the increased NPY after olanzapine administration is due to its direct effect on hypothalamic neurons and its H1R antagonistic property. In the present study, we showed that with an inverted U-shape dose-response curve, olanzapine increased NPY expression in the NPY-GFP hypothalamic neurons; however, this was not the case in the hypothalamic neurons of H1R knockout mice. Olanzapine inhibited the interaction of H1R and GHSR1a (ghrelin receptor) in the primary mouse hypothalamic neurons and NPY-GFP neurons examined by confocal fluorescence resonance energy transfer (FRET) technology. Furthermore, an H1R agonist, FMPH inhibited olanzapine activation of GHSR1a downstream signaling pAMPK and transcription factors of NPY (pFOXO1 and pCREB) in the hypothalamic NPY-GFP cell. However, an olanzapine analogue (E-Olan) with lower affinity to H1R presented negligible enhancement of pCREB within the nucleus of NPY neurons. These findings suggest that the H1R antagonist property of olanzapine inhibits the interaction of H1R and GHSR1a, activates GHSR1a downstream signaling pAMPK-FOXO1/pCREB and increases hypothalamic NPY: this could be one of the important molecular mechanisms of H1R antagonism of olanzapine-induced obesity in antipsychotic management of psychiatric disorders.

Dietary apple polyphenols promote fat browning in high-fat diet-induced obese mice through activation of adenosine monophosphate-activated protein kinase α.

BACKGROUND: Promoting brown and beige adipogenesis contributes to adaptive thermogenesis, which provides a defense against obesity and related disorders. Apple polyphenols (APs) play a significant role in treating variety of metabolic diseases. This study was conducted to determine the effects of APs on the development of brown and beige adipocytes and thermogenesis and investigate whether these effects are mediated by adenosine monophosphate-activated protein kinase (AMPK). High-fat diet (HFD)-induced obese mice and differentiated 3T3-L1 adipocytes were subjected to APs treatment. The thermogenic program and associated regulatory factors, and the involvement of AMPKα was assessed. RESULTS: Dietary APs supplementation reduced adiposity and improved insulin sensitivity in HFD-induced obese mice. Moreover, APs increased the oxygen consumption and heat production and decreased respiratory exchange ratio, which were accompanied by the upregulation of thermogenic genes expression and the activation of AMPKα in brown fat and inguinal white fat. Further, APs treatment directly increased expression of brown adipogenic markers and induced phosphorylation of AMPKα in differentiated 3T3-L1 adipocytes, whereas the beneficial effects of APs were reversed by AMPK inhibition. CONCLUSION: Our results provide new insights into the function of APs in regulating brown/beige adipogenesis and adaptive thermogenesis and suggest the potential application of APs in the prevention and therapeutics of obesity and associated metabolic diseases. © 2020 Society of Chemical Industry.

Gypenoside A protects ischemia/reperfusion injuries by suppressing miR-143-3p level via the activation of AMPK/Foxo1 pathway.

Ischemia-reperfusion (I/R) injury is a major side effect associated with coronary heart disease (CHD). Gypenoside A (GP) is one of the dominant active components of Gynostemma pentaphyllum and has the potential to attenuate myocardial I/R injuries. The major purpose of this study was to explore the mechanism driving the protective effect of GP on myocardial tissue by focusing on the interaction between GP and miR-143-3p. Cardiomyocytes were pre-treated with GP and subjected to oxygen-glucose deprivation/re-oxygenation (OGD/R). Changes in cell viability, apoptosis, and expression levels of factors involved in the adenosine monophosphate activated protein kinase (AMPK)/Foxo1-mediated miR-143-3p pathway were detected. The levels of AMPK and miR-143-3p were then modulated using an inhibitor and a mimic, respectively, to confirm their central roles in the effect of GP. The administration of GP attenuated OGD/R-induced injuries by increasing cell viability and suppressing apoptosis, which was associated with the activation of AMPK/Foxo1 signaling and the decreased level of miR-143-3p. The down-regulation of AMPK and up-regulation of miR-143-3p both counteracted the function of GP on cardiomyocytes. The role of miR-143-3p suppression in the anti-I/R effect of GP was also verified with rat model. The injection of miR-143-3p agomir inhibited the cardio-protective effect of GP in a manner similar to that in the in vitro assays. Our results confirm the cardio-protective effect of GP, which is exerted by suppressing the level of miR-143-3p via the activation of AMPK signaling.