Rationale: Potential adverse effects of fluoride on neurodevelopment has been extensively explored and mitochondria have been recognized as critical targets. Mitochondrial biogenesis serves a crucial role in maintaining mitochondrial homeostasis and salubrious properties of resveratrol (RSV) has been well-defined. However, the molecular mechanisms governing mitochondrial biogenesis in developmental fluoride neurotoxicity remain unclear and the related therapeutic dietary agent is lacking.
Methods: In vitro neuroblastoma SH-SY5Y cells and in vivo Sprague-Dawley rat model of developmental fluoride exposure were adopted. A total population of 60 children under long-term stable fluoride exposure were also recruited. This work used a combination of biochemical and behavioral techniques. Biochemical methods included analysis of mitochondrial function and mitochondrial biogenesis, as well as mRNA and protein expression of mitochondrial biogenesis signaling molecules, including silent information regulator 1 (SIRT1), peroxisome proliferator-activated receptor ? coactivator-1? (PGC-1?), nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM). Behavioral studies investigated spatial learning and memory ability of rats.
Results: Both in vivo and in vitro experiments showed that sodium fluoride (NaF) caused mitochondrial dysfunction and impaired mitochondrial biogenesis. Also, NaF elevated SIRT1 levels and suppressed SIRT1 deacetylase activity along with decreased levels of PGC-1?, NRF1 and TFAM, suggestive of dysregulation of mitochondrial biogenesis signaling molecules. Moreover, enhancement of mitochondrial biogenesis by TFAM overexpression alleviated NaF-induced neuronal death through improving mitochondrial function in vitro. Further in vivo and in vitro studies identified RSV, the strongest specific SIRT1 activator, improved mitochondrial biogenesis and subsequent mitochondrial function to protect against developmental fluoride neurotoxicity via activating SIRT1-dependent PGC-1?/NRF1/TFAM signaling pathway. Noteworthy, epidemiological data indicated intimate correlations between disturbed circulating levels of mitochondrial biogenesis signaling molecules and fluoride-caused intellectual loss in children.
Conclusions: Our data suggest the pivotal role of impaired mitochondrial biogenesis in developmental fluoride neurotoxicity and the underlying SIRT1 signaling dysfunction in such neurotoxic process, which emphasizes RSV as a potential therapeutic dietary agent for relieving developmental fluoride neurotoxicity.
Animals and experimental designs
… In study-1, female rats were developmentally exposed to fluoride via drinking water freely daily from pre-pregnancy to post-puberty, which covers the critical maternal, perinatal, and pubertal periods. The day of parturition was counted as postnatal day 0 (PND 0). Offspring female rats were still under the same treatments as mother rats till PND60 after the weaning period (PND21) (Figure 1F).
In study-2, offspring female rats were allotted into 4 different groups (n = 20 pups in each group). The treatment schedule was given below (Figure 6A):
- Group I — Control (receiving tap water only till PND 60).
- Group II — Fluoride-treated (100 mg/L NaF via drinking water till PND 60).
- Group III — RSV supplemented (100 mg/L NaF via drinking water till PND 60 + RSV at 200 mg/kg body weight/day by gavage from PND 10 to PND 60).
- Group IV — RSV and NIC supplemented (NaF at a dose of 100 mg/L via drinking water till PND 60 + RSV at 200 mg/kg body weight/day and NIC at 100 mg/kg body weight/day simultaneously by gavage from PND 10 to PND 60).
After corresponding treatments, all offspring rats were euthanized by cervical dislocation for the study of biochemical parameters.
Baodi district in Tianjin, China is divided into historical high fluoride areas and normal fluoride areas. In 2015, the volunteers aged 8-12 years were selected from local children who are permanent residents since birth. Children from Dakoutun town (high-fluoride districts, n = 30) and students from Lintingkou town (normal-fluoride/control areas, n = 30) were included in this study. Both the two study sites were not in the endemic areas for iodine deficiency disorders, or exposed to other potential neurotoxins like lead, arsenic or mercury.
