Berberine reverses free-fatty-acid-induced insulin resistance in 3T3-L1 adipocytes through targeting IKKβ

Berberine: Pharmacological Features in Health, Disease and Aging

BACKGROUND

Berberine is the main active compound of different herbs and is defined as an isoquinoline quaternary botanical alkaloid found in barks and roots of numerous plants. It exhibits a wide range of pharmacological effects, such as anti-obesity and antidiabetic effects. Berberine has antibacterial activity against a variety of microbiota, including many bacterial species, protozoa, plasmodia, fungi, and trypanosomes.

OBJECTIVE

This review describes the role of berberine and its metabolic effects. It also discusses how it plays a role in glucose metabolism, fat metabolism, weight loss, how it modulates the gut microbiota, and what are its antimicrobial properties along with its potential side effects with maximal tolerable dosage.

METHODS

Representative studies were considered and analyzed from different scientific databases, including PubMed and Web of Science, for the years 1982-2022.

RESULTS

Literature analysis shows that berberine affects many biochemical and pharmacological pathways that theoretically yield a positive effect on health and disease. Berberine exhibits neuroprotective properties in various neurodegenerative and neuropsychological ailments. Despite its low bioavailability after oral administration, berberine is a promising tool for several disorders. A possible hypothesis would be the modulation of the gut microbiome. While the evidence concerning the aging process in humans is more limited, preliminary studies have shown positive effects in several models.

CONCLUSION

Berberine could serve as a potential candidate for the treatment of several diseases. Previous literature has provided a basis for scientists to establish clinical trials in humans. However, for obesity, the evidence appears to be sufficient for hands-on use.

DPP-4 Inhibitors Suppress Tau Phosphorylation and Promote Neuron Autophagy through the AMPK/mTOR Pathway to Ameliorate Cognitive Dysfunction in Diabetic Mellitus

Dipeptidyl peptidase-4 (DPP-4) inhibitors have been considered as incretin-based agents that signal through GLP-1R. Our high-throughput RNA sequencing (RNA-seq) and bioinformatics methods indicated that GLP-1R, downregulated in diabetes mellitus (DM), was a potential target of DPP-4 inhibitors, which was further confirmed in DM rats. Thus, this study illuminated the alleviatory mechanism of DPP-4 on cognitive dysfunction in diabetes mellitus (DM), which may be associated with GLP-1R signaling. DM rats were administered with DPP-4 inhibitors, Chloroquine (an autophagy inhibitor), Exendin 9-39 (a GLP-1R antagonist), or Compound C (a specific inhibitor of AMPK). An in vitro model of DM was induced in rat hippocampal neuronal cell line H19-7 by exposure to high glucose (HG) and high fat (HF), followed by treatment with the above inhibitors and antagonists. It was found that cognitive dysfunction was promoted, and LC3 expression was lowered in DM rats by an autophagy inhibitor. The DPP-4 inhibitors decreased cognitive dysfunction, repressed Tau phosphorylation, and enhanced GLP-1R protein level, LC3 expression, and AMPK and mTOR phosphorylation in DM rats, while GLP-1R antagonist, an autophagy inhibitor, or AMPK inhibitor counteracted these effects. Such effects were also observed in HG/HF-induced neurons. In conclusion, our data elucidated the alleviatory mechanism of DPP-4 inhibitors in the cognitive dysfunction of DM rats via the AMPK/mTOR pathway.

Advances of berberine against metabolic syndrome-associated kidney disease: Regarding effect and mechanism

The prevalence of metabolic syndrome (MetS) is drastically growing worldwide, resulting in MetS-associated kidney disease. According to traditional theories, preventing blood pressure, lipid, glycose, and obesity and improving insulin resistance (IR), a couple of medications are required for MetS. It not only lowers patients' compliance but also elevates adverse reactions. Accordingly, we attempted to seek answers from complementary and alternative medicine. Ultimately, berberine (BBR) was chosen due to its efficacy and safety on MetS through multi-pathways and multi-targets. The effects and mechanisms of BBR on obesity, IR, diabetic nephropathy, hypertension, hyperlipidemia, and hyperuricemia were elaborated. In addition, the overall properties of BBR and interventions for various kidney diseases were also collected. However, more clinical trials are expected to further identify the beneficial effects of BBR.

Natural herbicidal alkaloid berberine regulates the expression of thalianol and marneral gene clusters in Arabidopsis thaliana

BACKGROUND

Berberine is a plant-derived herbicidal alkaloid. The herbicidal mechanism of berberine is still not clear. In this study, our aim is to clarify the mechanism of berberine inhibiting the root growth of Arabidopsis thaliana, aiming at providing new insight into identifying the molecular targets of berberine.

RESULTS

The whole-genome RNA sequencing had revealed that 403 genes were down-regulated, and 422 genes were up-regulated in Arabidopsis roots with berberine treatment. According to KEGG and GO analysis, the expression of two genes AT5G48010 (Thas) and AT5G42600 (MRN1) which are in the sesquiterpenoid and triterpenoid biosynthesis pathway were affected most. These two genes belong to thalianol and marneral gene clusters. RT-PCR showed that Arabidopsis responds to berberine by inhibiting root growth through repressing the expression of thalianol and marneral gene clusters, which was independent of the upstream effectors ARP6 and HTA9-1. GC-MS analysis showed that berberine could inhibit THAH in the biosynthetic network of triterpenoid gene cluster in Arabidopsis and thus cause the accumulation of thalianol.

CONCLUSION

Our study indicated the repression of the thalianol and marneral gene clusters as the primary mechanism of action of berberine in Arabidopsis, which may result in plant growth defects by interrupting the thalianol metabolic pathway. This provides novel clues as to the possible molecular herbicidal mechanism of berberine. © 2022 Society of Chemical Industry.

Berberine Relieves Metabolic Syndrome in Mice by Inhibiting Liver Inflammation Caused by a High-Fat Diet and Potential Association With Gut Microbiota

Whether berberine mediates its anti-inflammatory and blood sugar and lipid-lowering effects solely by adjusting the structure of the gut microbiota or by first directly regulating the expression of host pro-inflammatory proteins and activation of macrophages and subsequently acting on gut microbiota, is currently unclear. To clarify the mechanism of berberine-mediated regulation of metabolism, we constructed an obese mouse model using SPF-grade C57BL/6J male mice and conducted a systematic study of liver tissue pathology, inflammatory factor expression, and gut microbiota structure. We screened the gut microbiota targets of berberine and showed that the molecular mechanism of berberine-mediated treatment of metabolic syndrome involves the regulation of gut microbiota structure and the expression of inflammatory factors. Our results revealed that a high-fat diet (HFD) significantly changed mice gut microbiota, thereby probably increasing the level of toxins in the intestine, and triggered the host inflammatory response. The HFD also reduced the proportion of short-chain fatty acid (SCFA)-producing genes, thereby hindering mucosal immunity and cell nutrition, and increased the host inflammatory response and liver fat metabolism disorders. Further, berberine could improve the chronic HFD-induced inflammatory metabolic syndrome to some extent and effectively improved the metabolism of high-fat foods in mice, which correlated with the gut microbiota composition. Taken together, our study may improve our understanding of host-microbe interactions during the treatment of metabolic diseases and provide useful insights into the action mechanism of berberine.

