Fluoride-induced oxidative stress in rat's brain and its amelioration by buffalo (Bubalus bubalis) pineal proteins and melatonin

Effects of Quercetin against fluoride-induced neurotoxicity in the medial prefrontal cortex of rats: A stereological, histochemical and behavioral study

BACKGROUND

Exposure to high levels of fluoride leads to brain developmental and functional damage. Motor performance deficits, learning and memory dysfunctions are related to fluoride neurotoxicity in human and rodent studies.

MATERIALS AND METHODS

Here, we evaluated the effects of Quercetin treatment (25 mg/kg) against sodium fluoride-induced neurotoxicity (NaF, 200 ppm) in the medial prefrontal cortex (mPFC) of male adult rats based on oxidative markers, behavioral performances, mRNA expressions, and stereological parameters. After a 4-week experimental period, the brains of rats were collected and used for molecular and histological analysis.

RESULTS

We found that 4 weeks of NaF exposure decreased body weight, working memory, Brain-derived neurotrophic factor (BDNF) mRNA expression, total volume of mPFC, number of neurons and non-neuronal cells in the mPFC, and anti-oxidative markers (CAT, SOD, and GSH-Px), while increased lipid peroxidation, P53 mRNA expression and anxiety. Quercetin treatment could significantly reverse the neurotoxic effect of NaF in the mPFC.

CONCLUSIONS

In summary, Quercetin could decrease the detrimental effects of NaF in the mPFC of adult rats by improving antioxidant potency and consequently decreasing neuronal and non-neuronal apoptosis.

Inflammation- and cancer-related microRNAs in rat renal cortex after subchronic exposure to fluoride

The proximal tubule is a target of subchronic exposure to fluoride (F) in the kidney. Early markers are used to classify kidney damage, stage, and prognosis. MicroRNAs (miRNAs) are small sequences of non-coding single-stranded RNA that regulate gene expression and play an essential role in developing many pathologies, including renal diseases. This study aimed to evaluate the expression of Cytokine-Chemokine molecules (IL-1α/1β/4/6/10, INF-γ, MIP-1α, MCP-1, RANTES, and TGF β1/2/3) and inflammation-related miRNAs to evidence the possible renal mechanisms involved in subchronic exposure to F. Total protein and miRNAs were obtained from the renal cortex of male Wistar rats exposed to 0, 15 and 50 mg NaF/L through drinking water during 40 and 80 days. In addition, cytokines-chemokines were analyzed by multiplexing assay, and a panel of 77 sequences of inflammatory-related miRNAs was analyzed by qPCR. The results show that cytokines-chemokines expression was concentration- and time-dependent with F, where the 50 mg NaF/L were the main altered groups. The miRNAs expression resulted in statistically significant differences in thirty-four miRNAs in the 50 mg NaF/L groups at 40 and 80 days. Furthermore, a molecular interaction network analysis was performed. The relevant pathways modified by subchronic exposure to fluoride were related to extracellular matrix-receptor interaction, Mucin type O-glycan biosynthesis, Gap junction, and miRNAs involved with renal cell carcinoma. Thus, F-induced cytokines-chemokines suggest subchronic inflammation; detecting miRNAs related to cancer and proliferation indicates a transition from renal epithelium to pathologic tissue after fluoride exposure.

Impact of Chronic Sodium Fluoride Toxicity on Antioxidant Capacity, Biochemical Parameters, and Histomorphology in Cardiac, Hepatic, and Renal Tissues of Wistar Rats

The study was designed to determine the fluoride distribution after its oral exposure in drinking water and its associated impact on biochemical, antioxidant markers and histology in the liver, kidney, and heart of male Wistar rats. On 100 ppm exposure, the highest accretion of fluoride occurred in the liver followed by the kidney and heart. Fluoride exposure significantly (p˂0.05) increased the plasma levels of dehydrogenase, aminotransferases, kidney injury molecule-1 (KIM-1), and other plasma renal biomarkers but decreased the levels of total plasma proteins and albumin in a dose-dependent manner. Reduction (p˂0.05) in the activities of antioxidant enzymes viz. acetylcholinesterase, arylesterase, superoxide dismutase, catalase, glutathione peroxidase, and reductase with increased levels of protein and lipid peroxidation was recorded in the liver, kidney, and heart of fluoride-administered rats. Fluoride exposure (100 ppm) induced lipid peroxidation was highest in kidney (4.4 times) followed by liver (2.6 times) and heart (2.5 times) and as compared to their respective control. The percent rise in protein oxidation at 30% was almost equal in the kidney and liver but was 21.5% in the heart as compared to control. The histopathological alterations observed included congestion and hemorrhage along with degeneration and necrosis of parenchymal cells in hepato-renal tissues and myocardium, severity of which varied in a dose-dependent manner. Taken together, fluoride distribution in the liver, heart, and kidney after chronic fluoride intake correlated well with fluoride-induced hepatic and cardio-renal toxicity in a concentration-dependent manner. These results draw attention that chronic fluoride intake pose a significant health risk for human and animal residents of fluoride endemic areas.