*Original abstract and full test in html online at https://www.thno.org/v10p4822.htm
1. Edition F. Guidelines for drinking-water quality. WHO chronicle. 2011;38:104-8
2. Zhang L, Huang DZ, Yang J, Wei X, Qin J, Ou S. et al. Probabilistic risk assessment of Chinese residents’ exposure to fluoride in improved drinking water in endemic fluorosis areas. Environ Pollut. 2017;222:118-25
3. Khandare AL, Validandi V, Gourineni SR, Gopalan V, Nagalla B. Dose-dependent effect of fluoride on clinical and subclinical indices of fluorosis in school going children and its mitigation by supply of safe drinking water for 5 years: an Indian study. Environ Monit Assess. 2018;190:110
4. Yousefi M, Ghoochani M, Hossein Mahvi A. Health risk assessment to fluoride in drinking water of rural residents living in the Poldasht city, Northwest of Iran. Ecotoxicol Environ Saf. 2018;148:426-30
5. Choi AL, Sun G, Zhang Y, Grandjean P. Developmental fluoride neurotoxicity: a systematic review and meta-analysis. Environ Health Perspect. 2012;120:1362-8
6. Liu F, Ma J, Zhang H, Liu P, Liu YP, Xing B. et al. Fluoride exposure during development affects both cognition and emotion in mice. Physiol Behav. 2014;124:1-7
7. Jiang CY, Zhang S, Liu HL, Guan ZZ, Zeng Q, Zhang C. et al. Low glucose utilization and neurodegenerative changes caused by sodium fluoride exposure in rat’s developmental brain. Neuromol Med. 2014;16:94-105
8. Du L, Wan CW, Cao XM, Liu JL. The effect of fluorine on the developing human brain. Fluoride. 2008;41:327-30
9. Zhao Q, Niu Q, Chen J, Xia T, Zhou G, Li P. et al. Roles of mitochondrial fission inhibition in developmental fluoride neurotoxicity: mechanisms of action in vitro and associations with cognition in rats and children. Arch Toxicol. 2019;93:709-26
10. Chen L, Ning H, Yin Z, Song X, Feng Y, Qin H. et al. The effects of fluoride on neuronal function occurs via cytoskeleton damage and decreased signal transmission. Chemosphere. 2017;185:589-94
11. Dorn GW, Vega RB, Kelly DP. Mitochondrial biogenesis and dynamics in the developing and diseased heart. Genes Dev. 2015;29:1981-91
12. Sharma J, Johnston MV, Hossain MA. Sex differences in mitochondrial biogenesis determine neuronal death and survival in response to oxygen glucose deprivation and reoxygenation. BMC Neurosci. 2014;15:9
13. H Reddy P, P Reddy T. Mitochondria as a therapeutic target for aging and neurodegenerative diseases. Curr Alzheimer Res. 2011;8:393-409
14. Lv YJ, Yi Y, Dong SB, Hu HC, Pan Z, Li L. et al. Resveratrol counteracts bone loss via mitofilin-mediated osteogenic improvement of mesenchymal stem cells in senescence-accelerated mice. Theranostics. 2018;8:2387-406
15. Ma S, Motevalli SM, Chen JW, Xu MQ, Wang YB, Feng J. et al. Precise theranostic nanomedicines for inhibiting vulnerable atherosclerotic plaque progression through regulation of vascular smooth muscle cell phenotype switching. Theranostics. 2018;8:3693-706
16. Mudo G, Mäkelä J, Di Liberto V, Tselykh TV, Olivieri M, Piepponen P. et al. Transgenic expression and activation of PGC-1? protect dopaminergic neurons in the MPTP mouse model of Parkinson’s disease. Cell Mol Life Sci. 2012;69:1153-65
17. Guida N, Laudati G, Anzilotti S, Secondo A, Montuori P, Renzo GD. et al. Resveratrol via sirtuin-1 downregulates RE1-silencing transcription factor (REST) expression preventing PCB-95-induced neuronal cell death. Toxicol Appl Pharmacol. 2015;288:387-98
18. Laudati G, Mascolo L, Guida N, Sirabella R, Pizzorusso V, Bruzzaniti S. et al. Resveratrol treatment reduces the vulnerability of SH-SY5Y cells and cortical neurons overexpressing SOD1-G93A to thimerosal toxicity through SIRT1/DREAM/PDYN pathway. NeuroToxicol. 2019;71:6-15
