Magnoflorine prevent the skeletal muscle atrophy via Akt/mTOR/FoxO signal pathway and increase slow-MyHC production in streptozotocin-induced diabetic rats

Allantoin reduces glucotoxicity and lipotoxicity in a type 2 diabetes rat model by modulating the PI3K and MAPK signaling pathways

Objective

The current study aimed to investigate the potential therapeutic impact of allantoin on diabetes produced by a high-fat diet (HFD) and streptozotocin (STZ) in rats.

Subjects and methods

Male Sprague-Dawley rats were fed a high-fat diet to induce insulin resistance, followed by streptozotocin injection to induce diabetes. The effect of oral treatment of allantoin (200, 400 and 800 mg/kg/day) for 8 weeks was evaluated by calculating the alteration in metabolic parameters, biochemical indicators, the oral glucose tolerance tests (OGTT) and hyperinsulinemic-euglycemic clamp tests were performed. Histopathological studies were performed in the liver, kidney and pancreas. Next, the expressions of the MAPK and insulin signaling pathway were measured by Western blot analysis to elucidate the potential mechanism underlying these antidiabetic activities.

Results

The administration of allantoin resulted in a significant decrease in fasting blood glucose (FBG) levels, glycogen levels, and glycosylated hemoglobin levels in diabetic rats. Additionally, allantoin therapy led to a dose-dependent increase in body weight growth and serum insulin levels. In addition, the administration of allantoin resulted in a considerable reduction in lipid profile levels and amelioration of histological alterations in rats with diabetes. The administration of allantoin to diabetic rats resulted in a notable decrease in Malondialdehyde (MDA) levels, accompanied by an increase in the activity of antioxidant enzymes in the serum, liver, and kidney. The findings of oral glucose tolerance and hyperinsulinemic-euglycemic clamp tests demonstrated a significant rise in insulin resistance following the administration of allantoin. The upregulation of IRS-2/PI3K/p-Akt/GLUT expression by allantoin suggests a mechanistic relationship between the PI3K/Akt signaling pathway and the antihyperglycemic activity of allantoin. Furthermore, it resulted in a reduction in the levels of TGF-β1/p38MAPK/Caspase-3 expression in the aforementioned rat tissues affected by diabetes.

Conclusions

This study implies that allantoin treats type 2 diabetes by activating PI3K. Additionally, it reduces liver, kidney, and pancreatic apoptosis and inflammation-induced insulin resistance.re.

Epigenetics of Skeletal Muscle Atrophy

Skeletal muscle atrophy, characterized by diminished muscle strength and mass, arises from various causes, including malnutrition, aging, nerve damage, and disease-related secondary atrophy. Aging markedly escalates the prevalence of sarcopenia. Concurrently, the incidence of muscle atrophy significantly rises among patients with chronic ailments such as heart failure, diabetes, and chronic obstructive pulmonary disease (COPD). Epigenetics plays a pivotal role in skeletal muscle atrophy. Aging elevates methylation levels in the promoter regions of specific genes within muscle tissues. This aberrant methylation is similarly observed in conditions like diabetes, neurological disorders, and cardiovascular diseases. This study aims to explore the relationship between epigenetics and skeletal muscle atrophy, thereby enhancing the understanding of its pathogenesis and uncovering novel therapeutic strategies.

Diabetes-induced muscle wasting: molecular mechanisms and promising therapeutic targets

Diabetes has become a serious public health crisis, presenting significant challenges to individuals worldwide. As the largest organ in the human body, skeletal muscle is a significant target of this chronic disease, yet muscle wasting as a complication of diabetes is still not fully understood and effective treatment methods have yet to be developed. Here, we discuss the targets involved in inducing muscle wasting under diabetic conditions, both validated targets and emerging targets. Diabetes-induced skeletal muscle wasting is known to involve changes in various signaling molecules and pathways, such as protein degradation pathways, protein synthesis pathways, mitochondrial function, and oxidative stress inflammation. Recent studies have shown that some of these present potential as promising therapeutic targets, including the neuregulin 1/epidermal growth factor receptor family, advanced glycation end-products, irisin, ferroptosis, growth differentiation factor 15 and more. This study's investigation and discussion of such pathways and their potential applications provides a theoretical basis for the development of clinical treatments for diabetes-induced muscle wasting and a foundation for continued focus on this disease.

The Multiple Roles of Lactate in the Skeletal Muscle

Believed for a long time to be merely a waste product of cell metabolism, lactate is now considered a molecule with several roles, having metabolic and signalling functions together with a new, recently discovered role as an epigenetic modulator. Lactate produced by the skeletal muscle during physical exercise is conducted to the liver, which uses the metabolite as a gluconeogenic precursor, thus generating the well-known "Cori cycle". Moreover, the presence of lactate in the mitochondria associated with the lactate oxidation complex has become increasingly clear over the years. The signalling role of lactate occurs through binding with the GPR81 receptor, which triggers the typical signalling cascade of the G-protein-coupled receptors. Recently, it has been demonstrated that lactate regulates chromatin state and gene transcription by binding to histones. This review aims to describe the different roles of lactate in skeletal muscle, in both healthy and pathological conditions, and to highlight how lactate can influence muscle regeneration by acting directly on satellite cells.

