Beneficial effect of baicalin on insulin sensitivity in adipocytes of diet-induced obese mice

Baicalin suppresses macrophage JNK-mediated adipose tissue inflammation to mitigate insulin resistance in obesity

ETHNOPHARMACOLOGICAL RELEVANCE

Radix scutellariae (the root of Scutellaria baicalensis Georgi) is a traditional Chinese medicine (TCM) used to treat a wide range of inflammation-related diseases, such as obesity, diabetes, diabetic kidney disease, and COVID-19-associated inflammatory states in the lung and kidney. Baicalin is the major anti-inflammatory component of Radix scutellariae and has shown the potential to inhibit inflammation in metabolic disorders. In this study, we explored the ability and underlying mechanisms of baicalin to modulate the macrophage to mitigate insulin resistance in obesity.

MATERIALS AND METHODS

Obese mice were administered baicalin (50 mg/kg/day) intraperitoneally for 3 weeks. RAW264.7 and BMDM cells were stimulated with LPS and treated with baicalin for 24 h, while 3T3-L1 and primary white adipocytes were treated with the supernatants from baicalin-treated RAW264.7 cells for 24 h.

RESULTS

The results showed that baicalin significantly improved glucose and insulin tolerance as well as decreased fat and adipose tissue macrophage levels in obese mice. Besides, baicalin significantly reduced serum and adipose tissue IL-1β, TNF-α and IL-6 levels in obese mice, as well as suppressed LPS-induced IL-1β, TNF-α and IL-6 expression and release in macrophages. Furthermore, treatment with the supernatant from baicalin-treated RAW264.7 cells increased the levels of PGC-1α, SIRT1, p-IRS-1 and p-AKT in adipocytes. Moreover, baicalin treatment dramatically downregulated macrophage p-p38, p-JNK, and Ac-p65Lys310 levels while increasing SIRT1 both in vivo and in vitro. Importantly, JNK inhibitor SP600125 blocked most of the effects of baicalin on SIRT1, Ac-p65Lys310 and pro-inflammatory factors in macrophages.

CONCLUSION

Therefore, these results demonstrated for the first time that baicalin exerts its anti-inflammatory effects in obese adipose tissue macrophages mainly through suppressing JNK/SIRT1/p65 signaling. These findings amplified the mechanisms of baicalin and its potential to attenuate insulin resistance.

The PI3K/Akt signaling axis and type 2 diabetes mellitus (T2DM): From mechanistic insights into possible therapeutic targets

Type 2 diabetes mellitus (T2DM) is an immensely debilitating chronic disease that progressively undermines the well-being of various bodily organs and, indeed, most patients succumb to the disease due to post-T2DM complications. Although there is evidence supporting the activation of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway by insulin, which is essential in regulating glucose metabolism and insulin resistance, the significance of this pathway in T2DM has only been explored in a few studies. The current review aims to unravel the mechanisms by which different classes of PI3Ks control the metabolism of glucose; and also to discuss the original data obtained from international research laboratories on this topic. We also summarized the role of the PI3K/Akt signaling axis in target tissues spanning from the skeletal muscle to the adipose tissue and liver. Furthermore, inquiries regarding the impact of disrupting this axis on insulin function and the development of insulin resistance have been addressed. We also provide a general overview of the association of impaired PI3K/Akt signaling pathways in the pathogenesis of the most prevalent diabetes-related complications. The last section provides a special focus on the therapeutic potential of this axis by outlining the latest advances in active compounds that alleviate diabetes via modulation of the PI3K/Akt pathway. Finally, we comment on the future research aspects in which the field of T2DM therapies using PI3K modulators might be developed.

Clinical applications and mechanism insights of natural flavonoids against type 2 diabetes mellitus

Diabetes is a complex disease that affects a large percentage of the world's population, and it is associated with several risk factors. Self-management poses a significant challenge, but natural sources have shown great potential in providing effective glucose reducing solutions. Flavonoids, a class of bioactive substances found in different natural sources including medicinal plants, have emerged as promising candidates in this regard. Indeed, several flavonoids, including apigenin, arbutin, catechins, and cyanidin, have demonstrated remarkable anti-diabetic properties. The clinical effectiveness of these flavonoids is linked to their potential to decrease blood glucose concentration and increase insulin concentration. Thus, the regulation of certain metabolic pathways such as glycolysis and neoglycogenesis has also been demonstrated. In vitro and in vivo investigations revealed different mechanisms of action related to flavonoid compounds at subcellular, cellular, and molecular levels. The main actions reside in the activation of glycolytic signaling pathways and the inhibition of signaling that promotes glucose synthesis and storage. In this review, we highlight the clinical efficiency of natural flavonoids as well as the molecular mechanisms underlying this effectiveness.

