Effect of dietary protein or calcium supplement on the expression of collagen i and dentine phosphoprotein of rats with dental fluorosis

This study aims to assess the roles of dietary protein (Pr) and calcium (Ca) levels associated with excessive fluoride (F) intake and the impact of Pr, Ca, and F on expression of collagen I (COL I) and dentine phosphoprotein (DPP) in rat incisors. Seventy-two rats were randomly allotted to six groups (NC, NC + F, LPrLCa, LPrLCa + F, HPrLCa + F and LPrHCa + F). F, Pr, and Ca were orally administrated to rats for 120 days. The genes and proteins expression levels were quantified. We found that levels of COL1A1 and DSPP gene were respectively decreased by 41.9% and 43.1% in the NC + F group compared with NC group, were respectively decreased by 47.9% and 40.8% in the LPrLCa + F group compared with LPrLCa group, were respectively increased by 71.8% and 39.5% in the HPrLCa + F group and increased by 26.5% and 21.1% in the LPrHCa + F group compared with LPrLCa + F group. Meanwhile, the proteins' expression display with the genes' expression changes were consistent. This study demonstrated that the gene and protein expressions of COL I and DPP were reduced by F both in normal nutrition and malnutrition, and it was reversed by Pr and Ca supplementation, with the effect of Pr being greater than that of Ca.