Effect of fluoride on expression of phosphoinositide 3-kinase, protein kinase B1 mRNA and protein in bone tissue of rats / 中国地方病学杂志

ABSTRACT

Objective To observe the expression of phosphoinositide 3-kinase(PI3K) and protein kinase B1 (Akt1) in PI3K/Akt signaling pathway in rat bones with fluorosis, and to reveal the mechanisms of the skeletal fluorosis. Methods Thirty-six SD rats were randomly divided into 3 groups (control group, low-dose fluorosis group, high-dose fluorosis group) and 12 rats were in each group according to body weight. The rats were fed with different concentrations of fluoride (NaF) to establish fluorosis models. Controls were fed with tap water( < 0.5 mg/L), experimental animals in low- or high-dose groups were fed with water containing NaF 5.0,50.0 mg/L, respectively. Rats were sacrificed after 6 months of treating with fluoride and the serum was kept for testing the bone metabolic markers of none gla protein(BGP) and cathepsin K(Cath-K) by enzyme-linked immunosorbent assay(ELISA), the proteins and mRNA levels of PI3K and Akt1 in rat bones were detected by immunohistochemistry and real time PCR, respectively. Results Each group of serum BGP and Cath-k were compared, the difference was statistically significant(F = 73.45,39.36, all P < 0.05). The contents of BGP[(1.99 ± 0.62), (2.38 ± 0.16)μg/L] and Cath-K [(89.07 ± 19.66), (110.16 ± 9.81)pmol/L] in the low-and high-dose fluorosis groups were higher than those in the control group[(0.15 ± 0.03)μg/L,( 18.32 ± 2.27)pmol/L], and the high fluorosis group was obviously higher than the low fluorosis group (all P < 0.05). Each group of serum PI3K and Akt1 protein and mRNA were compared, the difference was statistically significant(F- 178.16,118.08,38.81,52.31, all P< 0.05). Compared to the control group (181.55 ± 4.24,188.46 ± 2.18,3.84 ± 1.69,4.33 ± 0.89), the protein and mRNA expressions of PI3K(171.66 ± 2.85,154.12 ± 4.15,11.31 ± 4.18,20.54 ± 6.68), Akt1(177.47 ± 3.16,156.42 ± 3.18,12.52 ± 3.13,19.43 ± 5.36) were higher in the low- and high-dose fluorosis groups (all P < 0.05), and the high fluorosis group was obviously higher than the low fluorosis group (all P < 0.05). Conclusions BGP and Cath-K contents could be used as bone metabolic indices in the endemic fluorosis disease. Fluoride can increase the expression of PI3K and Akt1 mRNA and protein in bone tissue of fluorosis rats, and PI3K/Akt1 signaling pathway may be involved in the pathogenesis of bone injury caused by fluoride.