The Anti-Diabetic Potential of Baicalin: Evidence from Rodent Studies

Baicalin is a biologically active flavonoid compound that benefits the organism in various pathological conditions. Rodent studies have shown that this compound effectively alleviates diabetes-related disturbances in models of type 1 and type 2 diabetes. Baicalin supplementation limited hyperglycemia and improved insulin sensitivity. The anti-diabetic effects of baicalin covered the main insulin-sensitive tissues, i.e., the skeletal muscle, the adipose tissue, and the liver. In the muscle tissue, baicalin limited lipid accumulation and improved glucose transport. Baicalin therapy was associated with diminished adipose tissue content and increased mitochondrial biogenesis. Hepatic lipid accumulation and glucose output were also decreased as a result of baicalin supplementation. The molecular mechanism of the anti-diabetic action of this compound is pleiotropic and is associated with changes in the expression/action of pivotal enzymes and signaling molecules. Baicalin positively affected, among others, the tissue insulin receptor, glucose transporter, AMP-activated protein kinase, protein kinase B, carnitine palmitoyltransferase, acetyl-CoA carboxylase, and fatty acid synthase. Moreover, this compound ameliorated diabetes-related oxidative and inflammatory stress and reduced epigenetic modifications. Importantly, baicalin supplementation at the effective doses did not induce any side effects. Results of rodent studies imply that baicalin may be tested as an anti-diabetic agent in humans.

Dietary flavonoids prevent diabetes through epigenetic regulation: advance and challenge

The pathophysiology of diabetes has been studied extensively in various countries, but effective prevention and treatment methods are still insufficient. In recent years, epigenetics has received increasing attention from researchers in exploring the etiology and treatment of diabetes. DNA methylation, histone modifications, and non-coding RNAs play critical roles in the occurrence, maintenance, and progression of diabetes and its complications. Therefore, preventing or reversing the epigenetic alterations that occur during the development of diabetes may reduce the individual and societal burden of the disease. Dietary flavonoids serve as natural epigenetic modulators for the discovery of biomarkers for diabetes prevention and the development of alternative therapies. However, there is limited knowledge about the potential beneficial effects of flavonoids on the epigenetics of diabetes. In this review, the multidimensional epigenetic effects of different flavonoid subtypes in diabetes were summarized. Furthermore, it was discussed that parental flavonoid diets might reduce diabetes incidence in offspring, which represent a promising opportunity to prevent diabetes in the future. Future work will depend on exploring anti-diabetic effects of different flavonoids with different epigenetic regulation mechanisms and clinical trials.Highlights• "Epigenetic therapy" could reduce the burden of diabetic patients• "Epigenetic diet" ameliorates diabetes• Targeting epigenetic regulations by dietary flavonoids in the diabetes prevention• Dietary flavonoids prevent diabetes via transgenerational epigenetic inheritance.

Alleviation of Fufang Fanshiliu decoction on type II diabetes mellitus by reducing insulin resistance: A comprehensive network prediction and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Fufang Fanshiliu decoction (FFSLD) is a Chinese herbal medicine prescription that has been used in type 2 diabetes mellitus (T2DM), while the underlying mechanism remains unclear.

AIM OF THE STUDY

To validate the efficacy and explore the potential mechanisms of FFSLD in treating T2DM via integrating a network pharmacological approach and experimental evaluation.

