Ginsenoside Rg3 Suppresses Palmitate-Induced Apoptosis in MIN6N8 Pancreatic beta-Cells

Ginsenoside Rg3 Protects Mouse Islet β-Cells Injured by High Glucose

To investigate the effect of Ginsenoside Rg3 on insulin secretion in mouse MIN6 cells and the possible mechanism. The cultured mouse pancreatic islet MIN6 cells were divided into control group (NC), Rg3 group (Rg3, 50 μg/L), high glucose group (HG, 33 mmol/L), High glucose and Rg3 group (HG + Rg3), after 48 h of continuous culture, CCK-8 was used to detect cell viability; mouse insulin enzyme-linked immunoassay kit to detect insulin release; ATP content detection kit to detect ATP; DCFH-DA to detect intracellular reactive oxygen species (ROS) levels; total glutathione (T-GSH)/oxidized glutathione (GSSG) assay kit to detect the ratio of GSH/GSSG; Using the mitochondrial membrane channel pore (MPTP) fluorescence detection kit in MIN6 cells and collect the intensity of green fluorescence; Western blot to detect the expression of antioxidant proteins Glutathione reductase (GR). The results showed that compared with the NC group, the cell viability of the HG was decreased (P < 0.05), insulin release decreased (P < 0.001), ATP content decreased significantly (P < 0.001), and ROS content increased (P < 0.01), the GSH/GSSH ratio of pancreatic islet cells decreased (P < 0.05),the green fluorescence intensity decreased (P < 0.001), indicating that the permeability of mitochondria increased and the content of antioxidant protein in the cells decreased (P < 0.05). Compared with the HG group, the cell viability of the HG + Rg3 group was significantly increased (P < 0.05), the amount of insulin released was significantly increased (P < 0.001), ATP content was significantly increased (P < 0.01), and the ROS content was significantly decreased (P < 0.01), GSH/GSSH ratio increased significantly (P < 0.05), the green fluorescence intensity was increased (P < 0.001), indicating that the permeability of mitochondria decreased and antioxidant protein GR content increased significantly (P < 0.05). Taken together, our results suggest that Rg3 has an antioxidant protective effect on mouse pancreatic islet cells damaged by high glucose and maintains pancreatic islet cell function and promotes insulin secretion.

Hypoglycemic effect of glycyrrhizic acid, a natural non-carbohydrate sweetener, on streptozotocin-induced diabetic mice

Glycyrrhizic acid (GZA) was extracted from the stem of licorice by enzymatic hydrolysis, separated and purified by silica gel column chromatography, its purity was determined by HPLC, and the structure was identified by FT-IR and NMR methods.

Cytoprotective effects of ginsenoside Rd on apoptosis-associated cell death in the isolated human pancreatic islets

Ginsenoside Rd (GS-Rd), one of the main pharmacologically active components of ginseng, has shown the potential to stabilize mitochondrial membrane integrity and decrease apoptotic death in neuronal and non-neuronal cells. The present study aimed to evaluate the effect of this bioactive molecule on the apoptosis-associated cell death in human pancreatic islets. In this regard human pancreatic islets were isolated and grouped for the treatment with GS-Rd. The isolated islets were treated with different concentrations of GS-Rd. After 24 and 72 h of incubation, the islets were evaluated in terms of viability, BAX, BCL2, and insulin gene expression, BAX, BCL2, and caspase-3 protein expression, apoptosis, and glucose-induced insulin/C-peptide secretion. Our results revealed the islet survival was significantly decreased in the control group after 72 h of incubation. However, GS-Rd inhibited the progress of the islet death in the treated groups. TUNEL staining revealed that the preventive effect of this molecule was caused by the inhibition of apoptosis-associated death. In this regard, the activation of caspase-3 was down-regulated in the presence of GS-Rd. GS-Rd did not exhibit undesirable effects on glucose-induced insulin and C-peptide stimulation secretion. In conclusion, GS-Rd inhibited the progress of death of cultured human pancreatic islets by diminishing the apoptosis of the islet cells.

