Oral administration of ginseng ameliorates cyclosporine-induced pancreatic injury in an experimental mouse model

Cyclosporine-induced kidney damage was halted by sitagliptin and hesperidin via increasing Nrf2 and suppressing TNF-α, NF-κB, and Bax

Cyclosporine A (CsA) is employed for organ transplantation and autoimmune disorders. Nephrotoxicity is a serious side effect that hampers the therapeutic use of CsA. Hesperidin and sitagliptin were investigated for their antioxidant, anti-inflammatory, and tissue-protective properties. We aimed to investigate and compare the possible nephroprotective effects of hesperidin and sitagliptin. Male Wistar rats were utilized for induction of CsA nephrotoxicity (20 mg/kg/day, intraperitoneally for 7 days). Animals were treated with sitagliptin (10 mg/kg/day, orally for 14 days) or hesperidin (200 mg/kg/day, orally for 14 days). Blood urea, serum creatinine, albumin, cystatin-C (CYS-C), myeloperoxidase (MPO), and glucose were measured. The renal malondialdehyde (MDA), glutathione (GSH), catalase, and SOD were estimated. Renal TNF-α protein expression was evaluated. Histopathological examination and immunostaining study of Bax, Nrf-2, and NF-κB were performed. Sitagliptin or hesperidin attenuated CsA-mediated elevations of blood urea, serum creatinine, CYS-C, glucose, renal MDA, and MPO, and preserved the serum albumin, renal catalase, SOD, and GSH. They reduced the expressions of TNF-α, Bax, NF-κB, and pathological kidney damage. Nrf2 expression in the kidney was raised. Hesperidin or sitagliptin could protect the kidney against CsA through the mitigation of oxidative stress, apoptosis, and inflammation. Sitagliptin proved to be more beneficial than hesperidin.

Evidence of the interactions between immunosuppressive drugs used in autoimmune rheumatic diseases and Chinese herbal medicine: A scoping review

OBJECTIVES

Chinese herbal medicine (CHM) has been shown to be effective in autoimmune rheumatic diseases, but harmful herb-drug interactions might be inherent. We aim to review the evidence regarding herb-drug interactions between immunosuppressive drugs used in autoimmune rheumatic diseases and CHM.

METHODS

We searched PubMed, EMBASE and CINAHL from inception till 30 April 2023 using keywords that encompassed 'herb-drug interactions', 'herbs' and 'immunosuppressants'. Articles were included if they contained reports about interactions between immunosuppressive drugs used in the treatment of rheumatic diseases with CHM. Level of evidence for each pair of interaction was graded using the algorithm developed by Colalto.

RESULTS

A total of 65 articles and 44 unique pairs of interactions were identified. HDIs were reported for cyclophosphamide, cyclosporine, tacrolimus, methotrexate, mycophenolic acid, glucocorticoids, sulfasalazine, tofacitinib and biologic disease-modifying antirheumatic drugs. Among these, cyclosporine (n = 27, 41.5%) and tacrolimus (n = 19, 29.2%) had the highest number of documented interactions. Hypericum perforatum had the highest level of evidence of interaction with cyclosporine and tacrolimus. Consumption reduced the bioavailability and therapeutic effects of the drugs. Schisandra sphenanthera had the highest level of evidence of interaction with tacrolimus and increased the bioavailability of the drug. Majority of the articles were animal studies.

CONCLUSION

Overall level of evidence for the included studies were low, though interactions between cyclosporine, tacrolimus, Hypericum perforatum and Schisandra sphenanthera were the most and well-documented. Healthcare professionals should actively enquire about the concurrent use of CHM in patients, especially when drugs with a narrow therapeutic index are consumed.

The dark side of drug repurposing. From clinical trial challenges to antimicrobial resistance: analysis based on three major fields

Drug repurposing is a strategic endeavor that entails the identification of novel therapeutic applications for pharmaceuticals that are already available in the market. Despite the advantageous nature of implementing this particular strategy owing to its cost-effectiveness and efficiency in reducing the time required for the drug discovery process, it is essential to bear in mind that there are various factors that must be meticulously considered and taken into account. Up to this point, there has been a noticeable absence of comprehensive analyses that shed light on the limitations of repurposing drugs. The primary aim of this review is to conduct a thorough illustration of the various challenges that arise when contemplating drug repurposing from a clinical perspective in three major fields-cardiovascular, cancer, and diabetes-and to further underscore the potential risks associated with the emergence of antimicrobial resistance (AMR) when employing repurposed antibiotics for the treatment of noninfectious and infectious diseases. The process of developing repurposed medications necessitates the application of creativity and innovation in designing the development program, as the body of evidence may differ for each specific case. In order to effectively repurpose drugs, it is crucial to consider the clinical implications and potential drawbacks that may arise during this process. By comprehensively analyzing these challenges, we can attain a deeper comprehension of the intricacies involved in drug repurposing, which will ultimately lead to the development of more efficacious and safe therapeutic approaches.

