The effects of fluoride on cell migration, cell proliferation, and cell metabolism in GH4C1 pituitary tumour cells

Is Fluoride Blameless?-The Influence of Fluorine Compounds on the Invasiveness of the Human Glioma-like Cell Line U-87

Glioblastoma remains one of the most treatment-resistant and malignant human cancers. Given the documented harmful effects of fluoride on the developing central nervous system and the rising incidence of brain tumors, especially among children, it is pertinent to explore the role of environmental toxins, including fluoride compounds, in the context of brain cancer. This study represents the first investigation into the influence of fluoride on mechanisms related to the invasiveness of human glioblastoma cells. We examined the effects of sodium fluoride (NaF) exposure on the migratory and invasive abilities of the U-87 human glioblastoma cell line, assessing levels of metalloproteinases MMP-2 and MMP-9 secreted by these cells. Additionally, the activation of metabolic pathways associated with invasiveness, including AKT and NF-κB, was analyzed. Our results suggest that the effects induced by NaF at physiologically high concentrations (0.1-10 µM) in U-87 glioblastoma cells may promote a pro-invasive phenotype.

On the osteogenic differentiation of dental pulp stem cells by a fabricated porous nano-hydroxyapatite substrate loaded with sodium fluoride

In the present study, nano-hydroxyapatite (n-HA) powder was extracted from carp bone waste to fabricate porous n-HA substrates by a molding and sintering process. Subsequently, the substrates were loaded with different amounts of sodium fluoride (NaF) through immersion in NaF suspensions for 10, 7.5, and 5 min. The NaF-loaded n-HA substrates were then examined for their structural and physical properties, chemical bonds, loading and release profile, pH changes, cytotoxicity, and osteogenic effect on dental pulp stem cells (DPSCs) at the level of RNA and protein expression. The results showed that the n-HA substrates were porous (> 40% porosity) and had rough surfaces. The NaF could be successfully loaded on the substrates, which was 6.43, 4.50, and 1.47 mg, respectively for n-HA substrates with immersion times of 10, 7.5, and 5 min in the NaF suspensions. It was observed that the NaF release rate was rather fast during the first 24 h in all groups (39.06%, 36.43%, and 39.57% for 10, 7.5, and 5 min, respectively), and decreased dramatically after that, indicating a slow detachment of NaF. Furthermore, the pH of the medium related to all materials was changed during the first 4 days of immersion (from 7.38 to pH of about 7.85, 7.84, 7.63, and 7.66 for C0, C5, C7.5, and C10, respectively). The pH of media associated with the C7.5, and C10 increased up to 4 days and remained relatively constant until day 14 (pH = 7.6). The results of the cytotoxicity assay rejected any toxicity of the fabricated NaF-loaded n-HA substrates on DPSCs, and the cells could adhere to their surfaces with enlarged morphology. The results showed no effect on the osteogenic differentiation at the protein level. Nevertheless, this effect was observed at the gene level.

Anodic Production and Characterization of Biomimetic Oxide Layers on Grade 4 Titanium for Medical Applications

Biomaterials are the basis for the development of medicine because they allow safe contact with a living organism. The aim of this work was to produce innovative oxide layers with a microporous structure on the surface of commercially pure titanium Grade 4 (CpTi G4) and to characterize their properties as drug carriers. The anodization of the CpTi G4 subjected to mechanical grinding and electrochemical polishing was carried out in a solution of 1M ethylene glycol with the addition of 40 g of ammonium fluoride at a voltage of 20 V for 2, 18, 24, and 48 h at room temperature. It was found that the longer the anodization time, the greater the number of pores formed on the CpTi G4 surface as revealed using the FE-SEM method, and the greater the surface roughness determined in profilometric tests. As the anodizing time increases, the amount of the drug in the form of gentamicin sulfate incorporated into the resulting pores decreases. The most favorable drug release kinetics profile determined via UV-VIS absorption spectroscopy was found for the CpTi G4 anodized for 2 h.