Distribution of Fluoride in Plasma, Brain, and Bones and Associated Oxidative Damage After Induced Chronic Fluorosis in Wistar Rats

The study was aimed to determine fluoride levels in plasma, brain, and bones of Wistar rats following chronic administration of fluoride at different dose levels and the consequent oxidative damage inflicted in these tissues. Brain histomorphology and bone radiographs were also evaluated to assess the extent of damage in these organs. Eighteen rats were randomly divided into three groups with six animals in each group. Group I served as control and groups II and III received 50 and 100 ppm fluoride in tap water, respectively for 180 days. A dose-dependent rise in the levels of fluoride in plasma, brain, and bones was observed in rats. Significant (P < 0.05) alterations in levels of total thiols, glutathione peroxidase, glutathione reductase, acetylcholinesterase, catalase, superoxide dismutase, lipids, as well as protein peroxidation in blood and brain were observed as compared to control in a dose-dependent manner. Radiological examination of bone revealed thinning of bone cortex with haphazard ossification, reduced bone density, and widening of marrow cavity indicating occurrence of flawed bone remodeling upon chronic fluoride exposure. Improper mineralization in bones of intoxicated rats indirectly reflected reduced bone tensile strength. Moreover, alterations in plasma Ca:P ratio and high levels of fluoride in bone ash indicated that chronic fluoride exposure leads to alterations in the bone matrix further corroborating the radio-graphical findings. Additionally, severe microscopic alterations were recorded in the cerebrum and cerebellum of treated rats which included neuronal necrosis, gliosis, spongiosis, perivascular cuffing, congestion, and hemorrhage which correlated well with oxidative changes induced by fluoride intoxication in the brain tissue of rats.

Fluoride exposure and duration and quality of sleep in a Canadian population-based sample

BACKGROUND

Fluoride from dietary and environmental sources may concentrate in calcium-containing regions of the body such as the pineal gland. The pineal gland synthesizes melatonin, a hormone that regulates the sleep-wake cycle. We examined associations between fluoride exposure and sleep outcomes among older adolescents and adults in Canada.

METHODS

We used population-based data from Cycle 3 (2012-2013) of the Canadian Health Measures Survey. Participants were aged 16 to 79 years and 32% lived in communities supplied with fluoridated municipal water. Urinary fluoride concentrations were measured in spot samples and adjusted for specific gravity (UF_SG; n = 1303) and water fluoride concentrations were measured in tap water samples among those who reported drinking tap water (n = 1016). We used multinomial and ordered logistic regression analyses (using both unweighted and survey-weighted data) to examine associations of fluoride exposure with self-reported sleep outcomes, including sleep duration, frequency of sleep problems, and daytime sleepiness. Covariates included age, sex, ethnicity, body mass index, chronic health conditions, and household income.

RESULTS

Median (IQR) UF_SG concentration was 0.67 (0.63) mg/L. Median (IQR) water fluoride concentration was 0.58 (0.27) mg/L among participants living in communities supplied with fluoridated municipal water and 0.01 (0.06) mg/L among those living in non-fluoridated communities. A 0.5 mg/L higher water fluoride level was associated with 34% higher relative risk of reporting sleeping less than the recommended duration for age [unweighted: RRR = 1.34, 95% CI: 1.03, 1.73; p = .026]; the relative risk was higher, though less precise, using survey-weighted data [RRR = 1.96, 95% CI: 0.99, 3.87; p = .05]. UF_SG was not significantly associated with sleep duration. Water fluoride and UF_SG concentration were not significantly associated with frequency of sleep problems or daytime sleepiness.

CONCLUSIONS

Fluoride exposure may contribute to sleeping less than the recommended duration among older adolescents and adults in Canada.

Fluoride-Free Diet Stimulates Pineal Growth in Aged Male Rats

The pineal gland is a naturally calcifying endocrine organ which secretes the sleep-promoting hormone melatonin. Age-related changes of the pineal have been observed, including decreased pinealocyte numbers, increased calcification, and a reduction in melatonin production. Since fluoride is attracted to calcium within the pineal gland, this study sought to examine the effects of a fluoride-free diet on the morphology of the pineal gland of aged male rats (26 months old). All animals had previously been raised on standard fluoridated food and drinking water. These control animals were compared to other animals that were placed on a fluoride-free diet ("fluoride flush") for 4 or 8 weeks. At 4 weeks, pineal glands from fluoride-free animals showed a 96% increase in supporting cell numbers and at 8 weeks a 73% increase in the number of pinealocytes compared to control animals. In contrast, the number of pinealocytes and supporting cells in animals given an initial 4-week fluoride flush followed by a return to fluoridated drinking water (1.2 ppm NaF) for 4 weeks were not different from control animals. Our findings therefore demonstrate that a fluoride-free diet encouraged pinealocyte proliferation and pineal gland growth in aged animals and fluoride treatment inhibited gland growth. These findings suggest that dietary fluoride may be detrimental to the pineal gland.

Effect of hesperidin on fluoride-induced neurobehavioral and biochemical changes in rats

Fluoride is the second largest contaminant of drinking water. Fluoride toxicity is a major concern in the endemic areas where a high amount of fluoride is present in ground water. Oxidative stress has been proposed to be one of the mechanisms of fluoride-induced toxicity. Antioxidant-rich food has been found to alleviate fluoride-induced toxicity. Therefore, in this study, we have examined the effect of hesperidin on fluoride-induced neurobehavioral changes in rats. In the current study, male Sprague-Dawley rats were exposed to sodium fluoride through drinking water (120 ppm). Hesperidin (200 mg kg^-1  d^-1 ; per os) was administered either alone or in combination with fluoride-containing drinking water. Bisphinol A diglycidyl ether (BADGE) was used as peroxisome proliferator-activated receptor-γ (PPAR-γ) antagonist and was administered (10 mg kg^-1  d^-1 ; intraperitoneal injection) with/without hesperidin along with fluoride-containing drinking water. The behavioral changes in the animals were assessed by analyzing rotarod test, novel object recognition test, and forced swim test (FST). After 8 weeks, animals were killed to isolate blood and brain for monitoring biochemical changes. The 8-week exposure of fluoride resulted in motor impairment as observed with reduced fall time in rotarod test, memory impairment as observed with reduced preference index in novel object recognition test, and depression-like behavior as observed with reduced mobility index in the FST. Treatment with hesperidin improved neurobehavioral impairment along with restoration in brain biochemical changes (ie, acetylcholinesterase activity and antioxidant and oxidative stress parameters). The protective effect of hesperidin was reversed by coadministration of BADGE. The neuroprotective effect of hesperidin appears to be contributed through PPAR-γ receptor.

