Experimental study of cartilage lesions and COLIXA 3 protein expression in rats cartilage with chronic fluorosis

Objective To explore whether different degrees of fluorosis influence the expression of cartilage COLIXA3 protein in fluorosis model rats. Methods Forty male Wistar rats 3 to 4 weeks old were randomly divided into 5 groups according to body mass, and these rats were fed with distilled water containing sodium fluoride(NaF) of 0(control), 25, 50, 100 and 150 mg/L for 6 months, respectively, in order to establish the animal model of drinking water type fluorosis. Pathomorphologieal changes of the osseous tissues of rats were analyzed under light microscope and transmission electron microscope, and the expression of COLIXA3 protein of femur metaphysis was examined by immunohistochemistry. Results HE staining showed different degrees of femoral metaphyseal ossification of cartilage in each experimental group, bone density increased, with sclerotic lesions of skeletal fluorosis. The control group showed no abnormal cartilage. Electron microscopy showed that the experimental groups with varying degrees of cartilage cell swelling, cell matrix fades, 50 mg/L group .showed hyperplasia, and 100,150 mg/L groups were observed with organelles decreased, part of the disintegration of the cartilage cell lacunae, lmmunohistochemical staining of rat chondrocytes COLIXA3 was positive, cytoplasm with brown granules, cartilage COLIXA3 protein expression(23.3 ± 4.5, 41.2 ± 5.6, 26.4 ~ 7.5) in the 25, 50 and 100 mg/L groups enhanced. Compared to the control group (6.1 ± 3.5), the expression of 50 and 100 mg/L groups was significantly increased, and the differences were statistically significant(all P 0.05). Conclusions There has pathological changes of sclerosing skeletal fluorosis in animal model. Low-dose fluoride promotes while high-dose inhibits cartilage cell proliferation. When fluorine concentration in external environment is too high and with extended exposure to fluoride, direct toxic effects of fluoride on cartilage cells is observed. Fluorine affects and promotes the expression of COLIXA3 protein in cartilage. Low-dose fluoride can promote COLIXA3 protein expression, as the dose increases (over 100 mg/L), the effect decreases. Key words: Fluorosis, dental; Cartilage; COLIXA3 gene ; Rat