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Objective:To investigate the effects of excessive fluoride exposure on astrocytes and the expression of glial fibrillary acidic protein (GFAP), in vitro and in vivo. Methods:(1) In vivo experiment: 24 SPF SD rats, half male and half female, were randomly divided into control and fluoride exposed groups according to sex and body weight, 12 rats in each group. Rats were fed with < 1 mg/L and 50 mg/L sodium fluoride solution prepared by tap water for 6 months, respectively. The expression levels of GFAP protein in rat brain tissue were measured by immunofluorescence, immunohistochemistry and Western blotting. (2) In vitro experiment: adult (6-month-old) rat cortical astrocytes were extracted and cultured in primary culture (4 mmol/L sodium fluoride solution for 24 h), and the astrocytes were identified by immunofluorescence, and GFAP mRNA and protein expression levels were detected by real-time fluorescence quantitative PCR and Western blotting, respectively, and astrocytes apoptosis and calcium ion content were detected by flow cytometry. Results:(1) In vivo experiment: the results of immunofluorescence, immunohistochemistry and Western blotting showed that the GFAP protein expression level in brain tissue of rats exposed to fluoride was higher than that of control group (0.440 ± 0.200 vs 0.250 ± 0.120, t =-5.93, P = 0.027; 0.270 ± 0.020 vs 0.240 ± 0.050, t =-4.87, P = 0.040; 1.017 ± 0.001 vs 0.486 ± 0.006, t =-52.48, P = 0.001). (2) In vitro experiment: GFAP positive cells were identified as astrocytes by immunofluorescence; GFAP mRNA expression level was higher in fluoride exposed group than that of control group by real-time fluorescence quantitative PCR (2.780 ± 0.120 vs 0.134 ± 0.005, t =-37.84, P = 0.001). The Western blotting results showed that the GFAP protein expression level was higher in fluoride exposed group than that of control group (2.76 ± 0.10 vs 1.38 ± 0.05, t =-20.44, P = 0.002). Flow cytometry results showed that the apoptosis rate of astrocytes was higher in fluoride exposed group than that of control group (%: 55.0 ± 1.0 vs 3.5 ± 0.6, t =-10.28, P = 0.009) and the calcium ion content was lower than that of control group (%: 54 ± 9 vs 72 ± 13, t = 4.64, P = 0.043). Conclusion:Excessive fluoride exposure causes increased GFAP expression in astrocytes in vitro and in vivo, promotes apoptosis, and affects calcium signaling pathways.
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Objective:To observe the expression levels of glial fibrillary acidic protein (GFAP), β-tubulin Ⅲ and synaptophsin, and explore the role of tripartite synapse in the mechanism of central nervous system (CNS) injury and the neuroprotective effect of chondroitin sulfate (CS).Methods:One month old clean grade, 48 female Sparague-Dawley rats and 48 male Sparague-Dawley rats, were randomly divided into 8 groups according to body weight (90 - 120 g) by random number table method, with 12 rats in each group, half male and half female. These rats were fed with water containing different concentrations of sodium fluoride (NaF) [ < 0.5 mg/L (control, CN), 10.0 mg/L (low dose fluoride, LF) and 50.0 mg/L (high dose fluoride, HF)]. Some rats were fed directly for 185 days (CN, LF and HF groups). In addition, rats of CN + normal saline (NS), LF + NS, HF + NS groups and LF + CS, HF + CS groups, were intraperitoneally injected with NS or 0.66 mg/kg CS for 5 consecutive days after 180 days of feeding. After the experiment, the pathological changes of hippocampal CA4 of brain tissue in each group were observed by hematoxylin eosin staining under light microscope, and the expression and distribution of GFAP, β-tubulin Ⅲ and synaptophsin in hippocampal CA4 of rats were detected by immunohistochemistry, the expression of GFAP, β-tubulin Ⅲ and synaptophsin at protein level in hippocampus of rats were detected by Western blotting.Results:Under light microscope, eosinophilic change, loss and irregular arrangement of neuron in the hippocampal CA4 were observed in LF, HF, LF + NS and HF + NS groups. The morphology of LF + CS and HF + CS groups was not significantly changed compared with CN group, but was significant changed compared with LF, HF, LF + NS and HF + NS groups. Immunohistochemical results showed that the rates of positive area of GFAP, β-tubulin Ⅲ and synaptophsin in female and male rats in LF and HF groups were significantly decreased than those in CN group ( P < 0.05); the positive area rates of female and male rats in LF + CS and HF + CS groups were higher than those in LF and HF groups, respectively ( P < 0.05). Western blotting results showed that the proten expression levels of GFAP, β-tubulin Ⅲ and synaptophsin of female and male rats in LF and HF groups (LF group: 0.90 ± 0.09, 0.82 ± 0.08, 1.43 ± 0.14, 0.92 ± 0.02, 1.21 ± 0.15, 0.87 ± 0.02, HF group: 0.58 ± 0.14, 0.73 ± 0.03, 0.63 ± 0.06, 0.67 ± 0.03, 0.87 ± 0.04, 0.70 ± 0.05) were lower than those in CN group (1.24 ± 0.08, 1.09 ± 0.10, 2.64 ± 0.30, 1.54 ± 0.09, 1.72 ± 0.10, 1.13 ± 0.06, P < 0.05). Conclusions:The tripartite synapse and extracellular matrix may take part in pathogenesis of the damages of CNS results from chronic fluorosis; CS may reduce the injury to a certain extent.