Fluoride and Pineal Gland

The pineal gland is an endocrine gland whose main function is the biosynthesis and secretion of melatonin, a hormone responsible for regulating circadian rhythms, e.g., the sleep/wake cycle. Due to its exceptionally high vascularization and its location outside the blood–brain barrier, the pineal gland may accumulate significant amounts of calcium and fluoride, making it the most fluoride-saturated organ of the human body. Both the calcification and accumulation of fluoride may result in melatonin deficiency.

Melatonin Ameliorates Neuropharmacological and Neurobiochemical Alterations Induced by Subchronic Exposure to Arsenic in Wistar Rats

An experimental study was conducted in Wistar rats to characterize the arsenic ("As")-induced alterations in neurobiochemistry in brain and its impact on neuropharmacological activities with or without the melatonin (MLT) as an antioxidant given exogenously. Male Wistar rats were randomly divided in to four groups of six each. Group I served as untreated control, while group II received As [sodium (meta) arsenite; NaAsO₂] at 10 mg/kg bw (p.o.) for a period of 56 days. Experimental rats in group III received treatment similar to group II but in addition received MLT at 10 mg/kg bw (p.o.) from day 32 onwards. Rats in group IV received MLT alone from day 32 onwards similar to group III. Sub-chronic exposure to As (group II) significantly reduced both voluntary locomotor and forced motor activities and melatonin supplementation (group III) showed a significant improvement in motor activities, when subjected to test on day 42 or 56. Rats exposed to As showed a significant increase in anxiety level and a marginal nonsignificant reduction in pain latency. Sub-chronic administration of As induced (group II) significant increase in the levels of thiobarbituric acid reactive substance (TBARS) called malondialdehyde (MDA) in the brain tissue (5.55 ± 0.57 nmol g^-1), and their levels were significantly reduced by MLT supplementation (group III 3.96 ± 0.15 nmol g^-1). The increase in 3-nitrotyrosine (3-NT) levels in As-exposed rats indicated nitrosative stress due to the formation of peroxynitrite (ONOO^-). However, exogenously given MLT significantly reduced the 3-NT formation as well as prostaglandin (PGE₂) levels in the brain. Similarly, MLT administration have suppressed the release of pro-inflammatory cytokines (viz., IL-1β, IL-6, and TNF-α) and amyloid-β_1-40 (Aβ) deposition in the brain tissues of experimental rats. To conclude, exogenous administration of melatonin can overcome the sub-chronic As-induced oxidative and nitrosative stress in the CNS, suppressed pro-inflammatory cytokines, and restored certain disturbed neuropharmacological activities in Wistar rats.

Fluorine may intensify the mechanisms of polycystic ovary syndrome (PCOS) development via increased insulin resistance and disturbed thyroid-stimulating hormone (TSH) synthesis even at reference levels

We were interested whether fluorine, at the concentrations regarded as normal, can play a role in PCOS pathogenesis. The effect was not described in PCOS. Women with PCOS were diagnosed according to Rotterdam's criteria. The average age of 40 examined women with PCOS was 26.3 ± 5.5 years, BMI-29.16 ± 0.8, WHR-0.91 ± 0.08. Main Outcome Measures: ECLIA was used to analyse testosterone, FSH, LH, oestradiol, TSH, prolactin, insulin and SHBG. Fluorine content was analysed by potentiometry using ion selective electrode. Fluorine content in serum of women with PCOS did not statistically significantly differ from that of the control group and amounted to 0.224 ± 0.043 and 0.228 ± 0.023 ppm, respectively. There were significant differences in the levels of TSH and HOMA-IR between the groups. Based on the correlation matrix, a negative correlation with the level of SHBG protein and the level of glucose on fasting was showed for the group with a lower of fluorine, and a positive correlation with HDL level was observed in the group with higher concentration of fluorine. In the phenotype with a higher level of androgens, there was a negative correlation with triglycerides level and a positive correlation with HDL. Fluorine, even in concentrations regarded as proper, takes part in PCOS pathogenesis. It increases the synthesis of TSH and increases insulin resistance. Higher insulin resistance leads to the reduced synthesis of SHBG transport protein. Therefore, the key factor in PCOS pathogenesis is testosterone, but fluorine facilitates disruptions in carbohydrates and lipids metabolism leading to increased levels of androgens in blood.