Endothelial LRP1 protects against neurodegeneration by blocking cyclophilin A

The low-density lipoprotein receptor–related protein 1 (LRP1) is an endocytic and cell signaling transmembrane protein. Endothelial LRP1 clears proteinaceous toxins at the blood–brain barrier (BBB), regulates angiogenesis, and is increasingly reduced in Alzheimer’s disease associated with BBB breakdown and neurodegeneration. Whether loss of endothelial LRP1 plays a direct causative role in BBB breakdown and neurodegenerative changes remains elusive. Here, we show that LRP1 inactivation from the mouse endothelium results in progressive BBB breakdown, followed by neuron loss and cognitive deficits, which is reversible by endothelial-specific LRP1 gene therapy. LRP1 endothelial knockout led to a self-autonomous activation of the cyclophilin A–matrix metalloproteinase-9 pathway in the endothelium, causing loss of tight junctions underlying structural BBB impairment. Cyclophilin A inhibition in mice with endothelial-specific LRP1 knockout restored BBB integrity and reversed and prevented neuronal loss and behavioral deficits. Thus, endothelial LRP1 protects against neurodegeneration by inhibiting cyclophilin A, which has implications for the pathophysiology and treatment of neurodegeneration linked to vascular dysfunction.

Dextran sulfate sodium-induced colitis and ginseng intervention altered oral pharmacokinetics of cyclosporine A in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Application of cyclosporine A (CsA) as a rescue treatment in acute severe ulcerative colitis (UC) is limited by its narrow therapeutic window and great interpatient variability. As a substrate of cytochrome P450 3A enzyme (CYP3A) and P-glycoprotein (P-gp), the oral pharmacokinetics of CsA is susceptible to disease status and concomitant medications. Combined treatment with ginseng, a famous medicinal herb frequently prescribed for ameliorating abnormal immune response in many diseases including UC, showed immunologic safety in CsA-based immunosuppression.

AIM OF THE STUDY

Since the therapeutic levels of CsA can be achieved within 24 h, this study first assessed the impact of acute colitis and ginseng intervention on the single oral dose pharmacokinetics of CsA and explored the underlying mechanisms in dextran sulfate sodium (DSS)-induced colitis rats and Caco-2 cells.

MATERIALS AND METHODS

Rats received drinking water (normal group), 5% DSS (UC group), or 5% DSS plus daily oral ginseng extract (GS+UC group). On day 7, GS+UC group only received an oral dose of CsA (5 mg/kg), while animals of normal or UC group received an oral, intravenous (1.25 mg/kg), or intraperitoneal dose of CsA (1.25 mg/kg), respectively. Blood, liver/intestine tissues and fecal samples were collected for determining CsA and main hydroxylated metabolite HO-CsA or measuring hepatic/intestinal CYP3A activity. Caco-2 cells were incubated with gut microbial culture supernatant (CS) of different groups or ginseng (decoction or polysaccharides), and then CYP3A, P-gp and tight junction (TJ) proteins were determined.

RESULTS

Oral CsA exhibited enhanced absorption, systemic exposure and tissue accumulation, and lower fecal excretion, while intravenous or intraperitoneal CsA showed lower systemic exposure and enhanced distribution, in colitis rats. Diminished intestinal and hepatic P-gp expression well explained the changes with DSS-induced colitis. Moreover, blood exposures of HO-CsA in both normal and colitis after oral dosing were significantly higher than intravenous/intraperitoneal dosing, supporting the dominant role of intestinal first-pass metabolism. Interestingly, colitis reduced CYP3A expression in intestine and liver but only potentiated intestinal CYP3A activity, causing higher oral systemic exposure of HO-CsA. Oral ginseng mitigated colitis-induced down-regulation of CYP3A and P-gp expression, facilitated HO-CsA production, biliary excretion and colonic sequestration of CsA, while not affected CsA oral systemic exposure. In Caco-2 cells, gut microbial CS from both colitis and GS+UC group diminished P-gp function, while ginseng polysaccharides directly affected ZO-1 distribution and suppressed TJ proteins expression, explaining unaltered oral CsA systemic exposure.