Ameliorative effects of nano Moringa on fluoride-induced testicular damage via down regulation of the StAR gene and altered steroid hormones

Fluoride is a common environmental contaminant that has harmful effects on human health when it is present in high concentrations. Fluoride enters the bloodstream after being absorbed by the gastrointestinal system when fluoride-contaminated groundwater is consumed by people. The aim of the present study was to determine whether polyphenol-rich nano Moringa oleifera (NMO) could protect rat testicles from sodium fluoride (NaF) damage by evaluating sperm quality, sex hormones, testicular oxidative status, histopathology, and StAR gene expression. Twenty-eight adult Wistar rats were divided equally and randomly into four groups: group one received distilled water; group two received NMO at a dosage of 250 mg/kg/body weight; group three received NaF at a dosage of 10 mg/kg/body weight; and group four received NaF and NMO. The rats were orally administrated daily for a duration of eight weeks. The study's findings demonstrated that, in comparison to rats exposed to NaF alone, co-administration of NMO and NaF enhanced sperm motility and viability, decreased sperm morphological changes, restored the balance between oxidant and antioxidant status, improved testosterone and dehydroepiandrosterone, improved testicular histology, raised the Johnson score, and upregulated the StAR gene in testicular tissue. These findings show that NMO is promise as a prophylactic medication against sodium fluoride-induced testicular damage because administration of NMO had no adverse effects and enhanced reproductive health.

Aloe vera protects against fluoride-induced teratogenic effects during pre- and postnatal development in mice

Pregnancy and feto-gestational toxicities on exposure to fluoride and its possible amelioration on co-administration with aloe vera were studied in pregnant Swiss albino mice. Once the confirmed pregnancy was tested, animals were equally divided into four groups as follows: group I was given no treatment and served as control, and groups II and III were administered with 100 and 300 ppm sodium fluoride, respectively, while group IV was co- administered aloe vera (300 mg/kg bw) along with sodium fluoride (300 ppm) daily for 14 days prior to gestation and continued till the 18th day of gestation. Animals were sacrificed on the 19th day of gestation for prenatal observations. Maternal body weight, the gravid uterine weight, number of corpora lutea in both the ovaries, number of implantations and resorptions, number of live (mature and immature) fetuses, and number of dead fetuses were examined in each dam. The treatment continued in another set of animals till the completion of the weaning period to observe postnatal changes due to test substances on the mother and pups. Sodium fluoride-treated animals showed morphometric and skeletal changes which were more pronounced in the high-dose group showing significantly decreased body weight gain in pregnant mothers and dead/immature fetuses. Morphometric changes included open eyelids, limb defects, wrinkles on the whole body, anophthalmia, pulmonary edema, enlarged esophagus, and decreased body weight of fetuses and pups. Alizarin-prepared skeletal structures of fetuses of such female mice showed delayed ossification or bending in the number of bones of skull, thoracic, and limb regions. However, concomitant exposure to sodium fluoride and aloe vera in treated animals led to a marked improvement in all the prenatal and postnatal variables. The study suggests that sodium fluoride at high concentrations may be teratogenic while co-administration of aloe vera during fluoride exposure might be beneficial in reducing these toxic effects. The use of aloe vera as a preventive agent or as a complimentary agent is thus recommended following fluoride exposure through the oral route.

Synergistic effects of arsenic and fluoride on oxidative stress and apoptotic pathway in Leydig and Sertoli cells

Excessive intake of arsenic (As) and fluoride (F), which are present in underground drinking water, have adverse effects on human health, and especially on the male reproductive system. In this regard, it's critical to figure out how As and F affect Leydig and Sertoli cells, which are key cells in the male reproductive system. The goal of this study was to determine the synergistic effects of co-exposure of As and F, via drinking water, on Leydig and Sertoli cells, which are models for the male reproductive system, as well as the mechanisms underlying these effects in terms of oxidative damage and apoptosis. Leydig and Sertoli cells were exposed to concentrations of 7.7 µM (0.57 ppm) As and 0.4 mM (7.24 ppm) F based on the highest daily intake of drinking water for 24 h. The present results revealed that As and/or F treatment reduced cell viability and proliferation in Leydig and Sertoli cells, elevated lactate dehydrogenase, a cytotoxicity marker, and triggered oxidative stress and apoptosis. Furthermore, it has been proven that when As and F are exposed in combination, they have a synergistic effect. In conclusion, by revealing the harmful effects of As and F on Leydig and Sertoli cells, and thus on male infertility, it is possible to reduce As and F exposure to prevent infertility after exposure to these molecules not only separately but also together. It will be considered to determine new action and action plans to reduce As and F exposure.