Fluoride induces apoptosis via inhibiting SIRT1 activity to activate mitochondrial p53 pathway in human neuroblastoma SH-SY5Y cells

There has been a great concern about the neurotoxicity of fluoride since it can pass through the blood-brain barrier and accumulate in the brain. It has been suggested that apoptosis plays a vital role in neurotoxicity of fluoride. However, whether p53-mediated apoptotic pathway is involved is still unclear. Our results showed that apoptosis was induced after treatment with 40 and 60 mg/L of NaF for 24 h in human neuroblastoma SH-SY5Y cells. Exposure to 60 mg/L of NaF for 24 h significantly upregulated the levels of p53 and apoptosis-related proteins including PUMA, cytochrome c (cyto c), cleaved caspase-3 and cleaved PARP, whereas downregulated Bcl-2 in SH-SY5Y cells. Meanwhile, fluoride increased p53 nuclear translocation, cyto c release from mitochondria to cytoplasm and mitochondrial translocation of Bax in SH-SY5Y cells. Fluoride-induced increases of apoptotic rates and apoptosis-related protein levels were significantly attenuated by inhibiting p53 transcriptional activity with pifithrin-α. In addition, fluoride inhibited the deacetylase activity of SIRT1 and increased p53 (acetyl K382) level in SH-SY5Y cells. Apoptosis and upregulation of cleaved caspase-3, cleaved PARP and p53 (acetyl K382) induced by fluoride could be ameliorated by SIRT1 overexpression or its activator resveratrol in SH-SY5Y cells. Taken together, our study demonstrates that fluoride induces apoptosis by inhibiting the deacetylase activity of SIRT1 to activate mitochondrial p53 pathway in SH-SY5Y cells, which depends on p53 transcriptional activity. Thus, SIRT1 may be a promising target to protect against neurotoxicity induced by fluoride.

Sodium fluoride causes oxidative stress and apoptosis in the mouse liver

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.

Abnormal spermatogenesis following sodium fluoride exposure is associated with the downregulation of CREM and ACT in the mouse testis

cAMP response element modulator (CREM) is involved in regulating gene expression in normal spermatogenesis. The transcriptional activity of CREM is partly regulated by activator of CREM in the testis (ACT). To investigate the effects of different concentrations of sodium fluoride (NaF) on the gene and protein expression of CREM and ACT in the mouse testis, sexually mature male Kunming mice were exposed to 50, 100, or 150 mg/L NaF in their drinking water for 90 days. NaF reduced the sperm count and viability and increased the percentage of malformed sperm in a dose-dependent manner. The mRNA expression of CREM and ACT was markedly downregulated in the NaF-treated groups. Furthermore, immunohistochemistry revealed that CREM and ACT proteins were decreased significantly in the 50, 100, and 150 mg/L NaF-treated groups compared to the control group. These findings indicate that the decreased gene and protein expression of CREM and ACT in the testis is associated with an impairment of reproductive functions by NaF.

Melatonin protect the development of preimplantation mouse embryos from sodium fluoride-induced oxidative injury

Recently study shows that melatonin can protect embryos from the culture environment oxidative stress. However, the protective effect of melatonin on the mouse development of preimplantation embryos under sodium fluoride (NaF) induced oxidative stress is still unclear. Here, we showed that exposure to NaF significantly increased the reactive oxygen species (ROS) level, decreased the blastocyst formation rates, and increased the fragmentation, apoptosis and retardation of blastocysts in the development of mouse preimplantation embryos. However, the protective of melatonin remarkable increased the of blastocyst formation rates, maintained mitochondrial function and total antioxidant capacity by clearing ROS. Importantly the data showed that melatonin improved the activity of enzymatic antioxidants, including glutathione(GSH), superoxide dismutase(SOD), and malonaldehyde (MDA), and increased the expression levels of antioxidative genes. Taken together, our results indicate that melatonin prevent NaF-induced oxidative damage to mouse preimplantation embryo through down regulation of ROS level, stabilization of mitochondrial function and modulation of the activity of antioxidases and antioxidant genes.

Effect of deltamethrin and fluoride co-exposure on the brain antioxidant status and cholinesterase activity in Wistar rats

The study evaluated the effect of commercial preparation of deltamethrin, Butox^®, and fluoride (F^-) co-exposure on the brain antioxidant status and cholinesterase activity in rats. Group A was untreated. Group B was gavaged Butox^®, providing deltamethrin at the dose rate of 1.28 mg per kg body weight per day. Group C was administered F^-, as NaF, in drinking water providing 20 ppm F^-. Group D received both deltamethrin and F^- at the same dosages as groups B and C, respectively. Although, glutathione S-transferase activity was induced only in Butox^® alone treated group, the activities of superoxide dismutase and catalase were inhibited in all treatment groups when compared to the control group. Elevated lipid peroxidation was observed in the groups exposed to F^-. The activity of erythrocyte acetylcholinesterase (AChE) was inhibited in Butox^® treated groups, whereas brain AChE activity was inhibited in all treatment groups. In conclusion, both deltamethrin (given as Butox^®) and F^- inhibit AChE activity and produce oxidative stress in brain with F^- producing more oxidative damage. However, compared to the individual exposures, the co-exposure of these chemicals does not produce any exacerbated alteration in these biochemical parameters.