CONCLUSIONS

DSS-induced colitis significantly altered oral CsA disposition through regulating intestinal and hepatic P-gp and CYP3A. One-week ginseng treatment enhanced colonic accumulation while not altered the systemic exposure of CsA after single oral dosing, indicating pharmacokinetic compatibility between the two medications.

The safety, immunological benefits, and efficacy of ginseng in organ transplantation

Korean ginseng (Panax ginseng) is associated with a variety of therapeutic effects, including antioxidative, anti-inflammatory, vasorelaxative, antiallergic, antidiabetic, and anticancer effects. Accordingly, the use of ginseng has reached an all-time high among members of the general public. However, the safety and efficacy of ginseng in transplant recipients receiving immunosuppressant drugs have still not been elucidated. Transplantation is the most challenging and complex of surgical procedures and may require causation for the use of ginseng. In this regard, we have previously examined the safety, immunological benefits, and protective mechanisms of ginseng with respect to calcineurin inhibitor-based immunosuppression, which is the most widely used regimen in organ transplantation. Using an experimental model of calcineurin inhibitor-induced organ injury, we found that ginseng does not affect drug levels in the peripheral blood and tissue, favorably regulates immune response, and protects against calcineurin inhibitor-induced nephrotoxicity and pancreatic islet injury. On the basis of our experimental studies and a review of the related literature, we propose that ginseng may provide benefits in organ transplant recipients administered calcineurin inhibitors. Through the present review, we aimed to briefly discuss our current understanding of the therapeutic benefits of ginseng related to transplant patient survival.

Assessment of nephrotoxicity of herbal medicine containing aristolochic acid in mice

BACKGROUND/AIMS

It is undetermined if herbal medicines (HM) containing aristolochic acid (AA)-containing have similar nephrotoxicity to AA itself.

METHODS

We administered HM containing a high concentration of AA for 5 days (short-term study) or a low concentration of AA for 30 days (long-term study) to C57BL/6 mice; for comparison, same dose of AA compound was used as controls.

RESULTS

The nephrotoxicity in the HM- and AA-treated mice was compared in terms of renal function, histopathology, oxidative stress, apoptotic cell death, and mitochondrial damage. Short-term HM treatment resulted in acute kidney injury (marked renal dysfunction, acute tubular necrosis, and neutrophil gelatinase-associated lipocalin [NGAL] expression) in which the severity of renal dysfunction and histopathology was comparable with that induced by the administration of AA alone. Long-term HM treatment resulted in features of chronic kidney disease (CKD, mild renal dysfunction and tubular atrophy and dilatation). No significant differences in these parameters were observed between the HM- and AA-treated mice. HM-induced oxidative stress (8-hydroxy-2'-deoxyguanosine and manganese- dependent superoxide dismutase expression) and apoptotic cell death (terminal deoxynucleotidyl transferase dUTP nick end labelling [TUNEL]-positive cells and active caspase-3 expression) were similar in HM- and AA-treated mice in the short-term and long-term studies. Mitochondrial injury, evaluated by electron microscopy, was also similar in HM- and AA-treated mice in the short-term and long-term studies.

CONCLUSION

The nephrotoxic potential of HM containing AA was similar to that of AA itself.

Advances in Research on the Protective Mechanisms of Traditional Chinese Medicine (TCM) in Islet β Cells

The dysfunction and decreased number of islet β cells are central to the main pathogenesis of diabetes. Improving islet β cell function and increasing the number of β cells are effective approaches to treat diabetes and constitute the main direction of diabetes drug development. The role of Chinese medicine in the treatment of diabetes began to be recognized. In recent years, Chinese medicine monomers have been found to increase insulin synthesis and secretion, reduce β cell-apoptosis, and protect the function of β cells. The results of in vivo animal experiments and in vitro studies on insulinoma cells also suggested TCMs could promote the proliferation of pancreatic islet β cells and induce other cells differentiation or transdifferentiation to islet β cells. Thereby, they may play a role in the treatment of diabetes. In this paper, we will review islet β cell protection with TCMs and the related mechanisms found in recent studies. An in-depth explanation of the role of TCM in islet β cell protection can provide a theoretical basis and research ideas for the development of TCM-based diabetes treatment drugs.

