The protective effect of smilax glabra extract on advanced glycation end products-induced endothelial dysfunction in HUVECs via RAGE-ERK1/2-NF-κB pathway

Ethnopharmacological relevance

Smilax glabra Roxb. (SGR) is a traditional Chinese herb that has been used in folk for the treatment of diabetic vascular complications. Advanced glycation end products (AGEs)-induced endothelial dysfunction has been thought to be a major cause of diabetic vascular complications. The present study was conducted to investigate the protective effect of SGR extract on AGEs-induced endothelial dysfunction and its underlying mechanisms.

Materials and methods

Human umbilical vein endothelial cells (HUVECs) were exposed to 200 μg/ml AGEs to induce endothelial dysfunction. Acridine orange/ethidium bromide (AO/EB) fluorescence assay and Annexin-V/PI double-staining were performed to determine endothelium apoptosis. Dihydroethidium (DHE) fluorescence probe, SOD and MDA kits were used to evaluate oxidative stress. The effect of SGR extract on AGEs-induced TGF-beta1 expression was determined by immunocytochemistry and western blotting. Attenuations of SGR extract on receptor for AGEs (RAGE) expression, extracellular regulated protein kinases (ERK1/2) activation and NF-κB phosphorylation were determined by immunofluorescence assay and western blotting. The blockade assays for RAGE and ERK1/2 were carried out using a specific RAGE-antibody (RAGE-Ab) or a selective ERK1/2 inhibitor PD98059 in immunofluorescence assay.

Results

The pretreatment of SGR extract (0.125, 0.25 and 0.5 mg crude drug/ml) significantly attenuated AGEs-induced endothelium apoptosis, and down-regulated TGF-beta1 protein expression in HUVECs. It was also well shown that SGR extract could down-regulate dose-dependently ROS over-generation, MDA content, TGF-beta1 expression, ERK1/2 and NF-κB activation whereas increase significantly SOD activity. Furthermore, the AGEs-induced ERK1/2 activation could be attenuated by the blockade of RAGE-Ab (5 μg/ml) while the NF-κB activation was ameliorated by ERK1/2 inhibitor PD98059 (10 μM).

Conclusion

These results indicated that SGR extract could attenuate AGEs-induced endothelial dysfunction via RAGE-ERK1/2-NF-κB pathways. Our findings suggest that SGR extract may be beneficial for attenuating endothelial dysfunction in diabetic vascular complications.     

Antihyperglycemic effect of the traditional Chinese scutellaria–coptis herb couple and its main components in streptozotocin-induced diabetic rats

Ethnopharmacological relevance

Scutellaria–coptis herb couple (SC) is the main herb couple in many traditional Chinese compound formulas used for the treatment of diabetes mellitus, which has been used to treat diabetes mellitus for thousands of years in China. In this study we provide experimental evidence for the clinical use of SC in the treatment of diabetes mellitus.

Aim of the study

To confirm the anti-diabetic effect of SC extract and its main components, and to explore its mechanism from the effect on intestinal disaccharidases by in vivo and in vitro experiment.

Materials and methods

SC extract was prepared and the main components (namely berberine and baicalin) contained in the extract were assayed with high performance liquid chromatography (HPLC). And diabetic model rats were induced by intraperitoneal injection of streptozotocin (STZ). After grouped randomly, diabetic rats were administered SC extract, berberine, baicalin, berberine+baicalin, acarbose and vehicle for 33 d, respectively. Body weight, food intake, urine volume, urine sugars, fasting plasma glucose and fasting plasma insulin were monitored to evaluate the antidiabetic effects on diabetic rats. Intestinal mucosa homogenate was prepared and the activities of intestinal disaccharidases were assayed. Moreover, oral sucrose tolerance test (OSTT) was performed and the inhibitory effects of SC extract and its main components (berberine and baicalin) on the maltase and sucrase in vitro was evaluated.

Results

After the treatment of SC extract and its main components, the body weight and the fasting plasma insulin level were found to be increased while food intake, urine volume, urine sugars and fasting plasma were decreased. OSTT showed that SC extract and its main components could lower the postprandial plasma glucose level of diabetic rats. Furthermore, SC extract and its main components could inhibit the activities of intestinal disaccharidases in diabetic rats, whereas only SC extract and berberine could inhibit the activity of maltase in vitro.