Protective Role of tert-Butylhydroquinone Against Sodium Fluoride-Induced Oxidative Stress and Apoptosis in PC12 Cells

The neurotoxicity of fluoride is associated with oxidative stress due to imbalance between production and removal of reactive oxygen species (ROS). In contrast, induction of detoxifying and antioxidant genes through activation of NF-E2-related factor 2 (Nrf2) has been implicated in preventing oxidative stress and apoptosis in neurodegenerative diseases. The present study aimed to investigate the possible neuroprotective role of tert-butylhydroquinone (tBHQ), a general Nrf2 activator, on sodium fluoride (NaF)-induced oxidation damage and apoptosis in neuron-like rat pheochromocytoma (PC12) cells. Pretreatment with tBHQ protected PC12 cells against NaF-induced cytotoxicity as measured by MTT assay and apoptosis detection, simultaneously, inhibited NaF-induced overproduction of intracellular ROS and reduction of total glutathione content. Furthermore, NaF or tBHQ induced the stabilization of Nrf2, and enhanced expression of heme oxygenase-1 (HO-1) and γ-glutamylcysteine synthetase (γ-GCS) as a consequence of Nrf2 inducing. These findings indicated that tBHQ pretreatment conferred protective effect on PC12 cells against NaF-induced apoptotic cell death and oxidation-redox imbalance through stabilization of Nrf2 and elevation of downstream HO-1 and γ-GCS expressions.

Activation of the AGE/RAGE system in the brains of rats and in SH-SY5Y cells exposed to high level of fluoride might connect to oxidative stress

To explore the mechanisms by which chronic fluorosis damages the brain, we determined the levels of the advanced glycation end-products (AGEs), the receptor for AGE (RAGE), NADPH oxidase-2 (NOX2), reactive oxygen species (ROS) and malondialdehyde (MDA) in the brains of rats and/or SH-SY5Y cells exposed to different levels of sodium fluoride (5 or 50 ppm in the drinking water for 3 or 6 months and in the incubation medium for as long as 48 h, respectively). The levels of AGEs, RAGE and NOX2 protein and mRNA were measured by an Elisa assay, Western blotting and real-time PCR, respectively. The ROS content was assessed by fluorescein staining and MDA by thiobarbituric acid-reactive substance assay. In comparison to the unexposed controls, the protein and mRNA levels of AGEs, RAGE and NOX2 in the brains of rats after 6 months of exposure and in SH-SY5Y cells following high-dose exposure to fluoride were elevated. In contrast, no significant changes in these parameters were detected in the rats exposed for 3 months. In addition, the levels of ROS and MDA in the SH-SY5Y cells exposed to high-dose of fluoride were elevated in a manner that correlated positively with the levels of AGE/RAGE. In conclusion, our present results indicate that excessive fluoride can activate the AGE/RAGE pathway, which might in turn enhance oxidative stress.

Fluoride concentrations in the pineal gland, brain and bone of goosander (Mergus merganser) and its prey in Odra River estuary in Poland

The aim of the study was to investigate fluoride concentrations in bone, brain and pineal gland of goosander Mergus merganser wintering in the Odra estuary (Poland) as well as in fish originating from its digestive tract. The fluoride concentrations were determined with potentiometric method. Medians of concentrations in goosander had the highest and the lowest values in pineal gland and brain (>760 and <190 mg/kg, respectively). Fluoride concentration in the pineal gland was significantly greater than in the bone and the brain of the duck. In fish, the fluoride concentration ranged from 37 to 640 mg/kg and significant correlation was revealed between the fluoride concentration and fish weight and length. Based on own results and data of other authors, a daily fluoride intake by the goosander in the Odra estuary was estimated at 15 mg. So high fluoride concentrations like in the duck have not been found in mammal brains.

Effect of resveratrol on hematological and biochemical alterations in rats exposed to fluoride

We investigated the protective effects of resveratrol on hematological and biochemical changes induced by fluoride in rats. A total of 28 rats were divided into 4 groups: control, resveratrol, fluoride, and fluoride/resveratrol (n = 7 each), for a total of 21 days of treatment. Blood samples were taken and hematological and biochemical parameters were measured. Compared to the control group, the fluoride-treated group showed significant differences in several hematological parameters, including decreases in WBC, RBC, and PLT counts and neutrophil ratio. The group that received resveratrol alone showed a decrease in WBC count compared to the control group. Furthermore, in comparison to the control group, the fluoride group showed significantly increased ALT enzyme activity and decreased inorganic phosphorus level. The hematological and biochemical parameters in the fluoride + resveratrol treated group were similar to control group. In the fluoride + resveratrol group, resveratrol restored the changes observed following fluoride treatment, including decreased counts of WBC, RBC, and PLT, decreased neutrophil ratio and inorganic phosphorus levels, and elevated ALT enzyme activity. The present study showed that fluoride caused adverse effects in rats and that resveratrol reduced hematological and biochemical alterations produced by fluoride exposure.

Protective effect of resveratrol on sodium fluoride-induced oxidative stress, hepatotoxicity and neurotoxicity in rats

Protective effect of resveratrol on sodium fluoride-induced oxidative stress, hepatotoxicity and neurotoxicity were studied in rats. A total of 28 Wistar albino male rats were used. Four study groups were randomly formed with seven animals in each. The groups were treated for 21days with distilled water (control group), with water containing 100ppm fluoride (fluoride group), with resveratrol (12.5mg/kg i.p., resveratrol group), or with 100ppm fluoride+12.5mg/kg resveratrol i.p. (fluoride+resveratrol group). At the end of the trial, blood samples were collected by cardiac puncture and tissue samples were taken simultaneously. The total antioxidant and oxidant status in plasma and tissues as well as plasma 8-hydroxydeoxyguanosine levels were measured. Histopathological analyses of rat liver and brain tissues were performed in all groups to identify any changes. In the fluoride group, the total oxidant levels increased in plasma, liver and brain and total antioxidant levels decreased, as did the plasma 8-hydroxy-deoxyguanosine levels. These changes were prevented by co-administration of resveratrol. In addition, fluoride-associated severe histopathological changes in brain and liver tissues were not observed in the fluoride+resveratrol group. Consequently, these data suggested that resveratrol had beneficial effects in alleviating fluoride-induced oxidative stress.

