[In vivo and in vitro study on the effect of excessive fluoride on type I collagen of rats].

In order to investigate the effects of excessive fluoride on type I collagen in rat bone, rat fluorosis model is induced by giving 221 mg/L NaF in drinking water for two months. The level of serum BGP, inorganic ingredient, the content of collagen and the degree of collagen cross-linking in fluorosis rat bone are determined. Rat calvaria osteoblasts are separated by enzyme digestion. After the treatment of 0.5 and 1.0 mmol/L NaF for 48 hour, effects of excessive fluoride on the expression level of type I collagen of the osteoblasts are detected through immunohistochemical method. The results show that after NaF treatment for two months, the serum BGP and inorganic ingredient content in fluorosis rat bone increase significantly in comparison to those of in control group (P < 0.05). On the contrast, the content of collagen and the degree of collagen cross-linking in fluorosis rat bone decrease significantly (P < 0.05) compared with control group. In in vitro study, the osteoblasts secrete less type I collagen after NaF treatment than they do in control group cells. The results suggest that excessive fluoride can inhibit the synthesis of type I collagen. The decrease of collagen may be one of causal factors to skeletal fluorosis.