BACKGROUND: Excessive exposure to fluoride can reduce intelligence. Methylenetetrahydrofolate dehydrogenase, cyclohydrolase, and formyltetrahydrofolate synthetase 1 ( MTHFD1 ) polymorphisms have important roles in neurodevelopment. However, the association of MTHFD1 polymorphisms with children's intelligence changes in endemic fluorosis areas has been rarely explored. METHODS: A cross-sectional study was conducted in four randomly selected primary schools in Tongxu County, Henan Province, from April to May in 2017. A total of 694 children aged 8 to 12 years were included in the study with the recruitment by the cluster sampling method. Urinary fluoride (UF) and urinary creatinine were separately determined using the fluoride ion-selective electrode and creatinine assay kit. Children were classified as the high fluoride group and control group according to the median of urinary creatinine-adjusted urinary fluoride (UF Cr ) level. Four loci of MTHFD1 were genotyped, and the Combined Raven's Test was used to evaluate children's intelligence quotient (IQ). Generalized linear model and multinomial logistic regression model were performed to analyze the associations between children's UF Cr level, MTHFD1 polymorphisms, and intelligence. The general linear model was used to explore the effects of gene-environment and gene-gene interaction on intelligence. RESULTS: In the high fluoride group, children's IQ scores decreased by 2.502 when the UF Cr level increased by 1.0 mg/L (β = -2.502, 95% confidence interval [CI]:-4.411, -0.593), and the possibility for having "excellent" intelligence decreased by 46.3% (odds ratio = 0.537, 95% CI: 0.290, 0.994). Children with the GG genotype showed increased IQ scores than those with the AA genotype of rs11627387 locus in the high fluoride group ( P   <  0.05). Interactions between fluoride exposure and MTHFD1 polymorphisms on intelligence were observed (Pinteraction < 0.05). CONCLUSION Our findings suggest that excessive fluoride exposure may have adverse effects on children's intelligence, and changes in children's intelligence may be associated with the interaction between fluoride and MTHFD1 polymorphisms.
Child ; Creatinine ; Cross-Sectional Studies ; Fluorides/urine* ; Formate-Tetrahydrofolate Ligase ; Humans ; Intelligence/genetics* ; Methylenetetrahydrofolate Dehydrogenase (NADP) ; Methylenetetrahydrofolate Reductase (NADPH2)

OBJECTIVETo explore whether the intake of dietary carotenoids could protect against skeletal fluorosis in Guizhou province in which coal-burning fluorosis is endemic.

METHODSA case-control study of 196 patients with skeletal fluorosis and 196 age and gender-matched controls was conducted in Zhijin, Guizhou Province. Face-to-face interviews were conducted to assess habitual dietary intake using a 75-item food frequency questionnaire and various covariates with structured questionnaires. Urinary fluoride was measured using an ion-selective electrode method. The genotype of superoxide dismutase 2 (SOD2) rs11968525 was detected by TaqMan method.

RESULTSWe observed significant dose-dependent inverse associations of skeletal fluorosis with intake of β-carotene, lutein/zeaxanthin, lycopene, and total carotenoids (P-trend = 0.002 to 0.018), whereas α-carotene and β-cryptoxanthin intakes were not found to be related to skeletal fluorosis, after adjustment for potential confounders. The adjusted ORs and 95% CI of skeletal fluorosis for the highest versus lowest quartile were 0.30 (0.10, 0.86) for β-carotene, 0.23 (0.08, 0.66) for lycopene, 0.26 (0.10, 0.75) for lutein/zeaxanthin and 0.34 (0.14, 0.74) for total carotenoids (all P-trend < 0.05). Stratified analyses showed that the protective effects of lutein/zeaxanthin and total carotenoids on skeletal fluorosis were more evident for individuals with the AG+AA genotypes of SOD2 (rs11968525).

CONCLUSIONIncreased intakes of β-carotene, lutein/zeaxanthin, lycopene, and total carotenoids are independently associated with a lower risk of coal-burning skeletal fluorosis. SOD2 (rs11968525) polymorphisms might modify the inverse associations between dietary carotenoids and skeletal fluorosis.

