ABSTRACT
Background Fluorine accumulates in the brain tissue after long-term excessive intake and subsequently cause nerve damage and decline of learning and memory ability. Receptor of advanced glycation end-products (RAGE)/p38 mitogen-activated protein kinase (p38MAPK)/nuclear factor kappa-B (NF-κB) signaling pathway is considered to be involved in the associated mechanism. Objective To study the changes of RAGE/ p38MAPK/ NF-κB signaling pathway in rats with subchronic fluorosis, and to explore the protective effects of extract of Ginkgo biloba 761 (EGb761) and RAGE antagonist (FPS-ZM1) on neuromemory ability. Methods Ninety male clean SD rats were divided into 9 groups with 10 rats in each group. The modeling period was 6 months. Control group (C group): free drinking tap water (fluoride content <0.5 mg·L−1), low- and high-dose fluoride groups (LF group, HF group): free drinking tap water with 10 or 50 mg·L−1 fluoride; intervention group of Ginkgo biloba extract (CE, LFE, and HFE groups): on the basis of the C group, LF group, and HF group, 100 mg·kg−1·d−1 EGb761 was given daily via intragastric administration; FPS-ZM1 intervention groups (CF, LFF, and HFF groups): 7 d before the end of modeling, 1 mg·kg−1·d−1 FPS-ZM1 was injected intraperitoneally daily on the basis of the C group, LF group, and HF group. The contents of fluoride in brain and blood of each group were detected. The learning and memory ability was tested by water maze experiment. The histopathologic changes of the hippocampus were detected by Nissl staining. The protein expression levels of RAGE and its ligand high mobility group protein B1 (HMGB1), NF-κB, p38MAPK, phospho-p38MAPK (p-p38MAPK), interleukin-6 (IL-6), and tumour necrosis factor-α (TNF-α) in brain tissue were detected by Western blotting. The mRNA expression levels of RAGE, HMGB1, and p38MAPK were detected by quantitative real-time PCR. Results Compared with the C group, the contents of blood fluoride and brain fluoride in the LF and the HF groups were increased (P<0.05). The results of the water maze experiment showed that, compared with the C group, the escape latency time of the LF group and the HF group was longer and the crossing times were reduced; compared with the HF group, the escape latency time of the HFE group and the HFF group was shortened, and the crossing times were increased (P<0.05). The Nissl staining results showed that the number of Nissl body in the HF group decreased compared with the C group; compared with the HF group, the number of Nissl body in the HFE group and the HFF group increased. The Western blotting results showed that compared with the relative protein expression levels of RAGE, HMGB1, NF-κB, p38MAPK, p-p38MAPK, IL-6, and TNF-α in the C group , the levels of above indicators in the HF group and the levels of RAGE, HMGB1, NF-κB, p-p38MAPK, and IL-6 in the LF group were up-regulated (P<0.05); compared with the HF group, the levels of above indicators in the HFE group and the HFF group were all down-regulated (P<0.05); compared with the relative protein expression levels of RAGE and HMGB1 in the LF group, the levels in the LFE group and the LFF group were all down-regulated (P<0.05). The quantitative real-time PCR results showed that compared with the C group, the mRNA expression levels of RAGE and HMGB1 in the LF group and the HF group were up-regulated; compared with the LF group, the mRNA expression levels of RAGE in the LFE group and the LFF group were down-regulated ; compared with the HF group, the mRNA expression levels of RAGE and HMGB1 in the HFE group and the HFF group were down-regulated (P<0.05). Conclusion The central nervous system injury caused by subchronic fluorosis may be related to the activation of RAGE/p38-MAPK/NF-κB signaling pathway, which can impair the learning and memory ability of rats, while EGb761 and FPS-ZM1 may have certain protective effects on the nerve injury.
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Objective To study the impairment and the expression of receptor of advanced glycation endproduct (RAGE) in cultured rat glomerular mesangial cells ( GMC ) induced by constant and intermittent high glucose, and to investigate the pathogenesis of diabetic nephropathy. Methods After being cultured under constant and intermittent high glucose with different concentrations for 24 and 48 hours, the morphological changes of rat mesangial cells were observed, the proliferation of GMC was detected by MTT assay, the activity of superoxide dismutase (SOD)and the level of malondialdehyde (MDA)in supernatant were measured by spectrophotometer,and the expressions of RAGE mRNA were evaluated by RT-PCR. Results ( 1 ) Compared with the control group,the cellular morphology was changed in case of constant and intermittent high glucose. The damage of GMC with intermittent high glucose concentrations was more serious. (2)The activity of SOD was decreased and the level of MDA was raised in case of intermittent high glucose concentrations compared with the constant high glucose concentrations (P＜0.05). (3)The expression of RAGE mRNA with intermittent high glucose concentrations was significantly higher than that with constant high glucose concentrations ( P＜0. 01 ). Conclusions The damaging effects and increased expression of RAGE in cultured rat GMC induced by blood glucose fluctuation was much worse than that with constant high glucose. The blood glucose fluctuation may be one of the causes that induce diabetic nephropathy.