Sodium fluoride activates ERK and JNK via induction of oxidative stress to promote apoptosis and impairs ovarian function in rats

The toxicity of sodium fluoride (NaF) to female fertility is currently recognized; however, the mechanisms are unclear. Previously, we reported a reduction in successful pregnancy rates, ovarian atrophy and dysfunction following exposure to NaF. The purpose of this study was to elucidate the underlying molecular mechanisms. Female Sprague-Dawley rats (10 rats/group) received 100 or 200mg/L NaF in their drinking water for 6 months or were assigned to an untreated control group. Apoptotic indices and oxidative stress indicators in blood and ovarian tissue were analyzed following sacrifice. The results confirmed the NaF-induced ovarian apoptosis, with concomitant activation of oxidative stress. Further investigations in ovarian granular cells showed that exposure to NaF activated extracellular regulated protein kinase (ERK) and c-Jun NH2 kinase (JNK), disrupting the ERK and JNK signaling pathways, while p38 and PI3K remained unchanged. These data demonstrated that oxidative stress may play a key role in NaF-induced ovarian dysfunction by activating the apoptotic ERK and JNK signaling pathways.

Effects of melatonin and epiphyseal proteins on fluoride-induced adverse changes in antioxidant status of heart, liver, and kidney of rats

Several experimental and clinical reports indicated the oxidative stress-mediated adverse changes in vital organs of human and animal in fluoride (F) toxicity. Therefore, the present study was undertaken to evaluate the therapeutic effect of buffalo (Bubalus bubalis) epiphyseal (pineal) proteins (BEP) and melatonin (MEL) against F-induced oxidative stress in heart, liver, and kidney of experimental adult female rats. To accomplish this experimental objective, twenty-four adult female Wistar rats (123–143 g body weights) were divided into four groups, namely, control, F, F + BEP, and F + MEL and were administered sodium fluoride (NaF, 150 ppm elemental F in drinking water), MEL (10 mg/kg BW, i.p.), and BEP (100 µg/kg BW, i.p.) for 28 days. There were significantly (P < 0.05) high levels of lipid peroxidation and catalase and low levels of reduced glutathione, superoxide dismutase, glutathione reductase, and glutathione peroxidase in cardiac, hepatic, and renal tissues of F-treated rats. Administration of BEP and MEL in F-treated rats, however, significantly (P < 0.05) attenuated these adverse changes in all the target components of antioxidant defense system of cardiac, hepatic, and renal tissues. The present data suggest that F can induce oxidative stress in liver, heart, and kidney of female rats which may be a mechanism in F toxicity and these adverse effects can be ameliorated by buffalo (Bubalus bubalis) epiphyseal proteins and melatonin by upregulation of antioxidant defense system of heart, liver, and kidney of rats.

Ameliorative effects of oleanolic acid on fluoride induced metabolic and oxidative dysfunctions in rat brain: Experimental and biochemical studies

Beneficial effects of oleanolic acid on fluoride-induced oxidative stress and certain metabolic dysfunctions were studied in four regions of rat brain. Male Wistar rats were treated with sodium fluoride at a dose of 20 mg/kg b.w./day (orally) for 30 days. Results indicate marked reduction in acidic, basic and neutral protein contents due to fluoride toxicity in cerebrum, cerebellum, pons and medulla. DNA, RNA contents significantly decreased in those regions after fluoride exposure. Activities of proteolytic enzymes (such as cathepsin, trypsin and pronase) were inhibited by fluoride, whereas transaminase enzyme (GOT and GPT) activities increased significantly in brain tissue. Fluoride appreciably elevated brain malondialdehyde level, free amino acid nitrogen, NO content and free OH radical generation. Additionally, fluoride perturbed GSH content and markedly reduced SOD, GPx, GR and CAT activities in brain tissues. Oral supplementation of oleanolic acid (a plant triterpenoid), at a dose of 5mg/kgb.w./day for last 14 days of fluoride treatment appreciably ameliorated fluoride-induced alteration of brain metabolic functions. Appreciable counteractive effects of oleanolic acid against fluoride-induced changes in protein and nucleic acid contents, proteolytic enzyme activities and other oxidative stress parameters indicate that oleanolic acid has potential antioxidative effects against fluoride-induced oxidative brain damage.

A role of fluoride on free radical generation and oxidative stress in BV-2 microglia cells

The generation of ROS and lipid peroxidation has been considered to play an important role in the pathogenesis of chronic fluoride toxicity. In the present study, we observed that fluoride activated BV-2 microglia cell line by observing OX-42 expression in immunocytochemistry. Intracellular superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), reactive oxygen species (ROS), superoxide anions (O₂^∙−), nitric oxide synthase (NOS), nitrotyrosine (NT) and nitric oxide (NO), NOS in cell medium were determined for oxidative stress assessment. Our study found that NaF of concentration from 5 to 20 mg/L can stimuli BV-2 cells to change into activated microglia displaying upregulated OX-42 expression. SOD activities significantly decreased in fluoride-treated BV-2 cells as compared with control, and MDA concentrations and contents of ROS and O₂^∙− increased in NaF-treated cells. Activities of NOS in cells and medium significantly increased with fluoride concentrations in a dose-dependent manner. NT concentrations also increased significantly in 10 and 50 mg/L NaF-treated cells compared with the control cells. Our present study demonstrated that toxic effects of fluoride on the central nervous system possibly partly ascribed to activiting of microglia, which enhanced oxidative stress induced by ROS and reactive nitrogen species.