Bone Diseases, Metabolic ; genetics ; prevention & control ; urine ; Carotenoids ; administration & dosage ; Case-Control Studies ; China ; Coal ; Energy Intake ; Environmental Exposure ; analysis ; Feeding Behavior ; Female ; Fluoride Poisoning ; genetics ; prevention & control ; urine ; Fluorides ; urine ; Humans ; Middle Aged ; Polymorphism, Genetic ; Superoxide Dismutase ; genetics ; Surveys and Questionnaires

The effects of fluoride exposure on the functions of reproductive and endocrine systems have attracted widespread attention in academic circle nowadays. However, it is unclear whether the gene-environment interaction may modify the secretion and activity of hypothalamus-pituitary- ovarian (HPO) axis hormones. Thus, the aim of this study was to explore the influence of fluoride exposure and follicle stimulating hormone receptor (FSHR) gene polymorphism on reproductive hormones in Chinese women. A cross sectional study was conducted in seven villages of Henan Province, China during 2010-2011. A total of 679 women aged 18-48 years were recruited through cluster sampling and divided into three groups, i.e. endemic fluorosis group (EFG), defluoridation project group (DFPG), and control group (CG) based on the local fluoride concentration in drinking water. The serum levels of gonadotropin releasing hormone (GnRH), follicle stimulating hormone (FSH), luteinizing hormone (LH), and estradiol (E2) were determined respectively and the FSHR polymorphism was detected by real time PCR assay. The results provided the preliminary evidence indicating the gene-environment interaction on HPO axis hormones in women.
Adolescent ; Adult ; Age Factors ; Asian Continental Ancestry Group ; China ; Cross-Sectional Studies ; Estradiol ; blood ; Female ; Fluoridation ; adverse effects ; Fluorides ; administration & dosage ; adverse effects ; urine ; Follicle Stimulating Hormone ; blood ; Gene-Environment Interaction ; Gonadotropin-Releasing Hormone ; blood ; Humans ; Hypothalamus ; physiology ; Luteinizing Hormone ; blood ; Middle Aged ; Ovary ; physiology ; Pituitary Gland ; physiology ; Polymorphism, Single Nucleotide ; Receptors, FSH ; genetics ; Tobacco Smoke Pollution ; Young Adult

OBJECTIVETo observe the impacts on skeletal fluorosis pain, joint motor dysfunction and urine fluoride excretion in the treatment with fire needle therapy, electroacupuncture and calcium carbonate D3.

METHODSThe randomized controlled trial was adopted. Ninety-five patients were randomized into a fire needle group (31 cases), an electroacupuncture group (33 cases) and a calcium carbonate D3 group (31 cases). In the fire needle group and the electroacupuncture group, Ashi points, Dazhui (GV 14), Geshu (BL 17), Quchi (LI 11), Hegu (LI 4), Xuehai (SP 10) points were selected and stimulated with fire needle and electroacupuncture separately, three times a week. In the calcium carbonate D3 group, calcium carbonate D3 tablets was prescribed for oral administration, 600 mg each time, twice a day. The duration of treatment was 2 months in the electroacupuncture group and calcium carbonate D3 group and 1 month in the fire needle group. VAS score, the range of motion (ROM) and urine fluoride value were compared before and after treatment in the patients of the three groups.

RESULTSAfter treatment, VAS value and ROM were improved significantly in the patients of the three groups (all P < 0.05), the difference was not significant in comparison of the three groups (all P > 0.05). After treatment, the urine fluoride value was increased significantly in the fire needle group [(7.89 +/- 3.61) mg/L vs (9.81 +/- 4.17) mg/L, P < 0.01] and was increased in the electroacupuncture group [(7.53 +/- 3.46) mg/L vs (8.97 +/- 4.21) mg/L, P < 0.05]. The difference was not significant in comparison before and after treatment in the calcium carbonate D3 group (P > 0.05).

CONCLUSIONThe fire needle therapy, electroacupuncture and calcium carbonate D3 all have the clinical value in the prevention and treatment of skeletal fluorosis and the difference in the therapeutic effect has not been discovered among them yet at present. But it has been found that the fire needle therapy and electroacupuncture display the active significance in the promotion of urine fluoride excretion.

Adult ; Aged ; Bone Diseases ; drug therapy ; therapy ; urine ; Calcium Carbonate ; administration & dosage ; Electroacupuncture ; instrumentation ; Female ; Fluorides ; urine ; Humans ; Male ; Middle Aged ; Needles ; Treatment Outcome

OBJECTIVETo explore the influence of water fluoride exposure on reproductive hormones in female.

METHODSCross-sectional study was conducted in seven villages of a county in Henan province by using simple random sampling including high fluoride area, defluoridation project area and control area on April, 2011 based on the preliminary study results of fluoride concentration in drinking water. Women who were born and growth or lived in the village at least 5 years and aged 18-48 years old were recruited using cluster sampling. They were divided into high fluoride group (HFG, 116 subjects), defluoridation project group (DFPG, 132 subjects) and control group (CG, 227 subjects) in accordance with the above areas. All subjects accepted questionnaire and physical checkup. Fasting blood and morning urine samples were collected. The concentration of fluoride in urine was determined by fluoride ion selective electrode method. The serum level of GnRH was detected using enzyme linked immunosorbent assay (ELISA). The serum level of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), estradiol (E2) were determined by chemiluminesence immunoassay (CLIA).

