Phosphorylation of the insulin receptor by AMP-activated protein kinase (AMPK) promotes ligand-independent activation of the insulin signalling pathway in rodent muscle

Dietary inclusion of Clostridium butyricum cultures alleviated impacts of high-carbohydrate diets in largemouth bass (Micropterus salmoides)

A 60-d feeding trial was conducted to explore the potential regulatory effects of dietary Clostridium butyricum cultures (CBC) supplementation in high-carbohydrate diet (HCD) on carbohydrate utilisation, antioxidant capacity and intestinal microbiota of largemouth bass. Triplicate groups of largemouth bass (average weight 35·03 ± 0·04 g), with a destiny of twenty-eight individuals per tank, were fed low-carbohydrate diet and HCD supplemented with different concentration of CBC (0 %, 0·25 %, 0·50 % and 1·00 %). The results showed that dietary CBC inclusion alleviated the hepatic glycogen accumulation induced by HCD intake. Additionally, the expression of hepatic ampkα1 and insulin signaling pathway-related genes (ira, irb, irs, p13kr1 and akt1) increased linearly with dietary CBC inclusion, which might be associated with the activation of glycolysis-related genes (gk, pfkl and pk). Meanwhile, the expression of intestinal SCFA transport-related genes (ffar3 and mct1) was significantly increased with dietary CBC inclusion. In addition, the hepatic antioxidant capacity was improved with dietary CBC supplementation, as evidenced by linear decrease in malondialdehyde concentration and expression of keap1, and linear increase in antioxidant enzyme activities (total antioxidative capacity, total superoxide dismutase and catalase) and expression of antioxidant enzyme-related genes (nrf2, sod1, sod2 and cat). The analysis of bacterial 16S rRNA V3-4 region indicated that dietary CBC inclusion significantly reduced the enrichment of Firmicutes and potential pathogenic bacteria genus Mycoplasma but significantly elevated the relative abundance of Fusobacteria and Cetobacterium. In summary, dietary CBC inclusion improved carbohydrate utilization, antioxidant capacity and intestinal microbiota of largemouth bass fed HCD.

Insulin Resistance/Hyperinsulinemia, Neglected Risk Factor for the Development and Worsening of Heart Failure with Preserved Ejection Fraction

Heart failure (HF) has become a subject of continuous interest since it was declared a new pandemic in 1997 because of the exponential increase in hospitalizations for HF in the latest years. HF is the final state to which all heart diseases of different etiologies lead if not adequately treated. It is highly prevalent worldwide, with a progressive increase with age, reaching a prevalence of 10% in subjects over the age of 65 years. During the last two decades, it was possible to see that the prevalence of heart failure with preserved ejection fraction (HFpEF) was increasing while that of heart failure with reduced ejection fraction (HFrEF) was decreasing. HFpEF is typically characterized by concentric remodeling of the left ventricle (LV) with impaired diastolic function and increased filling pressures. Over the years, also the prevalence of insulin resistance (IR)/hyperinsulinemia (Hyperins) in the general adult population has progressively increased, primarily due to lifestyle changes, particularly in developed and developing countries, with a range that globally ranges between 15.5% and 46.5%. Notably, over 50% of patients with HF also have IR/Hyperins, and the percentage is even higher in those with HFpEF. In the scientific literature, it has been well highlighted that the increased circulating levels of insulin, associated with conditions of insulin resistance, are responsible for progressive cardiovascular alterations over the years that could stimulate the development and/or the worsening of HFpEF. The aim of this manuscript was to review the scientific literature that supports a pathophysiologic connection between IR/Hyperins and HFpEF to stimulate the scientific community toward the identification of hyperinsulinemia associated with insulin resistance as an independent cardiovascular risk factor in the development and worsening of HF, believing that its adequate screening in the general population and an appropriate treatment could reduce the prevalence of HFpEF and improve its progression.

Alpha-Mangosteen lessens high-fat/high-glucose diet and low-dose streptozotocin induced-hepatic manifestations in the insulin resistance rat model

CONTEXT

α-Mangosteen (α-MG) attenuates insulin resistance (IR). However, it is still unknown whether α-MG could alleviate hepatic manifestations in IR rats.

OBJECTIVE

To investigate the effect of α-MG on alleviating hepatic manifestations in IR rats through AMP-activated protein kinase (AMPK) and sterol-regulatory element-binding protein-1 (SREBP-1) pathway.

MATERIALS AND METHODS

IR was induced by exposing male Sprague-Dawley rats (180-200 g) to high-fat/high-glucose diet and low-dose injection of streptozotocin (HF/HG/STZ), then treated with α-MG at a dose of 100 or 200 mg/kg/day for 8 weeks. At the end of the study (11 weeks), serum and liver were harvested for biochemical analysis, and the activity of AMPK, SREBP-1c, acetyl-CoA carboxylase (ACC), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, insulin receptor substrate (IRS)-1, Bax and liver histopathology were analyzed.

RESULTS

α-MG at both doses significantly lowered ALT, AST, triglyceride, and cholesterol total by 16.5, 15.7, 38, and 36%, respectively. These beneficial effects of α-MG are associated with the downregulation of the IR-induced inflammation in the liver. Furthermore, α-MG, at both doses, activated AMPK by 24-29 times and reduced SREBP-1c by 44-50% as well as ACC expression by 19-31% similar to metformin. All treatment groups showed liver histopathology improvement regarding fat deposition in the liver.

CONCLUSIONS

Based on the findings demonstrated, α-MG protected against HF/HG/STZ-induced hepatic manifestations of the IR rats, at least in part via the modulation of the AMPK/SREBP-1c/ACC pathway and it could be a potential drug candidate to prevent IR-induced hepatic manifestations.

The Negative Impact of Insulin Resistance/Hyperinsulinemia on Chronic Heart Failure and the Potential Benefits of Its Screening and Treatment

This opinion article highlights the potential alterations caused by insulin resistance and hyperinsulinemia on the cardiovascular system and their negative impact on heart failure (HF), and describes the potential benefits of an early screening with consequent prompt treatment. HF is the final event of several different cardiovascular diseases. Its incidence has been increasing over the last decades because of increased survival from ischemic heart disease thanks to improvements in its treatment (including myocardial revascularization interventions) and the increase in life span. In particular, incidence of HF with preserved ejection fraction (HFpEF) is significantly increasing, and patients with HFpEF often are also affected by diabetes mellitus and insulin resistance (IR), with a prevalence > 45%. Concentric left ventricular (LV) remodeling and diastolic dysfunction are the main structural abnormalities that characterize HFpEF. It is well documented in the literature that IR with chronic hyperinsulinemia, besides causing type 2 diabetes mellitus, can cause numerous cardiovascular alterations, including endothelial dysfunction and increased wall thicknesses of the left ventricle with concentric remodeling and diastolic dysfunction. Therefore, it is conceivable that IR might play a major role in the pathophysiology and the progressive worsening of HF. To date, several substances have been shown to reduce IR/hyperinsulinemia and have beneficial clinical effects in patients with HF, including SGLT2 inhibitors, metformin, and berberine. For this reason, an early screening of IR could be advisable in subjects at risk and in patients with heart failure, to promptly intervene with appropriate therapy. Future studies aimed at comparing the efficacy of the substances used both alone and in association are needed.

A Descriptive Review of the Action Mechanisms of Berberine, Quercetin and Silymarin on Insulin Resistance/Hyperinsulinemia and Cardiovascular Prevention

Insulin resistance (IR) and the associated hyperinsulinemia are early pathophysiological changes which, if not well treated, can lead to type 2 diabetes, endothelial dysfunction and cardiovascular disease. While diabetes care is fairly well standardized, the prevention and treatment of IR lacks a single pharmaceutical approach and many lifestyle and dietary interventions have been proposed, including a wide range of food supplements. Among the most interesting and well-known natural remedies, alkaloid berberine and the flavonol quercetin have particular relevance in the literature, while silymarin-the active principle of the Silybum marianum thistle-was traditionally used for lipid metabolism disorders and to sustain liver function. This review describes the major defects of insulin signaling leading to IR and the main properties of the three mentioned natural substances, their molecular targets and synergistic action mechanisms. The actions of berberine, quercetin and silymarin are partially superimposable as remedies against reactive oxygen intermediates generated by a high-lipid diet and by NADPH oxidase, which is triggered by phagocyte activation. Furthermore, these compounds inhibit the secretion of a battery of pro-inflammatory cytokines, modulate intestinal microbiota and are especially able to control the various disorders of the insulin receptor and post-receptor signaling systems. Although most of the evidence on the effects of berberine, quercetin and silymarin in modulating insulin resistance and preventing cardiovascular disease derive from experimental studies on animals, the amount of pre-clinical knowledge strongly suggests the need to investigate the therapeutic potential of these substances in human pathology.