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Objective To study the mechanism of central nervous system (CNS) injury in chronic fluorosis and the neuroprotective effect of chondroitin sulfate (CS).Methods Forty-eight female Sprague-Dawley rats weighting 90-120 g were divided into 8 groups according to body weight by random number table,6 rats in each group:control group,drinking tap water freely;low dose and high dose fluoride groups,freely drinking tap water with fluoride content of 10 and 50 mg/L,respectively;control + normal saline (NS),low dose fluoride + NS,and high dose fluoride + NS groups,each group was fed for 180 d,and treated with intraperitoneal injection of 0.66 mg/kg NS for 5 d (once a day);low dose fluoride + CS and high dose fluoride + CS groups,each group was fed for 180 d,0.66 mg/kg CS was injected intraperitoneally for 5 d (once a day).All groups were fed standard nutritive animal feed for 185 d and dissected for brain tissue.The pathologic change was observed after hematoxylin-eosin (HE)staining;the expression levels of phosphorylated extracellular signal-regulated protein kinase 1/2 (phospho-Erk1/2)and glutamate receptors 1,2 (GluR1,GluR2) in the brain cortex were detected by immunohistochemistry;the protein levels of Erk1/2,phospho-Erk1/2,GluR1,and GluR2 in the brain cortex were detected by Western blotting.Results Brain cortex of all rats in the fluoride groups showed eosinophilic degeneration,loss and disordered arrangement of neurons,and the brain morphological changes in each fluoride + CS groups were significantly improved compared with those in the fluoride groups.Immunohistochemistry results showed that compared with the control group [(0.44 ± 0.09)％,(1.49 ± 0.05)％,(2.51 ± 0.54)％],the expression levels of phospho-Erk1/2 [(1.47 ±0.09)％,(1.03 ± 0.05)％],and GluR2 [(2.37 ± 0.06)％,(3.38 ± 0.12)％] in the low dose and high dose fluoride groups were increased,and the expression levels of GluR1 [(1.49 ± 0.02)％,(0.99 ± 0.19)％] were decreased (P ＜ 0.05).Western blotting results showed that compared with the control group (1.00 ± 0.12,1.76 ± 0.33),the protein levels of Erk1/2 (3.10 ± 0.76,1.99 ± 0.01) and phospho-Erk1/2 (3.27 ± 0.25,2.67 ± 0.05) in low dose and high dose fluoride groups were significantly increased (P ＜ 0.05);compared with low dose fluoride group,the protein levels of Erk1/2,and phospho-Erk1/2 (1.30 ± 0.31,2.20 ± 0.34) in low dose fluoride + CS group decreased significantly (P ＜0.05).Compared with control group (1.86 ± 0.47,1.17 ± 0.27),the protein levels of GluR1 (1.09 ± 0.26,0.61 ± 0.14) in low dose and high dose fluoride groups decreased significantly,while the protein level of GluR2 (1.99 ± 0.42,3.38 ±0.27) increased significantly (P ＜ 0.05);compared with low dose and high dose fluoride groups,the protein levels of GluR2 in low dose fluoride + CS and high dose fluoride + CS groups (1.53 ± 0.41,2.65 ± 0.32) decreased significantly (P ＜ 0.05).The protein level of phospho-Erk1/2 was negatively correlated with GluR1 protein level (r =-0.975,-0.991,P ＜ 0.05) in low dose and high dose fluoride groups,and it was positively correlated with the protein level of GluR2 (r =0.986,0.993,P ＜ 0.05).Conclusion The CNS injury caused by chronic fluorosis may be related to GluR1 and GluR2 activated Erk1/2 signaling pathway,and CS has certain protection to the injury.
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Breast cancer is one of the main cancers leading to women mortality in the world. Since the causes are still obscure, the microcalcification clusters are the primary indicators of breast cancer, and the detection is of importance to the prevention and treatment of the disease. Microcalcifications appear in the small clusters of a few pixels and as spots which are slightly brighter than their backgrounds. It becomes a challenge to detect all the microcalcifications. This paper presents an approach for detecting microcalcifications in digital mammograms employing a dual-threshold method developed from LoG edge detection. Two thresholds are proposed in our method based on two additional criterions. Experimental results show that the proposed method can locate the microcalcifications exactly in mammogram as well as restrain the contours produced by the noises.