Expression of GFAP, β-tubulin Ⅲ and synaptophsin and intervention effects of chondroitin sulfate in brain of rats with chronic fluorosis / 中华地方病学杂志

ABSTRACT

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.