MiR-124 Prevents the Microglial Proinflammatory Response by Inhibiting the Activities of TLR4 and Downstream NLRP3 in Palmitic Acid-Treated BV2 Cells

Neuroinflammation is a mechanism by which obesity or a high-fat diet leads to cognitive impairment. MiR-124, a highly expressed microRNA in the brain, can alleviate neuroinflammation by regulating microglial activation, but its mechanism is unclear. The aim of the study was to explore whether miR-124 exerted this effect through TLR4/MyD88/NF-κB p65/NLRP3 signaling in palmitic acid-treated BV2 cells. Prepared BV2 cells were treated with palmitic acid to establish an in vitro model of a high-fat diet. An miR-124 mimic and inhibitor were adopted to upregulate and downregulate the expression of miR-124, respectively. TAK-242 and NLRP3 siRNA were used to downregulate the expression of TLR4 and NLRP3. The expression levels of miR-124, signaling proteins (TLR4, MyD88, and NF-κB p65), inflammasome markers (NLRP3 and IL-1β), and microglial activated markers (CD206, Arg-1, CD86, and iNOS) were measured by qPCR and western blotting. The pyroptosis rate was assessed using flow cytometry. First, palmitic acid upregulated TLR4/MyD88/NF-κB p65 signaling, increased NLRP3 expression, elevated the pyroptosis rate, and promoted the microglial proinflammatory response in BV2 cells. Second, the miR-124 mimic and inhibitor separately alleviated and aggravated the effect of palmitic acid on microglial activation and NLRP3 expression. The miR-124 mimic also downregulated TLR4/MyD88/NF-κB p65 signaling. Third, TAK-242 did not affect the expression of miR-124 but simulated the protective effect of the miR-124 mimic on microglial activation and NLRP3 expression. Fourth, NLRP3 siRNA also inhibited the microglial proinflammatory response in BV2 cells. MiR-124 prevented the microglial proinflammatory response through TLR4/MyD88/NF-κB p65/NLRP3 signaling in palmitic acid-treated BV2 cells.

Exogenous IGF-1 improves tau pathology and neuronal pyroptosis in high-fat diet mice with cognitive dysfunction

Insulin-like growth factor-1 (IGF-1) improves obesity-induced cognitive dysfunction, but its mechanism is not fully clarified. The aim of the study was to reveal whether IGF-1 treated cognitive dysfunction by improving tau pathology and neuronal pyroptosis in high-fat diet mice. During in vitro experiment, C57BL/6J mice were fed with high-fat diet, and were treated with PEG-IGF-1, IGF-1 receptor blocker AXL1717, HO-1 blocker Znpp IX or their combinations. Cognitive function was evaluated using Morris water maze. Expression of Nrf2, HO-1, p-tau, NLRP3, caspase-1 and IL-1β in hippocampus was determined using western blotting. Pyroptosis rate in hippocampus was measured using flow cytometry. During in vivo experiment, HN-h cells were treated with palmitic acid, pyroptosis blocker nonecrosulfonamide or their combinations. The expression of the proteins and rate of pyroptosis were also measured using western blotting and flow cytometry. During in vitro experiment, high-fat diet mice showed cognitive dysfunction, significant hyperphosphorylation of tau protein and neuronal pyroptosis in hippocampus compared with the sham mice. After exogenous IGF-1 treatment, these abnormalities were reversed and Nrf2/HO-1 signaling pathway was activated. Inhibition of the signaling pathway using AXL1717 or Znpp IX re-deteriorated cognitive function, tau pathology and neuronal pyroptosis in hippocampus. During in vivo experiment, inhibition of pyroptosis using nonecrosulfonamide improved tau pathology in palmitic acid-treated HN-h cells. Exogenous IGF-1 improved tau pathology induced by high-fat diet through inhibition of neuronal pyroptosis and activation of Nrf2/HO-1 signaling pathway.

Berberine improves intralipid-induced insulin resistance in murine

Insulin resistance (IR) is a major metabolic risk factor even before the onset of hyperglycemia. Recently, berberine (BBR) is found to improve hyperglycemia and IR. In this study, we investigated whether BBR could improve IR independent of hyperglycemia. Acute insulin-resistant state was induced in rats by systemic infusion of intralipid (6.6%). BBR was administered via different delivery routes before or after the beginning of a 2-h euglycemic-hyperinsulinemic clamp. At the end of experiment, rats were sacrificed, gastrocnemius muscle was collected for detecting mitochondrial swelling, phosphorylation of Akt and AMPK, as well as the mitochondrial permeability regulator cyclophilin D (CypD) protein expression. We showed that BBR administration markedly ameliorated intralipid-induced IR without affecting blood glucose, which was accompanied by alleviated mitochondrial swelling in skeletal muscle. We used human skeletal muscle cells (HSMCs), AML12 hepatocytes, human umbilical vein endothelial cells, and CypD knockout mice to investigate metabolic and molecular alternations. In either HSMCs or AML12 hepatocytes, BBR (5 μM) abolished palmitate acid (PA)-induced increase of CypD protein levels. In CypD-deficient mice, intralipid-induced IR was greatly attenuated and the beneficial effect of BBR was diminished. Furthermore, we demonstrated that the inhibitory effect of BBR on intralipid-induced IR was mainly mediated by skeletal muscle, but not by intestine, liver, or microvasculature; BBR administration suppressed intralipid-induced upregulation of CypD expression in skeletal muscle. These results suggest that BBR alleviates intralipid-induced IR, which is related to the inhibition of CypD protein expression in skeletal muscle.

Berberine for Appetite Suppressant and Prevention of Obesity

Berberine (BBR), a natural plant product, has been shown to have antidiabetic, cholesterol-reducing effects. To investigate the action of BBR as appetite suppressants, two experimental protocols were performed. In the first experiment, the mice were fed either a normal-chow diet or a high-fat diet (HF). The mice received daily intraperitoneal injections of BBR (10 mg/kg or saline at 1 ml/kg) for 3 weeks. To determine the antiobesity effects of BBR, the food consumption, body weight, fat contents, serum leptin, and glucose level were investigated. In the second experiment, we set out to validate the effect of BBR on central neuropeptide Y (NPY) stimulated rats. Experiments were carried out in 24-hour fasted rats, and then food intake and glucose level were subsequently recorded for 1 hour. The experimental groups were subdivided into the intra-3rd ventricular microinjections of ACSF (artificial cerebrospinal fluid), neuropeptide Y (NPY; 100 nM), NPY+BBR (10 nM), and NPY+BBR (100 nM) group. And then the blood glucose level was examined. In the first experiment, treatment with BBR in the HF diet mice reduced food intake, body weight, fat contents, serum leptin, and glucose level. In the second experiment, the NPY-injected group increased food intake by 39.3%, and food intake was reduced in the BBR group by 47.5%, compared with the ACSF-injected group. Also, the serum glucose level in the NPY+BBR (100 nM) group was significantly lower than that in the NPY (100 nM) group. The results suggest that BBR improved lipid dysregulation in obesity by controlling the central obesity related pathway.

Berberine improves insulin resistance in adipocyte models by regulating the methylation of hypoxia-inducible factor-3α

Methylation of hypoxia-inducible factor-3α (HIF3A) was previously demonstrated to be highly associated with insulin resistance (IR) in patients with gestational diabetes mellitus (GDM). We aimed to study the therapeutic effects of Berberine (BBR) on GDM and the possible mechanisms. The expressions and methylated states of HIF3A in pregnant women with GDM were compared with that in healthy controls. The IR cell models of 3T3-L1 adipocytes was constructed by 1 μmol/l dexamethasone (Dex) and 1 μmol/l insulin (Ins). To evaluate the effects of BBR on IR adipocyte models, cells were subjected to BBR treatment at different concentrations. Transfection of HIF3A siRNA further confirmed the role of HIF3A in the BBR-induced improving effects. Low expression and high methylation of HIF3A gene were frequent in the GDM pregnancies. BBR treatment noticeably increased the glucose usage rates, adiponectin secretion and cell differentiation of IR 3T3-L1 adipocytes. Increased HIF3A expression and decreased methylated state of HIF3A were also found in IR adipocytes. Furthermore, HIF3A silencing not only reversed the effects of BBR on improving insulin sensibility, but also partially abolished the expression alterations of insulin-related genes in IR adipocytes induced by BBR treatment. Our results suggest that BBR improves insulin sensibility in IR adipocyte models, and the improving effects of BBR are possibly realized through the inhibition of HIF3A methylation.