Ginseng for the treatment of diabetes and diabetes-related cardiovascular complications: a discussion of the evidence 1

Diabetes mellitus (DM) is a chronic metabolic disorder associated with elevated blood glucose levels due either to insufficient insulin production (type 1 DM) or to insulin resistance (type 2 DM). The incidence of DM around the world continues to rise dramatically with more than 400 million cases reported today. Among the most serious consequences of chronic DM are cardiovascular complications that can have deleterious effects. Although numerous treatment options are available, including both pharmacological and nonpharmacological, there is substantial emerging interest in the use of traditional medicines for the treatment of this condition and its complications. Among these is ginseng, a medicinal herb that belongs to the genus Panax and has been used for thousands of years as a medicinal agent especially in Asian cultures. There is emerging evidence from both animal and clinical studies that ginseng, ginseng constituents including ginsenosides, and ginseng-containing formulations can produce beneficial effects in terms of normalization of blood glucose levels and attenuation of cardiovascular complications through a multiplicity of mechanisms. Although more research is required, ginseng may offer a useful therapy for the treatment of diabetes as well as its complications.

Red Ginseng Administration Before Islet Isolation Attenuates Apoptosis and Improves Islet Function and Transplant Outcome in a Syngeneic Mouse Marginal Islet Mass Model

BACKGROUND

Transplantation of isolated islets is a promising treatment for diabetes. Red ginseng (RG) is steamed ginseng and has been reported to enhance insulin secretion-stimulating and anti-apoptotic activities in pancreatic β-cells. In this study, we examined the hypothesis that pre-operative RG treatment enhances islet cell function and anti-apoptosis and investigated whether RG improves islet engraftment by transplant of a marginal mass of syngeneic islets pretreated with RG in diabetic mice.

METHODS

Balb/c mice were randomly divided into 2 groups, and 1 group was administered RG (400 mg/kg/day orally) for 7 days before islet isolation. In vitro islet viability and function were assessed. After cytokine treatment, cell viability, function, and apoptosis of islet cells were analyzed. Furthermore, we studied the effects of RG in a syngeneic islet graft model. A marginal mass of syngeneic mouse islets was transplanted into diabetic hosts.

RESULTS

Islet pretreatment with RG showed 1.4-fold higher glucose-induced insulin secretion than did control islets. RG pretreatment upregulated B-cell lymphoma 2 (Bcl-2) expression and downregulated Bcl-associated X protein (BAX), caspase-3, and inducible nitric oxide synthase (iNOS) expression. Glucose-induced insulin release, NO, and apoptosis were significantly improved in RG-pretreated islets compared with cytokine-treated islets. RG-pretreated mice exhibited improved marginal mass islet graft survival compared with controls.

CONCLUSIONS

These results suggest that pre-operative RG administration enhanced islet function before transplantation and attenuated cytokine-induced damage associated with apoptosis. These studies indicate that inhibition of apoptosis by RG significantly improved islet cell and graft function after isolation and transplantation, respectively.

Ginsenoside Rg3 prevents INS-1 cell death from intermittent high glucose stress

BACKGROUND

Ginsenoside Rg3 has been proposed to mediate anti-diabetic effects, but their direct effect on pancreatic β cell viability and mechanisms are not clearly understood. Recent studies suggest that intermittent high glucose (IHG) could be more harmful to pancreatic β cells than sustained high glucose. There are few reports about the effect of the ginsenosideRg3 to β cell apoptosis and proliferation against IHG.

METHODS

INS-1 cells were treated with alternative glucose concentration with or without ginsenoside Rg3. Cell apoptosis and viability were detected by Annexin V staining and MTT assay. The activation of mitogen-activated protein kinases (MAPKs) was analyzed by Western blotting using specific antibodies. Quantification of secreted insulin protein was measured using rat/mouse Insulin ELISA kits. Bromodeoxyuridine (BrdU) staining and florescence in situ hybridization (FISH) analysis was performed to compare cell proliferation.

RESULT

INS-1 cell viability was decreased under IHG and increased with Rg3 treatment.Rg3 significantly reduced the apoptotic INS-1 cells against IHG. The quantification of secreted insulin concentration was increased with Rg3. Rg3 increased INS-1 cell proliferation. ERK and p38 MAPK pathways reduced by IHG were activated by the ginsenoside Rg3.

CONCLUSION

Ginsenoside Rg3 protected INS-1 cell death from IHG with reducing apoptosis and increasing proliferation.

