Yao-Wu Liu

Ginsenoside Re attenuates diabetes-associated cognitive deficits in rats.

OBJECTIVE This study was designed to investigate the effect of ginsenoside Re (Re) on cognitive functions, oxidative stress and inflammation in streptozotocin-induced diabetic rats. RESEARCH DESIGN AND METHOD Diabetic rats were treated with Re (40mg/kg) for 8weeks, blood glucose and body weight were measured monthly and weekly, respectively. Cognitive performances were evaluated with Morris water maze. Brain was obtained for measurements of TNF-α and malondialdehyde (MDA) contents in both temporal cortex and hippocampus, blood was collected for assays of TNF-α, MDA and reduced glutathione (GSH) levels. RESULTS Learning and memory abilities were significantly (both P<0.01) impaired in diabetic rats, accompanied by the marked (all P<0.01) elevations of TNF-α and MDA levels in temporal cortex and hippocampus. Increment of MDA and decrement of GSH in serum also occurred with significant differences (both P<0.01). Chronic treatment with Re markedly (P<0.05) improved the cognition of diabetic rats, evidenced by the decreased escape latency and the increased percentage of time spent in the target quadrant. Furthermore, Re treatment remarkably (P<0.05) reduced the levels of TNF-α and MDA in both brain areas of diabetic rats. Decline of MDA level and elevation of GSH level in serum were also seen in Re-treated diabetic rats, coupled with decrease in serum glucose level, all with statistically significant differences. CONCLUSIONS Our findings firstly provide the first evidence that ginsenoside Re can remarkably attenuate diabetes-associated cognitive decline, secondly confirm the involvement of oxidative stress and inflammation in the development of cognitive impairment caused by diabetes, finally point toward the potential of ginsenoside Re as an adjuvant therapy to conventional anti-hyperglycemic regimens as well as diabetes-associated cognitive decline.

The Akt-FoxO3a-manganese superoxide dismutase pathway is involved in the regulation of oxidative stress in diabetic nephropathy.

•  What is the central question of this study? Oxidative stress is known to play an important role in the development and progression of diabetic nephropathy. However, the mechanism of overproduction of reactive oxygen species (ROS) in high‐glucose conditions is not completely clear. •  What is the main finding and its importance? We demonstrated that high‐glucose concentrations induced excessive production of ROS and stimulated the phosphoinositide 3‐kinase–Akt–FoxO3a signalling pathway via the upregulation of transforming growth factor‐β1, resulting in phosphorylation and inactivation of FoxO3a and a reduction in the expression of its target gene, FoxO3a‐dependent manganese superoxide dismutase, and then further excessive production of ROS.

Total saponins from Rhizoma Anemarrhenae ameliorate diabetes-associated cognitive decline in rats: Involvement of amyloid-beta decrease in brain

ETHNOPHARMACOLOGICAL RELEVANCE As a well-known Chinese Materia Medica Rhizoma Anemarrhenae has multiple pharmacological activities including antipyretic, anti-inflammatory, anti-diabetic actions, etc. This study was designed to investigate effects of total saponins from Rhizoma Anemarrhenae (TS) on diabetes-associated cognitive decline in rats and influence on amyloid-beta (Aβ) levels in brain and inflammation. MATERIALS AND METHODS Diabetic rats induced by intraperitoneal administration of streptozotocin, were randomized into two groups: diabetes and TS-treated diabetes. Blood glucose and body weight were measured monthly and weekly, respectively. After seven weeks, cognitive performances were evaluated with Morris water maze. Then, brain was obtained for assay of Aβ and TNF-α levels, and blood was collected for TNF-α assay. RESULTS Aβ(1-40), Aβ(1-42) and TNF-α levels were dramatically (all P<0.01) increased both in temporal cortex and hippocampus of diabetic rats, coupled with impairment of cognition, compared with those of the control. Chronic TS (200mg/kg) treatment markedly (P<0.05) improved the learning ability of diabetic rats, and significantly (all P<0.05) reduced Aβ(1-40), Aβ(1-42) and TNF-α levels in cortex as well as Aβ(1-40) level in hippocampus, whereas showed a decreased tendency for Aβ(1-42) and TNF-α levels in hippocampus. Moreover, eight-week treatment with TS remarkably (P<0.05) inhibited the elevation of TNF-α level in serum of diabetic rats, and significantly (both P<0.01) decrease the fasting blood glucose level and increase the body weight of diabectic rats. CONCLUSION Our findings demonstrate that diabetes-associated cognitive decline is, at least in part, due to brain Aβ accumulation in diabetic condition, and efficacy of TS to diabetes-associated cognitive decline in rats is a sum of reduction of Aβ accumulation and inflammation in brain as well as attenuation of major symptoms of diabetes.

Up-regulation of glyoxalase 1 by mangiferin prevents diabetic nephropathy progression in streptozotocin-induced diabetic rats.