MATERIALS AND METHODS

T2DM mice model induced by high-fat diet feeding combined with streptozotocin injection was selected to investigate the alleviation of FFSLD against T2DM, via detecting the levels of glucose, insulin, glucagon (GC), triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C). Network pharmacological analysis was used to predict the potential mechanisms, including the pharmacokinetics and drug-likeness screening, active ingredients and potential targets prediction, network analysis, and enrichment analysis. The candidate bioactive molecules of FFSLD, and targets information excavated through TCMSP, Uniprot, GeneCards, OMIM databases, were combined for comprehensive analysis by constructing "drug-compound-target-disease" and "protein-protein interaction" networks. Enrichment analysis was performed via Gene Ontology (GO) and Koto Encyclopedia of Genes and Genomes (KEGG) databases. HepG2 insulin-resistance (IR) cells model induced by high glucose was used to verify the potential mechanisms of FFSLD against T2DM which were predicted by the network pharmacology.

RESULTS

The animal study showed that FFSLD significantly decreased the blood glucose, and reversed the abnormal levels of insulin, GC, TG, TC, HDL-C, and LDL-C in T2DM mice. Network pharmacological analysis indicated that 106 active compounds of FFSLD might be correlated with 628 targets in treating T2DM, and the mechanism would probably be related to insulin resistance that harbored a high response value (P = 5.88844 E^-33) though regulating Akt1, ESR1, oxidoreductase activity, and JAK/STAT signalings. Experimental validation showed that FFSLD reduced the ROS level, up-regulated the expressions of p-AKT, Nrf-2, and ESR1, and down-regulated the expressions of JAK2, STAT3, and Keap-1 in the HepG2-IR cells model.

CONCLUSIONS

This study demonstrated that the therapeutic effect of FFSLD on T2DM was related to IR alleviation. The underlying mechanisms were associated with the regulation of PI3K/AKT, JAK/STAT, oxidative stress, and ESR signaling pathways.

Baicalin promotes the activation of brown and white adipose tissue through AMPK/PGC1α pathway

Obesity occurs when energy intake overtops energy expenditure. Promoting activation of brown adipose tissue (BAT) and white adipose tissue (WAT) has been proven a promising therapeutic strategy for obesity. Baicalin (BAI) has been shown to be protective for various animal models of cardiovascular diseases, such as pulmonary hypertension, atherosclerosis and myocardial hypertrophy. However, whether BAI could stimulate activation of BAT or browning of WAT remains unknown. Here we show that BAI limits weight gaining, ameliorates glucose tolerance, improves cold tolerance and promotes brown-like tissue formation in diet induced obesity mice model. BAI increases the mitochondrial copy number as judged by mtDNA detection. BAI also increases the expression of UCP1 and other classical browning-specific genes in BAT and WAT and cultured C3H10T1/2 adipocytes through a mechanism involving AMPK/PGC1α pathway. Collectively, our study established a role for BAI in regulating energy metabolism, which will provide new idea and theoretical basis for the treatment of obesity.

Baicalin protects against insulin resistance and metabolic dysfunction through activation of GALR2/GLUT4 signaling

BACKGROUND

Type 2 diabetes mellitus is a complex metabolic disorder associated with obesity, glucose intolerance and insulin resistance. Activation of GALR2 has been proposed as a therapeutic target for the treatment of insulin resistance. The previous studies showed that baicalin could mitigate insulin resistance, but the detailed mechanism of baicalin on insulin resistance has not been fully explored yet.

PURPOSE

In the present study, we evaluated whether baicalin mitigated insulin resistance via activation of GALR2 signaling pathway.

STUDY DESIGN/METHODS

Baicalin (25 mg/kg/d and 50 mg/kg/d) and/or GALR2 antagonist M871 (10 mg/kg/d) were injected individually or in combinations into obese mice once a day for three weeks, and normal and GALR2 knockdown myotubes were treated with baicalin (100 μM and 400 μM) or metformin (4 mM) in the absence or presence of M871 (800 nM) for 12 h, respectively. The molecular mechanism was explored in skeletal muscle and L6 myotubes.

RESULTS

The present findings showed that baicalin mitigated hyperglycemia and insulin resistance and elevated the levels of PGC-1α, GLUT4, p-p38MAPK, p-AKT and p-AS160 in skeletal muscle of obese mice. Strikingly, the baicalin-induced beneficial effects were abolished by GALR2 antagonist M871 in obese mice. In vitro, baicalin dramatically augmented glucose consumption and the activity of PGC1α-GLUT4 axis in myotubes through activation of p38MAPK and AKT pathways. Moreover, baicalin-induced elevations in glucose consumption related genes were abolished by GALR2 antagonist M871 or silencing of GALR2 in myotubes.