Combination of metformin and berberine represses the apoptosis of sebocytes in high-fat diet-induced diabetic hamsters and an insulin-treated human cell line

Obesity and insulin resistance affect metabolic reactions, but their ensuing contributions to macrophage metabolism remain insufficiently understood. We investigated the contributions of berberine and metformin combination to the inhibition of sebocyte apoptosis in high-fat diet-induced diabetic hamsters and an insulin-treated human cell line. Golden hamsters were fed a high-glucose high-fat diet and administered a 6-week treatment with a combination of metformin and two concentrations of berberine (100 or 50 mg·kg^-1 ). Body weights of treated hamsters were remarkably reduced compared with those of controls. Histological examination indicated that berberine repressed liver fat accumulation. Moreover, insulin and glucose concentrations were noticeably decreased by the combination treatments. In glucose tolerance tests, hamsters receiving berberine displayed higher tolerance to glucose, compared with the control group. Sebocytes isolated from high-fat diet-induced diabetic hamsters and insulin-treated human sebocytes displayed elevated cell death rates, which were attenuated by berberine and metformin treatments. Further studies showed that the effects of metformin and berberine on cellular apoptosis were mediated via the Bik pathway. Thus, berberine may effectively decrease circulating glucose levels, ameliorate insulin resistance, reduce body weight, and attenuate sebocyte apoptosis in diabetic hamsters, potentially decreasing vulnerability to the cardiovascular complications of diabetes. SIGNIFICANCE OF THE STUDY: The present data indicate that insulin stimulates changes in the expression levels of cell death-associated proteins, which participate in sebaceous gland diseases during obesity or diabetes. The anti-apoptotic effects of BBR and MET in sebaceous gland cells are regulated partially by Bik expression. To the best of our knowledge, this study is the first to suggest cell death counteracting effects of BBR in hamster and human sebocytes as well as to propose BBR as an innovative therapeutic agent for insulin-related sebaceous gland diseases, including acne.

Fibroblast growth factor-1 as a mediator of paracrine effects of canine adipose tissue-derived mesenchymal stem cells on in vitro-induced insulin resistance models

Background

In the field of diabetes research, many studies on cell therapy have been conducted using mesenchymal stem cells. This research was intended to shed light on the influence of canine adipose-tissue-derived mesenchymal stem cell conditioned medium (cAT-MSC CM) on in vitro insulin resistance models that were induced in differentiated 3T3-L1 adipocytes and the possible mechanisms involved in the phenomenon.

Results

Gene expression levels of insulin receptor substrate-1 (IRS-1) and glucose transporter type 4 (GLUT4) were used as indicators of insulin resistance. Relative protein expression levels of IRS-1 and GLUT4 were augmented in the cAT-MSC CM treatment group compared to insulin resistance models, indicating beneficial effects of cAT-MSC to DM, probably by actions of secreting factors. With reference to previous studies on fibroblast growth factor-1 (FGF1), we proposed FGF1 as a key contributing factor to the mechanism of action. We added anti-FGF1 neutralizing antibody to the CM-treated insulin resistance models. As a result, significantly diminished protein levels of IRS-1 and GLUT4 were observed, supporting our assumption. Similar results were observed in glucose uptake assay.

Conclusions

Accordingly, this study advocated the potential of FGF-1 from cAT-MSC CM as an alternative insulin sensitizer and discovered a signalling factor associated with the paracrine effects of cAT-MSC.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1671-1) contains supplementary material, which is available to authorized users.

Xiao Ke Qing improves glycometabolism and ameliorates insulin resistance by regulating the PI3K/Akt pathway in KKAy mice

Xiao Ke Qing (XKQ) granule has been clinically used to treat type 2 diabetes mellitus (T2DM) for 10 years in Chinese traditional medication. However, its mechanisms against hyperglycemia remain poorly understood. This study aims to investigate XKQ mechanisms on diabetes and diabetic liver disease by using the KKAy mice model. Our results indicate that XKQ can significantly reduce food and water intake. XKQ treatment also remarkably decreases both the fasting blood glucose and blood glucose in the oral glucose tolerance test. Additionally, XKQ can significantly decrease the serum alanine aminotransferase level and liver index and can alleviate the fat degeneration in liver tissues. Moreover, XKQ can ameliorate insulin resistance and upregulate the expression of IRS-1, PI3K (p85), p-Akt, and GLUT4 in the skeletal muscle of KKAy mice. XKQ is an effective drug for T2DM by ameliorating insulin resistance and regulating the PI3K/Akt signaling pathway in the skeletal muscle.

Berberine Attenuated Proliferation, Invasion and Migration by Targeting the AMPK/HNF4α/WNT5A Pathway in Gastric Carcinoma

Background: Recent epidemiologic studies have found that patients with diabetes have a higher risk of gastric cancer (GC), and the long-term use of metformin is associated with a lower risk of gastric cancer. It is believed that blocking tumor energy metabolic alterations is now emerging as a new therapeutic approach of cancer. Berberine, a natural isoquinoline alkaloid, could modulate lipid metabolism and glucose homeostasis by regulating the expression of HNF4α in many metabolic diseases. Here, we investigated the effect of Berberine on GC and its possible molecular mechanism through targeting HNF4α.

Methods and Results: (1) AGS and SGC7901 gastric cancer cells were treated with Berberine (BBR). We found that in AGS and SGC7901 cell, BBR inhibited cell proliferation in a time- and dose-dependent manner through downregulating C-myc. BBR also induced G₀-G₁ phase arrest with the decreased expression of cyclin D1. Moreover, BBR attenuated the migration and invasion by downregulating MMP-3. (2) The lentivirus infection was used to silence the expression of HNF4α in SGC7901 cell. The results demonstrated that the knockdown of HNF4α in SGC7901 slowed cells proliferation, induced S phase arrest and dramatically attenuated gastric cancer cells’ metastasis and invasion. (3) We performed GC cells perturbation experiments through BI6015 (an HNF4α antagonist), AICAR (an AMPK activator), Compound C (AMPK-kinase inhibitor), metformin and BBR. Our findings indicated that BBR downregulated HNF4α while upregulating p-AMPK. Moreover, the inhibition of HNF4α by BBR was AMPK dependent. (4) Then the LV-HNF4α-RNAi SGC7901 cell model was used to detect the downstream of HNF4α in vitro. The results showed that the knockdown of HNF4α significantly decreased WNT5A and cytoplasmic β-catenin, but increased E-cadherin in vitro. Berberine also downregulated WNT5A and cytoplasmic β-catenin, the same as LV-HNF4α-RNAi and BI6015 in GC cells. (5) Finally, the SGC7901 and LV-HNF4α-RNAi SGC7901 mouse-xenograft model to evaluate the effect of BBR and HNF4α gene on GC tumor growth. The result illustrated that BBR and knockdown of HNF4α suppressed tumor growth in vivo, and BBR decreased HNF4α, WNT5A and cytoplasmic β-catenin levels, the same effect as HNF4α knockout in vivo.

Conclusion: BBR not only had proliferation inhibition effect, attenuated the invasion and migration on GC cell lines, but also suppressed the GC tumor growth in vivo. The anti-gastric cancer mechanism of BBR might be involved in AMPK-HNF4α-WNT5A signaling pathway. HNF4α antagonists, such as BBR, could be a promising anti-gastric cancer treatment supplement.

Effect of Radix isatidis polysaccharide on alleviating insulin resistance in type 2 diabetes mellitus cells and rats

OBJECTIVES

The objective of this paper was to explore the effects of Radix isatidis polysaccharide (RIP) extracted from Radix isatis on alleviating insulin resistance.