EFFECTS OF GINSENG AND ITS FOUR PURIFED GINSENOSIDES (Rb2, Re, Rg1, Rd) ON HUMAN PANCREATIC ISLET β CELL IN VITRO

Ginseng has attracted interest because of its potential therapeutic role in diabetes therapy. No direct evidence has shown the effects of ginseng and its components, ginsenosides, on human islet β cell. In this study, we evaluated ginseng extract and ginsenosides (Rb2, Re, Rg1, Rd) on human pancreatic β cell function. The results provide direct evidence that ginseng extract promotes human pancreatic β cell function. Ginsenoside Rb2 increased islet β cell insulin release and promoted β cell migration. Ginsenoside Re had some impact on cell migration, but had no effect on islet function by evaluating insulin release. The other ginsenosides had no effect on insulin release and islet migration. To date, this is the first study that examines the impact of ginsenosides on human pancreatic islets in vitro.

Ginsenoside Rg3 enhances islet cell function and attenuates apoptosis in mouse islets

BACKGROUND

The transplantation of isolated islets is thought to be an attractive approach for curative treatment of diabetes mellitus. Panax ginseng has been used in oriental countries for its pharmacologic effects, such as antidiabetic and antiinflammatory activities. 20(S)-ginsenoside Rg3 (Rg3), an active ingredient of ginseng saponins, has been reported to enhance insulin secretion-stimulating and antiapoptotic activities in pancreatic beta cells. We performed this study to examine the hypothesis that preoperative Rg3 administration can enhance islet cell function and antiapoptosis before islet transplantation.

METHODS

Balb/c mice were randomly divided into 2 groups according to the administration of Rg3 after islet isolation. Mouse islets were cultured in medium supplemented with or without Rg3. In vitro, islet viability and function were assessed. After treatment of islets with a cytokine cocktail (tumor necrosis factor α, interferon-γ, and interleukin-1β), cell viability, function, and apoptosis were assessed.

RESULTS

Cell viability was similar between the 2 groups. Islets cultured in medium supplemented with Rg3 showed 2.3-fold higher glucose-induced insulin secretion than islets cultured in medium without Rg3. After treatment with a cytokine cocktail, glucose-induced insulin release, total insulin content of islets, and apoptosis were significantly improved in Rg3-treated islets compared with cytokine-treated islets. Cytokine-treated islets produced significantly higher levels of nitric oxide (NO) than islets treated with Rg3.

CONCLUSIONS

These results suggest that preoperative Rg3 administration enhanced islet function before islet transplantation and attenuated both cytokine-induced damage associated with NO production and apoptosis. Rg3 administration might be a prospective management to enhanced islet function and ameliorate early inflammation after transplantation.

A review on the medicinal potential of Panax ginseng saponins in diabetes mellitus

This review article summarizes the anti-diabetic effects and mechanisms ofPanax ginsengsaponins and its active specific ginsenosides.

Saturated free fatty acids induce cholangiocyte lipoapoptosis

Recent studies have identified a cholestatic variant of nonalcoholic fatty liver disease (NAFLD) with portal inflammation and ductular reaction. Based on reports of biliary damage, as well as increased circulating free fatty acids (FFAs) in NAFLD, we hypothesized the involvement of cholangiocyte lipoapoptosis as a mechanism of cellular injury. Here, we demonstrate that the saturated FFAs palmitate and stearate induced robust and rapid cell death in cholangiocytes. Palmitate and stearate induced cholangiocyte lipoapoptosis in a concentration-dependent manner in multiple cholangiocyte-derived cell lines. The mechanism of lipoapoptosis relied on the activation of caspase 3/7 activity. There was also a significant up-regulation of the proapoptotic BH3-containing protein, PUMA. In addition, palmitate-induced cholangiocyte lipoapoptosis involved a time-dependent increase in the nuclear localization of forkhead family of transcription factor 3 (FoxO3). We show evidence for posttranslational modification of FoxO3, including early (6 hours) deacetylation and dephosphorylation that coincide with localization of FoxO3 in the nuclear compartment. By 16 hours, nuclear FoxO3 is both phosphorylated and acetylated. Knockdown studies confirmed that FoxO3 and its downstream target, PUMA, were critical for palmitate- and stearate-induced cholangiocyte lipoapoptosis. Interestingly, cultured cholangiocyte-derived cells did not accumulate appreciable amounts of neutral lipid upon FFA treatment.