CONCLUSIONS

The present study for the first time demonstrated that baicalin protected against insulin resistance and metabolic dysfunction mainly through activation of GALR2-GLUT4 signal pathway. Our findings identified that activation of GALR2-GLUT4 signal pathway by baicalin could be a new therapeutic approach to treat insulin resistance and T2DM in clinic.

Zebrafish and Flavonoids: Adjuvants against Obesity

Obesity is a pathological condition, defined as an excessive accumulation of fat, primarily caused by an energy imbalance. The storage of excess energy in the form of triglycerides within the adipocyte leads to lipotoxicity and promotes the phenotypic switch in the M1/M2 macrophage. These changes induce the development of a chronic state of low-grade inflammation, subsequently generating obesity-related complications, commonly known as metabolic syndromes. Over the past decade, obesity has been studied in many animal models. However, due to its competitive aspects and unique characteristics, the use of zebrafish has begun to gain traction in experimental obesity research. To counteract obesity and its related comorbidities, several natural substances have been studied. One of those natural substances reported to have substantial biological effects on obesity are flavonoids. This review summarizes the results of studies that examined the effects of flavonoids on obesity and related diseases and the emergence of zebrafish as a model of diet-induced obesity.

Long-term treatment of polysaccharides-based hydrogel microparticles as oral insulin delivery in streptozotocin-induced type 2 diabetic mice

To develop a more effective and safer drug for the treatment of type 2 diabetes mellitus (T2DM), polysaccharides-based hydrogel microparticles as oral insulin delivery was prepared and explored. This study was aimed to evaluate the antidiabetic effects and hypoglycemic mechanism with long-term administration(four weeks) of oral insulin hydrogel microparticles in type 2 diabetic mice on a model of diabetes using a high fat diet combined with streptozotocin. The results revealed that the long-term treatment of oral insulin polysaccharides-based hydrogel microparticles could significantly alleviate the symptoms of polyphagia, polydipsia, polyuria and weight loss in diabetic mice. Also, oral administration of insulin hydrogel microparticles could significantly reduce fasting blood glucose levels, ameliorate insulin resistance and increase insulin sensitivity in the mice with T2DM. The concentration of plasma TG, TC, LDL-C, FFA, BUN, CRE significantly decreased and the levels of HDL-C increased showed that insulin polysaccharides-based hydrogel microparticles were effective in regulating lipid metabolism and prevent diabetic nephropathy complication in diabetic mice. In addition, the supplementation of insulin hydrogel microparticles could significant improve the antioxidant capacity by increasing the level of SOD, CAT and decreasing the level of MDA, GPT, NO, TNF-α, and reverse histological deterioration of kidney and pancreas in diabetic mice. The above outcome concluded that insulin polysaccharides-based hydrogel microparticles may exhibit promising anti-diabetic activity and the potential to be a drug candidate for T2DM.

Novel Programmed Cell Death as Therapeutic Targets in Age-Related Macular Degeneration?

Age-related macular degeneration (AMD) is a leading cause of severe visual loss among the elderly. AMD patients are tormented by progressive central blurring/loss of vision and have limited therapeutic options to date. Drusen accumulation causing retinal pigment epithelial (RPE) cell damage is the hallmark of AMD pathogenesis, in which oxidative stress and inflammation are the well-known molecular mechanisms. However, the underlying mechanisms of how RPE responds when exposed to drusen are still poorly understood. Programmed cell death (PCD) plays an important role in cellular responses to stress and the regulation of homeostasis and diseases. Apart from the classical apoptosis, recent studies also discovered novel PCD pathways such as pyroptosis, necroptosis, and ferroptosis, which may contribute to RPE cell death in AMD. This evidence may yield new treatment targets for AMD. In this review, we summarized and analyzed recent advances on the association between novel PCD and AMD, proposing PCD's role as a therapeutic new target for future AMD treatment.