METHODS

The insulin resistance models of 3T3-L1 preadipocytes and type 2 diabetic rats were established to evaluate the insulin resistance activity of RIP.

KEY FINDINGS

Radix isatidis polysaccharide within the concentration range of 25-100 μg/ml could reduce cell supernatant glucose and TNF-α levels (P < 0.01) and increase the expression of PI-3K P85, Glut4, IRS-1 and Akt protein in symptoms of IR 3T3-L1 preadipocytes. In the meantime, RIP contributed to relieve the weight loss of diabetic rats whose liver weight and liver index were decreased due to the effects of RIP. Experiments in rats also showed that RIP had capacity in reduced serum TC, TG, LDL-C, FFA, FBG, FINS, MDA, ALT, AST activities and increased serum HDL-C, SOD, ISI (P < 0.05 or 0.01). In addition, the oral glucose tolerance in rats was improved (P < 0.05) and liver damage was restored due to RIP.

CONCLUSIONS

Radix isatidis polysaccharide significantly alleviates insulin resistance in 3T3-L1 preadipocytes and type 2 diabetic rats. These beneficial effects of RIP may associate with their roles in improving the glucose metabolism, lipid metabolism and oxidative stress.

Effects of Vaspin on Insulin Resistance in Rats and Underlying Mechanisms

Insulin resistance (IR) is the main pathogenesis of metabolic syndrome and a shared pathophysiological change in conditions such as diabetes mellitus, adiposity, hypertension, and atherosclerosis. Visceral adipose tissue-derived serpin (Vaspin) is a newly discovered adipocytokine with insulin-sensitizing and anti-inflammatory effects. To examine if vaspin can improve insulin resistance in rats fed a high-fat diet via the insulin receptor substrate/phosphatidylinositol 3 kinase/protein kinase B/glucose transport (IRS/PI3K/Akt/Glut) and inhibitory κB alpha/nuclear factor-kappa B (IκBα/NF-κB) signalling pathways, thirty male Sprague-Dawley (SD) rats were randomly divided into three groups: the normal control group (NC group, n = 10), high-fat diet group (HFD group, n = 10) and vaspin intervention group (HFD + vaspin group, n = 10). Results showed that intervention with vaspin significantly decreased fasting blood glucose (FBG) and fasting insulin (FINS) concentrations in HFD − fed rats without significantly affecting body weight or triglyceride (TG) or total cholesterol (TC) levels. The areas under the intraperitoneal glucose tolerance test (IPGTT) and the insulin tolerance test (ITT) curves were significantly decreased in HFD + vaspin group compared with the HFD group, and the glucose infusion rate (GIR) showed the same trends. Western blot, real-time polymerase chain reaction (RT-PCR) and immunofluorescence staining showed that vaspin could improve insulin resistance in liver, skeletal muscle and adipose tissue by activating the IRS/PI3K/Akt/Glut signalling pathway and inhibiting the IκBα/NF-κB signalling pathway.

The Pathogenesis of Diabetes Mellitus by Oxidative Stress and Inflammation: Its Inhibition by Berberine

A substantial knowledge on the pathogenesis of diabetes mellitus (DM) by oxidative stress and inflammation is available. Berberine is a biologically active botanical that can combat oxidative stress and inflammation and thus ameliorate DM, especially type 2 DM. This article describes the potential of berberine against oxidative stress and inflammation with special emphasis on its mechanistic aspects. In diabetic animal studies, the modified levels of proinflammatory cytokines and oxidative stress markers were observed after administering berberine. In renal, fat, hepatic, pancreatic and several others tissues, berberine-mediated suppression of oxidative stress and inflammation was noted. Berberine acted against oxidative stress and inflammation through a very complex mechanism consisting of several kinases and signaling pathways involving various factors, including NF-κB (nuclear factor-κB) and AMPK (AMP-activated protein kinases). Moreover, MAPKs (mitogen-activated protein kinases) and Nrf2 (nuclear factor erythroid-2 related factor 2) also have mechanistic involvement in oxidative stress and inflammation. In spite of above advancements, the mechanistic aspects of the inhibitory role of berberine against oxidative stress and inflammation in diabetes mellitus still necessitate additional molecular studies. These studies will be useful to examine the new prospects of natural moieties against DM.

Barberry in the treatment of obesity and metabolic syndrome: possible mechanisms of action

Obesity is a consequence of an imbalance between energy intake and energy expenditure. It affects people of both genders and all age groups, ethnicity and socioeconomic groups, and in developed and developing countries. Obesity is often accompanied by the metabolic syndrome (MetS). MetS is characterized by a clustering of cardiovascular risk factors, including high blood pressure, adiposity, dyslipidemia and glucose intolerance, which together increase the risk of atherosclerotic cardiovascular disease, type 2 diabetes mellitus and other causes of mortality. Nowadays, there is a growing interest in the use of plant-based agents instead of synthetic drugs to manage chronic diseases such as MetS; one such example is Berberis vulgaris. B. vulgaris contains isoquinonline alkaloids such as berberine, berberrubine and berbamine. Recent studies have proved that berberine exhibits pharmacological activities and positive effects on the risk factors of obesity and MetS. We have reviewed original articles related to the possible molecular mechanisms of action of berberine on obesity and MetS. Berberine suppresses adipocyte differentiation and decreases obesity. It also regulates glucose metabolism via decreasing insulin resistance and increasing insulin secretion. Other effects of berberine include antihyperlipidemic and antihypertensive activities and endothelial protection.

Berberine and Its Role in Chronic Disease

Berberine is a quaternary ammonium salt from the protoberberine group of isoquinoline alkaloids. It is found in such plants as Berberis [e.g. Berberis aquifolium (Oregon grape), Berberis vulgaris (barberry), Berberis aristata (tree turmeric)], Hydrastis canadensis (goldenseal), Xanthorhiza simplicissima (yellowroot), Phellodendron amurense ^[2] (Amur corktree), Coptis chinensis (Chinese goldthread), Tinospora cordifolia, Argemone mexicana (prickly poppy) and Eschscholzia californica (Californian poppy). In vitro it exerts significant anti-inflammatory and antioxidant activities. In animal models berberine has neuroprotective and cardiovascular protective effects. In humans, its lipid-lowering and insulin-resistance improving actions have clearly been demonstrated in numerous randomized clinical trials. Moreover, preliminary clinical evidence suggest the ability of berberine to reduce endothelial inflammation improving vascular health, even in patients already affected by cardiovascular diseases. Altogether the available evidences suggest a possible application of berberine use in the management of chronic cardiometabolic disorders.

Berberine in Combination with Insulin Has Additive Effects on Titanium Implants Osseointegration in Diabetes Mellitus Rats

This study evaluated the effects of berberine in combination with insulin on early osseointegration of implants in diabetic rats. Fifty male Sprague-Dawley rats were randomly divided into 5 groups: healthy rats were used as control (HC), and streptozotocin-induced diabetic rats were treated with insulin, berberine, berberine + insulin (IB), or no treatment. Each rat received one machined-surface cp-Ti implant into the right tibia and was given insulin injection and/or gavage feeding with berberine daily for 8 weeks until being sacrificed. Serum levels of alkaline phosphatase (ALP) and bone gamma-carboxyglutamic acid-containing protein (BGP) were analyzed in each group. Peri-implant mineral apposition was marked by fluorochrome double-labeling and osseointegration was histomorphologically examined. The ALP and BGP levels decreased in diabetic rats but were successfully corrected by insulin and berberine combined treatment. Moreover, untreated diabetic rats had less labeled mineral apposition and impaired osseointegration. In contrast, Groups I, B, and IB were observed with increased peri-implant bone formation. The combination treatment of insulin and berberine was more effective than each administrated as a monotherapy. These results suggest that berberine combined with insulin could promote osseointegration in diabetic rats, thereby highlighting its potential application to patients, though further studies are needed.