Ginseng increases Klotho expression by FoxO3-mediated manganese superoxide dismutase in a mouse model of tacrolimus-induced renal injury

The antioxidant function of Klotho is well-documented as a regulatory factor implicated in countering the aging process. This study investigated whether ginseng upregulates Klotho and its antiaging signaling in a setting of calcineurin inhibitor-induced oxidative stress. Although tacrolimus treatment reduced Klotho level in the serum and kidney, ginseng treatment was found to reverse the levels. Tacrolimus-induced oxidative stress was reduced by ginseng treatment, with functional and histological improvements. Effect of ginseng on Klotho-induced manganese superoxide dismutase signaling pathway during tacrolimus treatment in mice revealed that ginseng suppressed phosphatidylinositol 3-kinase/serine-threonine kinase Akt-mediated phosphorylation of forkhead box protein O3a and promoted the binding of forkhead box protein O3a to manganese superoxide dismutase promoter. In the mitochondria, ginseng reduced mitochondrial reactive oxygen species production, mitochondrial membrane potential, and oxygen consumption rate, whereas blocking phosphatidylinositol 3-kinase activity with LY294002 enhanced them. These findings together suggested that ginseng attenuated tacrolimus-induced oxidative stress via signaling between Klotho and the phosphatidylinositol 3-kinase/serine-threonine kinase Akt/forkhead box protein O3a-related antioxidant pathway.

The effects of addition of coenzyme Q10 to metformin on sirolimus-induced diabetes mellitus

BACKGROUND/AIMS

This study was performed to determine whether adding coenzyme Q10 (CoQ10) to metformin (MET) has a beneficial effect as a treatment for sirolimus (SRL)-induced diabetes mellitus (DM).

METHODS

DM was induced in rats by daily treatment with SRL (0.3 mg/kg, subcutaneous) for 28 days, and animals were treated with CoQ10 (20 mg/kg, oral) and MET (250 mg/kg, oral) alone or in combination for the latter 14 days of SRL treatment. The effects of CoQ10 and MET on SRL-induced DM were assessed with the intraperitoneal glucose tolerance test (IPGTT) and by determining plasma insulin concentration and the homeostatic model assessment of insulin resistance (HOMA-R) index. We also evaluated the effect of CoQ10 on pancreatic islet size, apoptosis, oxidative stress, and mitochondria morphology.

RESULTS

IPGTT revealed overt DM in SRL-treated rats. The addition of CoQ10 to MET further improved hyperglycemia, decreased HOMA-R index, and increased plasma insulin concentration compared with the SRL group than MET alone therapy. While SRL treatment induced smaller islets with decreased insulin staining intensity, the combination of CoQ10 and MET significantly improved insulin staining intensity, which was accompanied by a reduction in oxidative stress and apoptosis. In addition, co-treatment of CoQ10 and MET significantly increased the levels of antiperoxidative enzymes in the pancreas islet cells compared with MET. At the subcellular level, addition of CoQ10 to MET improved the average mitochondrial area and insulin granule number.

CONCLUSION

Addition of CoQ10 to MET has a beneficial effect on SRL-induced DM compared to MET alone.

Effect of Conversion to CTLA4Ig on Tacrolimus-Induced Diabetic Rats

BACKGROUND

The effect of conversion to cytotoxic T lymphocyte-associated protein 4 immunoglobulin (CTLA4Ig) treatment on tacrolimus (TAC)-induced renal dysfunction is well known, but its effect on TAC-induced diabetes mellitus (DM) is still undetermined. In the present study, we tested the diabetogenicity of CTLA4Ig and evaluated the effect of conversion to CTLA4Ig treatment on TAC-induced diabetic rats.

METHODS

We tested diabetogenicity of CTLA4Ig by escalating doses (0.25, 0.5, 1, 2, and 4 mg/kg weekly) for 4 weeks. In the conversion study, we administered TAC (1.5 mg/kg) for 3 weeks and confirmed TAC-induced DM by intraperitoneal glucose tolerance test. Thereafter, TAC administration was continued, withdrawn, or replaced by CTLA4Ig treatment (1 or 2 mg/kg) for additional 3 weeks. The effect of CTLA4Ig on TAC-induced DM in vivo and in vitro was evaluated by assessing pancreatic islet function, histopathology, oxidative stress, apoptosis, and macrophage infiltration.