The Quest to Enhance the Efficacy of Berberine for Type-2 Diabetes and Associated Diseases: Physicochemical Modification Approaches

Berberine is a quaternary isoquinoline alkaloid that has been isolated from numerous plants which are still in use today as medicine and herbal supplements. The great deal of enthusiasm for intense research on berberine to date is based on its diverse pharmacological effects via action on multiple biological targets. Its poor bioavailability resulting from low intestinal absorption coupled with its efflux by the action of P-glycoprotein is, however, the major limitation. In this communication, the chemical approach of improving berberine's bioavailability and pharmacological efficacy is scrutinised with specific reference to type-2 diabetes and associated diseases such as hyperlipidaemia and obesity. The application of modern delivery systems, research from combination studies to preparation of berberine structural hybrids with known biologically active compounds (antidiabetic, antihyperlipidaemic and antioxidant), as well as synthesis approaches of berberine derivative are presented. Improvement of bioavailability and efficacy through in vitro and ex vivo transport studies, as well as animal models of bioavailability/efficacy in lipid metabolism and diabetes targets are discussed.

San-Huang-Tang protects obesity/diabetes induced NAFLD by upregulating PGC-1α/PEPCK signaling in obese and galr1 knockout mice models

ETHNOPHARMACOLOGICAL RELEVANCE

San-Huang-Tang (ST), a classic prescription, has been clinically used to cure diabetes and diabetes-associated metabolic disorders. Established studies have reported that ST can alleviate inflammation, obesity, hyperglycemia and insulin resistance.

AIM OF THE STUDY

To the best of our knowledge, here, we reported for the first time the underlying mechanistic therapeutic efficacy of the ST against nonalcoholic fatty liver disease (NAFLD) in high-fat induced obese and galr1-deficient diabetic mice.

MATERIALS AND METHODS

The obese and galr1-deficient mice were treated with ST at a dose of 10 g/kg every day for three weeks. Then food intake, body weight and insulin resistance indexes were measured. Western blotting, qRT-PCR, and plasma biochemical analyses were applied.

RESULTS

ST reduced food intake, body weight, blood glucose level and insulin resistance, improved glucose tolerance in obese and galr1-deficient mice. Mechanistically, we confirmed that ST protected against NAFLD through activation of PGC-1α and its downstream signaling pathways as shown by the attenuated hepatic adipogenesis and lipid accumulation, increased hepatic fatty acid oxidation, regulated plasma lipid parameters, and increased energy expenditure and metabolic function in fat and muscle.

CONCLUSIONS

Reduction in food intake produced by ST may contribute to the observed metabolic effects. Our findings strongly suggest that ST might be a potential novel therapeutic drug against obesity/diabetes-induced NAFLD and other metabolic disorders.

P2X7 receptor mediates NLRP3 inflammasome activation in depression and diabetes

The increasing prevalence of depression and diabetes mellitus has become a major public health problem worldwide. Studies have shown that people with diabetes are at a high risk of being diagnosed with depression, and diabetes complicates depression treatment by promoting the deterioration of glycemic control, reducing self-care ability and quality of life, and causing severe functional disability and early mortality. Moreover, health deterioration dramatically increases the financial cost of social and health care system. Thus, how to treat depression, diabetes, and diabetes complicated by depression has become one of the world’s urgent concerns. The activation of nod-like receptor family pyrin domain containing 3 (NLRP3) is closely related to mental illness. This finding provides a new perspective for studying depression. NLRP3 plays an important role in the development of diabetes. In this review, we elaborate the definition and epidemiology of depression, diabetes, and diabetic depression and introduce the functional characteristics of an NLRP3 inflammasome and upstream P2X7 receptor. Moreover, related research on NLRP3 inflammasomes and P2X7 receptors is summarized and used as a reference for confirming that the excessive activation of P2X7- NLRP3 leads to the increased release of inflammatory cytokines, such as IL-1β, in depression and diabetes. We provide insights into the P2X7–NLRP3–IL-1β pathway as an important pathological mechanism and novel therapeutic target in diabetes and depression. Given that the P2X7–NLRP3–IL-1β pathway may play an important role in diabetes confounded by comorbid depression, the possibility of intervention with baicalin is proposed.