4-Hydroxyisoleucine ameliorates an insulin resistant-like state in 3T3-L1 adipocytes by regulating TACE/TIMP3 expression

BACKGROUND

Obesity-associated insulin resistance (IR) is highly correlated with soluble tumor necrosis factor-α (sTNF-α), which is released from transmembranous TNF-α by TNF-α converting enzyme (TACE). In vivo, TACE activity is suppressed by tissue inhibitor of metalloproteinase 3 (TIMP3). Agents that can interact with TACE/TIMP3 to improve obesity-related IR would be highly valuable. In the current study, we assessed whether (2S,3R,4S)-4-hydroxyisoleucine (4-HIL) could modulate TACE/TIMP3 and ameliorate an obesity-induced IR-like state in 3T3-L1 adipocytes.

MATERIALS AND METHODS

3T3-L1 adipocytes were incubated in the presence of 25 mM glucose and 0.6 nM insulin to induce an IR-like state, and were then treated with different concentrations of 4-HIL or 10 µM pioglitazone (positive control). The glucose uptake rate was determined using the 2-deoxy-[(3)H]-D-glucose method, and the levels of sTNF-α in the cell supernatant were determined using ELISA. The protein expression of TACE, TIMP3, and insulin signaling-related molecules was measured using western blotting.

RESULTS

Exposure to high glucose and insulin for 18 hours increased the levels of sTNF-α in the cell supernatant. The phosphorylation of insulin receptor substrate-1 (IRS-1) Ser(307) and Akt Ser(473) was increased, whereas the protein expression of IRS-1, Akt, and glucose transporter-4 was decreased. The insulin-induced glucose uptake was reduced by 67% in 3T3-L1 adipocytes, which indicated the presence of an IR-like state. The above indexes, which demonstrated the successful induction of an IR-like state, were reversed by 4-HIL in a dose-dependent manner by downregulating and upregulating the protein expression of TACE and TIMP3 proteins, respectively.

CONCLUSION

4-HIL improved an obesity-associated IR-like state in 3T3-L1 adipocytes by targeting TACE/TIMP3 and the insulin signaling pathway.

Effects of berberine on amelioration of hyperglycemia and oxidative stress in high glucose and high fat diet-induced diabetic hamsters in vivo

This study investigated the effects of berberine on amelioration of hyperglycemia and hyperlipidemia and the mechanism involved in high glucose and high fat diet-induced diabetic hamsters. Golden hamsters fed with high glucose and high fat diet were medicated with metformin, simvastatin, and low or high dose of berberine (50 and 100 mg·kg(-1)) for 6 weeks. The results showed that the body weights were significantly lower in berberine-treated groups than control group. Histological analyses revealed that the treatment of berberine inhibited hepatic fat accumulation. Berberine significantly reduced plasma total cholesterol, triglyceride, free fatty acid, low density lipoprotein cholesterol, malondialdehyde, thiobarbituric acid-reactive substance, and 8-isoprostane level but significantly increased plasma superoxide dismutase activity. Glucose and insulin levels were significantly reduced in metformin and berberine-treated groups. Glucose tolerance tests documented that berberine-treated mice were more glucose tolerant. Berberine treatment increased expression of skeletal muscle glucose transporter 4 mRNA and significantly decreased liver low density lipoprotein receptor mRNA expression. The study suggested that berberine was effective in lowering blood glucose and lipids levels, reducing the body weight, and alleviating the oxidative stress in diabetic hamsters, which might be beneficial in reducing the cardiovascular risk factors in diabetes.

Effects of er-miao-san extracts on TNF-alpha-induced MMP-1 expression in human dermal fibroblasts

BACKGROUND

Various health benefits have been attributed to Er-Miao-San (EMS), a traditional Chinese herbal formulation that contains equal amounts of cortex phellodendri (Phellodendron amurense Ruprecht) and rhizoma atractylodis (Atractylodes lancea D.C). However, its effect on the anti-inflammatory activity in human dermal fibroblasts (HDFs) and the mechanism underlying this effect are unknown.

RESULTS

This study investigated the effects of EMS on TNF-α-induced MMP-1 expression in HDFs. Our data show that EMS inhibited TNF-α-induced MMP-1 expression in a concentration-dependent manner. Interestingly, EMS maintained IκB content without inhibiting the phosphorylation of MAPKs, which are well-established upstream kinases of NF-κB. Moreover, EMS reduced the level of nuclear p65 protein in HDFs. Luciferase assay revealed that EMS inhibits the transcriptional activity of NF-κB by stabilizing IκB. Our results show that EMS exerts its anti-inflammatory effect by inhibiting NF-κB-regulated genes such as IL-1β and IL-8. Moreover, EMS effectively inhibited TNF-α-induced expression of MMP-1 via the NF-κB pathway.

CONCLUSIONS

Taken together, our data suggest that EMS could potentially be used as an anti-inflammatory and anti-aging treatment.

Effects of berberine and red yeast on proinflammatory cytokines IL-6 and TNF-α in peripheral blood mononuclear cells (PBMCs) of human subjects

BACKGROUND AND AIMS

Obesity is a condition associated with chronic or acute inflammatory response characterized by an increase of proinflammatory cytokine levels. Peripheral blood mononuclear cells (PBMCs) migrate in adipose tissue inducing synthesis and secretion of adipocytokines as IL-6 and TNF-α. The aim of this study was to investigate the effect of berberine (a natural alkaloid) and red yeast (a natural antioxidant) on IL-6 and TNF-α cytokines release and gene expression, in circulating lipopolisaccarides (LPS) stimulated PBMCs.

METHODS AND RESULTS

PBMCs isolated from whole blood of healthy donors were stimulated with LPS to induce cytokines production; simultaneously cells were treated with increasing doses of berberine and red yeast. The substances were administered alone or in association. IL-6 and TNF-α protein levels in the culture medium and their mRNA levels were assessed by ELISA and real time PCR, respectively. Berberine and red yeast treatment prevented the LPS induction of IL-6 release in the culture medium of PBMCs. In addition, berberine plus red yeast treatment showed a synergic inhibitory effect on IL-6 release at low concentration. Berberine and red yeast showed an inhibitory effect also on LPS induction of TNF-α release exerting a synergic effect mainly at high concentrations. On the contrary, berberine and red yeast did not significantly affect IL-6 and TNF-α mRNA levels induced by LPS. In this case, only concomitant treatment of PBMCs with high doses of berberine and red yeast inhibits LPS induced IL-6 or TNF-α mRNA levels.

CONCLUSIONS

The results of our study show that both berberine and red yeast were able to carry out anti-inflammatory action through an inhibition of proinflammatory IL-6 and TNF-α protein release. Moreover, when given in combination these substances were able to inhibit IL-6 and TNF-α gene expression in PBMCs activated by LPS. Therefore, these substances could represent a useful pharmacological treatment to reduce the proinflammatory status accompanied with obesity.

The antihyperglycemic effects of Rhizoma Coptidis and mechanism of actions: a review of systematic reviews and pharmacological research

Rhizoma Coptidis (Huang Lian in Chinese pinyin) is among the most widely used traditional Chinese herbal medicines and has a profound history of more than 2000 years of being used as a therapeutic herb. The antidiabetic effects of Rhizoma Coptidis have been extensively investigated in animal experiments and clinical trials and its efficacy as a promising antihyperglycemic agent has been widely discussed. In the meantime, findings from modern pharmacological studies have contributed the majority of its bioactivities to berberine, the isoquinoline alkaloids component of the herb, and a number of experiments testing the antidiabetic effects of berberine have been initiated. Therefore, we conducted a review of the current evidence profile of the antihyperglycemic effects of Rhizoma Coptidis as well as its main component berberine and the possible mechanism of actions, in order to summarize research evidence in this area and identify future research directions.