Advanced glycation endproducts (AGEs) and its precursor methylglyoxal are associated with diabetic nephropathy (DN). Mangiferin has many beneficial biological activities, including anti-inflammatory, anti-oxidative and anti-diabetic effects. We investigated the effect of mangiferin on DN and its potential mechanism associated with glyoxalase 1 (Glo-1), a detoxifying enzyme of methylglyoxal, in streptozotocin-induced rat model of DN. Diabetic rats were treated orally with mangiferin (15, 30, and 60 mg/kg) or distilled water for 9 weeks. Kidney tissues were collected for morphologic observation and the determination of associated biochemical parameters. The cultured mesangial cells were used to measure the activity of Glo-1 in vitro. Chronic treatment with mangiferin significantly ameliorated renal dysfunction in diabetic rats, as evidenced by decreases in albuminuria, blood urea nitrogen, kidney weight index, periodic acid-schiff stain positive mesangial matrix area, glomerular extracellular matrix expansion and accumulation, and glomerular basement membrane thickness. Meanwhile, mangiferin treatment caused substantial increases in the enzymatic activity of Glo-1 in vivo and in vitro, and protein and mRNA expression of Glo-1, reduced levels of AGEs and the protein and mRNA expression of their receptor (RAGE) in the renal cortex of diabetic rats. Moreover, mangiferin significantly attenuated oxidative stress damage as reflected by the lowered malondialdehyde and the increased glutathione levels in the kidney of diabetic rats. However, mangiferin did not affect the blood glucose and body weight of diabetic rats. Therefore, mangiferin can remarkably ameliorate DN in rats through inhibiting the AGEs/RAGE aix and oxidative stress damage, and Glo-1 may be a target for mangiferin action.

Over-production of nitric oxide by oxidative stress-induced activation of the TGF-β1/PI3K/Akt pathway in mesangial cells cultured in high glucose.

Aim:To investigate whether NO over-production in rat mesangial cells cultured in high glucose (HG) is related to activation of the TGF-β1/PI3K/Akt pathway.Methods:Rat mesangial cells line (HBZY-1) was exposed to HG (24.44 mmol/L) or H2O2 (10 μmol/L) for 16 h. NO release was quantified using the Griess assay. The TGF-β1 level was measured using ELISA. The protein expression of p-Akt, t-Akt, Bim, and iNOS was examined by Western blotting. The mRNA levels of TGF-β1 and Bim were measured using RT-PCR. The cell proliferation rate was estimated using a BrdU incorporation assay.Results:Treatment of the cells with HG, H2O2, or TGF-β1 (5 ng/mL) significantly increased the NO level that was substantially inhibited by co-treatment with the NADPH oxidase inhibitor diphenylene iodonium (DPI), TGF-β1 inhibitor SB431542, or PI3K inhibitor LY294002. Both HG and H2O2 significantly increased the protein and mRNA levels of TGF-β1 in the cells, and HG-induced increases of TGF-β1 protein and mRNA were blocked by co-treatment with DPI. Furthermore, the treatment with HG or H2O2 significantly increased the expression of phosphorylated Akt and iNOS and cell proliferation rate, which was blocked by co-treatment with DPI, SB431542, or LY294002. Moreover, the treatment with HG or H2O2 significantly inhibited Bim protein and mRNA expression, which was reversed by co-treatment with DPI, SB431542, or LY294002.Conclusion:The results demonstrate that high glucose causes oxidative stress and NO over-production in rat mesangial cells in vitro via decreasing Bim and increasing iNOS, which are at least partially mediated by the TGF-β1/PI3K/Akt pathway.

Mangiferin Attenuates Renal Fibrosis Through Down-Regulation of Osteopontin in Diabetic Rats

This study was designed to investigate the effects of mangiferin on renal fibrosis, osteopontin production, and inflammation in the kidney of diabetic rats. Diabetes was induced through the single administration of streptozotocin (55 mg/kg, i.p.). Diabetic rats were treated with mangiferin (15, 30, and 60 mg/kg/day, i.g.) for 9 weeks. The kidney was fixed in 10% formalin for glomerulus fibrosis examination using Masson trichrome staining. Kidney and blood were obtained for assays of the associated biochemical parameters. Chronic mangiferin treatment prevented renal glomerulus fibrosis evidenced by decreases in Mason‐stained positive area of glomeruli, protein expression of type IV collagen, and α‐smooth muscle actin in the kidney of diabetic rats, in comparison with decreases in mRNA and protein expression of osteopontin as well as protein expression of cyclooxygenase 2 and NF‐кB p65 subunit in the renal cortex of diabetic rats. Moreover, mangiferin reduced the levels of interleukin 1β in both the serum and the kidney of diabetic rats. Our findings demonstrate that mangiferin prevents the renal glomerulus fibrosis of diabetic rats, which is realized through the suppression of osteopontin overproduction and inflammation likely via inactivation of NF‐кB. Copyright