RESULTSThe average age was (39.44 ± 7.34), (38.84 ± 8.03), (37.45 ± 7.70) years old in female from DFPG, HFG and CG respectively, there were no significant differences among the three groups (F = 3.02, P = 0.05). The urine fluoride levels were (1.34 ± 1.07), (2.59 ± 1.57), (0.92 ± 0.46) mg/ml in female from DFPG, HFG and CG respectively, there was a significant difference among three groups (F = 105.38, P < 0.01). No significant differences were observed of serum GnRH, LH, T, FSH and E2 among three groups in follicular phase (P > 0.05). The serum levels of E2 in Ovulatory period were 67.73, 58.09, 84.96 pg/ml in female from DFPG, HFG and CG respectively. It was lower in HFG than that in CG (H = 4.00, P < 0.05). The serum levels of T in Ovulatory period were 0.55, 0.45, 0.55 ng/ml in female from DFPG, HFG and CG respectively. It was lower in HFG than that in DFPG (H = 6.47, P < 0.05), but no significant difference was observed between HFG and CG (H = 2.41, P > 0.05). The serum levels of GnRH in Luteal phase were 24.09, 20.16, 23.50 ng/ml in female from DFPG, HFG and CG respectively. It was lower in HFG than that in DFPG (H = 14.14, P < 0.05) and CG (H = 12.53, P < 0.05). The serum level of E2 in luteal phase were 81.47, 64.60, 74.55 pg/ml in female from DFPG, HFG and CG respectively. It was lower in HFG than that in DFPG (H = 5.69, P < 0.05). As for LH, FSH and T, no significant differences were observed among the three groups (P > 0.05 respectively). The abnormal rates of E2 level were 22.73 (30/102), 37.93 (44/72), 20.26 (46/181) in female from DFPG, HFG and CG respectively. The E2 abnormal rate in female from HFG was higher that from DFPG (χ(2) = 6.82, P < 0.05) and CG (χ(2) = 12.38, P < 0.05).

CONCLUSIONFluoride exposure may influence reproductive hormones in female, especially in ovulatory and luteal phase of menstrual cycle.

Adult ; Cross-Sectional Studies ; Drinking Water ; chemistry ; Environmental Exposure ; adverse effects ; Estradiol ; blood ; Female ; Fluorides ; adverse effects ; urine ; Follicle Stimulating Hormone ; blood ; Gonadotropin-Releasing Hormone ; blood ; Humans ; Luteinizing Hormone ; blood ; Menstrual Cycle ; drug effects ; Middle Aged ; Progesterone ; blood ; Testosterone ; blood

Animals ; Bone and Bones ; drug effects ; Copper ; pharmacology ; therapeutic use ; Fluoride Poisoning ; prevention & control ; Fluorides ; blood ; toxicity ; urine ; Lipid Metabolism ; drug effects ; Molybdenum ; toxicity ; Rabbits ; Trace Elements ; pharmacology ; therapeutic use

OBJECTIVETo explore the changes of protein expression of mitochondrial fission gene dynamin-related 1(Drp 1) in the cortical neurons of rats with chronic fluorosis.

METHODSA total of 120 one-month-old SD rats (each weighing approximately 100-120 g at the beginning of the experiment) were randomly divided into three groups, and fed with the different doses of fluoride containing in drinking water (untreated control containing 0 mg/L fluoride, and low-fluoride & high-fluoride supplemented with 10 and 50 mg/L fluoride,respectively). After 3 or 6 months exposure, 20 rats from each group were killed. Then the protein expression of mitochondrial fission gene, Drp1, was detected by immunohistochemistry and western-blotting method.

RESULTSDental fluorosis and urinary fluorosis were obviously found in the rats exposed to fluoride. At the experiment period of 3 months, the numbers of positive cells of Drp1 detected by immunohistochemistry changed. Compared with the control group (36.3 ± 5.8), the changes in low-fluoride group (34.7 ± 4.1) showed no significant difference (t = 1.5, P > 0.05),but the increase in high-fluoride group (45.0 ± 4.7) had statistical significance (t = 8.8, P < 0.05). The western-blotting method had consistent results. Compared with the control group (0.59 ± 0.03), a significant increase of the average topical density in low- fluoride (0.62 ± 0.03) and high-fluoride (0.71 ± 0.02) groups were found (t = 0.02,0.11, P < 0.05). At the experiment period of 6 months, the numbers of positive cells of Drp1 detected by immunohistochemistry significantly changed. Compared with the control group (33.2 ± 4.4), the number in low- fluoride and high-fluoride groups were separately (36.6 ± 3.8) and (39.4 ± 4.2),both increased significantly (t = 3.5,6.3, P < 0.05). Same results could be found in western-blotting method,compared with the control group (0.65 ± 0.06), the average topical density in low- fluoride (0.80 ± 0.09) and high-fluoride (0.76 ± 0.08) groups both increased significantly (t = 0.1,0.1, P < 0.05).