Antioxidant and anti-inflammatory activities of berberine in the treatment of diabetes mellitus

Oxidative stress and inflammation are proved to be critical for the pathogenesis of diabetes mellitus. Berberine (BBR) is a natural compound isolated from plants such as Coptis chinensis and Hydrastis canadensis and with multiple pharmacological activities. Recent studies showed that BBR had antioxidant and anti-inflammatory activities, which contributed in part to its efficacy against diabetes mellitus. In this review, we summarized the antioxidant and anti-inflammatory activities of BBR as well as their molecular basis. The antioxidant and anti-inflammatory activities of BBR were noted with changes in oxidative stress markers, antioxidant enzymes, and proinflammatory cytokines after BBR administration in diabetic animals. BBR inhibited oxidative stress and inflammation in a variety of tissues including liver, adipose tissue, kidney and pancreas. Mechanisms of the antioxidant and anti-inflammatory activities of BBR were complex, which involved multiple cellular kinases and signaling pathways, such as AMP-activated protein kinase (AMPK), mitogen-activated protein kinases (MAPKs), nuclear factor erythroid-2-related factor-2 (Nrf2) pathway, and nuclear factor- κ B (NF- κ B) pathway. Detailed mechanisms and pathways for the antioxidant and anti-inflammatory activities of BBR still need further investigation. Clarification of these issues could help to understand the pharmacology of BBR in the treatment of diabetes mellitus and promote the development of antidiabetic natural products.

Berberine on metabolic and cardiovascular risk factors: an analysis from preclinical evidences to clinical trials

INTRODUCTION

Type 2 diabetes mellitus and hypercholesterolemia have proven to give an increased incidence of cardiovascular diseases (CVD). Recent studies have suggested that the natural alkaloid berberine could have pharmacological activities potentially useful in diabetes and hypercholesterolemia management.

AREAS COVERED

The aim of this review is to evaluate the metabolic properties of the natural alkaloid berberine, and its potential application to the treatment of diabetes and CVD prevention.

EXPERT OPINION

Berberine proved to be effective in improving glycemic control and lipid profile. The modern investigation on berberine pharmacological activity is actually developing and numerous scientific evidences are actually in progress and reported in international congresses. The near future perspective is the isolation or neo-synthesis of berberine analogs with a higher bioavailability. The anti-hyperlipidemic and anti-diabetic effects of berberine have to be related to markers of improvement in organ damage in humans; longer trials are needed to better evaluate the safety profile of the molecule, when administered alone or in association with other anti-hyperlipidemic or anti-diabetic drugs, especially in the European population.

α-Linolenic acid suppresses cholesterol and triacylglycerol biosynthesis pathway by suppressing SREBP-2, SREBP-1a and -1c expression

α-Linolenic acid (ALA), a major fatty acid in flaxseed oil, has multiple functionalities such as anti-cardiovascular and anti-hypertensive activities. In this study, we investigated the effects of ALA on lipid metabolism and studied the possible mechanisms of its action in differentiated 3T3-L1 adipocytes using DNA microarray analysis. From a total of 34,325 genes in the DNA chip, 87 genes were down-regulated and 185 genes were up-regulated at least twofold in differentiated 3T3-L1 adipocyte cells treated with 300 μM ALA for a week, 5-12 days after induction of cell differentiation, compared to ALA-untreated 3T3-L1 adipocytes (control). From the Reactome analysis results, eight lipid metabolism-related genes involved in cholesterol and triacylglycerol biosynthesis pathway and lipid transport were significantly down-regulated by ALA treatment. Furthermore, ALA significantly decreased the mRNA expressions of sterol regulatory element binding protein (SREBP)-2, SREBP-1a, SREBP-1c and fatty acid synthase (FAS) in 3T3-L1 adipocyte cells. On the other hand, the average levels of the gene expressions of carnitine palmitoyltransferase 1a (CPT-1a) and leptin in 300 μM ALA treatment were increased by 1.7- and 2.9-fold, respectively, followed by an increase in the intracellular ATP content. These results show that ALA is likely to inhibit cholesterol and fatty acid biosynthesis pathway by suppressing the expression of transcriptional factor SREBPs. Furthermore, ALA promotes fatty acid oxidation in 3T3-L1 adipocytes, thereby increasing its health benefits.

Antidiabetic properties of berberine: from cellular pharmacology to clinical effects

Berberine is an alkaloid that is highly concentrated in the roots, rhizomes, and stem bark of various plants. It affects glucose metabolism, increasing insulin secretion, stimulating glycolysis, suppressing adipogenesis, inhibiting mitochondrial function, activating the 5' adenosine monophosphate-activated protein kinase (AMPK) pathway, and increasing glycokinase activity. Berberine also increases glucose transporter-4 (GLUT-4) and glucagon-like peptide-1 (GLP-1) levels. On GLP-1 receptor activation, adenylyl cyclase is activated, and cyclic adenosine monophosphate is generated, leading to activation of second messenger pathways and closure of adenosine triphosphate-dependent potassium channels. Increased intracellular potassium causes depolarization, and calcium influx through the voltage-dependent calcium channels occurs. This intracellular calcium increase stimulates the migration and exocytosis of the insulin granules. In glucose-consuming tissues, such as adipose, or liver or muscle cells, berberine affects both GLUT-4 and retinol-binding protein-4 in favor of glucose uptake into cells; stimulates glycolysis by AMPK activation; and has effects on the peroxisome proliferator-activated receptor γ molecular targets and on the phosphorylation of insulin receptor substrate-1, finally resulting in decreased insulin resistance. Moreover, recent studies suggest that berberine could have a direct action on carbohydrate metabolism in the intestine. The antidiabetic and insulin-sensitizing effect of berberine has also been confirmed in a few relatively small, short-term clinical trials. The tolerability is high for low dosages, with some gastrointestinal complaints appearing to be associated with use of high dosages.

Berberine-improved visceral white adipose tissue insulin resistance associated with altered sterol regulatory element-binding proteins, liver x receptors, and peroxisome proliferator-activated receptors transcriptional programs in diabetic hamsters

The diabetic "lipotoxicity" hypothesis presents that fat-induced visceral white adipose tissue insulin resistance plays a central role in the pathogenesis of type 2 diabetes. Berberine, a hypolipidemic agent, has been reported to have antidiabetic activities. The molecular mechanisms for this property are, however, not well clarified. Therefore in this study type 2 diabetic hamsters were induced by high-fat diet with low-dose streptozotocin. Then, we investigated the gene expression alterations and explored the molecular mechanisms underlying the therapeutic effect of berberine on fat-induced visceral white adipose tissue insulin resistance in diabetic hamsters by microarray analysis followed by real-time reverse transcription-polymerase chain reaction (RT-PCR) confirmation. Type 2 diabetic hamsters exhibited hyperglycemia and relative hyperinsulinemia, glucose intolerance, insulin resistance, intra-adipocyte lipid accumulation, significant increase in body weight and visceral white adipose tissue weight, abnormal serum adipokines levels, and deleterious dyslipidemia. Furthermore, they had increased sterol regulatory element-binding proteins (SREBPs) expression and decreased liver X receptors (LXRs) and peroxisome proliferator-activated receptors (PPARs) expression in visceral white adipose tissue. After 9-week berberine treatment, fat-induced insulin resistance and diabetic phenotype in type 2 diabetic hamsters were significantly improved. Compared with diabetic hamsters, expression of LXRs and PPARs significantly increased and SREBPs significantly decreased in visceral white adipose tissue from berberine-treated diabetic hamsters. These results suggest that altered visceral white adipose tissue LXRs, PPARs, and SREBPs transcriptional programs are involved in the therapeutic mechanisms of berberine on fat-induced visceral white adipose tissue insulin resistance in type 2 diabetic hamsters.