19. Gomes BAQ, Silva JPB, Romeiro CFR, dos Santos SM, Rodrigues CA, Gonçalves PR. et al. Neuroprotective mechanisms of resveratrol in Alzheimer’s disease: role of SIRT1. Oxid Med Cell Longev. 2018;2018:8152373
20. Pal S, Sarkar C. Protective effect of resveratrol on fluoride induced alteration in protein and nucleic acid metabolism, DNA damage and biogenic amines in rat brain. Environ Toxicol Pharmacol. 2014;38:684-99
21. Sarkar C, Pal S. Ameliorative effect of resveratrol against fluoride-induced alteration of thyroid function in male wistar rats. Biol Trace Elem Res. 2014;162:278-87
22. Atmaca N, Yildirim E, Guner B, Kabakci R, Bilmen FS. Effect of resveratrol on hematological and biochemical alterations in rats exposed to fluoride. Biomed Res Int. 2014;2014:698628
23. Tu W, Zhang Q, Liu Y, Han L, Wang Q, Chen P. et al. Fluoride induces apoptosis via inhibiting SIRT1 activity to activate mitochondrial p53 pathway in human neuroblastoma SH-SY5Y cells. Toxicol Appl Pharmacol. 2018;347:60-9
24. Wang ZH, Zhang JL, Duan YL, Zhang QS, Li GF, Zheng DL. MicroRNA-214 participates in the neuroprotective effect of resveratrol via inhibiting ?-synuclein expression in MPTP-induced Parkinson’s disease mouse. Biomed Pharmacother. 2015;74:252-6
25. Zhu D, Zhang J, Wu J, Li G, Yao W, Hao J. et al. Paliperidone protects SH-SY5Y cells against MK-801-induced neuronal damage through inhibition of Ca2+ influx and regulation of SIRT1/miR-134 signal pathway. Mol Neurobiol. 2016;53:2498-509
26. Mumtaz N, Pandey G, Labhasetwar PK. Global fluoride ocurrence, available technologies for fluoride removal, and electrolytic defluoridation: a review. Crit Rev Env Sci Tec. 2015;45:2357-89
27. Livak K, Schmittgen T. Analysis of relative gene expression data using real-time quantitative PCR and the 2-??Ct Method. Methods. 2000;25:402-408
28. Li CY, Peng J, Ren LP, Gan LX, Lu XJ, Liu Q. et al. Roles of histone hypoacetylation in LAT expression on T cells and Th2 polarization in allergic asthma. J Transl Med. 2013;11:26
29. Liu HL, Lam LT, Zeng Q, Han SQ, Fu G, Hou CC. Effects of drinking water with high iodine concentration on the intelligence of children in Tianjin, China. J Public Health. 2009;31:32-8
30. Wu J, Wang W, Liu Y, Sun J, Ye Y, Li B. et al. Modifying role of GSTP1 polymorphism on the association between tea fluoride exposure and the brick-tea type fluorosis. PLoS One. 2015;10:e0128280
31. Sheng B, Wang X, Su B, Lee Hg, Casadesus G, Perry G. et al. Impaired mitochondrial biogenesis contributes to mitochondrial dysfunction in Alzheimer’s disease. J Neurochem. 2012;120:419-29
32. Golpich M, Amini E, Mohamed Z, Azman Ali R, Mohamed Ibrahim N, Ahmadiani A. Mitochondrial dysfunction and biogenesis in neurodegenerative diseases: pathogenesis and treatment. CNS Neurosci Ther. 2017;23:5-22
33. Qin G, Wu M, Wang J, Xu Z, Xia J, Sang N. Sulfur dioxide cntributes to the cardiac and mitochondrial dysfunction in rats. Toxicol Sci. 2016;151:334-46
34. Jiang S, Li T, Ji T, Yi W, Yang Z, Wang SM. et al. AMPK: potential therapeutic target for ischemic stroke. Theranostics. 2018;8:4535-51
35. de Oliveira MR, Jardim FR, Setzer WN, Nabavi SM, Nabavi SF. Curcumin, mitochondrial biogenesis, and mitophagy: exploring recent data and indicating future needs. Biotechnol Adv. 2016;34:813-26
36. Zhou Y, Wang SH, Li YX, Yu SS, Zhao Y. SIRT1/PGC-1? signaling promotes mitochondrial functional recovery and reduces apoptosis after intracerebral hemorrhage in rats. Front Mol Neurosci. 2018;10:443