Imaging Methods Applicable in the Diagnostics of Alzheimer's Disease, Considering the Involvement of Insulin Resistance

Alzheimer's disease (AD) is an incurable neurodegenerative disease and the most frequently diagnosed type of dementia, characterized by (1) perturbed cerebral perfusion, vasculature, and cortical metabolism; (2) induced proinflammatory processes; and (3) the aggregation of amyloid beta and hyperphosphorylated Tau proteins. Subclinical AD changes are commonly detectable by using radiological and nuclear neuroimaging methods such as magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), and single-photon emission computed tomography (SPECT). Furthermore, other valuable modalities exist (in particular, structural volumetric, diffusion, perfusion, functional, and metabolic magnetic resonance methods) that can advance the diagnostic algorithm of AD and our understanding of its pathogenesis. Recently, new insights into AD pathoetiology revealed that deranged insulin homeostasis in the brain may play a role in the onset and progression of the disease. AD-related brain insulin resistance is closely linked to systemic insulin homeostasis disorders caused by pancreas and/or liver dysfunction. Indeed, in recent studies, linkages between the development and onset of AD and the liver and/or pancreas have been established. Aside from standard radiological and nuclear neuroimaging methods and clinically fewer common methods of magnetic resonance, this article also discusses the use of new suggestive non-neuronal imaging modalities to assess AD-associated structural changes in the liver and pancreas. Studying these changes might be of great clinical importance because of their possible involvement in AD pathogenesis during the prodromal phase of the disease.

Plantain flour: A potential anti-obesity ingredient for intestinal flora regulation and improved hormone secretion

Introduction

Development of functional food ingredients with anti-obesity is a growing interest in the global food industry. Plantain (Musa spp. AAB), a special type of cooking/starchy banana, is widely growing in African and Latin American countries. The flour made from unripe plantain pulp, which is considered as a natural source of indigestible carbohydrates such as resistant starch (RS), could be used in the formulation of diverse functional foods due to its anti-obesity properties. However, the mechanisms underlying the anti-obesity properties of plantain flour are not explored.

Methods

In this study, we investigated the changes in serum hormone levels, liver transcriptome profiles, and the modulation of gut microbiota in high-fat-fed Sprague-Dawley (SD) rats. The male SD rats were divided into six groups, viz. two control groups [non-obese (NC) or obese (OC)] which were not given the supplementation, one positive control (PC) group which received orlistat supplementation (60 mg/kg body weight/day), and three groups of obese rats which were supplemented with unripe plantain flour (UPF) at a dosage (body weight/day) of 1.25 g/kg (low-dose, LD), 2.50 g/kg (intermediate-dose, MD) or 5.0 g/kg (high-dose, HD).

Results and discussion

It was found that UPF supplementation could lower the insulin levels of the obese rats. Moreover, UPF supplementation had a positive impact on gut microbiota, decreasing the relative abundances of Blautia, Parasutterella and Fusicatenibacter which were closely related to obesity, and increasing the relative abundances of probiotics (Allobaculum, Romboutsia, Staphylococcus, and Bacteroides). The spearman correlation analysis revealed that UPF supplementation reduced the relative abundance of Parasutterella and possibly decreased the blood sugar levels, leading to a decrease in the relative abundances of Blautia and Fusicatenibacter and a subsequent decrease in insulin levels. Furthermore, transcriptomic analysis of the liver tissues displayed that the peroxisome proliferator activated receptor-1α (PPAR) and AMP-activated protein kinase (AMPK) signaling pathway genes (Pparaa, Cpt1a, Prkaa1, Prkab1, Prkaa2, and Ppargc1a) were upregulated in those groups supplemented with UPF. These results indicated that UPF could mediate the glucolipid metabolism in the obese rats. Taken together, our findings suggested that the anti-obesity properties of UPF could be achieved by decreasing the insulin levels, positive-regulating of the gut microbiota composition as well as altering gene expression related to glucolipid metabolism.

Camel milk protein hydrosylate alleviates hepatic steatosis and hypertension in high fructose-fed rats

CONTEXT

Camel milk is used in traditional medicine to treat diabetes mellitus hypertension and other metabolic disorders.

OBJECTIVE

This study evaluated the antisteatotic and antihypertensive effects of camel milk protein hydrolysate (CMH) in high fructose (HF)-fed rats and compared it with the effects afforded by the intact camel milk protein extract (ICM).

MATERIALS AND METHODS

Adult male Wistar rats were divided into 6 groups (n = 8 each) as 1) control, 2) ICM (1000 mg/kg), 3) CMH (1000 mg/kg), 4) HF (15% in drinking water), 5) HF (15%) + ICM (1000 mg/kg), and 6) HF (15%) + CMH (1000 mg/kg). All treatments were given orally for 21 weeks, daily.

RESULTS

Both ICM and CMH reduced fasting glucose and insulin levels, serum and hepatic levels of cholesterol and triglycerides, and serum levels of ALT and AST, angiotensin II, ACE, endothelin-1, and uric acid in HF-fed rats. In addition, both ICM and CMH reduced hepatic fat deposition in the hepatocytes and reduced hepatocyte damage. This was associated with an increase in the hepatic activity of AMPK, higher PPARα mRNA, reduced expression of fructokinase C, SREBP1, SREBP2, fatty acid synthase, and HMG-CoA-reductase. Both treatments lowered systolic and diastolic blood pressure. However, the effects of CMH on all these parameters were greater as compared to ICM.

DISCUSSION AND CONCLUSIONS

The findings of this study encourage the use of CMH in a large-scale population and clinical studies to treat metabolic steatosis and hypertension.

AdipoRon induces AMPK activation and ameliorates Alzheimer's like pathologies and associated cognitive impairment in APP/PS1 mice

Alzheimer's disease (AD) is a progressive devastating neurodegenerative disorder characterized by extracellular amyloid beta (Aβ₄₂) plaque formation, hyperphosphorylation of tau protein leading to intracellular neurofibrillary tangle formation. Recently discovered hallmark features responsible for AD pathogenesis are neuronal insulin resistance, dysregulation in adiponectin and AMPK signaling. The presence of adiponectin and its receptor in the brain with its unique anti-diabetic effects and association with neurodegenerative diseases has raised our interest in exploring orally active small molecule adiponectin receptor agonist, AdipoRon. To date, all the available drugs for the treatment of AD provides symptomatic relief and do not stall the progression of the disease. Indeed, it is becoming increasingly apparent to find appropriate targets. Here, we attempt to shed lights on adiponectin receptor agonist, AdipoRon and its downstream molecular targets in reducing disease pathogenesis and insulin resistance. In brain, AdipoRon induced AMPK activation, increased insulin sensitivity, reduced amyloid beta plaque deposition and improved cognitive impairment. Levels of BACE were also downregulated while LDLR, APOE and neprilysin were upregulated promoting amyloid beta clearance from brain. AdipoRon further reduced the chronic inflammatory marker, GFAP and improved synaptic markers PSD-95 and synaptophysin in APP/PS1 mice. Our in-vitro studies further confirmed the potential role of AdipoRon in improving insulin sensitivity by increasing GLUT 4 translocation, glucose uptake and insulin signaling under hyperinsulinemic condition. Our findings suggest that AdipoRon could be a promising lead in the future treatment strategies in the development of effective AD treatment.

Aqueous extract of Scrophularia ningpoensis improves insulin sensitivity through AMPK-mediated inhibition of the NLRP3 inflammasome

BACKGROUND

Scrophularia ningpoensis Hemsl. is a commonly used medicinal plant in China for the treatment of diabetes mellitus (DM), but its mechanism of action remains poorly described. Type 2 diabetes mellitus (T2DM) accounts for > 90% of all DM cases and is characterized by insulin resistance.

PURPOSE

The aim of this study was to investigate whether the insulin sensitivity can be improved by treatment with aqueous extract of S. ningpoensis (AESN) and further explore its mechanism(s) of activity.

METHODS

Primary mouse hepatocytes and human HepG2 hepatocytes were used to investigate the effects of AESN on cell viability, AMP-activated protein kinase (AMPK) activation and glucose output under normal culture conditions. To mimic hyperglycemia and insulin resistance in vitro, hepatocytes were exposed to high glucose (HG), and the influences of AESN on AMPK phosphorylation, NLRP3 inflammation activation, insulin signaling, lipid accumulation and glucose output were investigated. Increasing doses of AESN (50, 100 and 200 mg/kg/day) were administered by gavage to db/db mice for 8 weeks, and then biochemical analysis and histopathological examinations were performed.