Baicalin and its aglycone: a novel approach for treatment of metabolic disorders

BACKGROUND

The current strategies for prevention and treatment of insulin resistance and type 2 diabetes are not fully effective and frequently accompanied by many negative effects. Therefore, novel ways to prevent insulin resistance and type 2 diabetes are urgently needed. The roots of Scutellaria radix are commonly used in traditional Chinese medicines for prevention and treatment of type 2 diabetes, atherosclerosis, hypertension, hyperlipidemia, dysentery, and other respiratory disorders. Baicalin and baicalein are the major and active ingredient extracts from Scutellaria baicalensis.

METHODS

A comprehensive and systematic review of literature on baicalin and baicalein was carried out.

RESULTS

Emerging evidence indicated that baicalin and baicalein possessed hepatoprotective, anti-oxidative, anti-dyslipidemic, anti-lipogenic, anti-obese, anti-inflammatory, and anti-diabetic effects, being effective for treating obesity, insulin resistance, non-alcoholic fatty liver, and dyslipidemia. Besides, baicalin and baicalein are almost non-toxic to epithelial, peripheral, and myeloid cells.

CONCLUSION

The purpose of this study is to focus on the therapeutic applications and accompanying molecular mechanisms of baicalin and baicalein against hyperglycemia, insulin resistance, type 2 diabetes, hyperlipidemia, obesity, and non-alcoholic fatty liver, and trying to establish a novel anti-obese and anti-diabetic strategy.

Baicalin ameliorates polycystic ovary syndrome through AMP-activated protein kinase

Polycystic ovary syndrome (PCOS) is a complex endocrine disorder and regarded as the leading cause of anovulatory infertility. PCOS is characterized by reproductive dysfunction and metabolic disorders. Baicalin (BAL) is one of the most potent bioactive flavonoids isolated from the radix of Scutellaria baicalensis. In the present study, we investigated the potential effects of BAL on PCOS in dehydroepiandrosterone-treated rats. We found that BAL notably reduced the serum levels of free testosterone, total testosterone, follicle-stimulating hormone, luteinizing hormone, progesterone, and estradiol in PCOS rats. The increase of serum insulin level and HOMA-IR was markedly inhibited by BAL. Moreover, BAL decreased body weights, increased the number of rats with the regular estrous cycle, and ameliorated ovarian histological changes and follicular development in the DHEA-treated PCOS rats. The increase of pro-inflammatory cytokines (TNFα, IL-1β, and IL-18) and decrease of anti-inflammatory cytokine (IL-10) in PCOS rats were suppressed by BAL. BAL induced a significant decrease in the mRNA expression of steroidogenic enzymes, including 3β-HSD, CYP11A1, CYP19A1, StAR, in ovarian tissues in PCOS rats. Furthermore, BAL inhibited the decrease of AMPK protein level and phosphorylation, the decrease of Akt phosphorylation and the increase of 5α-reductase enzyme 1 expression in ovarian tissues in PCOS rats. The effects of BAL were inhibited by an inhibitor of AMPK, dorsomorphin. The upregulation of AMPK contributed to the beneficial effects of BAL. The results highlight the potential role of BAL for the intervention of PCOS.

Baicalin ameliorates hepatic insulin resistance and gluconeogenic activity through inhibition of p38 MAPK/PGC-1α pathway

BACKGROUND

Although the results of our and other studies show that baicalin can enhance glucose uptake and insulin sensitivity in skeletal muscle and adipocytes of mice, the specific metabolic contribution of baicalin on hepatic insulin resistance and gluconeogenic activity is still unclear.

PURPOSE

The aim of this study is to investigate whether baicalin is involved in regulation of hepatic insulin resistance and gluconeogenic activity and its underlying mechanisms.

STUDY DESIGN/METHODS

In the present study, high-fat diet-induced obese mice were given 50 mg/kg baicalin intraperitoneally (i.p.) once a day for 21 consecutive days, and hepatocytes were treated with baicalin (100 μM) or metformin (100 μM) in the presence of glucagon (200 nM) for 12 h. Then insulin resistance indexes and genes related to gluconeogenesis were examined in liver tissues.

