The current study was conducted to investigate the effect of sodium fluoride (NaF) on the oxidative stress and apoptosis as well as their relationship in the mouse liver by using methods of flow cytometry, quantitative real-time polymerase chain reaction (qRT-PCR), western blot, biochemistry and experimental pathology. 240 four-week-old ICR mice were randomly divided into 4 groups and exposed to different concentration of NaF (0 mg/kg, 12 mg/kg, 24 mg/kg and 48 mg/kg) for a period of 42 days. The results showed that NaF caused oxidative stress and apoptosis. NaF-caused oxidative stress was accompanied by increasing reactive oxygen species (ROS) and malondialdehyde (MDA) levels, and decreasing mRNA expression levels and activities of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione peroxidase (GSH-PX) and glutathione-s-transferase (GST). NaF induced apoptosis via tumor necrosis factor recpter-1 (TNF-R1) signaling pathway, which was characterized by significantly increasing mRNA and protein expression levels of TNF-R1, Fas associated death domain (FADD), TNFR-associated death domain (TRADD), cysteine aspartate specific protease-8 (caspase-8) and cysteine aspartate specific protease-3 (caspase-3) in dose- and time-dependent manner. Oxidative stress is involved in the process of apoptotic occurrence, and can be triggered by promoting ROS production and reducing antioxidant function. NaF-caused oxidative stress and apoptosis finally impaired hepatic function, which was strongly supported by the histopathological lesions and increased serum alanine amino transferase (ALT), aspartic acid transferase (AST), alkaline phosphatase (AKP) activities and TBIL contents.

It has been reported that excessive intake of fluoride can induce renal lesions. However, its pathogenesis is still less understood. Therefore, this study was conducted to investigate oxidative damage and the relationships between the oxidative damage and renal lesions in fluoride-treated mice by using the methods of histopathology, biochemistry, flow cytometry and quantitative real-time polymerase chain reaction (qRT-PCR). A total of 240 ICR mice were randomly divided into four equal groups (sodium fluoride was given orally at the dose of 0, 12, 24 and 48 mg/kg body weight for 42 days, respectively). We found that fluoride in excess of 12 mg/kg induced renal oxidative damage, which was characterized by increasing the levels of reactive oxygen species (ROS) production and contents of malondialdehyde (MDA) and protein carbonyls (PC), and decreasing the abilities of anti-superoxide anion (ASA) and anti-hydroxyl radical (AHR), glutathione (GSH) content, as well as activities and mRNA expression levels of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione peroxidase (GSH-Px). Concurrently, fluoride caused degeneration and necrosis of the tubular cells, renal tubular hyaline casts and glomeruli swelling, which were consistent with the alteration of renal function parameters including elevated contents of serum creatinine (Cr), serum uric acid (UA), blood urea nitrogen (BUN), and the activities of urinary N-acetyl-b-D-glucosaminidase (NAG), renal lactate dehydrogenase (LDH), and reduced activities of sodium-potassium adenosine triphosphatase (Na+/K+-ATPase) and acid phosphatase (ACP) in the kidney. The above-mentioned results showed that fluoride in excess of 12 mg/kg induced renal oxidative damage, which then caused renal lesions and dysfunctions. These findings also clearly demonstrated that oxidative damage is one of the mechanisms of fluoride-induced renal lesions and dysfunctions.

Background/Aims: Excessive fluoride intake can induce cytotoxicity, DNA damage and cell-cycle changes in many tissues and organs, including the kidney. However, the underlying molecular mechanisms of fluoride-induced renal cell-cycle changes are not well understood at present. In this study, we used a mouse model to investigate how sodium fluoride (NaF) induces cell-cycle changes in renal cells. Methods: Two hundred forty ICR mice were randomly assigned to four equal groups for intragastric administration of NaF (0, 12, 24 and 48 mg/kg body weight/day) for 42 days. Kidneys were taken to measure changes of the cell-cycle at 21 and 42 days of the experiment, using flow cytometry, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot methods. Results: NaF, at more than 12 mg/kg body weight, induced G2/M phase cell-cycle arrest in the renal cells, which was supported by the finding of significantly increased percentages of renal cells in the G2/M phase. We found also that G2/M phase cell-cycle arrest was accompanied by up-regulation of p-ATM, p-Chk2, p-p53, p-Cdc25C, p-CDK1, p21, and Gadd45a protein expression levels; up-regulation of ATM, Chk2, p53, p21, and Gadd45a mRNA expression levels; down-regulation of CyclinB1, mdm2, PCNA protein expression levels; and down-regulation of CyclinB1, CDK1, Cdc25C, mdm2, and PCNA mRNA expression levels. Conclusion: In this mouse model, NaF, at more than 12 mg/ kg, induced G2/M phase cell-cycle arrest by activating the ATM-Chk2-p53/Cdc25C signaling pathway, which inhibits the proliferation of renal cells and development of the kidney. Activation of the ATM-Chk2-p53/Cdc25C signaling pathway is the mechanism of NaF-induced renal G2/M phase cell-cycle arrest in this model.

Fluoride is widely distributed in the environment and often results in adverse health effects on animals and human beings. It has been proved that fluoride can induce inflammatory responses in vitro. However, very limited reports are focused on fluoride-induced inflammatory responses in vivo. In this study, mice were used to investigate sodium fluoride (NaF) induced renal inflammatory responses and the potential mechanism by using the methods of pathology, biochemistry, enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. A total of 240 ICR mice were randomly divided into four equal groups: the control group and three experimental groups (NaF was given orally at the dose of 0, 12, 24 and 48 mg/kg body weight for 42 days, respectively). The results showed that NaF in excess of 12 mg/kg induced the renal histopathological lesions, and inflammatory responses via the activation of nuclear factor-kappa B (NF-κB) signaling pathway and the reduction of anti-inflammatory cytokines expression. The activation of NF-κB signaling pathway was characterized by increasing the nitric oxide (NO) and prostaglandin E2 (PGE2) contents, inducible nitric oxide synthase (iNOS) activities and mRNA expression levels, and the mRNA and protein expression levels of cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and interleukin-8 (IL-8) in three NaF-treated groups. Concurrently, the mRNA and protein expression levels of the anti-inflammatory cytokines including interleukin-4 (IL-4) and interleukin-10 (IL-10) were decreased in three experimental groups when compared with those in the control group.

In this study, we investigated the roles of reactive oxygen species (ROS) and nuclear factor-κB (NF-κB) signaling in sodium fluoride-induced DNA damage and apoptosis in mouse splenocytes. Intragastric administration of 12, 24 or 48 mg/kg sodium fluoride resulted in a time- and dose-dependent increase in DNA fragmentation and apoptosis in mouse splenocytes on days 21 and 42. High ROS levels correlated with increased levels of phosphorylated IκB kinase and NF-κB p65 and decreased levels of inhibitory kappa B protein in splenocytes from mice treated with sodium fluoride. Moreover, splenocytes from sodium fluoride-treated mice showed high expression of pro-apoptotic proteins, including Bim, Bax, Bak, caspase-3 and poly ADP-ribose polymerase, and low expression of the anti-apoptotic proteins BcL-2 and BcL-xL. These results show that sodium fluoride induces apoptosis in mouse splenocytes by enhancing ROS-dependent NF-κB signaling.