RESULTS

AESN significantly activated AMPK and inhibited glucose output in hepatocytes, but did not impact cell viability under normal culture conditions. Moreover, in HG-treated hepatocytes, AESN protected against aberrant AMPK activity, NLRP3 inflammasome activation, insulin signaling, and lipid accumulation. AMPK inhibition abolished the regulatory effects of AESN on the NLRP3 inflammasome, insulin signaling, lipid accumulation, and glucose output of hepatocytes following HG exposure. Furthermore, AESN administration reduced blood glucose and serum insulin levels, improved lipid profiles and insulin resistance, and corrected the aberrant AMPK activity and NLRP3 inflammasome activation in liver tissues.

CONCLUSION

AESN improves insulin sensitivity via AMPK-mediated NLRP3 inflammasome inhibition.

Thymus serpyllum Exhibits Anti-Diabetic Potential in Streptozotocin-Induced Diabetes Mellitus Type 2 Mice: A Combined Biochemical and In Vivo Study

Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder that is characterized by hyperglycemia, insulin resistance, and lack of insulin production. It has been previously reported that Thymus serpyllum has therapeutic potential against many diseases. To investigate the antidiabetic action of Thymus serpyllum, this study aimed to analyze its restorative impact in diabetic mice, in which it was administered in diet. Diabetes was induced in BALB/c mice fed with a high-fat diet and two intraperitoneal injections of streptozotocin. With the onset of diabetes, the mice were administered daily with aqueous extract of Thymus serpyllum (500 mg/kg/d and 800 mg/kg/d) for 4 weeks. Body weight and fasting blood glucose levels were measured after every 1 week of the treatment. Subsequently, intraperitoneal glucose tolerance and insulin tolerance tests were conducted. In addition, liver tissue was isolated for assessment in terms of levels of gene expression of the AMPK, IRS1, and GLUT2 gene. Treatment with the aqueous extract of Thymus serpyllum was found to be significantly effective in controlling hyperglycemia and improving glucose and insulin tolerance. Predictable with these impacts, the extract of Thymus serpyllum upregulated the AMPK expression at the mRNA level, as well as upregulating the expression of IRS1 and GLUT2 gene. Histopathological examination of the liver, kidney, and pancreas also revealed the restorative impact in terms of cellular morphology. The results hence demonstrated that oral administration of aqueous extract of Thymus serpyllum can potentially attenuate hyperglycemia in the liver muscle of streptozotocin (STZ)-induced diabetic mice via AMPK and IRS1 upregulation.

Selenium and Selenoproteins at the Intersection of Type 2 Diabetes and Thyroid Pathophysiology

Type 2 diabetes (T2D) is considered one of the largest global public-health concerns, affecting approximately more than 400 million individuals worldwide. The pathogenesis of T2D is very complex and, among the modifiable risk factors, selenium (Se) has recently emerged as a determinant of T2D pathogenesis and progression. Selenium is considered an essential element with antioxidant properties, and is incorporated into the selenoproteins involved in the antioxidant response. Furthermore, deiodinases, the enzymes responsible for homeostasis and for controlling the activity of thyroid hormones (THs), contain Se. Given the crucial action of oxidative stress in the onset of insulin resistance (IR) and T2D, and the close connection between THs and glucose metabolism, Se may be involved in these fundamental relationships; it may cover a dual role, both as a protective factor and as a risk factor of T2D, depending on its basal plasma concentration and the individual’s diet intake. In this review we discuss the current evidence (from experimental, observational and randomized clinical studies) on how Se is associated with the occurrence of T2D and its influence on the relationship between thyroid pathophysiology, IR and T2D.

Progress in understanding the mechanisms of resistance to BCL-2 inhibitors

Venetoclax is a new type of BH3 mimetic compound that can target the binding site in the BCL-2 protein and induce apoptosis in cancer cells by stimulating the mitochondrial apoptotic pathway. Venetoclax is especially used to treat haematological malignancies. However, with the recent expansion in the applications of venetoclax, some cases of venetoclax resistance have appeared, posing a major problem in clinical treatment. In this article, we explored several common mechanisms of venetoclax resistance. Increased expression of the antiapoptotic proteins MCL-1 and BCL-XL plays a key role in conferring cellular resistance to venetoclax. These proteins can bind to the released BIM in the context of venetoclax binding to BCL-2 and thus continue to inhibit mitochondrial apoptosis. Structural mutations in BCL-2 family proteins caused by genetic instability lead to decreased affinity for venetoclax and inhibit the intrinsic apoptosis pathway. Mutation or deletion of the BAX gene renders the BAX protein unable to anchor to the outer mitochondrial membrane to form pores. In addition to changes in BCL-2 family genes, mutations in other oncogenes can also confer resistance to apoptosis induced by venetoclax. TP53 mutations and the expansion of FLT3-ITD promote the expression of antiapoptotic proteins MCL-1 and BCL-XL through multiple signalling pathways, and interfere with venetoclax-mediated apoptosis processes depending on their affinity for BH3-only proteins. Finally, the level of mitochondrial oxidative phosphorylation in venetoclax-resistant leukaemia stem cells is highly abnormal. Not only the metabolic pathways but also the levels of important metabolic components are changed, and all of these alterations antagonize the venetoclax-mediated inhibition of energy metabolism and promote the survival and proliferation of leukaemia stem cells. In addition, venetoclax can change mitochondrial morphology independent of the BCL-2 protein family, leading to mitochondrial dysfunction. However, mitochondria resistant to venetoclax antagonize this effect, forming tighter mitochondrial cristae, which provide more energy for cell survival.

Vitexin attenuates autoimmune hepatitis in mouse induced by syngeneic liver cytosolic proteins via activation of AMPK/AKT/GSK-3β/Nrf2 pathway

Autoimmune hepatitis (AIH) is a chronic progressive liver disease that currently does not have a successful therapeutic option. Vitexin, a bioflavonoid isolated from various medicinal plants, possesses a variety of activities; however, whether vitexin protects against AIH remains unclear. Therefore, the current study aims to investigate the hepatoprotective effects and mechanism of action of vitexin in both an experimental autoimmune hepatitis (EAH) mouse model and in D-galactosamine/lipopolysaccharide (D-GalN/LPS)-induced hepatocyte injury. Syngeneic liver antigen S100 was used to establish EAH. Vitexin treatment significantly decreased the infiltration of inflammatory and CD4⁺ T cells in the liver, reduced ALT and AST levels in the serum and attenuated hepatic injury due to oxidative stress. Moreover, vitexin mitigated the upregulation of Bax and cleaved caspase-3 and the downregulation of Bcl-2 in the livers of AIH mice. These regulations were accompanied by not only increased phosphorylation of AMPK, AKT and GSK-3β but also activation of Nrf2. Furthermore, vitexin inhibited apoptosis and the overexpression of inflammatory cytokines in D-GalN/LPS-treated AML12 cells. In addition, vitexin enhanced the phosphorylation of AMPK, AKT and GSK-3β. When AML12 cells were treated with an inhibitor of AMPK/AKT or specific siRNA targeting Nrf2, vitexin did not further induce the activation of Nrf2/HO-1. A molecular docking study confirmed that vitexin could interact with AMPK through hydrogen bonding interactions. In conclusion, vitexin ameliorated hepatic injury in EAH mice through activation of the AMPK/AKT/GSK-3β pathway and upregulation of the Nrf2 gene.

Pharmacodynamic effects of direct AMP kinase activation in humans with insulin resistance and non-alcoholic fatty liver disease: A phase 1b study

AMPK is an energy sensor modulating metabolism, inflammation, and a target for metabolic disorders. Metabolic dysfunction results in lower AMPK activity. PXL770 is a direct AMPK activator, inhibiting de novo lipogenesis (DNL) and producing efficacy in preclinical models. We aimed to assess pharmacokinetics, safety, and pharmacodynamics of PXL770 in humans with metabolic syndrome-associated fatty liver disease. In a randomized, double-blind four-week trial, 12 overweight/obese patients with non-alcoholic fatty liver disease (NAFLD) and insulin resistance received PXL770 500 mg QD; 4 subjects received matching placebo. Endpoints included pharmacokinetics, hepatic fractional DNL, oral glucose tolerance testing, additional pharmacodynamic parameters, and safety. PK parameters show adequate plasma exposure in NAFLD patients for daily oral dosing. PXL770 decreases DNL—both peak and AUC are reduced versus baseline—and improves glycemic parameters and indices of insulin sensitivity versus baseline. Assessment of specific lipids reveals decrease in diacyglycerols/triacylglycerols. Safety/tolerability are similar to placebo. These results unveil initial human translation of AMPK activation and support this therapeutic strategy for metabolic disorders.