RESULTS

Intraperitoneal glucose tolerance test in the CTLA4Ig groups did not differ from the control group. In addition, plasma insulin level, glucose-induced insulin secretion, and islet viability were not different between the CTLA4Ig and control groups. In the conversion study, TAC withdrawal ameliorated pancreatic islet dysfunction compared with the TAC group, and conversion to CTLA4Ig further improved pancreatic islet function compared with the TAC withdrawal group. TAC-induced oxidative stress, apoptotic cell death, and infiltration of macrophages decreased with TAC withdrawal, and CTLA4Ig conversion further reduced those values. In the in vitro study, CTLA4Ig decreased TAC-induced pancreatic islet cell death and reactive oxygen species production.

CONCLUSIONS

CTLA4Ig was not diabetogenic, and conversion to CTLA4Ig reduced TAC-induced pancreatic islet injury.

Expression of brain-derived neurotrophic factor in kidneys from normal and cyclosporine-treated rats

BACKGROUND

Accumulating evidence suggests that a decrease in brain-derived neurotrophic factor (BDNF) level induces a variety of psychiatric and neurological disorders. However, the expression and role of BDNF in the kidney have not been explored. The present study examined the expression of BDNF and tropomyosin-related kinase (Trk) receptors in an experimental model of chronic cyclosporine A (CsA) nephropathy.

METHODS

Sprague-Dawley rats on a salt-deplete diet were treated daily for four weeks with vehicle or CsA. Urine profiles, apoptotic cell death, oxidative stress (8-hydroxy-2'-deoxyguanosine, 8-OHdG), and expression of BDNF and Trk receptors (TrkB and TrkC) were compared between groups. The impact of vasopressin infusion on the urine-concentrating ability was examined by measuring the expression of aquaporin-2 (AQP-2) and BDNF and urine profiles in normal and CsA-treated rats.

RESULTS

Compared with the vehicle-treated rats, rats given CsA had enhanced urine volume and declined urine osmolality. Immunohistochemistry and immunoblotting showed that BDNF and Trk receptors were constitutively expressed in kidneys from vehicle-treated rats. This was confirmed by double immunofluorescent staining for Na-K-ATPase-α1, AQP-1, and AQP-2. By contrast, the expression of these factors decreased in kidneys from CsA-treated rats (BDNF: 51.1 ± 19.5% vs. 102.0 ± 30.3%, p < 0.01). Downregulation of BDNF was accompanied by impairment of urine osmolality, and this was reversed by exogenous infusion of vasopressin. Notably, the number of TUNEL-positive cells correlated negatively with BDNF expression and positively with urinary 8-OHdG excretion.

CONCLUSIONS

BDNF is expressed in the collecting duct of the kidney and may be associated with urine-concentrating ability in an experimental model of chronic CsA-induced nephropathy. Our study provides a new avenue for further investigation of chronic CsA nephropathy.

Ginseng extract reduces tacrolimus-induced oxidative stress by modulating autophagy in pancreatic beta cells

We previously reported that long-term treatment with a calcineurin inhibitor impairs autophagy process in pancreatic beta cells. This study investigated the effect of Korean red ginseng extract (KRGE) on autophagy modulated by oxidative stress. In mice with tacrolimus (Tac)-induced diabetes mellitus, KRGE alleviated islet dysfunction and decreased oxidative stress and autophagic vacuoles. In vitro, KRGE decreased autophagosome formation and attenuated lysosomal degradation, accompanied by improved beta cell viability and insulin secretion. Addition of 3-methyladenine (3-MA), an inhibitor of autophagosomes, to KRGE further improved cell viability and insulin secretion, and bafilomycin A (BA), an inhibitor of lysosomal function, reduced the effects of KRGE. At the subcellular level, Tac caused mitochondrial dysfunction (impaired mitochondrial oxygen consumption, ATP production, and increased reactive oxygen species production). But KRGE improved these parameters. The effect of KRGE on mitochondrial function enhanced by 3-MA but decreased by BA, suggesting a causal relationship between KRGE effect and autophagy modulation in Tac-induced mitochondrial dysfunction. These findings indicate that KRGE modulates autophagy favorably by reducing Tac-induced oxidative stress, and this effect is closely associated with improvement of mitochondrial function.