37. Lopez MS, Dempsey RJ, Vemuganti R. Resveratrol neuroprotection in stroke and traumatic CNS injury. Neurochem Int. 2015;89:75-82
38. Choi AL, Zhang Y, Sun G, Bellinger DC, Wang K, Yang XJ. et al. Association of lifetime exposure to fluoride and cognitive functions in Chinese children: a pilot study. Neurotoxicol Teratol. 2015;47:96-101
39. Bartos M, Gumilar F, Bras C, Gallegos CE, Giannuzzi L, Cancela LM. et al. Neurobehavioural effects of exposure to fluoride in the earliest stages of rat development. Physiol Behav. 2015;147:205-12
40. Barbier O, Arreola-Mendoza L, Del Razo LM. Molecular mechanisms of fluoride toxicity. Chem Biol Interact. 2010;188:319-33
41. Zuo H, Chen L, Kong M, Qiu L, Lu P, Wu P. et al. Toxic effects of fluoride on organisms. Life Sci. 2018;198:18-24
42. Li PA, Hou X, Hao S. Mitochondrial biogenesis in neurodegeneration. J Neurosci Res. 2017;95:2025-9
43. Golpich M, Rahmani B, Ibrahim NM, Dargahi L, Mohamed Z, Raymond AA. et al. Preconditioning as a potential strategy for the prevention of Parkinson’s disease. Mol Neurobiol. 2015;51:313-30
44. Martine U, Anne C. Mitochondrial biogenesis: a therapeutic target for neurodevelopmental disorders and neurodegenerative diseases. Curr Pharm Design. 2014;20:5574-93
45. Xu SC, Zhong M, Zhang L, Wang Y, Zhou Z, Hao YT. et al. Overexpression of TFAM protects mitochondria against ?-amyloid-induced oxidative damage in SH-SY5Y cells. The FEBS journal. 2009;276:3800-9
46. Piao Y, Kim HG, Oh MS, Pak YK. Overexpression of TFAM, NRF-1 and myr-AKT protects the MPP(+)-induced mitochondrial dysfunctions in neuronal cells. Biochim Biophys Acta. 2012;1820:577-85
47. Herskovits AZ, Guarente L. SIRT1 in neurodevelopment and brain senescence. Neuron. 2014;81:471-83
48. Lv JJ, Deng C, Jiang S, Ji T, Yang Z, Wang Z. et al. Blossoming 20: the energetic regulator’s birthday unveils its versatility in cardiac diseases. Theranostics. 2019;9:466-76
49. Gu X, Han D, Chen W, Zhang L, Lin Q, Gao J. et al. SIRT1-mediated FoxOs pathways protect against apoptosis by promoting autophagy in osteoblast-like MC3T3-E1 cells exposed to sodium fluoride. Oncotarget. 2016;7:65218-30
50. Suzuki M, Bartlett JD. Sirtuin1 and autophagy protect cells from fluoride-induced cell stress. Biochim Biophys Acta. 2014;1842:245-55
51. Jardim FR, de Rossi FT, Nascimento MX, da Silva Barros RG, Borges PA, Prescilio IC. et al. Resveratrol and brain mitochondria: a review. Mol Neurobiol. 2018;55:2085-101
52. Peng K, Tao Y, Zhang J, Wang J, Ye F, Dan G. et al. Resveratrol regulates mitochondrial biogenesis and fission/fusion to attenuate rotenone-induced neurotoxicity. Oxid Med Cell Longev. 2016;2016:6705621
53. Cote CD, Rasmussen BA, Duca FA, Zadeh-Tahmasebi M, Baur JA, Daljeet M. et al. Resveratrol activates duodenal SIRT1 to reverse insulin resistance in rats through a neuronal network. Nat Med. 2015;21:498-505
54. Feng X, Liang N, Zhu D, Gao Q, Peng L, Dong H. et al. Resveratrol inhibits ?-amyloid-induced neuronal apoptosis through regulation of SIRT1-ROCK1 signaling pathway. PloS One. 2013;8:2429-34
55. Zhang J, Feng X, Wu J, Xu H, Li G, Zhu D. et al. Neuroprotective effects of resveratrol on damages of mouse cortical neurons induced by ?-amyloid through activation of SIRT1/Akt1 pathway. Biofactors. 2014;40:258-67
56. Zhang L, Tu R, Wang Y, Hu Y, Li X, Cheng X. et al. Early-life exposure to lead induces cognitive impairment in elder mice targeting SIRT1 phosphorylation and oxidative alterations. Front Physiol. 2017;8:446