Ibuprofen Attenuates Cardiac Fibrosis in Streptozotocin-Induced Diabetic Rats

Objective: To investigate the effects of ibuprofen on cardiac fibrosis in a rat model of type 1 diabetes. Methods: The diabetic model was established by injecting streptozotocin into the rats. Then, ibuprofen or pioglitazone was given by gavage for 8 weeks. The cardiac fibrosis was assessed, and the major components of the renin-angiotensin system, the transforming growth factor β1 (TGF-β1) and the mammalian target of rapamycin (mTOR), were evaluated by histopathological, immunohistochemical, Western blot analysis or ELISA assay. Results: Obvious cardiac fibrosis was detected in the diabetic group and was alleviated by ibuprofen treatment. Angiotensin-converting enzyme (ACE), angiotensin (Ang) II and AngII type 1 receptor (AT1-R) levels were higher, and ACE2, Ang(1-7) and Mas receptor (Mas-R) were lower in the diabetic group. The ratio of ACE to ACE2 was raised in the diabetic group. All these changes were ameliorated by ibuprofen. TGF-β1 and mTOR were raised in the hearts of the diabetic group and were attenuated by ibuprofen treatment. There was no significant difference between the ibuprofen and the pioglitazone groups. Conclusion: Ibuprofen could ameliorate the cardiac fibrosis in diabetic rats by reduction of the ACE/AngII/AT1-R axis and enhancement of the ACE2/Ang(1-7)/Mas-R axis, leading to a decrease in TGF-β1 and mTOR.

Quantitative-profiling of neurotransmitter abnormalities in the disease progression of experimental diabetic encephalopathy rat

Diabetic encephalopathy (DE) is one of the most prevalent chronic complications of diabetes mellitus (DM), with neither effective prevention nor proven therapeutic regimen. This study aims to uncover the potential dysregulation pattern of the neurotransmitters in a rat model of streptozotocin (STZ)-induced experimental DE. For that purpose, male Sprague-Dawley (SD) rats were treated with a single intraperitoneal injection of STZ. Cognitive performance was detected with the Morris water maze (MWM) test. Serum, cerebrospinal fluid (CSF), and brain tissues were collected to measure the levels of neurotransmitters. Compared with the control rats, the acetylcholine (ACh) levels in serum, CSF, hippocampus, and cortex were all significantly down-regulated as early as 6 weeks in the STZ treatment group. In contrast, the glutamate (Glu) levels were decreased in CSF and the hippocampus, but unaffected in the serum and cortex of STZ-treated rats. As for γ-aminobutyric acid (GABA), it was down-regulated in serum, but up-regulated in CSF, hippocampus, and the cortex in the STZ-treated group. The mRNA expressions of neurotransmitter-related rate limiting enzymes (including AChE, GAD1, and GAD2) and pro-inflammatory cytokines (including IL-1β and TNF-α) were all increased in the DE rats. Our data suggest that DM induces isoform-dependent and tissue-specific neurotransmitter abnormalities, and that neuroinflammation may underlay the nervous system dysfunction observed in the progression of DE.

A novel CRAd in combination with cisplatin enhanced the antitumor efficacy in ovarian cancer.

Objectives The aim of this study was to investigate the combined effects of a novel survivin promoter-based conditionally replicating adenovirus (CRAd-S.RGD) plus cis-diamminedichloroplatinum (cisplatin, CDDP) in ovarian cancer in vitro and in vivo. Methods The viability of human ovarian cancer cell line SKOV3 was determined by MTT assay following the infection with different doses of CRAd-S.RGD, either alone or in combination with CDDP. The antitumor efficacies and survival curves were evaluated at the end of the treatment regimens with the subcutaneous administration of CRAd-S.RGD, CDDP, combined therapy of CRAd-S.RGD plus CDDP, or phosphate-buffered saline in a SKOV3 xenograft animal model. Furthermore, the apoptosis rate of tumor tissues in mice was determined subsequent to the treatments. Results In vitro, the CRAd-S.RGD destroyed SKOV3 cells by oncolysis in a dose-dependent manner, and the viability of SKOV3 cells was significantly lower in the combined-therapy group than that in the individual-therapy groups. In vivo, enhanced tumor inhibition and animal survival rates were obtained in a synergistic manner with CRAd-S.RGD plus CDDP, as compared with the treatment with CRAd-S.RGD or CDDP alone. There was an increase in the apoptosis rate of the cells following the combined therapy. The results clearly demonstrated that there was a synergistic effect in the combination of CRAd-S.RGD and CDDP in increased therapeutic efficacy. Similar therapeutic efficacy could be obtained with CRAd-S.RGD plus CDDP at 2 lower doses that minimized the drug toxicity to host tissues. Conclusions The strategy of CRAd-S.RGD in combination with CDDP was a potential therapeutic modality for the therapy in ovarian cancer. Abbreviations CDDP - cisplatin, cis-diamminedichloroplatinum, CRAd - conditionally replicating adenovirus, CRAd-survivin - the survivin promoter-based conditionally replicating adenovirus, CRAd-S.RGD - CRAd–survivin-RGD4C, MOI - multiplicity of infection, PBS - phosphate-buffered saline, PI - propidium iodide