Conclusions

According to our present findings, scutellaria–coptis herb couple (SC) possessed potent anti-hyperglycemic effect on STZ-induced diabetic rats. And SC extract and its main components exerted anti-hyperglycemic effect partly via inhibiting the increased activities of intestinal disaccharidases and elevating the level of plasma insulin in diabetic rats induced by STZ.     

Upregulation of PPARγ by Aegle marmelos ameliorates insulin resistance and β-cell dysfunction in high fat diet fed-streptozotocin induced type 2 diabetic rats

The global epidemic of type 2 diabetes demands the rapid evaluation of new and accessible interventions. This study investigated whether Aegle marmelos fruit aqueous extract (AMF; 250, 500 and 1000 mg/kg) improves insulin resistance, dyslipidemia and β‐cell dysfunction in high fat diet fed‐streptozotocin (HFD‐STZ)‐induced diabetic rats by modulating peroxisome proliferator‐activated receptor‐γ (PPARγ) expression. The serum levels of glucose, insulin, homeostasis model assessment of insulin resistance (HOMA‐IR), homeostasis model assessment of β‐cell function (HOMA‐B), lipid profile, TNF‐α and IL‐6 were evaluated. Further, the TBARS level and SOD activity in pancreatic tissue and PPARγ protein expression in liver were assessed. In addition, histopathological and ultrastructural studies were performed to validate the effect of AMF on β‐cells. The HFD‐STZ treated rats showed a significant increase in the serum levels of glucose, insulin, HOMA‐IR, TNF‐α, IL‐6, dyslipidemia with a concomitant decrease in HOMA‐B and PPARγ expression. Treatment with AMF for 21 days in diabetic rats positively modulated the altered parameters in a dose‐dependent manner. Furthermore, AMF prevented inflammatory changes and β‐cell damage along with a reduction in mitochondrial and endoplasmic reticulum swelling. These findings suggest that the protective effect of AMF in type 2 diabetic rats is due to the preservation of β‐cell function and insulin‐sensitivity through increased PPARγ expression. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of curcumin on rats/mice with diabetic nephropathy： a systematic review and Meta-analysis of randomized controlled trials

OBJECTIVE： To assess the renal protective effects of curcumin administration ondiabetic rats/mice.METHODS： Databases were searched electronically and conference papers searched manually for search terms to find relevant studies. Articles were assessed independently by two reviewers. Review Manager 5.1 was used fordata analysis.RESULTS： Fourteen randomized controlled experiments were included. Meta-analysis demonstrated that blood sugar levels and kidney weight to body weight ratios in the model group were higher than those in the normal group, and the curcumin group had significantly lower mesangial area to glomerular area ratios compared with the model group, and also lower levels of urinary protein,blood urea nitrogen and serum creatinine.CONCLUSION： Curcumin shows protective effects on the kidneys of rats/mice with diabetes.     

Protective effect of Icariin on the early stage of experimental diabetic nephropathy induced by streptozotocin via modulating transforming growth factor β1 and type IV collagen expression in rats

Ethnopharmacological relevance

Icariin is a major constituent of flavonoid isolated from the plant Herba epimedii, which is used as a traditional Chinese medicine to nourish the kidney and reinforce yang. Therefore, the pharmacological studied of its diabetic nephropathy effect was undertaken to validate its traditional use.

Materials and methods

Diabetes was induced in male Sprague-Dawley rats by an injection of streptozotocin (40 mg/kg i.v.). Sustained blood glucose levels (>16.7 mmol/l) were considered as diabetic and selected for experimentation. Thirty rats were randomly divided into three groups: control, diabetic, diabetic + Icariin (80 mg/kg, i.g.) administered 8 weeks from 5th to 12th week. Experiment was carried out at the beginning of 13th week. All rats were anaesthetized and then were killed to remove kidneys. Blood glucose, serum creatinine (Cr), blood urea nitrogen (BUN), the activity of superoxide dismutase (SOD), malondialdehyde (MDA) and hydroxyproline (Hyp) in the kidney tissue were measured. Glomerular morphology was observed by light microscopy. Immunohistochemistry and Western blot were employed to determine the proteins levels of TGF-β₁ and type IV collagen.