Bitter yet beneficial: The dual role of dietary alkaloids in managing diabetes and enhancing cognitive function

With the rising prevalence of diabetes and its association with cognitive impairment, interest in the use of dietary alkaloids and other natural products has grown significantly. Understanding how these compounds manage diabetic cognitive dysfunction (DCD) is crucial. This comprehensive review explores the etiology of DCD and the effects of alkaloids in foods and dietary supplements that have been investigated as DCD therapies. Data on how dietary alkaloids like berberine, trigonelline, caffeine, capsaicin, 1-deoxynojirimycin, nuciferine, neferine, aegeline, tetramethylpyrazine, piperine, and others regulate cognition in diabetic disorders were collected from PubMed, Research Gate, Web of Science, Science Direct, and other relevant databases. Dietary alkaloids could improve memory in behavioral models and modulate the mechanisms underlying the cognitive benefits of these compounds, including their effects on glucose metabolism, gut microbiota, vasculopathy, neuroinflammation, and oxidative stress. Evidence suggests that dietary alkaloids hold promise for improving cognition in diabetic patients and could open exciting avenues for future research in diabetes management.

Skeletal muscle atrophy after sciatic nerve damage: Mechanistic insights

Sciatic nerve injury leads to molecular events that cause muscular dysfunction advancement in atrophic conditions. Nerve damage renders muscles permanently relaxed which elevates intracellular resting Ca2+ levels. Increased Ca2+ levels are associated with several cellular signaling pathways including AMPK, cGMP, PLC-β, CERB, and calcineurin. Also, multiple enzymes involved in the tricarboxylic acid cycle and oxidative phosphorylation are activated by Ca2+ influx into mitochondria during muscle contraction, to meet increased ATP demand. Nerve damage induces mitophagy and skeletal muscle atrophy through increased sensitivity to Ca2+-induced opening of the permeability transition pore (PTP) in mitochondria attributed to Ca2+, ROS, and AMPK overload in muscle. Activated AMPK interacts negatively with Akt/mTOR is a highly prevalent and well-described central pathway for anabolic processes. Over the decade several reports indicate abnormal behavior of signaling machinery involved in denervation-induced muscle loss but end up with some controversial outcomes. Therefore, understanding how the synthesis and inhibitory stimuli interact with cellular signaling to control muscle mass and morphology may lead to new pharmacological insights toward understanding the underlying mechanism of muscle loss after sciatic nerve damage. Hence, the present review summarizes the existing literature on denervation-induced muscle atrophy to evaluate the regulation and expression of differential regulators during sciatic damage.

The Therapeutic Potential of Four Main Compounds of Zanthoxylum nitidum (Roxb.) DC: A Comprehensive Study on Biological Processes, Anti-Inflammatory Effects, and Myocardial Toxicity

Zanthoxylum nitidum (Roxb.) DC. (Z. nitidum) is a traditional Chinese medicinal plant that is indigenous to the southern regions of China. Previous research has provided evidence of the significant anti-inflammatory, antibacterial, and anticancer properties exhibited by Z. nitidum. The potential therapeutic effects and cardiac toxicity of Z. nitidum remain uncertain. The aim of this research was to investigate the potential therapeutic properties of the four main compounds of Z. nitidum in cardiovascular diseases, their impact on the electrical activity of cardiomyocytes, and the underlying mechanism of their anti-inflammatory effects. We selected the four compounds from Z. nitidum with a high concentration and specific biological activity: nitidine chloride (NC), chelerythrine chloride (CHE), magnoflorine chloride (MAG), and hesperidin (HE). A proteomic analysis was conducted on the myocardial tissues of beagle dogs following the administration of NC to investigate the role of NC in vivo and the associated biological processes. A bioinformatic analysis was used to predict the in vivo biological processes that MAG, CHE, and HE were involved in. Molecular docking was used to simulate the binding between compounds and their targets. The effect of the compounds on ion channels in cardiomyocytes was evaluated through a patch clamp experiment. Organ-on-a-chip (OOC) technology was developed to mimic the physiological conditions of the heart in vivo. Proteomic and bioinformatic analyses demonstrated that the four compounds of Z. nitidum are extensively involved in various cardiovascular-related biological pathways. The findings from the patch clamp experiments indicate that NC, CHE, MAG, and HE elicit a distinct activation or inhibition of the IK1 and ICa-L in cardiomyocytes. Finally, the anti-inflammatory effects of the compounds on cardiomyocytes were verified using OOC technology. NC, CHE, MAG, and HE demonstrate anti-inflammatory effects through their specific interactions with prostaglandin-endoperoxide synthase 2 (PTGS2) and significantly influence ion channels in cardiomyocytes. Our study provides a foundation for utilizing NC, CHE, MAG, and HE in the treatment of cardiovascular diseases.