Recent advances in cellular effects of fluoride: an update on its signalling pathway and targeted therapeutic approaches

Fluoride is a natural element essential in minute quantities in human's to maintain dental and skeletal health. However, the disease fluorosis manifests itself due to excessive fluoride intake mostly through drinking water and sometimes through food. At the cellular energetics level, fluoride is a known inhibitor of glycolysis. At the tissue level, the effect of fluoride has been more pronounced in the musculoskeletal systems due to its ability to retain fluoride. Fluoride alters dentinogenesis, thereby affecting the tooth enamel formation. In bones, fluoride alters the osteogenesis by replacing calcium, thus resulting in bone deformities. In skeletal muscles, high concentration and long term exposure to fluoride causes loss of muscle proteins leading to atrophy. Although fluorosis is quite a familiar problem, the exact molecular pathway is not yet clear. Extensive research on the effects of fluoride on various organs and its toxicity was reported. Indeed, it is clear that high and chronic exposure to fluoride causes cellular apoptosis. Accordingly, in this review, we have highlighted fluoride-mediated apoptosis via two vital pathways, mitochondrial-mediated and endoplasmic reticulum stress pathways. This review also elaborates on new cellular energetic, apoptotic pathways and therapeutic strategies targeted to treat fluorosis.

The Effect of Lycopene on DNA Damage and Repair in Fluoride-Treated NRK-52E Cell Line

Exposure of fluorine at toxic concentrations causes serious damage by accumulating in especially bones, kidneys, and other soft tissues. Fluorine at cytotoxic concentrations may cause DNA damage. This study aims to determine the level of DNA damage due to sodium fluoride (NaF) at different hours (3rd, 12th, and 24th hours) and in IC₅₀ concentrations designated for each hour and reveal the protective effect of lycopene on possible damage. The best enhancer concentrations (1 μM) of microtitration (MTT) viability test and proliferation of lycopene and IC₅₀ values of NaF at the 3rd, 12th, and 24th hour were 9600, 5500, and 3200 μM, respectively. DNA damage significantly increased in all NaF-treated groups in comparison with the control group (p < 0.05). DNA damage due to NaF+LYC application significantly decreased in comparison with the control group (p < 0.05). Lycopene application significantly increased the expression levels of the Ku70 and Ku80 genes which have a part in DNA repair (p < 0.05). The statistical data showed that application of lycopene which is an important antioxidant molecule may be beneficial for decreasing NaF-induced DNA damage. In conclusion, applying lycopene for cytotoxicity due to fluorine in NRK-52E cell line had different effects based on the dosage and time; thus, it can be a potential option for preventing fluorosis-induced toxicity and developing new treatment approaches.

Elemental Status and Lipid Peroxidation in the Blood of Children with Endemic Fluorosis

The study aimed to assess the levels of trace elements, minerals, and toxic elements as well as lipid peroxidation biomarkers (lipid acyl hydroperoxides, 2-thiobarbituric acid reactive substances (TBARS)) in the blood of children with chronic fluorosis from endemic fluorosis areas (Sosnivka village, Lviv region, western Ukraine). The results were compared with healthy children from Staryi Sambir (Lviv region, western Ukraine), whose drinking water contained permissible levels (< 1 ppm) of fluoride. Thirty-one children from the Sosnivka village in the Lviv region, including 16 females and 15 males aged 7-10 years, with clinically diagnosed fluorosis, were recruited for the study. The children had been exposed to fluoride (> 1.5 ppm) through drinking water for more than 5 years. In the blood, eight macro- and microelements (calcium, zinc, potassium, iron, copper, selenium, manganese, chromium), five additional elements (sulfur, bromine, chlorine, nickel, strontium), and four toxic elements (lead, mercury, cadmium, mercury) were assessed with the X-ray fluorescence method. The results of our study demonstrated a 14-fold decrease in the copper level, a 2.5-fold decrease in the calcium and zinc levels, and a 2-fold decrease in the selenium level in the blood of children with chronic fluorosis compared with the healthy children from the non-fluorosis area. In turn, a 1.7- and 1.4-fold increase in the strontium and lead content, respectively, was noted. The sulfur, chlorine, potassium, calcium, copper, zinc, and selenium levels in the blood samples of children with chronic fluorosis were lower than the reference value. The children had higher blood TBARS levels, while the acyl hydroperoxide levels were non-significantly increased in comparison with healthy children living in the non-fluorosis area. Additionally, the bromine level was correlated positively with the selenium level and acyl hydroperoxides. However, more studies are needed to clarify the relationship between blood mineral status, oxidative stress biomarkers, and chronic fluorosis.

Mitigative effect of Momordica cymbalaria fruit extract against sodium fluoride induced hepatotoxicity in Wistar male albino rats

OBJECTIVES

The main objective of the present study is to evaluate the mitigative effect of hydroalcoholic extract of Momordica cymbalaria fruits against sodium fluoride (NaF) induced hepatotoxicity.