Results

The enhancement of Cr and BUN was found in model group, which was significantly attenuated by treatment with Icariin. Meanwhile, elevated MDA and Hyp levels in renal tissue as well as decreased SOD activities in renal tissue were significantly remitted by Icariin. The renal pathological changes in Icariin treatment group were ameliorated. Furthermore, the Icariin decreased the expression of TGF-β₁ and collagen IV protein.

Conclusions

Icariin can evidently relieve renal damage in rats with diabetic nephropathy induced by STZ, which might be related to modulating the expression of collagen IV and TGF-β₁ protein.     

The effect of acupuncture at Jǐngjiājǐ (颈夹脊) on the repair and regeneration of cochlear hair cells of rats with sensorineural deafness

Objective

To observe the effect of acupuncture at Jǐngjiājǐ (颈夹脊) on the repair and regeneration of cochlear hair cells of guinea pigs with sensorineural deafness.

A study on the differences of effect on mast cells and serum 5-HT in the acupoint area of “CV 4” of rats by acupuncture stimulus and thermal stimulus

Objective

To observe the influence of acupuncture stimulus and thermal stimulus on the expression of mast cells (MCs) and 5-hydroxytryptamine (5-HT) in local acupoint area of Guānyuan (关元 CV 4) and serum 5-HT in rats.

H NMR-based metabonomic analysis of the effect of optimized rhubarb aglycone on the plasma and urine metabolic fingerprints of focal cerebral ischemia–reperfusion rats

Ethnopharmacological relevance

The ischemia cerebrovascular disease is one of leading causes of death and long-term disability in modern society. Rhubarb is one of the common traditional Chinese medicine with many effects, and the main pharmacodynamic ingredients are aloe-emodin, rhein, emodin, chrysophanol and physcion. The five components are also known as rhubarb aglycone. Rhubarb aglycone has been confirmed to play a remarkable curative effect on cerebral ischemia, but the mechanism is not clear. In this study, ¹H NMR-based metabonomics approach has been used to investigate the protective effect of the optimized rhubarb aglycone on rats of cerebral ischemia–reperfusion.

Materials and methods

Male Wistar rats were divided into four groups: sham operation group, model group, Nimodipine group and the optimized rhubarb aglycone group. Based on ¹H-NMR spectra of plasma and urine, principal component analyses were performed to identify different metabolic markers and explore the changes of associated biochemical pathways. Behavior research and brain histopathology examinations were also performed.

Results

It was showed that the optimized rhubarb aglycone treatment improved neurological deficits, cerebral infarction and neuronal apoptosis. Principal component analysis scores plots demonstrated that the cluster of model rats was separated from those of sham operation group; rats of the optimized rhubarb aglycone group were classified from model group, but the optimized rhubarb aglycone group closed to the sham operation group. Optimized rhubarb aglycone regulated the associated amino acid, energy and lipid metabolisms disturbed in model rats.

Conclusion

Our results suggested that the optimized rhubarb aglycone had protective effect on rats of cerebral ischemia–reperfusion and explored the metabolic regulation mechanism. This work showed that the NMR-based metabonomics approach might be a promising approach to study mechanisms of traditional Chinese medicines.     

Anti-diabetic effects of Centratherum anthelminticum seeds methanolic fraction on pancreatic cells, β-TC6 and its alleviating role in type 2 diabetic rats

Ethnopharmacological relevance

Seeds of Centratherum anthelminticum (Asteraceae) have been popularly used in Ayurvedic medicine to treat diabetes and skin disorders. Folk medicine from Rayalaseema (Andhra Pradesh, India) reported wide spread usage in diabetes.

Aim of the study

To investigate the hypoglycemic properties and mechanism of the methanolic fraction of C. anthelminticum seeds (CAMFs) on mouse β-TC6 pancreatic cell line and streptozotocin (STZ)-induced diabetic rat models.