Salbutamol ameliorates skeletal muscle wasting and inflammatory markers in streptozotocin (STZ)-induced diabetic rats

Diabetes accelerates muscle atrophy, leading to the deterioration of skeletal muscles. This study aimed to assess the potential of the β2-adrenoceptor agonist, salbutamol (SLB), to alleviate muscle atrophy in streptozotocin (STZ)-induced diabetic rats. Male Sprague Dawley rats were randomized into four groups (n=6): control, SLB, STZ (55 mg/kg, single i.p.), and STZ + SLB (6 mg/kg, orally for 4 weeks). After the final SLB dose, animals underwent tests to evaluate muscle strength and coordination, including forelimb grip strength, wire-hanging, actophotometer, rotarod, and footprint assessments. Rats were then sacrificed, and serum and gastrocnemius (GN) muscles were collected for further analysis. Serum evaluations included proinflammatory markers (tumor necrosis factor α, interleukin-1β, interleukin-6), muscle markers (creatine kinase, myostatin), testosterone, and lipidemic markers. Muscle oxidative stress (malonaldehyde, protein carbonyl), antioxidants (glutathione, catalase, superoxide dismutase), and histology were also performed. Additionally, 1H nuclear magnetic resonance serum profiling was conducted. SLB notably enhanced muscle grip strength, coordination, and antioxidant levels, while reduced proinflammatory markers and oxidative stress in STZ-induced diabetic rats. Reduced serum muscle biomarkers, increased testosterone, restored lipidemic levels, and improved muscle cellular architecture indicated SLB's positive effect on muscle condition in diabetic rats. Metabolomics profiling revealed that the STZ group significantly increased the phenylalanine-to-tyrosine ratio (PTR), lactate-to-pyruvate ratio (LPR), acetate, succinate, isobutyrate, and histidine. SLB administration restored these perturbed serum metabolites in the STZ-induced diabetic group. In conclusion, salbutamol significantly protected against skeletal muscle wasting in STZ-induced diabetic rats.

Sarcopenia, a condition shared by various diseases: can we alleviate or delay the progression?

Sarcopenia is a severe condition common to various chronic diseases and it is reckoned as a major health problem. It encompasses many different molecular mechanisms that have been for a while discovered but not definitely clarified. Although sarcopenia is a disability status that leads to serious health consequences, the scarcity of suitable animal models has curtailed research addressing this disorder. Another limitation in the field of clinical investigation of sarcopenic patients is the lack of a generally accepted definition coupled with the difficulty of adopting common diagnostic criteria. In fact, both do not permit to clarify the exact prevalence rate and consequently limit physicians to establish any kind of therapeutical approach or, when possible, to adopt preventive measures. Unfortunately, there is no standardized cure, apart from doing more physical activity and embracing a balanced diet, but newly discovered substances start being considered. In this review, authors try to give an overview addressing principal pathways of sarcopenia and offer critical features of various possible interventions.

Salbutamol Attenuates Diabetic Skeletal Muscle Atrophy by Reducing Oxidative Stress, Myostatin/GDF-8, and Pro-Inflammatory Cytokines in Rats

Type 2 diabetes is a metabolic disorder that leads to accelerated skeletal muscle atrophy. In this study, we aimed to evaluate the effect of salbutamol (SLB) on skeletal muscle atrophy in high-fat diet (HFD)/streptozotocin (STZ)-induced diabetic rats. Male Sprague Dawley rats were divided into four groups (n = 6): control, SLB, HFD/STZ, and HFD/STZ + SLB (6 mg/kg orally for four weeks). After the last dose of SLB, rats were assessed for muscle grip strength and muscle coordination (wire-hanging, rotarod, footprint, and actophotometer tests). Body composition was analyzed in live rats. After that, animals were sacrificed, and serum and gastrocnemius (GN) muscles were collected. Endpoints include myofibrillar protein content, muscle oxidative stress and antioxidants, serum pro-inflammatory cytokines (interleukin-1β, interleukin-2, and interleukin-6), serum muscle markers (myostatin, creatine kinase, and testosterone), histopathology, and muscle 1H NMR metabolomics. Findings showed that SLB treatment significantly improved muscle strength and muscle coordination, as well as increased lean muscle mass in diabetic rats. Increased pro-inflammatory cytokines and muscle markers (myostatin, creatine kinase) indicate muscle deterioration in diabetic rats, while SLB intervention restored the same. Also, Feret's diameter and cross-sectional area of GN muscle were increased by SLB treatment, indicating the amelioration in diabetic rat muscle. Results of muscle metabolomics exhibit that SLB treatment resulted in the restoration of perturbed metabolites, including histidine-to-tyrosine, phenylalanine-to-tyrosine, and glutamate-to-glutamine ratios and succinate, sarcosine, and 3-hydroxybutyrate (3HB) in diabetic rats. These metabolites showed a pertinent role in muscle inflammation and oxidative stress in diabetic rats. In conclusion, findings showed that salbutamol could be explored as an intervention in diabetic-associated skeletal muscle atrophy.