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Objective:To study the expression and clinical significance of receptor for advanced glycation end products (RAGE) in laryngeal squamous cell carcinoma (LSCC).Method:Immunohistochemical staining was used to detect the expressions of RAGE protein and semiquantitative method of reverse transcriptase polymerase chain reaction (RT-PCR) was used to analyze the expression level of RAGE mRNA in LSCC tissues and laryngeal normal tissues of 37 cases, respectively.Result:The mRNA and protein expression of RAGE was significantly higher in LSCC than that in normal laryngeal tissues(P0.05).Conclusion:The expression levels of RAGE were significantly higher in LSCC than these in laryngeal normal tissues, RAGE is involved in differentiation of LSCC.
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Objective To study the effects of the interaction of advanced glycation end products (AGEs) and the receptor of AGEs (RAGE) on apoptosis of mice podocytes. Methods Podocytes were exposed to soluble AGEs such as bovine serum albumin (BSA), carboxymethyl-lysin (CML)-BSA, AGE-BSA and matrix-bound AGEs (AGE-modified collagen Ⅳ ), and to different concentrations of AGE, such as 10 mg/L, 50 mg/L, 100 mg/L. Apoptosis was assessed by TUNEL staining. Fluorescence-activated cell sorting (FACS) was used for the quantification of apoptotic andnecrotic podocytes after Annexin V-fluorescein isothiocyanate (FITC) and propidium iodide (PI) labeling. Apoptosis was described as the ratio of apoptotic cells to the total number cells under the high-power field, siRNA was transfected into podocytes through combining Dharmacon on Targetplus SMART pool siRNA reagents and Amaxa RNAi nucleofection kit. Results The apoptosis rate was higher in podoeytes exposed to either CML-BSA or AGE-BSA than that exposed to BSA. There was a two- to three-fold increase in apoptosis when podocytes were cultured in AGE-modified collagen Ⅳ as compared with native collagen Ⅳ. The apoptotic response of podocytes to AGE-BSA exposure occurred in a dose-dependent manner. Podocyte necrosis occurred only at the highest concentration of AGE-BSA(100 mg/L). AGE-BSA failed to induce apoptosis in podocytes transfected with RAGE siRNA. RAGE-specific gene knockdown did not significantly reduce the apoptosis of podocytes cultured in AGE-modified collagen IV. Conclusions The AGE-RAGE interaction plays a major role in the apoptosis of podocytes triggered by soluble AGEs, but not by matrix-bound AGEs. Reduction of AGE burden and RAGE expression may be important therapeutic approaches to prevent the progression of kidney disease.
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BACKGROUND AND OBJECTIVES: Connective tissue growth factor (CTGF) is a profibrotic cytokine, which may play an important role in the development of diabetic cardiovascular complications. ACE inhibition significantly prevents cardiovascular events in diabetics, although the mechanism remains obscure. The purpose of this study was to explore the effect of ACE inhibitors on the expression of CTGF and oxidative stress in the diabetic heart, and determine the effects of long term treatment with ACE inhibitors on diabetic cardiomyopathy. MATERIALS AND METHODS: Thirty OLETF (Otsuka Long Evans Tokushima Fatty) diabetic and thirty LETO (Long Evans Tokushima Otsuka) nondiabetic control rats were randomized into four groups for 24 weeks of treatment with either ramipril (5 mg/kg/day, n=15, each groups) or saline (n=15, each groups). RESULTS: The OLETF diabetic rats had prominent perivascular fibrosis, as shown by picrosirius red stains, compared to the LETO nondiabetic rats. ACE inhibition significantly prevented perivascular fibrosis in OLETF rats (p<0.01). Immunohistochemical stains were used to detect proteins for the receptors of advanced glycation end products (RAGE), CTGF, collagen III and nitrotyrosine. Although there were no significant differences in the myocardiac collagen contents, as found by measuring the hydroxyproline concentration among the four groups, the OLFTF diabetic rats had significantly increased cardiac CTGF and collagen III protein expression compared with the nondiabetic rats. The ACE inhibitor attenuated the increases in RAGE (-50.3%; p<0.01), CTGF (-37.5%; p<0.01) and collagen III (-52.3%; p<0.01) expression in the diabetic heart microvascular area. The OLFTF rats showed marked an increment in cardiac nitrotyrosine, a marker of protein oxidation. Ramipril also inhibited the expression of cardiac nitrotyrosine (-78.3%; p<0.01). CONCLUSION: The present study shows a possible role of RAGE/nitrotyrosine/CTGF in the diabetic cardiomyopathy of OLETF rats. The long term treatment of high dose ACE inhibitors may have beneficial effects on the diabetic heart through both antioxidant and antifibrotic mechanisms.