CONCLUSION

Our data show that the saturated FFAs palmitate and stearate induced cholangiocyte lipoapoptosis by way of caspase activation, nuclear translocation of FoxO3, and increased proapoptotic PUMA expression. These results suggest that cholangiocyte injury may occur through lipoapoptosis in NAFLD and nonalcoholic steatohepatitis patients.

Ginsenoside Rg3 enhances the inhibitory effects of chemotherapy on esophageal squamous cell carcinoma in mice

The present study was conducted in order to investigate the inhibitory effects of ginsenoside Rg3 combined with chemotherapy on Eca-109 esophageal squamous cell carcinoma (ESCC) in mice. Tumor xenograft models were established in the right forelimb of 20 BALB/c nude mice by subcutaneous injection. The tumor-bearing mice were randomly assigned to 4 treatment groups (n=5 per group) as follows: the control group (saline), the ginsenoside Rg3 alone group (6 mg/kg/day, once a day for 3 weeks), the chemotherapy alone group (paclitaxel 10 mg/kg/day + cisplatin 5 mg/kg/day on days 1, 7, 14 and 21) and the chemotherapy + Rg3 group (combined treatment). The length and width of the tumor were directly measured with calipers at different time points and the tumor volume (cm³) was calculated using the formula 0.52 × length × width² every other day. The mice were sacrificed by cervical dislocation following completion of therapy, the tumors were removed and weighed and the expression levels of Ki-67 were determined by immunohistochemistry. The results indicated that the coadministration of ginsenoside Rg3 significantly enhanced the inhibitory effects of chemotherapy on tumor growth. In addition, the expression levels of Ki-67 in the chemotherapy + Rg3 group were significantly lower compared to those in the other 3 groups. The chemotherapy + Rg3 group also exhibited the lowest microvascular density among all four groups. These findings suggested that ginsenoside Rg3 may improve the antitumor efficacy of chemotherapy in Eca-109 ESCC in mice.

Efficacy and safety of ginsam, a vinegar extract from Panax ginseng, in type 2 diabetic patients: Results of a double-blind, placebo-controlled study

Aims/Introduction:  The efficacy, dose–response relationship and safety of ginsam, a vinegar extract from Panax ginseng, were evaluated in an 8‐week, double‐blind, randomized, placebo‐controlled study in drug‐naïve patients with type 2 diabetes.

Materials and Methods:  A total of 72 diabetic patients were randomized to receive 1500, 2000 or 3000 mg of ginsam, or placebo daily for 8 weeks (n = 18 in each group). The primary end‐point was the changes from the baseline HbA_1c level. The secondary end‐points were the changes of fasting and postprandial 2‐h glucose concentration, and the proportion of patients achieving a reduction in HbA_1c >0.5%.

Results:  In the intention‐to‐treat analysis, ginsam treatment reduced HbA_1c level significantly: −0.56 ± 0.25% in the 1500 mg group, −0.31 ± 0.12% in the 2000 mg group, and −0.29 ± 0.11% in the 3000 mg group (all P < 0.05), with a significant difference between the 1500 mg ginsam and the placebo group (−0.02 ± 0.12%, P = 0.021). The changes in fasting glucose concentration followed the same pattern: −21.40, −14.27 and −6.76 mg/dL for 1500, 2000, and 3000 mg, respectively, vs −2.25 mg/dL for the placebo. The percentage of patients whose HbA_1c level decreased by >0.5% differed significantly between the placebo group (11.1%) and the 1500 mg (27.8%) and 2000 mg (27.8%) groups. No severe adverse events were observed in any group.

Conclusions:  An 8‐week treatment with ginsam, a vinegar extract from P. ginseng, moderately improved HbA_1c level and was well tolerated in type 2 diabetic patients with inadequate glycemic control. This trial was registered with ClinicalTrial.Gov (no. NCT01008163). (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00185.x, 2011)

Ginseng and diabetes: the evidences from in vitro, animal and human studies

Panax ginseng exhibits pleiotropic beneficial effects on cardiovascular system, central nervous system, and immune system. In the last decade, numerous preclinical findings suggest ginseng as a promising therapeutic agent for diabetes prevention and treatment. The mechanism of ginseng and its active components is complex and is demonstrated to either modulate insulin production/secretion, glucose metabolism and uptake, or inflammatory pathway in both insulin-dependent and insulin-independent manners. However, human studies are remained obscure because of contradictory results. While more studies are warranted to further understand these contradictions, ginseng holds promise as a therapeutic agent for diabetes prevention and treatment. This review summarizes the evidences for the therapeutic potential of ginseng and ginsenosides from in vitro studies, animal studies and human clinical trials with a focus on diverse molecular targets including an AMP-activated protein kinase signaling pathway.