Protective role of gallic acid on sodium fluoride induced oxidative stress in rat brain

Gallic acid is known as a potent antioxidant active compound of the edible and medicinal plant Peltiphyllum peltatum. The main objective of this study was to evaluate the neuroprotective effects of gallic acid against sodium fluoride induced oxidative stress in rat brain. Gallic acid (10 and 20 mg/kg) and vitamin C (10 mg/kg) were intraperitoneally administrated for 1 week prior to sodium fluoride intoxication. After the treatment period, brain tissues were collected and homogenized, and antioxidant parameters were measured in the homogenates. The level of thiobarbituric acid reactive substances in sodium fluoride intoxicated rats (42.04 ± 2.14 nmol MDA eq/g tissue, p < 0.01 vs. normal) increased compared to the normal rats (35.99 ± 1.08 nmol MDA eq/g tissue). Pretreatment with gallic acid at 20 mg/kg was exhibited significant reduction in the thiobarbituric acid reactive substances level (37.06 ± 1.4 nmol MDA eq/g tissue, p > 0.05 vs. normal). This increasing in thiobarbituric acid reactive substances level was accompanied with a decrease in the level of reduced glutathione (6.74 ± 0.28 μg/mg of protein, p < 0.001 vs. normal), superoxide dismutase (53.24 ± 1.62 U/mg of protein, p < 0.001 vs. normal) and catalase (70.73 ± 2.94 μmol/min/mg of protein p < 0.001 vs. normal) activities in sodium fluoride intoxicated rat. Gallic acid at 20 mg/kg was significantly modified the level of reduced glutathione (11.02 ± 0.53 μg/mg of protein, p < 0.05 vs normal) and catalase activity (89.22 ± 3.67 μmol/min/mg of protein, p > 0.05 vs. normal) in rat brain. However, gallic acid at 20 mg/kg was significantly more effective in retrieving superoxide dismutase (124.78 ± 5.7 U/mg of protein) activity than vitamin C (115.5 ± 4.97 U/mg of protein).

Buffalo (Bubalus bubalis) epiphyseal proteins counteract arsenic-induced oxidative stress in brain, heart, and liver of female rats

Arsenic (As) toxicity through induction of oxidative stress is a well-known mechanism of organ toxicity. To address this problem, buffalo epiphyseal proteins (BEP, at 100 μg/kg BW, i.p. for 28 days) were administered intraperitoneally to female Wistar rats exposed to As (100 ppm sodium arsenite via drinking water for 28 days). Arsenic exposure resulted in marked elevation in lipid peroxidation in brain, cardiac, and hepatic tissues, whereas significant (p < 0.05) adverse change in catalase, superoxide dismutase, glutathione reductase, glutathione peroxidase, and reduced glutathione level were observed in cardiac, hepatic, and brain tissues of As-administered animals. BEP significantly (p < 0.05) counteracted all the adverse changes in antioxidant defense system brought about by As administration. Based on these results, we consider BEP as a potent antioxidant to be used for protection from arsenic-induced oxidative stress related damage of vital organs.

Effects of NaF on the expression of intracellular Ca2+ fluxes and apoptosis and the antagonism of taurine in murine neuron

Sodium fluoride (NaF) has been shown to be cytotoxic and produces inflammatory responses in humans. However, the cellular mechanisms underlying the neurotoxicity of fluoride are unclear. The present study aims to define a possible mechanism of NaF-induced neurotoxicity with respect to apoptosis and intracellular Ca(2+) fluxes. Meanwhile, the cytoprotective role of taurine in intervention, the toxic effects of NaF on neurons, is also investigated. The primary mouse hippocampal neurons were incubated with 5.0, 10.0, 15.0, 20.0, and 40.0 mg NaF/L in vitro and Kunming mice were exposed to 0.7, 2.8, and 11.2 mg NaF/kg and 7.5 and 15.0 mg taurine/kg in vivo. Intracellular Ca(2+) fluxes and apoptosis were assayed. Compared with the control, the significant differences of intracellular Ca(2+) concentration and apoptotic peaks were found in 5.0-40.0 mg NaF/L groups in vitro (p < 0.01) and in the groups of 0.7-11.2 mg NaF/kg in vivo (p < 0.01). Instantaneously, taurine can minimize F-induced neurotoxicity significantly at doses of 7.5 and 15.0 mg/kg (p < 0.01). The present study herein suggested that NaF could increase intercellular Ca(2+) concentration leading to apoptosis. Meanwhile, taurine could minimize neurotoxicity caused by fluoride through decreasing intercellular Ca(2+) concentration and cell apoptosis.