Role of alpha-lipoic acid in ameliorating Cyclosporine A-induced pancreatic injury in albino rats: A structural, ultrastructural, and morphometric study

The aim of this study was to investigate the effectiveness of alpha-lipoic acid (α-LA) against cyclosporine A (CsA)-induced pancreatic toxicity in rats. Thirty-two male albino rats were divided into four equal groups. Group I treated orally (per os, p.o.) with vehicles and served as control; Group II received α-LA (100 mg/kg b.w. /day, p.o.) for 21 days; Group III received CsA (25 mg/kg b.w./day, p.o.) for 21 days; and Group IV received α-LA 1 hr before oral treatment by CsA for 21 days. Histological examination of the pancreas of CsA-treated rats showed marked changes represented by wide interlobular septae that contained congested blood vessels, cytoplasmic vacuolation of some acinar cells, and distortion of the other cells. Most of the islets of Langerhans showed vacuolation, degenerative changes, and loss of uniform cellular distribution. Some of the islets appeared shrunken with few cells. In the CsA group, the immunohistochemical and morphometric study demonstrated a decrease in the number of insulin-secreting β-cells and also a reduction in islet diameters, with statistically significant difference (p < 0.001 and p = 0.004), respectively, compared with the control group. Ultrastructure of the exocrine and endocrine pancreatic cells of the CsA-treated group confirmed the light microscopic observation and showed dilated rough endoplasmic reticulum, decreased zymogen and secretory granules, damaged mitochondria, and abnormal nuclei. However, α-LA administration simultaneously with CsA resulted in some sort of regression of the previously mentioned effects.

CONCLUSION

α-LA attenuated CsA-induced structural and ultrastructural changes in pancreatic cells, which were nearly reverted to their normal structure.

Effects of addition of a dipeptidyl peptidase IV inhibitor to metformin on sirolimus-induced diabetes mellitus

The guideline for the management of new-onset diabetes after transplantation recommends metformin (MET) as a first-line drug, and addition of a second-line drug is needed to better control of hyperglycemia. We tested the effect of addition of a dipeptidyl peptidase IV (DPP IV) inhibitor to MET on sirolimus (SRL)-induced diabetes mellitus (DM). In animal model of SRL-induced DM, MET treatment improved pancreatic islet function (blood glucose level and insulin secretion) and attenuated oxidative stress and apoptotic cell death. Addition of a DPP IV inhibitor to MET improved these parameters more than MET alone. An in vitro study showed that SRL treatment increased pancreas beta cell death and production of reactive oxygen species (ROS), and pretreatment of ROS inhibitor, or p38MAPK inhibitor effectively decreased SRL-induced islet cell death. Exendin-4 (EXD), a substrate of DPP IV or MET significantly improved cell viability and decreased ROS production compared with SRL treatment, and combined treatment with the 2 drugs improved both parameters. At the subcellular level, impaired mitochondrial respiration by SRL were partially improved by MET or EXD and much improved further after addition of EXD to MET. Our data suggest that addition of a DPP IV inhibitor to MET decreases SRL-induced oxidative stress and improves mitochondrial respiration. This finding provides a rationale for the combined use of a DPP IV inhibitor and MET in treating SRL-induced DM.

Implications of red Panax ginseng in oxidative stress associated chronic diseases

The steaming process of Panax ginseng has been reported to increase its major known bioactive components, ginsenosides, and, therefore, its biological properties as compared to regular Panax ginseng. Biological functions of red Panax ginseng attenuating pro-oxidant environments associated with chronic diseases are of particular interest, since oxidative stress can be a key contributor to the pathogenesis of chronic diseases. Additionally, proper utilization of various biomarkers for evaluating antioxidant activities in natural products, such as ginseng, can also be important to providing validity to their activities. Thus, studies on the effects of red ginseng against various diseases as determined in cell lines, animal models, and humans were reviewed, along with applied biomarkers for verifying such effects. Limitations and future considerations of studying red ginseng were been discussed. Although further clinical studies are warranted, red ginseng appears to be beneficial for attenuating disease-associated symptoms via its antioxidant activities, as well as for preventing oxidative stress-associated chronic diseases.