Simiao Wan and its ingredients alleviate type 2 diabetes mellitus via IRS1/AKT2/FOXO1/GLUT2 signaling

Background

Type 2 diabetes mellitus (T2DM) is a metabolic disease. Simiao Wan (SMW) is a commonly used clinical drug for hyperuricemia treatment. SMW has been confirmed to improve insulin resistance and is expected to be a novel hypoglycemic agent. However, the hypoglycemic bioactive ingredients and mechanisms of action of SMW are unclear.

Objective

To explore the hypoglycemic effects and reveal the mechanisms of SMW and bioactive ingredients (SMW-BI).

Study design and methods

The hypoglycemic effects of SMW and SMW-BI were verified in a mouse model of T2DM induced by streptozotocin (STZ) and a high-fat and high-sugar diet (HFSD). Network pharmacology was used to predict the mechanisms of SMW and SMW-BI. Histological analysis and real-time quantitative polymerase chain reaction (RT-qPCR) verified network pharmacology results. RT-qPCR results were further verified by immunofluorescence (IFC) and molecular docking. The correlation between proteins and biochemical indicators was analyzed by Spearman's correlation.

Results

Chlorogenic acid, phellodendrine, magnoflorine, jateorhizine, palmatine, berberine, and atractydin were identified as SMW-BI. After 8 weeks of treatment, SMW and SMW-BI decreased the levels of fasting blood glucose (FBG), total cholesterol (TC), triacylglycerols (TG) and low-density lipoprotein cholesterol (LDL-C), increased the level of high-density lipoprotein cholesterol (HDL-C), alleviated weight loss, and increased serum insulin levels in T2DM mice. In addition, SMW and SMW-BI improved hepatocyte morphology in T2DM mice, decreased the number of adipocytes, and increased liver glycogen. Network pharmacological analysis indicated that SMW and SMW-BI may exert hypoglycemic by regulating insulin receptor substrate 1 (IRS1)/RAC-beta serine/threonine-protein kinase (AKT2)/forkhead box protein O1 (FOXO1)/glucose transporter type 2 (GLUT2) signaling. Moreover, correlation analysis showed that SMW and SMW-BI were associated with activation of IRS1, AKT2, and GLUT2, and inhibiting FOXO1. RT-qPCR revealed that SMW and SMW-BI could increase levels of IRS1, AKT2, and GLUT2 in the livers of T2DM mice and lower the level of FOXO1. Furthermore, immunofluorescence analysis showed that FOXO1 expression in the livers of T2DM mice decreased after oral administration of SMW and SMW-BI. Furthermore, molecular docking showed that SMW-BI could bind directly to IRS1 and AKT2.

Conclusion

SMW and SMW-BI are potential hypoglycemic drugs that alleviate T2DM by regulating IRS1/AKT2/FOXO1 signaling. Our study provides a research idea for screening the bioactive ingredients in traditional Chinese medicine (TCM).

Alkaloids as Promising Agents for the Management of Insulin Resistance: A Review

BACKGROUND

Insulin resistance is one of the main factors that lead to the development of type 2 diabetes mellitus (T2DM). The effect of alkaloids on insulin resistance has been extensively examined according to multiple scientific researches.

OBJECTIVE

In this work, we aimed to summarize the interesting results from preclinical and clinical studies that assessed the effects of natural alkaloids (berberine, nigelladine A, piperine, trigonelline, capsaicin, nuciferine, evodiamine, mahanine, and magnoflorine) on impaired insulin sensitivity and worsened insulin resistance, which play a pivotal role in the pathogenesis of type 2 diabetes.

METHODS

In the current review, PubMed, ScienceDirect, Springer, and Google Scholar databases were used. The inclusion criteria were based on the following keywords and phrases: insulin sensitivity, insulin resistance, alkaloids and insulin resistance, alkaloids and type 2 diabetes, mechanisms of action, and alkaloids.