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AMPK is impaired in metabolic diseases—PXL770 is a direct AMPK activator

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In humans with NAFLD, PXL770 inhibits hepatic de novo lipogenesis (target engagement)

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PXL770 also improves glucose tolerance and insulin sensitivity

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PXL770 reduces plasma levels of di- and triglycerides

Adiponectin: a potential target for obesity-associated Alzheimer's disease

Obesity and dementia are two growing problems worldwide. Obesity act as a crucial risk factor for various diseases including Alzheimer's disease (AD). Several preclinical studies showed that middle-age obesity can be act as a possible feature of mild cognitive impairment in later years. Some studies have also demonstrated that a high-fat diet causes AD pathology, including extracellular amyloid-beta accumulation, hyperphosphorylation of tau, and cognition impairment. The correlation and molecular mechanism related to obesity-associated AD needs to be better evaluated. Presently, obesity results in an altered expression of several hormones, growth factors, and adipokines. Multiple signaling pathways such as leptin, insulin, adiponectin, and glutamate are involved to regulate vital functions in the brain and act as neuroprotective mediators for AD in a normal state. In obesity, altered adiponectin (APN) level and its associated downstream pathway could result in multiple signaling pathway disruption. Presently, Adiponectin and its inducers or agonist are considered as potential therapeutics for obesity-associated AD. This review mainly focuses on the pleiotropic effects of adiponectin and its potential to treat obesity-associated AD.

Efficacy and safety of PXL770, a direct AMP kinase activator, for the treatment of non-alcoholic fatty liver disease (STAMP-NAFLD): a randomised, double-blind, placebo-controlled, phase 2a study

BACKGROUND

AMP kinase (AMPK) is an energy sensor implicated in regulation of lipid metabolism, inflammation, and insulin sensitivity. We aimed to assess efficacy and safety of PXL770, a novel direct AMPK activator, in patients with non-alcoholic fatty liver disease (NAFLD).

METHODS

STAMP-NAFLD, a randomised, double-blind, placebo-controlled phase 2a study, was done across 15 US clinical sites. Patients aged 18-75 years with liver fat content of at least 10% at baseline when assessed by MRI-proton density fat fraction (MRI-PDFF) were eligible. Patients were randomly assigned (1:1:1:1), via an interactive web response system, to receive oral PXL770 250 mg once daily, 250 mg twice daily, or 500 mg once daily, or matched placebo. Patients were stratified according to type 2 diabetes status and study site. The primary endpoint was relative change in liver fat content from baseline compared with placebo at week 12, assessed by MRI-PDFF. The primary endpoint was analysed in an ANCOVA model with treatment and stratification criteria as factors and baseline liver fat content as a covariate in the modified intention-to-treat population, defined as all as-randomised patients who received at least one dose of study treatment. Safety was analysed in the safety population, defined as all as-treated patients receiving at least one dose of the study treatment. The trial has been completed and the final results are reported. The trial is registered with ClinicalTrials.gov, NCT03763877.

FINDINGS

Between March 29, 2019, and March 13, 2020, 387 patients were screened, of whom 120 were included in the modified intention-to-treat and safety analyses (30 in the 250 mg once daily group, 30 in the 250 mg twice daily group, 29 in the 500 mg once daily group, and 31 in the placebo group). The mean relative change from baseline in liver fat content at week 12 was -1·1% in the placebo group, -1·0% in the 250 mg once daily group (mean difference versus placebo 0·1% [95% CI -15·4 to 15·7], p=0·99), -14·3% in the 250 mg twice daily group (-13·1% [-28·1 to 1·8], p=0·084), and -14·7% in the 500 mg once daily group (-13·5% [-28·5 to 1·4], p=0·076). At least one treatment-emergent adverse event occurred in 23 (77%) of 30 patients in the 250 mg once daily group, 20 (67%) of 30 patients in the 250 mg twice daily group, 21 (72%) of 29 patients in the 500 mg once daily group, and 21 (68%) of 31 patients in the placebo group. The most common treatment-emergent adverse event was diarrhoea (five [17%] of patients in the 250 mg once daily group, seven [23%] in the 250 mg twice daily group, six [21%] in the 500 mg once daily group, and none in the placebo group). No life-threatening events or treatment-related deaths occurred.

INTERPRETATION

PXL770 treatment did not meet the primary outcome of liver fat improvement compared with placebo. Treatment was well tolerated. Given indications that metabolic features improved with PXL770 treatment, AMPK activation might be a promising pharmacological target for patients with type 2 diabetes and NAFLD, and could also be considered for further assessment in patients with non-alcoholic steatohepatitis.

FUNDING

Poxel.

Regulation and role of glycophagy in skeletal muscle energy metabolism

Glycophagy is the autophagic degradation of glycogen via the lysosomal enzyme GAA/alpha-acid glucosidase. Glycophagy is considered a housekeeping process to degrade poorly branched glycogen particles, but the regulation and role of glycophagy in skeletal muscle metabolism remains enigmatic. Herein, prior muscle contraction promoted glycogen supercompensation 24 and 48 h post contraction, an effect associated with reduced glycophagy. Moreover, NOTCH or cAMP signaling promoted glycophagy, whereas acute glycophagy deficiency rewired cell metabolism by reducing glycolysis and enhancing AMPK and PPAR signaling and fatty acid and glutamine metabolism. These metabolic adaptations were associated with reduced inflammation and triglyceride content but enhanced phosphoinositide 3-kinase (PI3K)-AKT/protein kinase B signaling and insulin action, the latter of which was abolished by exogenous oxidative stress. Collectively, these data suggest glycophagy is dynamically regulated, while the function of glycophagy can be extended beyond a housekeeping process to having an additional role in regulating energy metabolism and insulin action.Abbreviations: AMPK, AMP-activated protein kinase; ASM, acid soluble metabolites; cAMP, cyclic adenosine monophosphate; EPS, electrical pulse stimulation; FCCP, carbonyl cyanide-p-trifluoromethoxyphenylhydrazone; GAA, glucosidase, alpha, acid; mTOR, mechanistic target of rapamycin kinase; NAD, nicotinamide adenine dinucleotide; PARP, poly (ADP-ribose) polymerase family; PI3K, phosphoinositide 3-kinase; PPAR, peroxisome proliferator activated receptor ; PYGM, muscle glycogen phosphorylase; STBD1, starch binding domain 1; TFEB, transcription factor EB.

Diabetic Kinome Inhibitors-A New Opportunity for β-Cells Restoration

Diabetes, and several diseases related to diabetes, including cancer, cardiovascular diseases and neurological disorders, represent one of the major ongoing threats to human life, becoming a true pandemic of the 21st century. Current treatment strategies for diabetes mainly involve promoting β-cell differentiation, and one of the most widely studied targets for β-cell regeneration is DYRK1A kinase, a member of the DYRK family. DYRK1A has been characterized as a key regulator of cell growth, differentiation, and signal transduction in various organisms, while further roles and substrates are the subjects of extensive investigation. The targets of interest in this review are implicated in the regulation of β-cells through DYRK1A inhibition-through driving their transition from highly inefficient and death-prone populations into efficient and sufficient precursors of islet regeneration. Increasing evidence for the role of DYRK1A in diabetes progression and β-cell proliferation expands the potential for pharmaceutical applications of DYRK1A inhibitors. The variety of new compounds and binding modes, determined by crystal structure and in vitro studies, may lead to new strategies for diabetes treatment. This review provides recent insights into the initial self-activation of DYRK1A by tyrosine autophosphorylation. Moreover, the importance of developing novel DYRK1A inhibitors and their implications for the treatment of diabetes are thoroughly discussed. The evolving understanding of DYRK kinase structure and function and emerging high-throughput screening technologies have been described. As a final point of this work, we intend to promote the term "diabetic kinome" as part of scientific terminology to emphasize the role of the synergistic action of multiple kinases in governing the molecular processes that underlie this particular group of diseases.

Therapeutic effect of oxyberberine on obese non-alcoholic fatty liver disease rats

BACKGROUND

Berberine (BBR) has been widely used to treat non-alcoholic fatty liver disease (NAFLD). The metabolites of BBR were believed to contribute significantly to its pharmacological effects. Oxyberberine (OBB), a gut microbiota-mediated oxidative metabolite of BBR, has been firstly identified in our recent work.

PURPOSE

Here, we aimed to comparatively investigate the anti-NAFLD properties of OBB and BBR.

METHODS

The anti-NAFLD effect was evaluated in high-fat diet-induced obese NAFLD rats with biochemical/ELISA tests and histological staining. The related gene and protein expressions were detected by qRT-PCR and Western blotting respectively. Molecular docking and dynamic simulation were also performed to provide further insight.