Black Ginseng Extract Counteracts Streptozotocin-Induced Diabetes in Mice

Black ginseng, a new type of processed ginseng that has a unique ginsenoside profile, has been shown to display potent pharmacological activities in in vitro and in vivo models. Although red ginseng is considered beneficial for the prevention of diabetes, the relationship between black ginseng and diabetes is unknown. Therefore, this study was designed to evaluate the anti-diabetic potential of black ginseng extract (BGE) in streptozotocin (STZ)-induced insulin-deficient diabetic mice, in comparison with red ginseng extract (RGE). HPLC analyses showed that BGE has a different ginsenoside composition to RGE; BGE contains Rg5 and compound k as the major ginsenosides. BGE at 200 mg/kg reduced hyperglycemia, increased the insulin/glucose ratio and improved islet architecture and β-cell function in STZ-treated mice. The inhibition of β-cell apoptosis by BGE was associated with suppression of the cytokine-induced nuclear factor-κB-mediated signaling pathway in the pancreas. Moreover, these anti-diabetic effects of BGE were more potent than those of RGE. Collectively, our data indicate that BGE, in part by suppressing cytokine-induced apoptotic signaling, protects β-cells from oxidative injury and counteracts diabetes in mice.

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.

Inhibition of dipeptidyl peptidase IV protects tacrolimus-induced kidney injury

Accumulating evidence shows that a gut-released hormone, the glucagon-like peptide-1 (GLP-1), has not only a glucose-lowering effect but also a renoprotective effect against kidney injury. In this study, we investigated whether a dipeptidyl peptidase (DPP) IV inhibitor has a protective effect against tacrolimus-induced renal injury. Rats were treated with tacrolimus (1.5 mg/kg, subcutaneously) and the DPP IV inhibitor MK0626 (10 or 20 mg/kg, oral gavage) for 4 weeks. MK0626 treatment attenuated tacrolimus-induced renal dysfunction, tubulointerstitial fibrosis, and arteriolopathy. Moreover, these improvements were accompanied by a reduction in oxidative stress and apoptosis. MK0626 treatment increased the blood level of GLP-1 and the level of its receptor in tissue sections but did not alter the levels of other DPP IV substrates, such as neuropeptide Y and the stromal cell-derived factor-1. These data suggest that DPP IV inhibition has an important role in the renoprotection against tacrolimus-induced nephrotoxicity via antioxidative and antiapoptotic effects and preservation of the GLP-1 system.

Dipeptidyl peptidase IV inhibitor MK-0626 attenuates pancreatic islet injury in tacrolimus-induced diabetic rats

Background

Tacrolimus (TAC)-induced pancreatic islet injury is one of the important causes of new-onset diabetes in transplant recipients. This study was performed to evaluate whether a dipeptidyl peptidase IV (DPP IV) inhibitor is effective in improving TAC-induced diabetes mellitus by reducing pancreatic islet injury.

Methods

Rats were treated with TAC (1.5 mg/kg, subcutaneously) and the DPP IV inhibitor MK-0626 (10 or 20 mg/kg, oral gavage) for 4 weeks. The effect of MK-0626 on TAC-induced diabetes was evaluated by assessing pancreatic islet function, histopathology. TAC-induced incretin dysfunction was also examined based on active glucagon-like peptide-1 (GLP-1) levels in the serum after glucose loading. The protective effect of MK-0626 was evaluated by measuring markers of oxidative stress, oxidative resistance, and apoptosis. To determine whether enhanced GLP-1 signaling is associated with these protective effects, we measured the expression of the GLP-1 receptor (GLP-1R) and the effect of the GLP-1 analog exendin-4 on cell viability and oxidative stress in isolated islets.

Results

MK-0626 treatment attenuated TAC-induced pancreatic islet dysfunction and islet morphology. TAC treatment led to a defect in active GLP-1 secretion; however, MK-0626 reversed these effects. TAC treatment increased the level of 8-hydroxy-2′-deoxyguanosine (8-OHdG), the number of apoptotic death, and the level of active caspase-3, and decreased the level of manganese superoxide dismutase and heme oxygenase-1; MK-0626 treatment reversed these changes. MK-0626 treatment restored the expression of GLP-1R, and direct administration of exendin-4 to isolated islets reduced TAC-induced cell death and 8-OHdG expression.

Conclusions

The DPP IV inhibitor MK-0626wasan effective antidiabetic agent that exerted antioxidative and antiapoptotic effects via enhanced GLP-1 signaling in TAC-induced diabetics.