METHODS

In this study, Wistar male albino rats were randomly divided into five groups of six rats each. Group I and II served as normal and toxic controls. Group III as plant control received extract at a dose of 400 mg/kg b. wt, p.o and Groups IV and V as treatment groups received extract at a dose 200 and 400 mg/kg b. wt, p.o for 30 days. All groups except Groups I and III received 100 ppm of NaF through drinking water. After completion of the study, blood collected for the estimation of liver blood serum biomarkers such as aspartate aminotransferases (AST), alanine aminotransferases (ALT), alkaline Phosphatase (ALP), direct and total bilirubin, total protein and albumin. The liver tissue homogenate was for estimation of lipid peroxidation, catalase, and reduced glutathione levels.

RESULTS

The results showed that NaF intoxication caused elevation of liver blood serum levels and lipid peroxidation; decreased levels of serum total protein, albumin and liver reduced glutathione, and catalase observed. The treatment groups showed decreased elevated serum biomarkers (ALT, AST, and ALP), liver lipid peroxidation and increased serum total protein and albumin, liver reduced glutathione and catalase levels in a dose-dependent manner. Histopathological studies also further strongly supported for mitigative effects of the plant.

CONCLUSIONS

In conclusion, our findings of the study indicated that M. cymbalaria fruits were a potential drug candidate in the treatment of NaF induced hepatotoxicity.

Toxicity of fluoride: critical evaluation of evidence for human developmental neurotoxicity in epidemiological studies, animal experiments and in vitro analyses

Recently, epidemiological studies have suggested that fluoride is a human developmental neurotoxicant that reduces measures of intelligence in children, placing it into the same category as toxic metals (lead, methylmercury, arsenic) and polychlorinated biphenyls. If true, this assessment would be highly relevant considering the widespread fluoridation of drinking water and the worldwide use of fluoride in oral hygiene products such as toothpaste. To gain a deeper understanding of these assertions, we reviewed the levels of human exposure, as well as results from animal experiments, particularly focusing on developmental toxicity, and the molecular mechanisms by which fluoride can cause adverse effects. Moreover, in vitro studies investigating fluoride in neuronal cells and precursor/stem cells were analyzed, and 23 epidemiological studies published since 2012 were considered. The results show that the margin of exposure (MoE) between no observed adverse effect levels (NOAELs) in animal studies and the current adequate intake (AI) of fluoride (50 µg/kg b.w./day) in humans ranges between 50 and 210, depending on the specific animal experiment used as reference. Even for unusually high fluoride exposure levels, an MoE of at least ten was obtained. Furthermore, concentrations of fluoride in human plasma are much lower than fluoride concentrations, causing effects in cell cultures. In contrast, 21 of 23 recent epidemiological studies report an association between high fluoride exposure and reduced intelligence. The discrepancy between experimental and epidemiological evidence may be reconciled with deficiencies inherent in most of these epidemiological studies on a putative association between fluoride and intelligence, especially with respect to adequate consideration of potential confounding factors, e.g., socioeconomic status, residence, breast feeding, low birth weight, maternal intelligence, and exposure to other neurotoxic chemicals. In conclusion, based on the totality of currently available scientific evidence, the present review does not support the presumption that fluoride should be assessed as a human developmental neurotoxicant at the current exposure levels in Europe.

Census of halide-binding sites in protein structures

Motivation

Halides are negatively charged ions of halogens, forming fluorides (F⁻), chlorides (Cl⁻), bromides (Br⁻) and iodides (I⁻). These anions are quite reactive and interact both specifically and non-specifically with proteins. Despite their ubiquitous presence and important roles in protein function, little is known about the preferences of halides binding to proteins. To address this problem, we performed the analysis of halide–protein interactions, based on the entries in the Protein Data Bank.

Results

We have compiled a pipeline for the quick analysis of halide-binding sites in proteins using the available software. Our analysis revealed that all of halides are strongly attracted by the guanidinium moiety of arginine side chains, however, there are also certain preferences among halides for other partners. Furthermore, there is a certain preference for coordination numbers in the binding sites, with a correlation between coordination numbers and amino acid composition. This pipeline can be used as a tool for the analysis of specific halide–protein interactions and assist phasing experiments relying on halides as anomalous scatters.

Availability and implementation

All data described in this article can be reproduced via complied pipeline published at https://github.com/rostkick/Halide_sites/blob/master/README.md.

Supplementary information

Supplementary data are available at Bioinformatics online.