CONCLUSIONSTaking excessive amount of fluoride might result in the changes of expression of Drp1, and the neurons damage from the chronic fluorosis might be associated with the hyperfunction of mitochondrial fusion.

Animals ; Drinking Water ; chemistry ; Dynamins ; genetics ; metabolism ; Fluoride Poisoning ; metabolism ; Fluorides ; urine ; Fluorosis, Dental ; metabolism ; Male ; Mitochondrial Dynamics ; Neurons ; metabolism ; pathology ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the changes of mRNA and protein expression of CaN in the bone of rats with chronic fluorosis, and the mechanism of skeletal fluorosis.

METHODSThirty-six SD rats were divided into three groups (12 in each group, half male and half female selected according to body weight): control, low-dose and high-dose fluorosis groups. Controls were fed tap water (NaF < 0.5 mg/L), experimental animals in the low- or high-dose groups were fed water containing NaF of 5.0 and 50.0 mg/L, respectively. The rats were sacrificed after 6 months of treatment with fluoride. The serum was kept for testing bone metabolic marker bone gla protein (BGP) by enzyme-linked immunosorbent assay (ELISA), the protein and mRNA levels of CaN in distal femur of the rats with chronic flurosis were assessed by immunohistochemistry and in-situ hybridization.

RESULTSThe levels of BGP (1.99 ± 0.62, 2.38 ± 0.16)µg/L in the low- or high-dose fluorosis groups were higher than that in the control group (0.15 ± 0.03) µg/L; and the high fluorosis group showed higher level than the low fluorosis group (all P < 0.05). Compared to the control group (131.11 ± 1.95, 111.82 ± 2.39), the protein and mRNA levels of CaN were higher in the low- or high-dose fluorosis groups (142.69 ± 1.17, 157.54 ± 1.88 and 121.28 ± 3.27, 134.63 ± 3.19, respectively), and the high fluorosis group showed higher levels than the low fluorosis group (all P < 0.05).

CONCLUSIONSBGP content could be used as a bone metabolic index in endemic fluorosis disease. Fluoride might up-regulate the mRNA and protein expression of CaN, and the changes in CaN level may be involved in the increase of the bone turnover and could be one of the pathogenetic factors in fluorosis.

Animals ; Bone and Bones ; metabolism ; Calcineurin ; genetics ; metabolism ; Female ; Fluoride Poisoning ; metabolism ; pathology ; Fluorides ; metabolism ; urine ; Fluorosis, Dental ; metabolism ; pathology ; Male ; Osteoblasts ; metabolism ; Osteocalcin ; blood ; RNA, Messenger ; metabolism ; Rats ; Rats, Sprague-Dawley ; Sodium Fluoride ; poisoning

OBJECTIVETo study the effect of fluoride on the oxidative stress of the rats in endemic fluorosis of coal burning and Mn-SOD expression at mRNA and protein levels.

METHODSSD rats were divided into 2 groups (the number of female and male in each group was the same): control group and fluorosis group. All rats of the fluorosis group were fed corn dried by burning coal from endemic fluorosis areas with high fluoride content (fluoride 17 mg/kg in feed) to establish an animal model of fluorosis. In these rats, dental fluorosis was evaluated. The fluoride content in the urine was measured by fluorine ion-elective electrode method. The hepatic tissue and serum level of malonaldehyde (MDA) and the activities of superoxide dismutase (SOD) and glutathion reductase (GR) were measured by biochemical methods. The index signs of liver function were also measured from the serum. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were performed to detect the alterations of Mn-SOD expression in the liver at mRNA and protein levels.

