How Does Ginsenoside Rh2 Mitigate Adipogenesis in Cultured Cells and Obese Mice?

Ginsenoside Rh2, an intermediate metabolite of ginseng, but not naturally occurring, has recently drawn attention because of its anticancer effect. However, it is not clear if and how Rh2 inhibits preadipocytes differentiation. In the present study, we hypothesized that ginsenoside Rh2 attenuates adipogenesis through regulating the peroxisome proliferator-activated receptor gamma (PPAR-γ) pathway both in cells and obese mice. Different concentrations of Rh2 were applied both in 3T3-L1 cells and human primary preadipocytes to determine if Rh2 inhibits cell differentiation. Dietary Rh2 was administered to obese mice to determine if Rh2 prevents obesity in vivo. The mRNA and protein expression of PPAR-γ pathway molecules in cells and tissues were measured by real-time polymerase chain reaction (RT-PCR) and Western blot, respectively. Our results show that Rh2 dose-dependently (30-60 μM) inhibited cell differentiation in 3T3-L1 cells (44.5% ± 7.8% of control at 60 μM). This inhibitory effect is accompanied by the attenuation of the protein and/or mRNA expression of adipogenic markers including PPAR-γ and CCAAT/enhancer binding protein alpha, fatty acid synthase, fatty acid binding protein 4, and perilipin significantly (p < 0.05). Moreover, Rh2 significantly (p < 0.05) inhibited differentiation in human primary preadipocytes at much lower concentrations (5-15 μM). Furthermore, dietary intake of Rh2 (0.1 g Rh2/kg diet, w/w for eight weeks) significantly (p < 0.05) reduced protein PPAR-γ expression in liver and hepatic glutathione reductase and lowered fasting blood glucose. These results suggest that ginsenoside Rh2 dose-dependently inhibits adipogenesis through down-regulating the PPAR-γ pathway, and Rh2 may be a potential agent in preventing obesity in vivo.

Efficacy and safety of Panax ginseng berry extract on glycemic control: A 12-wk randomized, double-blind, and placebo-controlled clinical trial

Background

Antihyperglycemic effects of Panax ginseng berry have never been explored in humans. The aims of this study were to assess the efficacy and safety of a 12-wk treatment with ginseng berry extract in participants with a fasting glucose level between 100 mg/dL and 140 mg/dL.

Methods

This study was a 12-wk, randomized, double-blind, placebo-controlled clinical trial. A total of 72 participants were randomly allocated to two groups of either ginseng berry extract or placebo, and 63 participants completed the study. The parameters related to glucose metabolism were assessed.

Results

Although the present study failed to show significant antihyperglycemic effects of ginseng berry extract on the parameters related to blood glucose and lipid metabolism in the total study population, it demonstrated that ginseng berry extract could significantly decrease serum concentration of fasting glucose by 3.7% (p = 0.035), postprandial glucose at 60 min during 75 g oral glucose tolerance test by 10.7% (p = 0.006), and the area under the curve for glucose by 7.7% (p = 0.024) in those with fasting glucose level of 110 mg/dL or higher, while the placebo group did not exhibit a statistically significant decrease. Safety profiles were not different between the two groups.

Conclusion

The present study suggests that ginseng berry extract has the potential to improve glucose metabolism in human, especially in those with fasting glucose level of 110 mg/dL or higher. For a more meaningful benefit, further research in people with higher blood glucose levels is required.

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.

Ginseng total saponin modulates podocyte p130Cas in diabetic condition

Proteinuric conditions demonstrate structural and compositional changes of the foot processes and slit diaphragms between podocytes. p130Cas in podocytes serves as an adapter protein anchoring glomerular basement membrane to actin filaments of podocyte cytoskeleton. To investigate the effect of ginseng total saponin (GTS) on the pathologic changes of podocyte p130Cas induced by diabetic conditions, we cultured mouse podocytes under: 1) normal glucose (5 mM, control); 2) high glucose (HG, 30 mM); 3) advanced glycosylation endproducts (AGE)-added; or 4) HG plus AGE-added conditions and treated with GTS. In confocal imaging, p130Cas colocalized with zonula occludens-1 and synaptopodin connecting to F-actin. However, diabetic conditions relocalized p130Cas molecules at perinuclear cytoplasmic area and reduced the intensity of p130Cas. In Western blotting, diabetic conditions, especially HG plus AGE-added condition, decreased cellular p130Cas protein levels at 24 and 48 h. GTS improved such quantitative and qualitative changes. These findings imply that HG and AGE have an influence on the redistribution and amount of p130Cas of podocytes, which can be reversed by GTS.