RESULTS

Results indicated OBB remarkably and dose-dependently attenuated the clinical manifestations of NAFLD, which (100 mg/kg) achieved similar therapeutic effect to metformin (300 mg/kg) and was superior to BBR of the same dose. OBB significantly inhibited aberrant phosphorylation of IRS-1 and up-regulated the downstream protein expression and phosphorylation (PI3K, p-Akt/Akt and p-GSK-3β/GSK-3β) to improve hepatic insulin signal transduction. Meanwhile, OBB treatment remarkably alleviated inflammation via down-regulating the mRNA expression of MCP-1, Cd68, Nos2, Cd11c, while enhancing Arg1 mRNA expression in white adipose tissue. Moreover, OBB exhibited closer affinity with AMPK in silicon and superior hyperphosphorylation of AMPK in vivo, leading to increased ACC mRNA expression in liver and UCP-1 protein expression in adipose tissue.

CONCLUSION

Taken together, compared with BBR, OBB was more capable of maintaining lipid homeostasis between liver and WAT via attenuating hepatic insulin pathway and adipocyte inflammation, which was associated with its property of superior AMPK activator.

NGBR is required to ameliorate type 2 diabetes in mice by enhancing insulin sensitivity

The reduction of insulin resistance or improvement of insulin sensitivity is the most effective treatment for type 2 diabetes (T2D). We previously reported that Nogo-B receptor (NGBR), encoded by the NUS1 gene, is required for attenuating hepatic lipogenesis by blocking nuclear translocation of liver X receptor alpha, suggesting its important role in regulating hepatic lipid metabolism. Herein, we demonstrate that NGBR expression was decreased in the liver of obesity-associated T2D patients and db/db mice. NGBR knockout in mouse hepatocytes resulted in increased blood glucose, insulin resistance, and beta-cell loss. High-fat diet (HFD)/streptozotocin (STZ)-treated mice presented the T2D phenotype by showing increased nonesterified fatty acid (NEFA) and triglyceride (TG) in the liver and plasma and increased insulin resistance and beta-cell loss. AAV-mediated NGBR overexpression in the liver reduced NEFA and TG in the liver and circulation and improved liver functions. Consequently, HFD/STZ-treated mice with hepatic NGBR overexpression had increased insulin sensitivity and reduced beta-cell loss. Mechanistically, NGBR overexpression restored insulin signaling of AMPKα1-dependent phosphorylation of AKT and GSK3β. NGBR overexpression also reduced expression of endoplasmic reticulum stress-associated genes in the liver and skeletal muscle to improve insulin sensitivity. Together, our results reveal that NGBR is required to ameliorate T2D in mice, providing new insight into the role of hepatic NGBR in insulin sensitivity and T2D treatment.

Cassia Abbreviata Enhances Glucose Uptake and Glucose Transporter 4 Translocation in C2C12 Mouse Skeletal Muscle Cells

Background.

This study aim at assessing C. abbreviata aqueous extracts for its potential to exhibit anti-diabetic activity in skeletal muscle cells. In addition to the toxicological and glucose absorption studies, the action of C. abbreviata extracts on some major genes involved in the insulin signaling pathway was established.

Methods.

The in vitro cytotoxic effects C. abbreviata was evaluated on muscle cells using the MTT assay and the in vitro glucose uptake assay conducted using a modified glucose oxidase method described by Van de Venter et al. (2008). The amount of GLUT-4 on cell surfaces was estimated quantitatively using the flow cytometry technique. Real time quantitative PCR (RT-qPCR) was used to determine the expression of GLUT-4, IRS-1, PI3 K, Akt1, Akt2, PPAR-γ.

Results.

Cytotoxicity tests revealed that all extracts tested at various concentrations were non-toxic (LC₅₀ > 5000). Aqueous extracts of leaves, bark and seeds resulted in a dose-dependent increase in glucose absorption by cells, after 1 h, 3 h and 6 h incubation period. Extracts of all three plant parts had the best effect after 3 h incubation, with the leaf extract showing the best activity across time (Glucose uptake of 29%, 56% and 42% higher than untreated control cells after treatment with 1 mg/ml extract at 1 h, 3 h and 6 h, respectively). All extracts, with the exception 500 µg/ml seed extract, induced a two-fold increase in GLUT-4 translocation while marginally inducing GLUT-10 translocation in the muscle cells. The indirect immunofluorescence confirmed that GLUT-4 translocation indeed occurred. There was an increased expression of GLUT-4, IRS1 and PI3 K in cells treated with insulin and bark extract as determined by the RT-qPCR.

Conclusion.

The study reveals that glucose uptake involves GLUT-4 translocation through a mechanism that is likely to involve the upstream effectors of the PI3-K/Akt pathway.

Effects of exogenous adiponectin supplementation in early pregnant PCOS mice on the metabolic syndrome of adult female offspring

Objective

PCOS is a heterogeneous endocrine disorder with both reproductive and metabolic abnormalities. At present, PCOS has been confirmed to have a certain genetic background. Compared with healthy women, the vast majority of PCOS patients have hyperandrogenemia, and this excessive androgen exposure during pregnancy may affect the development of female fetuses. The aim of the current study was to investigate the effect of adiponectin intervention during early pregnancy of obese mice with PCOS on the metabolic phenotype of adult female offspring.

Methods

After the PCOS model was established, C57BL/6J mice were divided into maternal-control, maternal-PCOS, and maternal-PCOS + APN groups. DHEA-induced PCOS mice were supplemented with adiponectin (10 mg/kg/day) in the early pregnancy in order to eliminate adverse hormone exposure and then traced for endocrine indicators in their adult female offspring, which were observed for metabolism syndrome or endocrine disturbance and exhibited the main effects of APN. To further explore the underlying mechanism, the relative expressions of phosphorylated AMPK, PI3K, and Akt were detected in the ovaries of offspring mice.

Results

The serum testosterone level of the maternal-PCOS + APN group in early pregnancy was significantly lower than that of the maternal-PCOS group (p < 0.01). The serum testosterone level in the offspring-PCOS + APN group was significantly lower than in the offspring-PCOS group (p <0.05), the diestrus time characterized by massive granulocyte aggregation in the estrus cycle was significantly shorter than in the offspring-PCOS group (p<0.05), and the phenotypes of PCOS-like reproductive disorders and metabolic disorders, such as obesity, insulin resistance, impaired glucose tolerance, and hyperlipidemia, were also significantly improved in the offspring-PCOS + APN group (p < 0.05). Compared with the control group, the expression levels of phosphorylated AMPK, PI3K, and Akt in the offspring-PCOS group were significantly decreased (p < 0.05), while those in the offspring-PCOS + APN group were significantly increased (p < 0.05).

Conclusions

APN intervention in early pregnancy significantly reduced the adverse effects of maternal obesity and high androgen levels during pregnancy on female offspring and corrected the PCOS-like endocrine phenotype and metabolic disorders of adult female offspring. This effect may be caused by the activation of the AMPK/PI3K-Akt signaling pathway in PCOS offspring mice.

Berberine attenuates fructose-induced insulin resistance by stimulating the hepatic LKB1/AMPK/PGC1α pathway in mice

Context: Berberine is an alkaloid that possesses various pharmacologic effects.Objective: To explore the mechanism of berberine to improve insulin sensitivity in fructose-fed mice.Materials and methods: Sixty male ICR mice were randomly divided into 6 groups (10 mice in each group): control, fructose, pioglitazone (10 mg/kg) and berberine (50, 100, and 200 mg/kg). Except for the control group, the mice received 20% fructose drinking for 10 weeks. Pioglitazone and berberine were orally administered once daily during the last 4 weeks. The insulin sensitivity was evaluated using an oral glucose tolerance test (OGTT). The serum levels of fasting glucose and insulin, blood lipids, and hormones were determined. The hepatic AMP and ATP contents were detected using high performance liquid chromatography (HPLC) analysis, and the protein expression was examined by immunoblotting.Results: Berberine significantly reversed the insulin resistance induced by fructose, including lowering fasting insulin levels (from 113.9 to 67.4) and area under the curve (AUC) during OGTT (from 1310 to 1073), decreasing serum leptin (from 0.28 to 0.13) and increasing serum adiponectin levels (from 1.50 to 2.80). Moreover, berberine enhanced the phosphorylation levels of protein kinase B (PKB/AKT; 2.27-fold) and glycogen synthase kinase-3β (GSK3β; 2.56-fold), and increased hepatic glycogen content (from 0.19 to 1.65). Furthermore, berberine upregulated the protein expression of peroxisome proliferator activated receptor gamma coactivator 1α (PGC1α; 2.61-fold), phospho-AMP-activated protein kinase (p-AMPK; 1.35-fold) and phospho-liver kinase B1 (p-LKB1; 1.41-fold), whereas it decreased the AMP/ATP ratio (from 4.25 to 1.82).Conclusion: The present study demonstrated the protective effects of berberine against insulin resistance induced by fructose. Our findings may provide an experimental basis for the application of berberine in the treatment of insulin resistance.