Materials and Methods

We investigated the crude methanolic fraction of C. anthelminticum seeds (CAMFs) on β-TC6 cell line and confirmed its effects on type 1 and type 2 diabetic rats to understand its mechanism in managing diabetes mellitus. CAMFs were initially tested on β-TC6 cells for cytotoxicity, 2-NBDG glucose uptake, insulin secretion and glucose transporter (GLUT-1, 2 and 4) protein expression. Furthermore, streptozotocin (STZ)-induced type 1 diabetic and STZ-nicotinamide-induced type 2 diabetic rats were intraperitoneally (i.p) injected or administered orally with CAMFs daily for 28 days. The effect of CAMFs on blood glucose and insulin levels was subsequently evaluated.

Results

In cell line studies, CAMFs showed non-cytotoxic effect on β-TC6 cell proliferation compared to untreated control cells at 50 μg/ml. CAMFs increased glucose uptake and insulin secretion dose-dependently by up-regulating GLUT-2 and GLUT-4 expression in these cells. Further in vivo studies on streptozotocin induced diabetic rat models revealed that CAMFs significantly reduced hyperglycemia by augmenting insulin secretion in type 2 diabetic rats. However, CAMFs displayed less significant effects on type 1 diabetic rats.

Conclusions

CAMFs demonstrated anti-diabetic potential on β-TC6 cells and type 2 diabetic rat model, plausibly through enhancing glucose uptake and insulin secretion.     

The effect of Lycium barbarum polysaccharides on the male rats׳ reproductive system and spermatogenic cell apoptosis exposed to low-dose ionizing irradiation

Ethnopharmacological relevance: Lycium barbarum, a Solanaceous defoliated shrubbery, has been used as a kind of traditional Chinese herbal medicines for thousands of years. Lycium barbarum polysaccharide (LBP) is the main bioactive component of Lycium barbarum. The aim of this study was to investigate the radioresistant effect of LBP on the damage of male rats’ reproductive system and spermatogenic cells caused by low-dose ⁶⁰Co-γ irradiation. Materials and methods: Male rats were randomly divided into 7 groups and treated with irradiation and/or LBP: normal control group, irradiation control group 1, irradiation control group 2, irradiation control group 3, LBP + irradiation group 1, LBP + irradiation group 2, and LBP + irradiation group 3. Results: It is found that mating function and testis organ coefficient in LBP + irradiation groups were significantly better than that of the corresponding irradiation control groups. LBP significantly up-regulates the expression of Bcl-2 while down-regulating the expression of Bax. And LBP also plays an important role in prevention mitochondrial membrane potential decrease. In addition, LBP can significantly reduce spermatogenic cells apoptosis. Conclusion: LBP has obvious protective effect on the male rats’ reproductive function and spermatogenic dysfunction induced by irradiation.     

The effect of mitragynine on cAMP formation and mRNA expression of mu-opioid receptors mediated by chronic morphine treatment in SK–N–SH neuroblastoma cell

Ethopharmacological relevance

Mitragynine is an indole alkaloid compound of Mitragyna speciosa (M. speciosa) Korth. (Rubiaceae). This plant is native to the southern regions of Thailand and northern regions of Malaysia and is frequently used to manage the withdrawal symptoms in both countries.

Aim of study

To investigate the effect of mitragynine after chronic morphine treatment on cyclic AMP (cAMP) level and mRNA expression of mu-opioid receptor (MOR) in human neuroblastoma SK–N–SH cell.

Method and Materials

Mitragynine was isolated from the Mitragyna speciosa plant using the acid–base extraction method. The cAMP level upon forskolin stimulation in the cells was determined using the Calbiochem^® Direct Immunoassay Kit. The mRNA expression of the MOR was carried out using quantitative RT-PCR.

Result

Cotreatment and pretreatment of morphine and mitragynine significantly reduced the production of cAMP level at a lower concentration of mitragynine while the higher concentration of this compound could lead to the development of tolerance and dependence as shown by the increase of the cAMP level production in foskolin stimulation. In MOR mRNA expression study, cotreatment of morphine with mitragynine significantly reduced the down-regulation of MOR mRNA expression as compared to morphine treatment only.

Conclusion

These finding suggest that mitragynine could possibly avoid the tolerance and dependence on chronic morphine treatment by reducing the up-regulation of cAMP level as well as reducing the down-regulation of MOR at a lower concentration of mitragynine.