GABAA Receptor- and Non-NMDA Glutamate Receptor-Mediated Actions of Korean Red Ginseng Extract on the Gonadotropin Releasing Hormone Neurons

Korean red ginseng (KRG) has been used worldwide as a traditional medicine for the treatment of various reproductive diseases. Gonadotropin releasing hormone (GnRH) neurons are the fundamental regulators of pulsatile release of gonadotropin required for fertility. In this study, an extract of KRG (KRGE) was applied to GnRH neurons to identify the receptors activated by KRGE. The brain slice patch clamp technique in whole cell and perforated patch was used to clarify the effect of KRGE on the membrane currents and membrane potentials of GnRH neurons. Application of KRGE (3 μg/μL) under whole cell patch induced remarkable inward currents (56.17±7.45 pA, n=25) and depolarization (12.91±3.80 mV, n=4) in GnRH neurons under high Cl^- pipette solution condition. These inward currents were not only reproducible, but also concentration dependent. In addition, inward currents and depolarization induced by KRGE persisted in the presence of the voltage gated Na⁺ channel blocker tetrodotoxin (TTX), suggesting that the responses by KRGE were postsynaptic events. Application of KRGE under the gramicidin perforated patch induced depolarization in the presence of TTX suggesting its physiological significance on GnRH response. Further, the KRGE-induced inward currents were partially blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; non-NMDA glutamate receptor antagonist, 10 μM) or picrotoxin (PIC; GABA_A receptor antagonist, 50 μM), and almost blocked by PIC and CNQX mixture. Taken together, these results suggest that KRGE contains ingredients with possible GABA and non-NMDA glutamate receptor mimetic activity, and may play an important role in the endocrine function of reproductive physiology, via activation of GABA_A and non-NMDA glutamate receptors in GnRH neurons.

Ginseng total saponin improves podocyte hyperpermeability induced by high glucose and advanced glycosylation endproducts

Early diabetic nephropathy is characterized by glomerular hyperpermeability as a result of impaired glomerular filtration structure caused by hyperglycemia, glycated proteins or irreversible advanced glycosylation endproducts (AGE). To investigate the effect of ginseng total saponin (GTS) on the pathologic changes of podocyte ZO (zonula occludens)-1 protein and podocyte permeability induced by diabetic conditions, we cultured mouse podocytes under: 1) normal glucose (5 mM, = control); 2) high glucose (HG, 30 mM); 3) AGE-added; or 4) HG plus AGE-added conditions and treated with GTS. HG and AGE increased the dextran filtration of monolayered podocytes at early stage (2-8 hr) in permeability assay. In confocal imaging, ZO-1 colocalized with actin filaments and β-catenin at cell contact areas, forming intercellular filtration gaps. However, these diabetic conditions suppressed ZO-1 immunostainings and disrupted the linearity of ZO-1. In Western blotting, diabetic conditions also decreased cellular ZO-1 protein levels at 6 hr and 24 hr. GTS improved such quantitative and qualitative changes. These findings imply that HG and AGE have an influence on the redistribution and amount of ZO-1 protein of podocytes thereby causing hyperpermeability at early stage, which can be reversed by GTS.

Effects of red ginseng extract on the epididymal sperm motility of mice exposed to ethanol

The protective effects of red ginseng extract and ginseng wine against ethanol-induced male reproductive toxicity were evaluated in male mice using computer-assisted sperm analysis. Mice were divided into 4 groups of 10 and fed plain saline, 6 g/kg per d of ethanol in saline, red ginseng extract plus ethanol, or a fermented preparation of red ginseng extract daily for 5 weeks. We found that the average seminal vesicle weight was significantly lower in the ethanol-treated group compared to the control group, while those of the ginseng-treated groups tended to be higher than the ethanol-treated group. We found a significant decrease in sperm motility and progressiveness in mice treated with ethanol for 5 weeks, while administration of ethanol plus red ginseng extract appeared to minimize the negative effects of ethanol toxicity on male fertility. Serum testosterone, luteinizing hormone (LH), and follicle stimulating hormone (FSH) were insignificantly lower in the ethanol-treated group than in the control group.