RESULTS

The outcomes reported in this review demonstrated that the selected alkaloids increased insulin sensitivity and reduced insulin resistance in vitro and in vivo evidence, as well as in clinical trials, through improving insulin-signaling transduction mainly in hepatocytes, myocytes, and adipocytes, both at cellular and molecular levels. Insulin signaling components (InsR, IRS-1, PI3K, Akt, etc.), protein kinases and phosphatases, receptors, ion channels, cytokines, adipokines, and microRNAs, are influenced by alkaloids at transcriptional and translational levels, also in terms of function (activity and/or phosphorylation). Multiple perturbations associated with insulin resistance, such as ectopic lipid accumulation, inflammation, ER stress, oxidative stress, mitochondrial dysfunction, gut microbiota dysbiosis, and β-cell failure, are reversed after treatment with alkaloids. Furthermore, various indices and tests are employed to assess insulin resistance, including the Matsuda index, insulin sensitivity index (ISI), oral glucose tolerance test (OGTT), and insulin tolerance test (ITT), which are all enhanced by alkaloids. These improvements extend to fasting blood glucose, fasting insulin, and HbA1c levels as well. Additionally, the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) and the Homeostasis Model Assessment of β-cell function (HOMA-β) are recognized as robust markers of insulin sensitivity and β-cell function, and it is noteworthy that alkaloids also lead to improvements in these two markers.

CONCLUSION

Based on the findings of the current review, alkaloids may serve as both preventive and curative agents for metabolic disorders, specifically type 2 diabetes. Nonetheless, there is an urgent need for additional clinical trials to explore the potential benefits of alkaloids in both healthy individuals and those with type 2 diabetes. Additionally, it is crucial to assess any possible side effects and interactions with antidiabetic drugs.

Berberis dictyophylla F. inhibits angiogenesis and apoptosis of diabetic retinopathy via suppressing HIF-1α/VEGF/DLL-4/Notch-1 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Xiao Bopi (XBP, སྐྱེར་བའི་བར་ཤུན།), as a classical Tibetan medicinal plant in China, which derived from the stem bark of Berberis dictyophylla F., has the function of "clearing heat and decreasing mKhris-pa". And it traditionally is utilized to treat the diabetes mellitus and its complications, such as diabetic retinopathy (DR). However, its underlying mechanisms remain unclear.

AIM OF THE STUDY

The purpose of this study aimed to explore the microvascular protection of water extract of XBP against the spontaneous retinal damage of db/db mice. Meanwhile, the underlying mechanisms of XBP on angiogenesis and apoptosis were further interpreted.

MATERIALS AND METHODS

We firstly used high-performance liquid chromatography to detected the representative chemical ingredients in the water extract of XBP. The DR model of db/db mice was then randomly divided into five groups: model group, calcium dobesilate (0.23 g/kg) group, and the water extract of XBP (0.375, 0.75 and 1.5 g/kg, respectively) groups. After 8 weeks of continuous administration, the parameters including body weight, fasting blood glucose, oral glucose tolerance test and insulin tolerance test were measured. The pathological changes and abnormal angiogenesis of the retina were detected by optical coherence tomography, HE, periodic acid-Schiff staining and transmission electron microscopy. Simultaneously, molecular docking was used to predict the potential connections between representative ingredients in XBP and angiogenesis/apoptosis-related proteins. The level of angiogenesis-related proteins and gene hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth (VEGF), delta-like ligand 4 (DLL-4) and Notch-1 were estimated by immunofluorescence analyses and real time-PCR. Further, TUNEL staining and immunofluorescence analyses were performed to investigate the apoptotic phenomenon and the expression of Bax, Bcl-2, Apaf-1, Cyto-c and cleaved caspase-3 and cleaved caspase-9 in the retina.

RESULTS

Phytochemical analysis revealed that magnoflorine, jatrorrhizine, palmatine and berberine were principally representative ingredients in XBP. The results demonstrated that XBP effectively increased glucose tolerance and insulin sensitivity, whereas no effect on body weight of DR mice. Moreover, retinal thickening, pathological and retinal ultrastructure changes in DR mice were evidently ameliorated by XBP. The molecular docking results demonstrated that the main components of XBP and the protein of angiogenesis and apoptosis had a potential bind. XBP restrained the gene and protein levels of HIF-1α, VEGF, DLL-4 and Notch-1 in retina. Additionally, the TUNEL-positive cell rate and the down-regulated proteins of Bax, Apaf-1, Cyto-c, cleaved Caspase-3 and cleaved Caspase 9 and increased Bcl-2 level were revised by XBP.

CONCLUSIONS

To sum up, the results suggested that XBP against DR could attribute to alleviating angiogenesis and apoptosis by suppressing the HIF-1α/VEGF/DLL-4/Notch-1 pathway. This evidence sheds a new light on the potential mechanisms of XBP in the treatment of DR.