Active ingredients and mechanisms of Phellinus linteus (grown on Rosa multiflora) for alleviation of Type 2 diabetes mellitus through network pharmacology

Phellinus linteus (mushroom) grown on Rosa multiflora (PL@RM), exposed beneficial effect and safety on Type 2 diabetes mellitus (T2DM) from Korean folk remedies. However, its active chemical constituents and mechanism(s) against T2DM have not been confirmed. Hence, we deciphered the active compounds and mechanism(s) of PL@RM against T2DM through network pharmacology. GC-MS of PL@RM manifested 54 compounds and drug-likeness properties of these compounds were confirmed by Lipinski's rule. The compound (40) related genes were composed of Similarity Ensemble Approach (SEA) and SwissTargetPrediction (STP). The overlapping genes (61) between the two databases were identified. Besides, the T2DM related genes (4,736) were extracted from DisGeNet and OMIM database. In parallel, a Venn diagram was constructed between the overlapping genes (61) and T2DM related genes (4,736), and finally, 48 genes were picked. The interactive networks between compounds and overlapping genes were plotted and visualized by RStudio. In addition, KEGG Pathway enrichment analysis was evaluated by String. String analysis showed that the mechanisms of PL@RM against T2DM were related to 16 pathways, where inhibition of gluconeogenesis by inactivating metabolic pathways was noted as the hub pathway of PL@RM against T2DM. Besides, bubble chart indicated that activation of the AMPK signaling pathway might enhance the insulin receptor (IR) phosphorylation, which is regarded the key signaling pathway of PL@RM against T2DM. Furthermore, the autodock vina revealed the promising binding affinity energy of the epicholesterol (the most drug-likeness compound) on HMGCR (hub gene). Overall, this work hints at the therapeutic evidence of PL@RM on T2DM, and this data expound the main chemical compounds and mechanisms of PL@RM against T2DM.

Emerging Role of Adipocyte Dysfunction in Inducing Heart Failure Among Obese Patients With Prediabetes and Known Diabetes Mellitus

Adipose tissue dysfunction is a predictor for cardiovascular (CV) events and heart failure (HF) in patient population with obesity, metabolic syndrome, and known type 2 diabetes mellitus. Previous preclinical and clinical studies have yielded controversial findings regarding the role of accumulation of adipose tissue various types in CV risk and HF-related clinical outcomes in obese patients. There is evidence for direct impact of infiltration of epicardial adipocytes into the underlying myocardium to induce adverse cardiac remodeling and mediate HF development and atrial fibrillation. Additionally, perivascular adipocytes accumulation is responsible for release of proinflammatory adipocytokines (adiponectin, leptin, resistin), stimulation of oxidative stress, macrophage phenotype switching, and worsening vascular reparation, which all lead to microvascular inflammation, endothelial dysfunction, atherosclerosis acceleration, and finally to increase in CV mortality. However, systemic effects of white and brown adipose tissue can be different, and adipogenesis including browning of adipose tissue and deficiency of anti-inflammatory adipocytokines (visfatin, omentin, zinc-α2-glycoprotein, glypican-4) was frequently associated with adipose triglyceride lipase augmentation, altered glucose homeostasis, resistance to insulin of skeletal muscles, increased cardiomyocyte apoptosis, lowered survival, and weak function of progenitor endothelial cells, which could significantly influence on HF development, as well as end-organ fibrosis and multiple comorbidities. The exact underlying mechanisms for these effects are not fully understood, while they are essential to help develop improved treatment strategies. The aim of the review is to summarize the evidence showing that adipocyte dysfunction may induce the onset of HF and support advance of HF through different biological mechanisms involving inflammation, pericardial, and perivascular adipose tissue accumulation, adverse and electrical cardiac remodeling, and skeletal muscle dysfunction. The unbalancing effects of natriuretic peptides, neprilysin, and components of renin–angiotensin system, as exacerbating cause of altered adipocytokine signaling on myocardium and vasculature, in obesity patients at high risk of HF are disputed. The profile of proinflammatory and anti-inflammatory adipocytokines as promising biomarker for HF risk stratification is discussed in the review.

Metabolic and transcriptome responses of RNAi-mediated AMPKα knockdown in Tribolium castaneum

Background

The AMP-activated protein kinase (AMPK) is an intracellular fuel sensor for lipid and glucose metabolism. In addition to the short-term regulation of metabolic enzymes by phosphorylation, AMPK may also exert long-term effects on the transcription of downstream genes through the regulation of transcription factors and coactivators. In this study, RNA interference (RNAi) was conducted to investigate the effects of knockdown of TcAMPKα on lipid and carbohydrate metabolism in the red flour beetle, Tribolium castaneum, and the transcriptome profiles of dsTcAMPKα-injected and dsEGFP-injected beetles under normal conditions were compared by RNA-sequencing.

Results

RNAi-mediated suppression of TcAMPKα increased whole-body triglyceride (TG) level and the ratio between glucose and trehalose, as was confirmed by in vivo treatment with the AMPK-activating compound, 5-Aminoimidazole-4-carboxamide1-β-D-ribofuranoside (AICAR). A total of 1184 differentially expressed genes (DEGs) were identified between dsTcAMPKα-injected and dsEGFP-injected beetles. These include genes involved in lipid and carbohydrate metabolism as well as insulin/insulin-like growth factor signaling (IIS). Real-time quantitative polymerase chain reaction analysis confirmed the differential expression of selected genes. Interestingly, metabolism-related transcription factors such as sterol regulatory element-binding protein 1 (SREBP1) and carbohydrate response element-binding protein (ChREBP) were also significantly upregulated in dsTcAMPKα-injected beetles.

Conclusions

AMPK plays a critical role in the regulation of beetle metabolism. The findings of DEGs involved in lipid and carbohydrate metabolism provide valuable insight into the role of AMPK signaling in the transcriptional regulation of insect metabolism.

l-Arginine supplementation of gilts during early gestation modulates energy sensitive pathways in pig conceptuses

Dietary l-arginine (ARG) supplementation has been studied as a nutritional strategy to improve reproductive performance of pregnant sows, since arginine is a conditionally essential amino acid. However, reports addressing the molecular mechanisms that mediate supplementation effects on embryos and fetuses development are still scarce. Therefore, we aimed to evaluate the effects of 1.0% ARG supplementation of commercial pregnant gilts on genes and proteins from energy metabolism and antioxidant defense pathways in embryos and fetuses. We also analyzed the global transcriptome profile of 25- and 35-day-old conceptuses. At Day 25, we observed a lower abundance of phospho-AMP-activated protein kinase (phospho-AMPK) protein and downregulation of oxidative phosphorylation system genes in ARG embryos. On the other hand, ARG fetuses showed greater expression of MLST8 and lower expression of MTOR genes, in addition to lower abundance of phospho-AMPK and phospho-mammalian target of rapamycin (phospho-mTOR) proteins. Transcriptome analysis at Day 35 did not present differentially expressed genes. For the antioxidant defense pathway, no differences were found between CON and ARG conceptuses, only trends. In general, supplementation of gilts with 1.0% ARG during early gestation affects energy sensitive pathways in 25- and 35-day conceptuses; however, no effects of supplementation were found on the antioxidative defense pathway in 25-day embryos.