RESULTS

The present findings showed that baicalin decreased body weight, HOMA-IR, and alleviated high fat diet-induced glucose intolerance, hyperglycemia and insulin resistance in diet-induced obese mice. Furthermore, baicalin markedly suppressed p-p38 MAPK, p-CREB, FoxO1, PGC-1α, PEPCK and G6Pase expression in liver of obese mice and hepatocytes. Moreover, inhibition of gluconeogenic genes by baicalin was also strengthened by p38MAPK inhibitor in hepatocytes.

CONCLUSION

Baicalin suppressed expression of PGC-1α and gluconeogenic genes, and reduced glucose production in high-fat diet-induced obese mice. Baicalin ameliorated hepatic insulin resistance and gluconeogenic activity mainly through inhibition of p38 MAPK/PGC-1α signal pathway. This study provides a possibility of using baicalin to treat hyperglycemia and hepatic insulin resistance in clinic.

Therapeutic Mechanisms of Herbal Medicines Against Insulin Resistance: A Review

Insulin resistance is a condition in which insulin sensitivity is reduced and the insulin signaling pathway is impaired. Although often expressed as an increase in insulin concentration, the disease is characterized by a decrease in insulin action. This increased workload of the pancreas and the consequent decompensation are not only the main mechanisms for the development of type 2 diabetes (T2D), but also exacerbate the damage of metabolic diseases, including obesity, nonalcoholic fatty liver disease, polycystic ovary syndrome, metabolic syndrome, and others. Many clinical trials have suggested the potential role of herbs in the treatment of insulin resistance, although most of the clinical trials included in this review have certain flaws and bias risks in their methodological design, including the generation of randomization, the concealment of allocation, blinding, and inadequate reporting of sample size estimates. These studies involve not only the single-flavored herbs, but also herbal formulas, extracts, and active ingredients. Numerous of in vitro and in vivo studies have pointed out that the role of herbal medicine in improving insulin resistance is related to interventions in various aspects of the insulin signaling pathway. The targets involved in these studies include insulin receptor substrate, phosphatidylinositol 3-kinase, glucose transporter, AMP-activated protein kinase, glycogen synthase kinase 3, mitogen-activated protein kinases, c-Jun-N-terminal kinase, nuclear factor-kappaB, protein tyrosine phosphatase 1B, nuclear factor-E2-related factor 2, and peroxisome proliferator-activated receptors. Improved insulin sensitivity upon treatment with herbal medicine provides considerable prospects for treating insulin resistance. This article reviews studies of the target mechanisms of herbal treatments for insulin resistance.

Synergistic Effect of Bupleuri Radix and Scutellariae Radix on Adipogenesis and AMP-Activated Protein Kinase: A Network Pharmacological Approach

Obesity has become a major health threat in developed countries. However, current medications for obesity are limited because of their adverse effects. Interest in natural products for the treatment of obesity is thus rapidly growing. Korean medicine is characterized by the wide use of herbal formulas. However, the combination rule of herbal formulas in Korean medicine lacks experimental evidence. According to Shennong's Classic of Materia Medica, the earliest book of herbal medicine, Bupleuri Radix (BR) and Scutellariae Radix (SR) possess the Sangsoo relationship, which means they have synergistic features when used together. Therefore these two are frequently used together in prescriptions such as Sosiho-Tang. In this study, we used the network pharmacological method to predict the interaction between these two herbs and then investigated the effects of BR, SR, and their combination on obesity in 3T3-L1 adipocytes. BR, SR, and BR-SR mixture significantly decreased lipid accumulation and the expressions of two major adipogenic factors, peroxisome proliferator-activated receptor-gamma (PPARγ) and CCAAT/enhancer-binding protein-alpha (C/EBPα), and their downstream genes, Adipoq, aP2, and Lipin1 in 3T3-L1 cells. In addition, the BR-SR mixture had synergistic effects compared with BR or SR on inhibition of adipogenic-gene expressions. BR and SR also inhibited the protein expressions of PPARγ and C/EBPα. Furthermore, the two extracts successfully activated AMP-activated protein kinase alpha (AMPK α), the key regulator of energy metabolism. When compared to those of BR or SR, the BR-SR mixture showed higher inhibition rates of PPARγ and C/EBPα, along with higher activation rate of AMPK. These results indicate a new potential antiobese pharmacotherapy and also provide scientific evidence supporting the usage of herbal combinations instead of mixtures in Korean medicine.