Magnoflorine Attenuates Cerebral Ischemia-Induced Neuronal Injury via Autophagy/Sirt1/AMPK Signaling Pathway

Ischemic stroke is a common cause of permanent disability worldwide. Magnoflorine has been discovered to have good antioxidation, immune regulation, and cardiovascular system protection functions. However, whether magnoflorine treatment protects against cerebral ischemic stroke and the mechanism of such protection remains unknown. Here, we investigated the effect of magnoflorine on the development of ischemic stroke disorder in rats. A middle cerebral artery occlusion (MCAO) model followed by 24 h reperfusion after 90 min ischemia was used. The rats were treated with magnoflorine (10 mg/kg or 20 mg/kg) for 15 consecutive days. The neurological deficit scores, cerebral infarct volume, and brain water content were measured. The neuronal density was determined using Nissl and NeuN staining. The oxidative stress levels were determined using commercial kits. Immunofluorescence staining of LC3 and western blot assay for LC3 and p62 were used to assess autophagy. Magnoflorine treatment significantly reduced the cerebral infarct volume and brain water content and improved the neurological deficit scores in the rat MCAO model. In addition, magnoflorine ameliorated neuronal injury and neuron density in the cortex of rats. Magnoflorine also prevented oxidative damage following ischemia, reflected by the decrement of nitric oxide and malondialdehyde and the increase of glutathione (GSH) and GSH peroxidase. Moreover, the fluorescence intensity of LC3 and the ratio of LC3-II to LC3-I were remarkably downregulated in ischemic rat administration of magnoflorine. Finally, the expression levels of p62, sirtuin 1 (Sirt1), and phosphorylated-adenosine monophosphate-activated protein kinase (AMPK) were upregulated with magnoflorine. Magnoflorine attenuated the cerebral ischemia-induced neuronal damage, which was possibly associated with antioxidative stress, suppression of autophagy, and activation of the Sirt1/AMPK pathway in the rats.

[Mibefradil improves skeletal muscle mass, function and structure in obese mice]

OBJECTIVE

To observe the effect of mibefradil on skeletal muscle mass, function and structure in obese mice.

METHODS

Fifteen 6-week-old C57BL/6 mice were randomized equally into normal diet group (control group), high-fat diet (HFD) group and high-fat diet +mibefradil intervention group (HFD +Mibe group). The grip strength of the mice was measured using an electronic grip strength meter, and the muscle content of the hindlimb was analyzed by X-ray absorptiometry (DXA). Triglyceride (TG) and total cholesterol (TC) levels of the mice were measured with GPO-PAP method. The cross-sectional area of the muscle fibers was observed with HE staining. The changes in the level of autophagy in the muscles were detected by Western blotting and immunofluorescence assay, and the activation of the Akt/mTOR signaling pathway was detected with Western blotting.

RESULTS

Compared with those in the control group, the mice in HFD group had a significantly greater body weight, lower relative grip strength, smaller average cross sectional area of the muscle fibers, and a lower hindlimb muscle ratio (P < 0.05). Immunofluorescence assay revealed a homogenous distribution of LC3 emitting light red fluorescence in the cytoplasm in the muscle cells in HFD group and HFD+Mibe group, while bright spots of red fluorescence were detected in HFD group. In HFD group, the muscular tissues of the mice showed an increased expression level of LC3 II protein with lowered expressions of p62 protein and phosphorylated AKT and mTOR (P < 0.05). Mibefradil treatment significantly reduced body weight of the mice, lowered the expression level of p62 protein, and increased forelimb grip strength, hindlimb muscle ratio, cross-sectional area of the muscle fibers, and the expression levels of LC3 II protein and phosphorylated AKT and mTOR (P < 0.05).

CONCLUSION

Mibefradil treatment can moderate high-fat diet-induced weight gain and improve muscle mass and function in obese mice possibly by activating AKT/mTOR signal pathway to improve lipid metabolism and inhibit obesityinduced autophagy.

Diabetic Muscular Atrophy: Molecular Mechanisms and Promising Therapies

Diabetes mellitus (DM) is a typical chronic disease that can be divided into 2 types, dependent on insulin deficiency or insulin resistance. Incidences of diabetic complications gradually increase as the disease progresses. Studies in diabetes complications have mostly focused on kidney and cardiovascular diseases, as well as neuropathy. However, DM can also cause skeletal muscle atrophy. Diabetic muscular atrophy is an unrecognized diabetic complication that can lead to quadriplegia in severe cases, seriously impacting patients' quality of life. In this review, we first identify the main molecular mechanisms of muscle atrophy from the aspects of protein degradation and synthesis signaling pathways. Then, we discuss the molecular regulatory mechanisms of diabetic muscular atrophy, and outline potential drugs and treatments in terms of insulin resistance, insulin deficiency, inflammation, oxidative stress, glucocorticoids, and other factors. It is worth noting that inflammation and oxidative stress are closely related to insulin resistance and insulin deficiency in diabetic muscular atrophy. Regulating inflammation and oxidative stress may represent another very important way to treat diabetic muscular atrophy, in addition to controlling insulin signaling. Understanding the molecular regulatory mechanism of diabetic muscular atrophy could help to reveal new treatment strategies.

