To explore the expressions of Notch3 and Jag1 proteins in bone tissues of fluorosis rats and their roles in the pathogenesis of skeletal fluorosis.

Twenty-four SD rats were randomly divided into control, low-fluoride, and high-fluoride groups, eight rats each. The three groups were fed with tap water and water containing 50 mg/L and 100 mg/L sodium fluoride, respectively. All rats were neutralized after six months. Fluoride levels in urine and bone were measured by fluoride ion selective electrode method. Bone tissue samples were observed for pathological changes. The protein levels of Notch3 and Jag1 in osteoblasts were detected by immunohistochemical assay. The expressions of Notch3 and Jag1 proteins and mRNA in bone tissues were detected by Western blot and real-time fluorescent quantitative PCR respectively.

Compared with the control group, the fluoride levels in urine and bone in the low- and high-fluoride groups were significant higher (all Ps<0.05). Osteosclerosis was observed under optical microscope. The protein and mRNA expression levels of Notch3 in bone tissues of the high-fluoride group were significant lower than those of controls (both Ps<0.05), meanwhile the protein and mRNA expression levels of Jag1 in bone tissues of the high-fluoride group were significant lower than those of the control and low-fluoride groups (all Ps<0.05). The protein expression levels of Notch3 and Jag1 in osteoblast of the low- and high-fluoride groups were significant lower than those of the controls (all Ps<0.05) by immunohistochemical assay.

Excessive fluoride could inhibit the expressions of Notch3 and Jag1 in bone tissues, especially in osteoblasts, and enhance osteogenesis as well, which might be connected to the pathogenesis of skeletal fluorosis.