Fluoride contamination, health problems and remediation methods in Asian groundwater: A comprehensive review

In low concentration, fluoride is considered a necessary compound for human health. Exposure to high concentrations of fluoride is the reason for a serious disease called fluorosis. Fluorosis is categorized as Skeletal and Dental fluorosis. Several Asian countries, such as India, face contamination of water resources with fluoride. In this study, a comprehensive overview on fluoride contamination in Asian water resources has been presented. Since water contamination with fluoride in India is higher than other Asian countries, a separate section was dedicated to review published articles on fluoride contamination in this country. The status of health effects in Asian countries was another topic that was reviewed in this study. The effects of fluoride on human organs/systems such as urinary, renal, endocrine, gastrointestinal, cardiovascular, brain, and reproductive systems were another topic that was reviewed in this study. Different methods to remove fluoride from water such as reverse osmosis, electrocoagulation, nanofiltration, adsorption, ion-exchange and precipitation/coagulation were introduced in this study. Although several studies have been carried out on contamination of water resources with fluoride, the situation of water contamination with fluoride and newly developed technology to remove fluoride from water in Asian countries has not been reviewed. Therefore, this review is focused on these issues: 1) The status of fluoride contamination in Asian countries, 2) health effects of fluoride contamination in drinking water in Asia, and 3) the existing current technologies for defluoridation in Asia.

Sodium Fluoride (NaF) Induces Inflammatory Responses Via Activating MAPKs/NF-κB Signaling Pathway and Reducing Anti-inflammatory Cytokine Expression in the Mouse Liver

At present, no reports are focused on fluoride-induced hepatic inflammatory responses in human beings and animals. This study aimed to investigate the mRNA and protein levels of inflammatory cytokines and signaling molecules for evaluating the effect of different doses (0, 12, 24, and 48 mg/kg) of sodium fluoride (NaF) on inflammatory reaction in the mouse liver by using methods of experimental pathology, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot analysis. We found that NaF in excess of 12 mg/kg caused the hepatic inflammatory responses, and the results showed that NaF activated the mitogen-activated protein kinases (MAPKs) signaling pathway by markedly increasing (p < 0.01 or p < 0.05) mRNA and protein levels of apoptosis signal-regulating kinase 1 (ASK1), mitogen-activated protein kinase kinases 1/2 (MEK1/2), extracellular signal-regulated protein kinases 1/2 (Erk1/2), mitogen-activated protein kinase kinases 4/7 (MEK4/7), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (p38) and mitogen-activated protein kinase kinases 3/6 (MEK3/6), and the nuclear factor-kappa B (NF-κB) signaling pathway by increasing (p < 0.01 or p < 0.05) the production of NF-κB and inhibitor of nuclear factor kappa-B kinase subunit beta (IKK-β) and reducing (p < 0.01 or p < 0.05) the production of the inhibitory kappa B (IκB). Thus, NaF that caused the hepatic inflammatory responses was characterized by increasing (p < 0.01 or p < 0.05) the production of pro-inflammatory mediators such as interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), monocyte chemotactic protein 1 (MCP-1), and cyclooxygenase-2 (COX-2) via the activation of MAPKs and NF-κB pathways, and by significantly inhibiting (p < 0.01 or p < 0.05) the production of anti-inflammatory mediators including interleukin-4 (IL-4) and transforming growth factor beta (TGF-β).

Sodium fluoride disrupts testosterone biosynthesis by affecting the steroidogenic pathway in TM3 Leydig cells

Fluorine is an essential trace element to which humans and animals are exposed through water, food, air and products used for dental health. Numerous studies have reported the detrimental effects of fluoride on testicular function and fertility; however, the underlying mechanisms of testosterone biosynthesis remain unclear. In this study, Leydig cells, the primary cells responsible for the production and regulation of steroid hormones in the testis, were used to elicit effects of sodium fluoride on the steroidogenic pathway. Leydig cells were treated with 0, 0.1, 1, 10 and 100 mg/L sodium fluoride for 24 h, respectively. The result of the study showed that sodium fluoride significantly decreased cell viability and cell proliferation, increased cell cytotoxicity and decreased the amounts of testosterone and 3',5'-cyclic adenosine monophosphate levels in a concentration-dependent manner. Also, these results indicated that NaF suppressed the expression of steroidogenic genes (steroidogenic acute regulatory protein, cholesterol side-chain cleavage enzyme, 3β-hydroxy dehydrogenase type I and 17β-hydroxy dehydrogenase type III) and proteins (luteinizing hormone receptor, cholesterol side-chain cleavage enzyme, 3β-hydroxy dehydrogenase), by changing the mRNA expression levels of the transcription factors (steroidogenic factor-1, GATA binding protein-4, nerve growth factor IB and nuclear receptor subfamily 0 group B member 1).