Natural products: Potential therapeutic agents to prevent skeletal muscle atrophy

The skeletal muscle (SkM) is the largest organ, which plays a vital role in controlling musculature, locomotion, body heat regulation, physical strength, and metabolism of the body. A sedentary lifestyle, aging, cachexia, denervation, immobilization, etc. Can lead to an imbalance between protein synthesis and degradation, which is further responsible for SkM atrophy (SmA). To date, the understanding of the mechanism of SkM mass loss is limited which also restricted the number of drugs to treat SmA. Thus, there is an urgent need to develop novel approaches to regulate muscle homeostasis. Presently, some natural products attained immense attraction to regulate SkM homeostasis. The natural products, i.e., polyphenols (resveratrol, curcumin), terpenoids (ursolic acid, tanshinone IIA, celastrol), flavonoids, alkaloids (tomatidine, magnoflorine), vitamin D, etc. exhibit strong potential against SmA. Some of these natural products have been reported to have equivalent potential to standard treatments to prevent body lean mass loss. Indeed, owing to the large complexity, diversity, and slow absorption rate of bioactive compounds made their usage quite challenging. Moreover, the use of natural products is controversial due to their partially known or elusive mechanism of action. Therefore, the present review summarizes various experimental and clinical evidence of some important bioactive compounds that shall help in the development of novel strategies to counteract SmA elicited by various causes.

Natural Aporphine Alkaloids with Potential to Impact Metabolic Syndrome

The incidence and prevalence of metabolic syndrome has steadily increased worldwide. As a major risk factor for various diseases, metabolic syndrome has come into focus in recent years. Some natural aporphine alkaloids are very promising agents in the prevention and treatment of metabolic syndrome and its components because of their wide variety of biological activities. These natural aporphine alkaloids have protective effects on the different risk factors characterizing metabolic syndrome. In this review, we highlight the activities of bioactive aporphine alkaloids: thaliporphine, boldine, nuciferine, pronuciferine, roemerine, dicentrine, magnoflorine, anonaine, apomorphine, glaucine, predicentrine, isolaureline, xylopine, methylbulbocapnine, and crebanine. We particularly focused on their impact on metabolic syndrome and its components, including insulin resistance and type 2 diabetes mellitus, endothelial dysfunction, hypertension and cardiovascular disease, hyperlipidemia and obesity, non-alcoholic fatty liver disease, hyperuricemia and kidney damage, erectile dysfunction, central nervous system-related disorder, and intestinal microbiota dysbiosis. We also discussed the potential mechanisms of actions by aporphine alkaloids in metabolic syndrome.

Administration of tauroursodeoxycholic acid attenuates dexamethasone-induced skeletal muscle atrophy

Glucocorticoids are known to induce skeletal muscle atrophy by suppressing protein synthesis and promoting protein degradation. Tauroursodeoxycholic acid (TUDCA) has beneficial effects in several diseases, such as hepatobiliary disorders, hindlimb ischemia and glucocorticoid-induced osteoporosis. However, the effects of TUDCA on glucocorticoid -induced skeletal muscle atrophy remains unknown. Therefore, in the present research, we explored the effects of TUDCA on dexamethasone (DEX)-induced loss and the potential mechanisms involved. We found TUDCA alleviated DEX-induced muscle wasting in C2C12 myotubes, identified by improved myotube differentiation index and expression of myogenin and MHC. And it showed that TUDCA activated the Akt/mTOR/S6K signaling pathway and inhibited FoxO3a transcriptional activity to decreased expression of MuRF1 and Atrogin-1, while blocking Akt by MK2206 blocked these effects of TUDCA on myotubes. Besides, TUDCA also attenuated DEX-induced apoptosis of myotubes. Furthermore, TUDCA was administrated to the mouse model of DEX-induced skeletal muscle atrophy. The results showed that TUDCA improved DEX-induced skeletal muscle atrophy and weakness (identified by increased grip strength and prolonged running exhaustive time) in mice by suppression of apoptosis, reduction of protein degradation and promotion of protein synthesis. Taken together, our research proved for the first time that TUDCA protected against DEX-induced skeletal muscle atrophy not only by improving myogenic differentiation and protein synthesis, but also through decreasing protein degradation and apoptosis of skeletal muscle.