Metformin regulates hepatic lipid metabolism through activating AMP-activated protein kinase and inducing ATGL in laying hens

Although many clinical trials have showed that metformin improves non-alcoholic fatty liver disease, which is a common liver disease associated with hepatic enzyme abnormalities, an animal model is required to investigate the effects of altered gene expression and post-translational processing (proteins) in mediating the observed responses. Laying hens appear to develop fatty livers, as in the case in human beings, when ingesting energy in excess of maintenance, and they can be used as an animal model for observing hepatic steatosis. The aim of this study was to investigate whether metformin could improve the non-alcoholic fatty liver of laying hens and to examine the possible mechanisms of lipid-lowering effects. Forty-eight Leghorn laying hens of Hy-Line variety W-36 - 44 weeks with 64.8% hen-day egg production - were randomly assigned into 4 treatments, each receiving 0, 10, 30, or 100mg of metformin with saline per kg body weight by daily wing vein injection. Results showed that, compared with the control, significant decreases existed in the laying rates; plasma triglyceride, cholesterol, and insulin levels; body weights; abdominal fat weights; hepatic lipid contents; and hepatic fatty acid synthase expression of layers receiving 30 or 100mg per kg body weight, whereas significant increases in their hepatic 5'adenosine monophosphate-activated protein kinase, acyl-CoA carboxylase phosphorylation, adipose triglyceride lipase, and carnitine palmitoyl transferase-1 expression were observed. These data suggest that metformin could reduce lipid deposits in the liver and that the laying hen is a valuable animal model for studying hepatic steatosis.

Berberine acutely activates the glucose transport activity of GLUT1

Berberine, which has a long history of use in Chinese medicine, has recently been shown to have efficacy in the treatment of diabetes. While the hypoglycemic effect of berberine has been clearly documented in animal and cell line models, such as 3T3-L1 adipocytes and L6 myotube cells, the mechanism of action appears complex with data implicating activation of the insulin signaling pathway as well as activation of the exercise or AMP kinase-mediated pathway. There have been no reports of the acute affects of berberine on the transport activity of the insulin-insensitive glucose transporter, GLUT1. Therefore, we examined the acute effects of berberine on glucose uptake in L929 fibroblast cells, a cell line that express only GLUT1. Berberine- activated glucose uptake reaching maximum stimulation of five-fold at >40 μM. Significant activation (P < 0.05) was measured within 5 min reaching a maximum by 30 min. The berberine effect was not additive to the maximal stimulation by other known stimulants, azide, methylene blue or glucose deprivation, suggesting shared steps between berberine and these stimulants. Berberine significantly reduced the K(m) of glucose uptake from 6.7 ± 1.9 mM to 0.55 ± 0.08 mM, but had no effect on the V(max) of uptake. Compound C, an inhibitor of AMP kinase, did not affect berberine-stimulated glucose uptake, but inhibitors of downstream kinases partially blocked berberine stimulation. SB203580 (inhibitor of p38 MAP kinase) did not affect submaximal berberine activation, but did lower maximal berberine stimulation by 26%, while PD98059 (inhibitor of ERK kinase) completely blocked submaximal berberine activation and decreased the maximal stimulation by 55%. It appears from this study that a portion of the hypoglycemic effects of berberine can be attributed to its acute activation of the transport activity of GLUT1.

Yi-Qi-Zeng-Min-Tang, a Chinese medicine, ameliorates insulin resistance in type 2 diabetic rats

AIM: To investigate the effects of the Chinese herbal decoction, Yi-Qi-Zeng-Min-Tang (YQZMT), on insulin resistance in type 2 diabetic rats.

METHODS: Sprague-Dawley rats were divided into two dietary regiments by feeding either normal pellet diet (NPD) or high fat diet (HFD). Four weeks later, the HFD-fed rats were injected intraperitoneally with low-dose streptozotocin (STZ). Rats with non-fasting blood glucose level ≥ 16.67 mmol/L were considered type 2 diabetic and further divided into five subgroups: the type 2 diabetes model group, low-dose, medium-dose and high-dose YQZMT groups, and rosiglitazone group. Age-matched NPD-fed rats served as controls. YQZMT or rosiglitazone were administered for 8 wk. Intraperitoneal glucose and insulin tolerance tests were performed before and after the treatment to measure the glucose tolerance and insulin sensitivity. Serum levels of biochemical parameters, adipocytokines, such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), as well as free fatty acids (FFAs), were also analyzed.

RESULTS: There was significant elevation of insulin resistance and serum levels of fasting glucose (12.82 ± 1.08 mmol/L vs 3.60 ± 0.31 mmol/L, P < 0.01), insulin (7197.36 ± 253.89 pg/mL vs 4820.49 ± 326.89 pg/mL, P < 0.01), total cholesterol (TC) (8.40 ± 0.49 mmol/L vs 2.14 ± 0.06 mmol/L, P < 0.01), triglyceride (2.24 ± 0.12 mmol/L vs 0.78 ± 0.05 mmol/L, P < 0.01), low-density lipoprotein cholesterol (LDL-c) (7.84 ± 0.51 mmol/L vs 0.72 ± 0.04 mmol/L, P < 0.01) and decrease in high-density lipoprotein cholesterol (HDL-c) (0.57 ± 0.03 mmol/L vs 1.27 ± 0.03 mmol/L, P < 0.01) in the low-dose STZ and high-fat diet induced type 2 diabetic group when compared with the control group. Administration of YQZMT induced dose- and time-dependent changes in insulin resistance, glucose and lipid profile, and reduced levels of FFA, TNF-α and IL-6 in the type 2 diabetic rats. After the treatment, compared with the diabetic group, the insulin resistance was ameliorated in the high-dose YQZMT (2.82 g/100 g per day) group, with a significant reduction in serum glucose (12.16 ± 1.00 mmol/L vs 17.65 ± 2.22 mmol/L, P < 0.01), homeostasis model assessment of basal insulin resistance (22.68 ± 2.37 vs 38.79 ± 9.02, P < 0.05), triglyceride (0.87 ± 0.15 mmol/L vs 1.99 ± 0.26 mmol/L, P < 0.01), TC (3.31 ± 0.52 mmol/L vs 6.50 ± 1.04 mmol/L, P < 0.01) and LDL-c (2.47 ± 0.50 mmol/L vs 6.00 ± 1.07 mmol/L, P < 0.01), and a significant increase in HDL-c (0.84 ± 0.08 mmol/L vs 0.50 ± 0.03 mmol/L, P < 0.01). But the body weight was not changed significantly.

CONCLUSION: YQZMT, which ameliorates insulin resistance and does not cause increase in body weight, may be a suitable therapeutic adjunct for the treatment of type 2 diabetes.

Hypoglycemic and insulin-sensitizing effects of berberine in high-fat diet- and streptozotocin-induced diabetic rats

Hypoglycemic effects of berberine (BBR) have been reported in several studies in cell and animal models. However, the mechanisms of action are not fully understood. The present study was therefore aimed at determining the effect and underlying mechanisms of action of BBR on diabetes in a high-fat diet- and streptozotocin-induced diabetic rat model. Ninety male Sprague-Dawley rats, 150 to 170 g, were housed individually in cages. Two groups (n = 12 each) were fed the AIN-93G diet (normal control) and the same diet modified to contain 33% fat and 2% cholesterol (high-fat control), respectively. The third group (n = 66) was fed the high-fat diet and injected intraperitoneally 2 weeks later with 35 mg/kg body weight of streptozotocin in citrate buffer (pH 4.5). The rats in both control groups were injected with the vehicle. After 12 days, rats with semifasting (5 hours) blood glucose levels between 14 and 25 mmol/L were divided into 4 groups (n = 12 each) and treated with 0 (diabetic control), 50, 100, and 150 mg/kg/d of BBR for 6 weeks while continuing on the high-fat diet. Hypoglycemic effects of BBR were consistently demonstrated by semifasting and fasting blood glucose levels, and insulin-sensitizing effects were seen during oral glucose tolerance testing. Berberine also reduced food intake while having no effect on body weight in diabetic rats. No effect of BBR was observed on plasma levels of insulin, adipokines (leptin and adiponectin), or inflammatory cytokines (tumor necrosis factor-α and C-reactive protein). Berberine did not affect the state of oxidative stress as assessed by the activity of superoxide dismutase and the concentrations of malondialdehyde and reduced and oxidized glutathione in the liver. These findings demonstrated the hypoglycemic and insulin-sensitizing capabilities of BBR, with the underlying mechanisms awaiting further investigation.