Chronic Exposure to Sodium Fluoride Triggers Oxidative Biochemistry Misbalance in Mice: Effects on Peripheral Blood Circulation

The excessive fluoride (F) exposure is associated with damage to cellular processes of different tissue types, due to changes in enzymatic metabolism and breakdown of redox balance. However, few studies evaluate doses of F compatible with human consumption. Thus, this study evaluated the effects of chronic exposure to sodium fluoride (NaF) on peripheral blood of mice from the evaluation of biochemical parameters. The animals were divided into three groups (n = 10) and received three concentrations of NaF in the drinking water for 60 days: 0 mg/L F, 10 mg/L F, and 50 mg/L F. The blood was then collected for trolox equivalent antioxidant capacity (TEAC), thiobarbituric acid reactive substances (TBARS), concentrations of nitric oxide (NO), superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH). The results showed that doses of 10 mg/L F and 50 mg/L F were able to increase TBARS concentration and decrease NO levels and CAT activity in the blood, but there was no statistical difference for SOD levels. The 50 mg/L F group showed an increase in TEAC levels and a decrease in the GSH content when compared to the control group. In this way, oxidative changes in blood from chronic exposure to F, especially at the highest dose, indicate that F may be a toxic agent and, therefore, the long-term exposure to excessive doses should be avoided.

Vitamin E and lycopene reduce coal burning fluorosis-induced spermatogenic cell apoptosis via oxidative stress-mediated JNK and ERK signaling pathways

Although fluoride has been widely used in toothpaste, mouthwash, and drinking water to prevent dental caries, the excessive intake of fluoride can cause fluorosis which is associated with dental, skeletal, and soft tissue fluorosis. Recent evidences have drawn the attention to its adverse effects on male reproductive system that include spermatogenesis defect, sperm count loss, and sperm maturation impairment. Fluoride induces oxidative stress through the activation of mitogen activated protein kinase (MAPK) cascade which can lead to cell apoptosis. Vitamin E (VE) and lycopene are two common antioxidants, being protective to reactive oxygen species (ROS)-induced toxic effects. However, whether and how these two antioxidants prevent fluoride-induced spermatogenic cell apoptosis are largely unknown. In the present study, a male rat model for coal burning fluorosis was established and the histological lesions and spermatogenic cell apoptosis in rat testes were observed. The decreased expression of clusterin, a heterodimeric glycoprotein reported to regulate spermatogenic cell apoptosis, was detected in fluoride-treated rat testes. Interestingly, the co-administration with VE or lycopene reduced fluorosis-mediated testicular toxicity and rescued clusterin expression. Further, fluoride caused the enhanced Jun N-terminal kinase (JNK, c-Jun) and extracellular signal-regulated protein kinase (ERK) phosphorylation, which was reduced by VE or lycopene. Thus, VE and lycopene prevent coal burning fluorosis-induced spermatogenic cell apoptosis through the suppression of oxidative stress-mediated JNK and ERK signaling pathway, which could be an alternative therapeutic strategy for the treatment of fluorosis.

Effects of fluoride on morphology, growth, development, and thyroid hormone of Chinese toad (Bufo gargarizans) embryos

Excessive fluoride in natural water ecosystem has the potential to detrimentally affect amphibians, but little is known of such effects or underlying mechanisms in Bufo gargarizans embryos. In the present study, the effects of fluoride exposure on B. gargarizans embryos were investigated. First, fluoride teratogenic experiment showed that the 9 days EC₅₀ of fluoride on B. gargarizans embryos was 177.62 mg/L. Then, we studied the sublethal effects of fluoride on B. gargarizans embryos at control, 0.7, 4.1, 19.6, 41.9, and 62.7 mg/L fluoride concentration. Malformation, growth, and development of embryos were monitored, and type 2 and 3 iodothyronine deiodinase (Dio2 and Dio3), thyroid hormone receptors (TRα and TRβ) mRNA levels were measured. Our results showed the morphological malformations, such as tail curvature (lordosis), edema, cuticularized ciliated cells, and hyperplasia were occurred during fluoride exposure. Growth and development were all inhibited at 19.5, 41.9, and 62.7 mg/L fluoride-treated groups after 9 days' exposure. According to real-time PCR results, exposure to fluoride upregulated Dio3 and TRβ mRNA expression and downregulated Dio2 and TRα mRNA level. All above indicated that excessive fluoride could induce morphology malformations, inhibit embryonic growth and development, and disrupt the normal function of maternal thyroid hormone in B. gargarizans embryos. Environ. Mol. Mutagen. 59:123-133, 2018. © 2017 Wiley Periodicals, Inc.