The effect of chronic, mild heat stress on metabolic changes of nutrition and adaptations in rumen papillae of lactating dairy cows

Global warming and accompanying high ambient temperatures reduce feed intake of dairy cows and shift the blood flow from the core of the body to the periphery. As a result, hypoxia may occur in the digestive tract accompanied by disruption of the intestinal barrier, local endotoxemia and inflammation, and altered nutrient absorption. However, whether the barrier of the rumen, like the intestine, is affected by ambient heat has not been studied so far. Lactating Holstein dairy cows were subjected to heat stress at 28°C (temperature-humidity index = 76; n = 5) with ad libitum feed intake or to thermoneutral conditions at 15°C (temperature-humidity index = 60; n = 5) and pair-feeding to heat-stressed animals for a total of 4 d. Gas exchange and feed intake behavior were measured in a respiration chamber, and rumen epithelia were taken after slaughter. Heat stress significantly reduced meal size and whole-body fat oxidation but increased meal frequency and carbohydrate oxidation. The mRNA expression of toll-like receptor 4 (TLR4) and tight junction proteins and the phosphorylation of TLR4 downstream targets (interleukin-1 receptor-associated kinase 4, stress-activated protein kinase, p38 mitogen-activated protein kinase, and nuclear factor k-B) in the rumen epithelium were not affected by heat. The proteomics approach revealed increased expression of rumen epithelium proteins involved in the AMP-activated protein kinase (AMPK) and insulin signaling pathways in heat-stressed cows. Also, proteins involved in chaperone-mediated folding of proteins were upregulated, whereas those involved in antioxidant defense system were downregulated. Further, we found evidence for increased carbohydrate phosphorylation accompanied with an increased flux of carbohydrates through the hexosamine biosynthetic pathway, providing substrates for protein glycosylation. In conclusion, the mild heat stress did not induce barrier dysfunction or inflammatory responses in the rumen epithelium of dairy cows, probably because of adaptations in feed intake behavior and defense mechanisms at the tissue level.

The hypoglycemic mechanism of catalpol involves increased AMPK-mediated mitochondrial biogenesis

Mitochondria serve as sensors of energy regulation and glucose levels, which are impaired by diabetes progression. Catalpol is an iridoid glycoside that exerts a hypoglycemic effect by improving mitochondrial function, but the underlying mechanism has not been fully elucidated. In the current study we explored the effects of catalpol on mitochondrial function in db/db mice and C2C12 myotubes in vitro. After oral administration of catalpol (200 mg·kg⁻¹·d⁻¹) for 8 weeks, db/db mice exhibited a decreased fasting blood glucose level and restored mitochondrial function in skeletal muscle. Catalpol increased mitochondrial biogenesis, evidenced by significant elevations in the number of mitochondria, mitochondrial DNA levels, and the expression of three genes associated with mitochondrial biogenesis: peroxisome proliferator-activated receptor gammaco-activator 1 (PGC-1α), mitochondrial transcription factor A (TFAM) and nuclear respiratory factor 1 (NRF1). In C2C12 myotubes, catalpol significantly increased glucose uptake and ATP production. These effects depended on activation of AMP-activated protein kinase (AMPK)-mediated mitochondrial biogenesis. Thus, catalpol improves skeletal muscle mitochondrial function by activating AMPK-mediated mitochondrial biogenesis. These findings may guide the development of a new therapeutic approach for type 2 diabetes.

Proteomics insights into the effects of MSTN on muscle glucose and lipid metabolism in genetically edited cattle

The molecular mechanism underlying myostatin (MSTN)-regulated metabolic cross-talk remains poorly understood. In this study, we performed comparative proteomic and phosphoproteomic analyses of gluteus muscle tissues from MSTN^-/- transgenic cattle using a shotgun-based tandem mass tag (TMT) 6-plex labeling method to explore the signaling pathway of MSTN in metabolic cross-talk and cellular metabolism during muscle development. A total of 72 differentially expressed proteins (DEPs) and 36 differentially expressed phosphoproteins (DEPPs) were identified in MSTN^-/- cattle compared to wild-type cattle. Bioinformatics analyses showed that MSTN knockout increased the activity of many key enzymes involved in fatty acid β-oxidation and glycolysis processes in cattle. Furthermore, comprehensive pathway analyses and hypothesis-driven AMP-activated protein kinase (AMPK) activity assays suggested that MSTN knockout triggers the activation of AMPK signaling pathways to regulate glucose and lipid metabolism by increasing the AMP/ATP ratio. Our results shed new light on the potential regulatory mechanism of MSTN associated with metabolic cross-talk in muscle development, which can be used in animal breeding to improve meat production in livestock animals, and can also provide valuable insight into treatments for obesity and diabetes mellitus in humans.

Targeting the Inositol Pyrophosphate Biosynthetic Enzymes in Metabolic Diseases

In mammals, a family of three inositol hexakisphosphate kinases (IP6Ks) synthesizes the inositol pyrophosphate 5-IP7 from IP6. Genetic deletion of Ip6k1 protects mice from high fat diet induced obesity, insulin resistance and fatty liver. IP6K1 generated 5-IP7 promotes insulin secretion from pancreatic β-cells, whereas it reduces insulin signaling in metabolic tissues by inhibiting the protein kinase Akt. Thus, IP6K1 promotes high fat diet induced hyperinsulinemia and insulin resistance in mice while its deletion has the opposite effects. IP6K1 also promotes fat accumulation in the adipose tissue by inhibiting the protein kinase AMPK mediated energy expenditure. Genetic deletion of Ip6k3 protects mice from age induced fat accumulation and insulin resistance. Accordingly, the pan IP6K inhibitor TNP [N2-(m-trifluorobenzyl), N6-(p-nitrobenzyl)purine] ameliorates obesity, insulin resistance and fatty liver in diet induced obese mice by improving Akt and AMPK mediated insulin sensitivity and energy expenditure. TNP also protects mice from bone loss, myocardial infarction and ischemia reperfusion injury. Thus, the IP6K pathway is a potential target in obesity and other metabolic diseases. Here, we summarize the studies that established IP6Ks as a potential target in metabolic diseases. Further studies will reveal whether inhibition of this pathway has similar pleiotropic benefits on metabolic health of humans.

Atorvastatin promotes AMPK signaling to protect against high fat diet-induced non-alcoholic fatty liver in golden hamsters

Non-alcoholic fatty liver disease (NAFLD) is characterized by diffuse fatty acid degeneration and excess fat accumulation in the liver. Notably, the currently available medications used to treat NAFLD remain limited. The aim of the present study was to investigate the protective role of atorvastatin (Ato) against NAFLD in golden hamsters fed a high fat diet (HFD) and in HepG2 cells treated with palmitate, and identify the underlying molecular mechanism. Ato (3 mg/kg) was administered orally every day for 8 weeks to the hamsters during HFD administration. Hamsters in the model group developed hepatic steatosis with high serum levels of triglyceride, cholesterol, insulin and C-reactive protein, which were effectively reduced by treatment with Ato. Additionally, the relative liver weight of hamsters treated with Ato was markedly lower compared with that of the model group. Hematoxylin and eosin, and oil red O staining indicated that the livers of the animals in the model group exhibited large and numerous lipid droplets, which were markedly decreased after Ato treatment. Western blot analysis indicated that Ato inhibited fat accumulation in the liver through the AMP-activated protein kinase (AMPK)-dependent activation of peroxisome proliferator activated receptor α (PPARα), peroxisome proliferator-activated receptor-γ coactivator 1 α and their target genes. Furthermore, in vitro, Ato inhibited PA-induced lipid accumulation in HepG2 cells. This inhibitory effect was attenuated following Compound C treatment, indicating that AMPK may be a potential target of Ato. In conclusion, the increase in AMPK-mediated PPARα and its target genes may represent a novel molecular mechanism by which Ato prevents NAFLD.

A systematic review on the mechanisms of vitamin K effects on the complications of diabetes and pre-diabetes

Diabetes mellitus and pre-diabetes are prevalent endocrine disorders associated with substantial morbidity and premature mortality. Vitamin K is known to have several beneficial effects on complications of diabetes and pre-diabetes. However, systematic consolidation of evidence is required to quantify these effects in order to inform clinical practice and research. A systematic search in PubMed, Scopus, Embase, ProQuest, and Google Scholar databases was undertaken from database inception up to October 2018 to evaluate functional roles of different forms of vitamin K on diabetes and pre-diabetes. From 3,734 identified records, nine articles met the inclusion criteria and were evaluated. Vitamin K supplementation was found to be associated with significant reductions in blood glucose (six studies), increased fasting serum insulin (four studies), reduced hemoglobin A1c (three studies), reduced homeostatic model assessment-insulin resistance index (HOMA-IR) (two studies), and increased ß-cell function (two studies) in diabetic animal studies. Following 2-hour oral glucose tolerance test, vitamin K supplementation was observed to be effective in reducing blood glucose and insulin levels in the pre-diabetic population. However, no evidence of effect was observed for fasting blood sugar, insulin, HOMA-IR, and homeostatic model assessment-β-cell function index (two studies). A statistically significant effect was also noted with vitamin K in improving dyslipidemia (three studies) as well as oxidative stress and inflammatory markers (five studies) in diabetic animals. In conclusion, clinical trials and animal studies confirm that vitamin K supplementation may improve both clinical features and complications of diabetes and pre-diabetes. However, quantification of clinical efficacy in the pre-diabetic population and among individuals with comorbidities requires further investigation.

