In vitro effect of sodium fluoride on antioxidative enzymes and apoptosis during murine odontogenesis

Abstract

Excessive fluoride ingestion has been identified as a risk factor for fluorosis and oxidative stress. The oxidative stress results from the loss of equilibrium between oxidative and antioxidative mechanisms that can produce kinase activation, mitochondrial disturbance and DNA fragmentation, resulting in apoptosis. Actually many people are exposed to no-adverted fluoride consumption in acute or chronic way. The aim of this study was to determine the effect of sodium fluoride on first molar germ in relation to its effect on antioxidative enzymes immunoexpression and apoptosis. Thirty first molar germs from 1-day-old Balb/c mice were cultured for 24 h with sodium fluoride (0 mM, 1 mM and 5 mM). Immunoexpression determination of CuZnSod, MnSod, catalase, Bax, Bid, caspase 8, caspase 9, caspase 3 and TUNEL assay were performed. Cellular disorganization in ameloblast and odontoblast-papilla zones was observed. CuZnSod and MnSod immunoexpression decrease in experimental groups. Caspase 8, caspase 3, Bax, Bid increase expression and more TUNEL positive cells in both experimental groups than control, suggest that apoptosis induced by fluoride is related to oxidative stress due to reduction of the enzymatic antioxidant.

Molecular Mechanisms of Cytotoxicity and Apoptosis Induced by Inorganic Fluoride

“…Elevated expression of another proapoptotic member Bax and corresponding suppression of Bcl-2 expression at both the mRNA and protein levels have been shown to implicate in apoptosis in the NaF-treated renal tubules [27] and osteoblastic MC3T3-E1 cells [24], as well as in the oral mucosal cells of rabbits that underwent topical application of fluoride-containing gel [136]. Immunoexpression of both Bax and Bid proteins was also described in the thirty first molar germs from 1-day-old Balb/c mice cultured with 5 mM NaF [20]. Activated form of Bid, tBid, triggers the oligomerization of Bax/Bad and induces the release of cytochrome c from mitochondria.…”

“…The enhanced expression levels of Fas, Fas-L, and caspase-8 mRNA and concomitant activation of activity caspase-3 were demonstrated in the human neuroblastoma SH-SY5Y cells treated with 40-80 mg/L NaF [130]. The conflicting results were obtained in the work of Jacinto-Alemán et al [20] who described an increased expression of caspase-3 and -8 in murine thirty first molar germs culture with 5 mM NaF but suggested that fluoride-induce apoptosis in these cells is related to oxidative stress due to reduction of the enzymatic antioxidant. The stimulation of caspase-3 not attributed to either intrinsic or extrinsic pathways has been described in the leucocytes of fluoride-intoxicated rats [131] and osteoblast-like MC3T3-E1 cells [132].…”

“…For instance, in teeth and bone tissues, micromolar concentrations of fluoride elicit potentially beneficial effects by promoting cell proliferation and growth, whereas millimolar fluoride doses suppress cell proliferation and induce apoptosis. Thus, an exposure to high fluoride doses has been reported to induce apoptotic cell death in ameloblasts [18][19][20], odontoblasts [21], and osteoblasts [22][23][24]. In the cells of other tissues, fluoride has been shown to negatively influence many metabolic, structural, and functional cellular functions in experimental animal models in vivo and in cultured cells in vitro.…”

Effect of sodium fluoride on the grey matter of spinal cord in the albino rat and the protective role of green tea extract

“…Agha et al [43] reported that the irregular heterochromatic nuclei observed after NaF treatment confirmed the induction of apoptosis. Jacinto-Aleman et al [44] suggested that, excessive fluoride ingestion can produce DNA fragmentation resulting in apoptosis. Ge et al [45] attributed the degenerative changes of mitochondria to the mitochondrial DNA mutation.…”

Is water fluoridation a hidden cause of obesity? Histological study on thyroid follicular cells of albino rats

“…DNA cannot repair itself and chromosomes are damaged. Moreover, Jacinto-Aleman et al [24] suggested that excessive fluoride ingestion has been identified as a risk factor for oxidative stress that can produce DNA fragmentation resulting in apoptosis, which was evident in our study in the form of desquamated cells in the lumen of the follicles.…”