Effects of Geniposide and Geniposidic Acid on Fluoxetine-Induced Muscle Atrophy in C2C12 Cells

Fluoxetine, an antidepressant known as a selective 5-hydroxytryptamine reuptake inhibitor (SSRI), can cause side effects such as muscle atrophy with long-term use, but the mechanism is not fully understood. Geniposide (GPS) and geniposidic acid (GPSA), the main components of Gardenia jasminoides fruit, have been shown to have biological activity in disease prevention, but their role in preventing FXT-related side effects such as muscle atrophy remains unclear. The process of muscle atrophy is a complex physiological mechanism involving the balance of protein synthesis and catabolism. In this study, we hypothesized that FXT may suppress hypertrophy signaling and activate the atrophy mechanisms, resulting in proteolysis and reduced protein synthesis, while geniposide (GPS) and geniposide acid (GPSA) may be beneficial in improving muscle weakness caused by FXT. The C2C12 cell model was used to examine the expression of hypertrophy signaling (PI3K, Akt, and mTOR) and protein break signals (FOXO, MuRF-1, and MyHC). Our data indicated that FXT inhibited MyHC and promoted MuRF-1 protein expression by downregulating the signaling pathways of p-ERK1/2, p-Akt, p-mTOR, and p-FOXO, resulting in a decrease in differentiation and myotube formation in C2C12 muscle cells, which further resulted in muscle atrophy. However, GPS and GPSA can positively regulate the atrophy mechanism induced by FXT in muscle cells, thereby ameliorating the imbalance in muscle synthesis. In conclusion, GPS and GPSA have the potential to attenuate the muscle loss caused by long-term FXT administration, diseases, or the aging process.

Amelioration of diabetic retinopathy in db/db mice by treatment with different proportional three active ingredients from Tibetan medicine Berberis dictyophylla F

ETHNOPHARMACOLOGICAL RELEVANCE

Berberis dictyophylla F., a famous Tibetan medicine, has been used to prevent and treat diabetic retinopathy (DR) for thousands of years in clinic. However, its underlying mechanisms remain unclear.

AIM OF THE STUDY

The present study was designed to probe the synergistic protection and involved mechanisms of berberine, magnoflorine and berbamine from Berberis dictyophylla F. on the spontaneous retinal damage of db/db mice.

MATERIALS AND METHODS

The 14-week spontaneous model of DR in db/db mice were randomly divided into eight groups: model group, calcium dobesilate (CaDob, 0.23 g/kg) group and groups 1-6 (different proportional three active ingredients from Berberis dictyophylla F.). All mice were intragastrically administrated for a continuous 12 weeks. Body weight and fasting blood glucose (FBG) were recorded and measured. Hematoxylin-eosin and periodic acid-Schiff (PAS) stainings were employed to evaluate the pathological changes and abnormal angiogenesis of the retina. ELISA was performed to assess the levels of IL-6, HIF-1α and VEGF in the serum. Immunofluorescent staining was applied to detect the protein levels of CD31, VEGF, p-p38, p-JNK, p-ERK and NF-κB in retina. In addition, mRNA expression levels of VEGF, Bax and Bcl-2 in the retina were monitored by qRT-PCR analysis.

RESULTS

Treatment with different proportional three active ingredients exerted no significant effect on the weight, but decreased the FBG, increased the number of retinal ganglionic cells and restored internal limiting membrane. The results of PAS staining demonstrated that the drug treatment decreased the ratio of endothelial cells to pericytes while thinned the basal membrane of retinal vessels. Moreover, these different proportional active ingredients can markedly downregulate the protein levels of retinal CD31 and VEGF, and serum HIF-1α and VEGF. The gene expression of retinal VEGF was also suppressed. The levels of retinal p-p38, p-JNK and p-ERK proteins were decreased by drug treatment. Finally, drug treatment reversed the proinflammatory factors of retinal NF-κB and serum IL-6, and proapoptotic Bax gene expression, while increased antiapoptotic Bcl-2 gene expression.

CONCLUSIONS

These results indicated that DR in db/db mice can be ameliorated by treatment with different proportional three active ingredients from Berberis dictyophylla F. The potential vascular protection mechanisms may be involved in inhibiting the phosphorylation of the MAPK signaling pathway, thus decreasing inflammatory and apoptotic events.

Nutraceuticals in the Prevention and Treatment of the Muscle Atrophy

Imbalance of protein homeostasis, with excessive protein degradation compared with protein synthesis, leads to the development of muscle atrophy resulting in a decrease in muscle mass and consequent muscle weakness and disability. Potential triggers of muscle atrophy include inflammation, malnutrition, aging, cancer, and an unhealthy lifestyle such as sedentariness and high fat diet. Nutraceuticals with preventive and therapeutic effects against muscle atrophy have recently received increasing attention since they are potentially more suitable for long-term use. The implementation of nutraceutical intervention might aid in the development and design of precision medicine strategies to reduce the burden of muscle atrophy. In this review, we will summarize the current knowledge on the importance of nutraceuticals in the prevention of skeletal muscle mass loss and recovery of muscle function. We also highlight the cellular and molecular mechanisms of these nutraceuticals and their possible pharmacological use, which is of great importance for the prevention and treatment of muscle atrophy.