RESULTSThe dental fluorosis was observed in the fluorosis group, and the incidence was 11/11. The fluoride contents [(3.50 ± 2.58) mg/L] in the urine of fluorosis rats were increased as compared with the control [(1.42 ± 0.38) mg/L] (P < 0.05). AST [(223.74 ± 71.51) U/L] and total protein [(72.43 ± 5.59) g/L] of the hepatic function index in fluorosis rats showed obviously abnormal as compared with the control [(169.28 ± 53.74) U/L and (82.36 ± 7.31) g/L], respectively (P < 0.05). In the liver the content of MDA [(10.41 ± 0.59) µmol/g protein] increased as compared to the control [(5.80 ± 1.31) µmol/g protein, P < 0.01], and the activities of SOD [(62.60 ± 8.65) U/mg protein] and GR [ (1.17 ± 0.66) U/g protein] markedly decreased in the fluorosis group compared to the control [SOD (117.28 ± 8.64) U/mg protein and GR [(8.80 ± 1.59) U/g protein; P < 0.05, P < 0.01]. The level of Mn-SOD in the liver was markedly decreased in the fluorosis group [(14.83 ± 2.50) U/mg protein] as compared with the control [(34.05 ± 5.22) U/mg protein, P < 0.01]. The levels of mRNA (0.64 ± 0.15) and protein (0.84 ± 0.13) of Mn-SOD were markedly decreased in the fluorosis group as compared with the control [(0.86 ± 0.21) and (1.04 ± 0.14)], respectively (P < 0.05, P < 0.01).

CONCLUSIONSFluorosis can decrease the activities of Mn-SOD, which is associated with decreased levels of mRNA and protein of Mn-SOD. Down-regulation of Mn-SOD expression may play an important role in the aggravation of oxidative stress in endemic fluorosis.

Animals ; Coal ; Down-Regulation ; Female ; Fluorides ; urine ; Fluorosis, Dental ; metabolism ; Glutathione Reductase ; blood ; metabolism ; Liver ; metabolism ; Liver Function Tests ; Male ; Malondialdehyde ; blood ; metabolism ; Oxidative Stress ; RNA, Messenger ; metabolism ; Rats ; Rats, Sprague-Dawley ; Superoxide Dismutase ; blood ; genetics ; metabolism

OBJECTIVETo investigate the expressions of mRNA and protein of p38, Osx, PI3K, Akt1 in the rats bone with chronic fluorosis.

METHODSDental fluorosis were observed and the fluoride contents in the urine and bone were detected by fluorin-ion selective electrode. The morphologic changes and ultrastructure of rats' bone were observed by light and electronic microscopy. The expressions of protein and mRNA of p38, Osx, PI3K and Akt1 were detected by immunohistochemistry and real-time PCR, respectively. The contents of BALP and BGP in serum were detected by ELISA.

RESULTSThe rates of dental fluorosis in the fluorosis rats were increased, and the fluoride contents in bone and urine of the fluorosis rats were increased compared to the control group, the difference was statistically significant (P < 0.05). The bone trabeculae thickness and density and the thickness of bone cortex in fluorosis rats were remarkably increased, the space of bone trabeculae was reduced, and in accordance with the matching morphometrical indices, the difference was statistically significant (P < 0.05) as compared with the control rats. The contents of BALP [(54.61 ± 2.27) U/L] and BGP [(2.38 ± 0.16) µg/L]in the fluoride groups were higher than those in the control group, the difference was statistically significant (P < 0.05). Ultrastructurally, the broadening of the osseouslacuna was observed. The reduced protuberances of the osteocytes, the unclear organelle structure, pyknosis, karyotheca increasation and edged chromatin were also observed. Compared to the control group, the expressions of protein and its mRNA of p38, Osx, PI3K and Akt1 were higher in the fluorosis rats than those in the control rats, and the difference was statistically significant (P < 0.05). There is no any expression of p38, Osx, PI3K and Akt1 in the osteocytes in fluorosis rats.

CONCLUSIONSThe over-expression of p38, Osx, PI3K and Akt1 in bone tissue of fluorosis rats may relate to the accumulation of fluorine in the body. The bone injury mainly occur in the stage of the differentiation and proliferation. The upregulation of P38MARK signal path and PI3K/Akt1 signal path may be involved in the pathogenesis of bone injury caused by fluoride.

Alkaline Phosphatase ; blood ; Animals ; Bone and Bones ; metabolism ; pathology ; ultrastructure ; Fluoride Poisoning ; metabolism ; pathology ; Fluorides ; metabolism ; urine ; Fluorosis, Dental ; metabolism ; pathology ; Immunohistochemistry ; Microscopy, Electron, Transmission ; Osteocalcin ; blood ; Phosphatidylinositol 3-Kinases ; genetics ; metabolism ; Proto-Oncogene Proteins c-akt ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Rats ; Rats, Sprague-Dawley ; Real-Time Polymerase Chain Reaction ; Signal Transduction ; Sodium Fluoride ; toxicity ; Transcription Factors ; genetics ; metabolism ; p38 Mitogen-Activated Protein Kinases ; genetics ; metabolism