Nutritional status and dental fluorosis among schoolchildren in communities with different drinking water fluoride concentrations in a central region in Mexico

Poor water quality and under nutrition are important factors affecting the health of many communities in developing countries. The aims of this study were: i) to describe the fluoride water concentration and the hydrogeological conditions in a region of a state located in the central in Mexico ii) to measure the association between undernutrition and dental fluorosis in children living in communities with different drinking water fluoride concentrations in a state located in the central region of Mexico.

METHODS

Field work was performed in the region to identify the prevailing groundwater flow characteristics and water wells were sampled to analyze water fluoride concentration. Children were selected from three communities that had different drinking water fluoride concentrations (i.e., 0.56, 0.70 and 1.60 mg/l). Fluoridated salt was available in these communities. The Thylstrup-Fejerskov Index (TFI) was used to assess dental fluorosis. Categories four or higher of this index involve changes in the entire tooth surface (ITF ≥ 4). The weight and height of the children were measured. The assessment of undernutrition was based on the World Health Organization criteria: children were classified as being at risk of low-height (Height-for-Age Z score < − 1.0 SD) and having low-height (Height-for-Age Z score < − 2.0 SD) for age and sex, the same cutoff points of the Z score were used to classify "risk of low-weight" and" low-weight children".

RESULTS

In the region the mineralization of the water captured by the wells is the result of a reaction with volcanic materials. The water fluoride concentration in the region ranged from 0.2 to 1.6 mg/l. A total of 734 schoolchildren participated in the study. The percentage of children in fluorosis categories (ITF ≥ 4) was 15.9%, 21.1% of the children were at risk of low height-for-age, and 8.0% had low height-for-age. The percentage of children with fluorosis (ITF ≥ 4) was 6.3%, 9.1% and 31.9% (p ˂ 0.001) and low high-for-age was 2.9%, 2.5% and 8.4% (p ˂ 0.001), for the communities with F concentrations of 0.56 mg/l, 0.70 mg/l and 1.6 mg/l, respectively. The logistic regression model showed an association between dental fluorosis (TFI ≥ 4) and low height-for-age (OR 2.09, p = 0.022) after adjusting for sex, number of teeth erupted, source of drinking water, use of fluoridated toothpaste and tap water fluoride concentration in the community.

CONCLUSION

Children with low height-for-age were more likely to have dental fluorosis in the TFI categories that affect the entire tooth surface. The results suggest that subpopulations with chronic undernutrition are more susceptible to dental fluorosis.

The toxicity of NaF on BmN cells and a comparative proteomics approach to identify protein expression changes in cells under NaF-stress: impact of NaF on BmN cells

Fluorides negatively affect the development of organisms and are a threat to human health and environmental safety. In this study, Bombyx mori N cell line (BmN) were used to explore effects of NaF on insect cells. We found that 8h (hrs) culture with high concentration of NaF (≥ 1 mM) induced significantly morphological changes. Dose-response curves of 72 h continuously cultured BmN treated with NaF showed that the half inhibitory concentration (IC50) value was 56.60 μM. Treatment of BmN with 100 and 300 μM of NaF induced apoptosis and necrosis. 2-D electrophoresis of whole cell extracted from BmN showed that treatment with 300 μM NaF up-regulated 32 proteins and down-regulated 11 proteins when compared with controls. We identified 5 different proteins by MALDI-TOF MS, and 4 of them were identified for the first time, including 2 up-regulated proteins (mitochondrial aldehyde dehydrogenase ALDH2 and prohibitin protein WPH) and 2 down-regulated proteins (calreticulin precursor CRT and DNA supercoiling factor SCF). These observations were further confirmed by fluorescence quantitative PCR. Together, our data suggest that these target proteins could be regarded as targets influenced by NaF and also provide clues for studies on the response metabolism pathway under NaF stress.

Efficacy of lycopene against fluoride toxicity in rats

CONTEXT

Oxidative damage to cellular components such as lipids and cell membranes by free radicals and reactive oxygen species (ROS) is thought to be associated with the development of degenerative diseases. Fluoride intoxication is associated with oxidative stress and altered anti-oxidant defense mechanism. Lycopene is a lipid-soluble powerful anti-oxidant that scavenges free radicals and ROS.

OBJECTIVE

This study was extended to investigate lycopene anti-oxidant efficacy in different organs of fluoride-intoxicated rats.