Immune-mediated anti-tumor effects of metformin; targeting metabolic reprogramming of T cells as a new possible mechanism for anti-cancer effects of metformin

Immunotherapy-based cancer treatment has revolutionized the era of cancer patients recuperation and it has brought a strong hope to treatment of some types of cancers. Metformin, a widely used antidiabetic drug, which has intensely been studied for its anticancer effects, is believed to have positive influences on immune responses against tumor cells. Metformin can affect metabolic pathways within cells mainly through activation of AMPK. Metabolic restriction of tumor microenvironment on effector immune cells is one of the important strategies favoring tumor cells to escape from immunogenic cell death. The metabolism of T cells has an axial role in shaping and supporting immune responses and may have an important role in anticancer immunity, suggesting that the functionality and durability of tumor-specific T cells need sufficient energy and nutrients. Energy biogenesis of tumor-specific cytotoxic T cells has become an interesting field of study and it is suggested that activation and maintenance of effector T cell responses in tumor microenvironment may occur by metabolic reprogramming of T cells. AMPK has been noticed as the main intracellular energy sensor and mitochondrial biogenesis key regulator which can control and regulate metabolic reprogramming in immune cells and increase antitumor immunity. Metabolic reprogramming of T cells to overcome metabolic restriction in tumor microenvironment, maiming effector T cell responses against tumor cells, has been noticed by several studies. Here we represent metformin, an AMPK activator, as a new candidate drug for metabolic reprogramming of tumor-specific T cells to increase the efficacy and accountability of cancer immunotherapy.

Polyphenols targeting diabetes via the AMP-activated protein kinase pathway; future approach to drug discovery

Regarding the widespread progression of diabetes, its related complications and detrimental effects on human health, investigations on this subject seems compulsory. AMP-activated protein kinase (AMPK) is a serine/threonine kinase and a key player in energy metabolism regulation. AMPK is also considered as a prime target for pharmaceutical and therapeutic studies on disorders such as diabetes, metabolic syndrome and obesity, where the body energy homeostasis is imbalanced. Following the activation of AMPK (physiological or pharmacological), a cascade of metabolic events that improve metabolic health is triggered. While there are several publications on this subject, this is the first report that has focused solely on polyphenols targeting diabetes via AMPK pathway. The multiple characteristics of polyphenolic compounds and their favorable influence on diabetes pathogenesis, as well as their intersections with the AMPK signaling pathway, indicate that these compounds have a beneficial effect on the regulation of glucose homeostasis. PPs could potentially occupy a significant position in the future anti-diabetic drug market.

Prospective of managing impaired brain insulin signalling in late onset Alzheimers disease with excisting diabetic drugs

Late onset Alzheimer's disease (AD) is the most common cause of dementia among elderly. The exact cause of the disease is until now unknown and there is no complete cure for the disease. Growing evidence suggest that AD is a metabolic disorder associated with impairment in brain insulin signalling. These findings enriched the scope for the repurposing of diabetic drugs in AD management. Even though many of these drugs are moving in a positive direction in the ongoing clinical studies, the extent of the success has seen to influence by several properties of these drugs since they were originally designed to manage the peripheral insulin resistance. In depth understandings of these properties is hence highly significant to optimise the use of diabetic drugs in the clinical management of AD; which is the primary aim of the present review article.

Therapeutic Potential of Oxytocin in Atherosclerotic Cardiovascular Disease: Mechanisms and Signaling Pathways

Coronary artery disease (CAD) is a major cardiovascular disease responsible for high morbidity and mortality worldwide. The major pathophysiological basis of CAD is atherosclerosis in association with varieties of immunometabolic disorders that can suppress oxytocin (OT) receptor (OTR) signaling in the cardiovascular system (CVS). By contrast, OT not only maintains cardiovascular integrity but also has the potential to suppress and even reverse atherosclerotic alterations and CAD. These protective effects of OT are associated with its protection of the heart and blood vessels from immunometabolic injuries and the resultant inflammation and apoptosis through both peripheral and central approaches. As a result, OT can decelerate the progression of atherosclerosis and facilitate the recovery of CVS from these injuries. At the cellular level, the protective effect of OT on CVS involves a broad array of OTR signaling events. These signals mainly belong to the reperfusion injury salvage kinase pathway that is composed of phosphatidylinositol 3-kinase-Akt-endothelial nitric oxide synthase cascades and extracellular signal-regulated protein kinase 1/2. Additionally, AMP-activated protein kinase, Ca²⁺/calmodulin-dependent protein kinase signaling and many others are also implicated in OTR signaling in the CVS protection. These signaling events interact coordinately at many levels to suppress the production of inflammatory cytokines and the activation of apoptotic pathways. A particular target of these signaling events is endoplasmic reticulum (ER) stress and mitochondrial oxidative stress that interact through mitochondria-associated ER membrane. In contrast to these protective effects and machineries, rare but serious cardiovascular disturbances were also reported in labor induction and animal studies including hypotension, reflexive tachycardia, coronary spasm or thrombosis and allergy. Here, we review our current understanding of the protective effect of OT against varieties of atherosclerotic etiologies as well as the approaches and underlying mechanisms of these effects. Moreover, potential cardiovascular disturbances following OT application are also discussed to avoid unwanted effects in clinical trials of OT usages.

Effect of metformin and flutamide on insulin, lipogenic and androgen-estrogen signaling, and cardiometabolic risk in a PCOS-prone metabolic syndrome rodent model

Polycystic ovary syndrome (PCOS) is highly associated with cardiometabolic risk and the metabolic syndrome (MetS), predisposing women to increased risk of developing type 2 diabetes and cardiovascular disease. Metformin is commonly used to treat insulin resistance-glucose intolerance, and flutamide, an androgen receptor (AR) antagonist, is used to target hyperandrogenemia and dyslipidemia. Currently, the physiological mechanism of action of these treatments on androgen, lipidogenic, and insulin signaling pathways remains unclear in PCOS. The aim of this study was to investigate the effects and mechanisms of action of metformin and flutamide on plasma lipid-apolipoprotein (Apo)B-lipoprotein and insulin-glucose metabolism, and endocrine-reproductive indices in a PCOS-prone MetS rodent model. PCOS-prone rodents were treated with metformin (300 mg/kg body wt), flutamide (30 mg/kg body wt), or metformin + flutamide combination treatment for 6 wk. Metformin was shown to improve fasting insulin and HOMA-IR, whereas flutamide and combination treatment were shown to reduce plasma triglycerides, ApoB48, and ApoB100, and this was associated with decreased intestinal secretion of ApoB48/triglyceride. Flutamide and metformin were shown to reduce plasma androgen indices and to improve ovarian primary and preovulatory follicle frequency. Metformin treatment increased hepatic estrogen receptor (ER)α, and metformin-flutamide decreased intestinal AR and increased ERα mRNA expression. Metformin-flutamide treatment upregulated hepatic and intestinal insulin signaling, including insulin receptor, MAPK1, and AKT2. In conclusion, cardiometabolic risk factors, in particular ApoB-hypertriglyceridemia, are independently modulated via the AR, and understanding the contribution of AR and insulin-signaling pathways further may facilitate the development of targeted interventions in high-risk women with PCOS and MetS.

AMPK activation is involved in hypoglycemic and hypolipidemic activities of mogroside-rich extract from Siraitia grosvenorii (Swingle) fruits on high-fat diet/streptozotocin-induced diabetic mice

AMPK is involved in hypoglycemic and hypolipidemic activities of mogrosides from Siraitia grosvenorii (Swingle) fruits on diabetic mice.

Metformin; an old antidiabetic drug with new potentials in bone disorders

The prevalence of diabetes mellitus especially type 2 diabetes mellitus is increasing all over the world. In addition to cardiomyopathy and nephropathy, diabetics are at higher risk of mortality and morbidity due to greater risk of bone fractures and skeletal abnormalities. Patients with diabetes mellitus have lower bone quality in comparison to their non-diabetic counterparts mainly because of hyperglycemia, toxic effects of advanced glycosylation end-products (AGEs) on bone tissue, and impaired bone microvascular system. AGEs may also contribute to the development of osteoarthritis further to osteoporosis. Therefore, glycemic control in diabetic patients is vital for bone health. Metformin, a widely used antidiabetic drug, has been shown to improve bone quality and decrease the risk of fractures in patients with diabetes in addition to glycemic control and improving insulin sensitivity. AMP activated protein kinase (AMPK), the key molecule in metformin antidiabetic mechanism of action, is also effective in signaling pathways involved in bone physiology. This review, discusses the molecules linking diabetes and bone turnover, role of AMPK in bone metabolism, and the effect of metformin as an activator of AMPK on bone disorders and malignancies.