Anti-invasion effect of rosmarinic acid via the extracellular signal-regulated kinase and oxidation-reduction pathway in Ls174-T cells

Rosmarinic acid is a major phenylpropanoid isolated from Prunella vulgaris L., which is a composition of herbal tea for centuries in China. However, the anti-invasion activity on Ls174-T human colon carcinoma cells has not been studied. In this study, we investigated the anti-metastasis functions according to wound healing assay, adhesion assay, and Transwell assay and found that rosmarinic acid could inhibit migration, adhesion, and invasion dose-dependently. Rosmarinic acid also could decrease the level of reactive oxygen species by enhancing the level of reduced glutathione hormone. In addition, rosmarinic acid repressed the activity and expression of matrix metalloproteinase-2,9. According to Western blot and quantitative real-time PCR assay, rosmarinic acid may inhibit metastasis from colorectal carcinoma mainly via the pathway of extracellular signal-regulated kinase. In animal experiment, intraperitoneal administration of 2 mg of rosmarinic acid reduced weight of tumors and the number of lung nodules significantly compared with those of control group. Therefore, these results demonstrated that rosmarinic acid can effectively inhibit tumor metastasis in vitro and in vivo.

Advance of studies on anti-atherosclerosis mechanism of berberine

Coptis Chinensis is a traditional Chinese medicine herb that has the effect of clearing heat and drying dampness, purging fire to eliminate toxin. Berberine is the main alkaloid of Coptis Chinensis, and, recent researches showed that berberine had the effect of anti-atherosclerosis. This paper reviewed the anti-atherosclerosis mechanism of berberine, which may be related to regulating lipids, anti-inflammation, decompression, reducing blood sugar, and inhibiting vascular smooth muscle cell proliferation.

Berberine reduces endoplasmic reticulum stress and improves insulin signal transduction in Hep G2 cells

AIM

Endoplasmic reticulum (ER) stress plays an important role in the pathogenesis of insulin resistance and pancreatic beta-cell dysfunction. The aim of this study is to investigate whether the insulin-sensitizing action of berberine is related to reducing ER stress.

METHODS

ER stress in cultured Hep G2 cells was induced with tunicamycin. Cells were pretreated with berberine in combination with or without insulin. The concentration of glucose was measured by glucose oxidase method. The molecular markers of ER stress, including ORP150, PERK, and eIF2 alpha were analyzed by Western blot or real time PCR. The activity of JNK was also evaluated. Moreover, the insulin signaling proteins such as IRS-1 and AKT were determined by Western blot.

RESULTS

The production of glucose stimulated with insulin was reduced. The expressions of ORP150 was decreased both in gene and protein levels when cells were pretreated with berberine, while the activation of JNK was blocked. The levels of phosphorylation both on PERK and eIF2 alpha were inhibited in cells pretreated with berberine. The level of IRS-1 ser(307) phosphorylation was decreased, whereas IRS-1 tyr phosphorylation was increased notablely. AKT ser(473) phosphorylation was also enhanced significantly in the presence of berberine.

CONCLUSION

The antidiabetic effect of berberine in Hep G2 cells maybe related to attenuation of ER stress and improvement of insulin signal transduction.

Berberine inhibits adipogenesis in high-fat diet-induced obesity mice

Our previous studies illustrated that berberine inhibited adipogenesis in murine-derived 3T3-L1 preadipocytes and human white preadipocytes. In this study, the effects of berberine on the adipogenesis of high-fat diet-induced obesity (FD) or normal diet (ND) mice and possible transcriptional impact are investigated. The results demonstrated that in FD mice, berberine reduced mouse weight gain and food intake and serum glucose, triglyceride, and total cholesterol levels accompanied with a down-regulation of PPARgamma expression and an up-regulation of GATA-3 expression. Berberine had no adverse effects on ND mice. These encouraging findings suggest that berberine has excellent pharmacological potential to prevent obesity.

Oxidized LDL impair adipocyte response to insulin by activating serine/threonine kinases

Oxidized LDL (oxLDL) increase in patients affected by type-2 diabetes, obesity, and metabolic syndrome. Likewise, insulin resistance, an impaired responsiveness of target tissues to insulin, is associated with those pathological conditions. To investigate a possible causal relationship between oxLDL and the onset of insulin resistance, we evaluated the response to insulin of 3T3-L1 adipocytes treated with oxLDL. We observed that oxLDL inhibited glucose uptake (-40%) through reduced glucose transporter 4 (GLUT4) recruitment to the plasma membrane (-70%), without affecting GLUT4 gene expression. These findings were associated to the impairment of insulin signaling. Specifically, in oxLDL-treated cells insulin receptor (IR) substrate-1 (IRS-1) was highly degraded likely because of the enhanced Ser(307)phosphorylation. This process was largely mediated by the activation of the inhibitor of kappaB-kinase beta (IKKbeta) and the c-Jun NH(2)-terminal kinase (JNK). Moreover, the activation of IKKbeta positively regulated the nuclear content of nuclear factor kappaB (NF-kappaB), by inactivating the inhibitor of NF-kappaB (IkappaBalpha). The activated NF-kappaB further impaired per se GLUT4 functionality. Specific inhibitors of IKKbeta, JNK, and NF-kappaB restored insulin sensitivity in adipocytes treated with oxLDL. These data provide the first evidence that oxLDL, by activating serine/threonine kinases, impaired adipocyte response to insulin affecting pathways involved in the recruitment of GLUT4 to plasma membranes (PM). This suggests that oxLDL might participate in the development of insulin resistance.

The characterization of high-fat diet and multiple low-dose streptozotocin induced type 2 diabetes rat model

Aim. Based on the previously established method, we developed a better and stable animal model of type 2 diabetes mellitus by high-fat diet combined with multiple low-dose STZ injections. Meanwhile, this new model was used to evaluate the antidiabetic effect of berberine. Method. Wistar male rats fed with regular chow for 4 weeks received vehicle (control groups), rats fed with high-fat diet for 4 weeks received different amounts of STZ once or twice by intraperitoneal injection (diabetic model groups), and diabetic rats were treated with berberine (100 mg/kg, berberine treatment group). Intraperitoneal glucose tolerance test and insulin tolerance test were carried out. Moreover, fasting blood glucose, fasting insulin, total cholesterol, and triglyceride were measured to evaluate the dynamic blood sugar and lipid metabolism. Result. The highest successful rate (100%) was observed in rats treated with a single injection of 45 mg/kg STZ, but the plasma insulin level of this particular group was significantly decreased, and ISI has no difference compared to control group. The successful rate of 30 mg/kg STZ twice injection group was significantly high (85%) and the rats in this group presented a typical characteristic of T2DM as insulin resistance, hyperglycemia, and blood lipid disorder. All these symptoms observed in the 30 mg/kg STZ twice injection group were recovered by the treatment of berberine. Conclusion. Together, these results indicated that high-fat diet combined with multiple low doses of STZ (30 mg/kg at weekly intervals for 2 weeks) proved to be a better way for developing a stable animal model of type 2 diabetes, and this new model may be suitable for pharmaceutical screening.