METHODS

Twenty-four adult rats were randomly divided into four groups of six animals each. Rats in group I received daily doses of vehicle. Group II rats were given lycopene (10 mg/kg body weight/day), by tubes, dissolved in 0.5 ml of corn oil for 5 weeks. Group III rats were given sodium fluoride (NaF) (10.3 mg/kg body weight/day), by tubes, for 5 weeks. In group IV rats, lycopene was administered 1 h later and NaF was administered for 5 weeks.

RESULTS

NaF administration induced oxidative stress as evidenced by elevated levels of lipid peroxidation (51.3, 65.9 and 67.6%) measured as malondialdehyde and total nitrate/nitrite (61.0, 59.7 and 68.9%) in red blood cells, heart and brain tissues. Moreover, significantly decreased reduced glutathione level, total anti-oxidant capacity and superoxide dismutase activity were observed in the examined tissues. The induced oxidative stress and the alterations in anti-oxidant system were normalized by the oral administration of lycopene treatment.

CONCLUSION

Lycopene administration could minimize the toxic effects of fluoride indicating its free-radical scavenging and powerful anti-oxidant activities.

Simultaneous administration of fluoride and selenite regulates proliferation and apoptosis in murine osteoblast-like MC3T3-E1 cells by altering osteoprotegerin

The receptor activator nuclear factor kappa-B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG), are important for maintaining the balance between bone formation and resorption. However, the regulation of microelements on these factors remains unclear. In this study, we used murine osteoblast-like MC3T3-E1 cells to examine the impact of sodium fluoride (NaF) and/or sodium selenite (Na2SeO3) on the OPG/RANKL system. MC3T3-E1 cells were treated with OPG or RANKL siRNA (or left untreated), and subsequently divided into a control group and five experimental groups, which were exposed to different concentrations of NaF and/or Na2SeO3, and subsequently analysed at 24 h. In particular, we examined cell viability, OPG and RANKL mRNA and protein expression, caspase-3 activity, and the cell cycle of the various cell groups. In summary, our findings suggest that the administration of NaF and/or Na2SeO3 affects the expression of OPG in osteoblast-like MC3T3-E1 cells, thereby contributing to the proliferation and apoptosis induced by the OPG.

Sodium fluoride affects proliferation and apoptosis through insulin-like growth factor I receptor in primary cultured mouse osteoblasts

Insulin-like growth factor-I receptor (IGF-IR) is important for maintaining proliferation and apoptosis in osteoblasts. However, the details about the effect of sodium fluoride supplementation on primary osteoblast cultures on mediating IGF-IR expression are still not well-known. In this study, we used mouse osteoblasts to examine the impact of sodium fluoride on the proliferation and apoptosis; the cells were treated with IGF-IR small interfering RNA (or left untreated) and subsequently divided into a control group and six experimental groups, which were exposed to different concentrations of NaF (10(-6), 10(-5), 10(-4), 10(-3), 5 × 10(-3), and 10(-2) mol/L) for analysis at 48 h. In particular, we examined cell proliferation, apoptosis, IGF-IR messenger RNA, and protein expression levels of the various cell groups. In summary, our findings suggest that the administration of NaF affects the expression of IGF-IR in mouse osteoblasts, contributing to the proliferation and apoptosis induced by fluoride.

Sodium fluoride induces apoptosis and alters bcl-2 family protein expression in MC3T3-E1 osteoblastic cells

Chronic excessive fluoride intake is known to be toxic and can lead to fluorosis and bone pathologies. However, the cellular mechanisms underlying NaF-induced cytotoxicity in osteoblasts are not well understood. The objectives of this study were to determine the effects of fluoride treatment on MC3T3-E1 osteoblastic cell viability, cell cycle analysis, apoptosis and the expression levels of bcl-2 family members: bcl-2 and bax. MC3T3-E1 cells were treated with 10(-5); 5 × 10(-5); 10(-4); 5 × 10(-4) and 10(-3)M NaF for up to 48 h. NaF was found to reduce cell viability in a temporal and concentration dependent manner and promote apoptosis even at low concentrations (10(-5)M). This increased apoptosis was due to alterations in the expression of both pro-apoptotic bax and anti-apoptotic bcl-2. The net result was a decrease in the bcl-2/bax ratio which was found at both the mRNA and protein levels. Furthermore, we also noted that NaF-induced S-phase arrest during the cell cycle of MC3T3-E1 cells. These data suggest that fluoride-induced osteoblast apoptosis is mediated by direct effects of fluoride on the expression of bcl-2 family members.