Treatment of Diabetes Using Traditional Chinese Medicine: Past, Present and Future

Diabetes is a major medical problem that imperils public health. Over two thousand years ago, Traditional Chinese Medicine (TCM) called diabetes-related symptoms "Xiaoke" disease. In ancient China, TCM and Chinese herbal medicines were used widely in treating Xiaoke and abundant experience has been accumulated. This article discusses the TCM theory on diabetes and its achievements in the prevention and treatment of diabetes in the past. Using Chinese herbal medicine, recent progress in diabetes therapeutics, including data from clinical trials, are presented. Mechanistic studies from basic research are discussed. Yin-yang balance and a holistic approach of TCM may complement diabetes treatment in Western medicine. With continuous efforts, TCM could play a more important role in fighting this disease.

Traditional chinese medicines in treatment of patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) occurs in 95% of the diabetic populations. Management of T2DM is a challenge. Traditional Chinese medicines (TCM) are usually served as adjuvants used to improve diabetic syndromes in combination of routine antidiabetic drugs. For single-herb prescriptions, Ginseng, Bitter melon, Golden Thread, Fenugreek, Garlic, and Cinnamon might have antidiabetic effects in T2DM patients. Among 30 antidiabetic formulas approved by the State Food and Drugs Administrator of China, top 10 of the most frequently prescribed herbs are Membranous Milkvetch Root, Rehmannia Root, Mongolian Snakegourd Root, Ginseng, Chinese Magnoliavine Fruit, Kudzuvine Root, Dwarf Lilyturf Tuber, Common Anemarrhena Rhizome, Barbary Wolfberry Fruit, and India Bread, which mainly guided by the theory of TCM. Their action mechanisms are related to improve insulin sensitivity, stimulate insulin secretion, protect pancreatic islets, and even inhibit intake of intestinal carbohydrates. However, it is very difficult to determine antihyperglycemic components of TCM. Nevertheless, TCM are becoming popular complementary and alternative medicine in treatment of syndromes of T2DM. In the future, it requires further validation of phytochemical, pharmacological, and clinical natures of TCM in T2DM in the future studies, especially for those herbs with a high prescription frequency.

MKP-1 mediates glucocorticoid-induced ERK1/2 dephosphorylation and reduction in pancreatic ß-cell proliferation in islets from early lactating mothers

Maternal pancreatic islets undergo a robust increase of mass and proliferation during pregnancy, which allows a compensation of gestational insulin resistance. Studies have described that this adaptation switches to a low proliferative status after the delivery. The mechanisms underlying this reversal are unknown, but the action of glucocorticoids (GCs) is believed to play an important role because GCs counteract the pregnancy-like effects of PRL on isolated pancreatic islets maintained in cell culture. Here, we demonstrate that ERK1/2 phosphorylation (phospho-ERK1/2) is increased in maternal rat islets isolated on the 19th day of pregnancy. Phospho-ERK1/2 status on the 3rd day after delivery (L3) rapidly turns to values lower than that found in virgin control rats (CTL). MKP-1, a protein phosphatase able to dephosphorylate ERK1/2, is increased in islets from L3 rats. Chromatin immunoprecipitation assay revealed that binding of glucocorticoid receptor (GR) to MKP-1 promoter is also increased in islets from L3 rats. In addition, dexamethasone (DEX) reduced phospho-ERK1/2 and increased MKP-1 expression in RINm5F and MIN-6 cells. Inhibition of transduction with cycloheximide and inhibition of phosphatases with orthovanadate efficiently blocked DEX-induced downregulation of phospho-ERK1/2. In addition, specific knockdown of MKP-1 with siRNA suppressed the downregulation of phospho-ERK1/2 and the reduction of proliferation induced by DEX. Altogether, our results indicate that downregulation of phospho-ERK1/2 is associated with reduction in proliferation found in islets of early lactating mothers. This mechanism is probably mediated by GC-induced MKP-1 expression.