Evaluation of total oxidative status and total antioxidant capacity in patients with endemic fluorosis

The objective of the present study was to determine the plasma total oxidative status (TOS) and total antioxidant capacity (TAC) in patients with endemic fluorosis. A total of 79 (35 males and 44 females; mean age 44.0 ± 11.9 years) patients with endemic fluorosis and 55 (23 males and 32 females; mean age 48.3 ± 8.5 years) age-, sex- and body mass index-matched healthy controls were included in this study. The urine fluoride levels and plasma TOS and TAC levels were measured. The urine fluoride levels of fluorosis patients were significantly higher than control subjects as expected (1.91 ± 0.15 vs. 0.49 ± 0.13 mg/L, respectively; p < 0.001). TOS was significantly higher in fluorosis group than in control group (17.55 ± 3.82 vs. 15.06 ± 4.31 μmol H(2)O(2) Eq/L, respectively; p = 0.001). TAC was significantly lower in fluorosis group than in control group (1.60 ± 0.36 vs. 1.82 ± 0.51 mmol Trolox Eq/L, respectively; p = 0.004). Oxidative stress index (OSI) was significantly higher in fluorosis group than in control group (11.5 ± 3.8 vs. 8.8 ± 3.7, respectively; p < 0.001). Correlation analysis in all the groups indicated that TAC was negatively correlated with urine fluoride (r = -0.25, p = 0.003), TOS was positively correlated with urine fluoride (r = 0.34, p < 0.001) and OSI was positively correlated with urine fluoride (r = 0.36, p < 0.001). The results of our study demonstrate that oxidative stress plays an important role in the pathogenesis of the endemic fluorosis.

Serum copper, zinc, and magnesium levels in patients with chronic fluorosis

Although there are many studies on effect of fluoride on trace elements in experimental animals, few studies exist on serum trace elements levels in patients with endemic fluorosis. We aimed to determine the serum levels of trace elements including serum copper (Cu), zinc (Zn), and serum levels of minerals including calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), potassium (K) in patients with endemic fluorosis. The study group consisted of 30 patients with endemic fluorosis (17 females, 13 males, mean age 33.53±9.85 years). An age, gender, and body mass index matched 30 healthy volunteers comprised control group (21 females, ten males with a mean age 33.93±7.39 years). Urine fluoride levels of chronic fluorosis patients were significantly higher than that of control subjects as expected (1.92±0.10 mg/l vs. 0.41±0.09 mg/l, respectively; P<0.001). Serum Cu levels (89.14±16.77 μg/dL vs. 102.69±25.04 μg/dL, respectively, P=0.017), serum Zn levels (77.98±20.58 μg/dL vs. 94.57±35.87μg/dL, respectively, P=0.032), and serum Mg levels (1.92±0.18 mg/dL vs. 2.07±0.31 mg/dL, respectively, p=0.022) was significantly lower in chronic fluorosis patients than in controls. There were no statistically significant differences between the fluorosis group and control group with respect to serum levels of Na, K, Ca, and P. We concluded that chronic fluorosis is associated with reduced serum levels of Cu, Zn, and Mg.

Effect of pineal proteins at different dose level on fluoride-induced changes in plasma biochemicals and blood antioxidants enzymes in rats

Pineal glands secrets melatonin and various proteins and peptides which has many physiological functions. In keeping with this view, present experiment was conducted to know the effect of buffalo (Bubalus bubalis) pineal proteins (PP) at different dose level on fluoride-induced changes in plasma biochemicals and blood antioxidants enzymes in female rats. For this, we took 30 adult female Wistar rats (133-145 g body weights, BW) and divided into five groups (control, group I; 150 ppm fluoride (F), group II; F+ 50 µg pineal proteins, group III; F+ 100 µg PP, group IV; F+ 200 µg PP, group V). We administered fluoride (150 ppm, drinking water) and F+ pineal proteins at 50, 100, and 200 µg/kg BW, i.p. daily for 21 days. Blood samples were collected at the end of the experiments to estimate plasma glucose, proteins, F, lipid peroxidation (LPO), alkaline phosphatase (ALP), and acetyl cholinesterase (AChE) activity. Red blood cells (RBCs) were separated for analysis of LPO, AChE, catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPx), and glutathione reductase (GR) in different groups of animals. Total plasma glucose and protein level did not significantly change in F-treated rats. Plasma ALP and F level were significantly (p < 0.05) high in group II as compared with control and groups III, IV, and V. Administration of PP at different dose level significantly (p < 0.05) reduced the F concentration and ALP activity. Plasma and RBCs AChE activity was significantly (p < 0.05) reduced in F-treated animals as compared with control rats and significantly (p < 0.05) elevated on exogenous administration of PP (groups III and IV). Plasma and RBCs LPO level was significantly (p < 0.05) high in F-alone-treated rats, and PP caused significant (p < 0.05) reduction of LPO in groups IV and V. However, PP treatment in group IV brought better amelioration of F-induced high LPO than in groups III and V. At no dose level, PP-ameliorated F-induced depression of RBCs GSH, CAT, GR, and GPx level. Interestingly, SOD activity was elevated in dose-dependent manner at different dose level of PP in groups III, IV, and V than control and F-administered rats. These findings clearly indicate the beneficial effects of buffalo pineal proteins on fluoride-induced adverse changes in certain plasma biochemical and blood antioxidant systems of rats. It further indicates that PP has dose-dependent ameliorative function against F-induced adverse effects in plasma and blood.

Cerebral epiphyseal proteins and melatonin modulate the hepatic and renal antioxidant defense of rats

The cerebral epiphysis (pineal gland) secrets melatonin and number of other proteins and peptides. It was thus hypothesized that antioxidant properties of epiphyseal proteins and melatonin could potentially benefit from exogenous therapies. In view of the therapeutic potential of these proteins, the present experiment was conducted to investigate the effect of buffalo epiphyseal proteins (BEP, at 100 μg/kg BW, i.p.) and melatonin (MEL, at 10 mg/kg BW, i.p) on changes in hepatic and renal antioxidant enzymes of adult female Wistar rats. Buffalo epiphyseal proteins significantly (P < .05) increased hepatic lipid peroxidation (LPO), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), reduced glutathione (GSH), and renal LPO, catalase (CAT), GR, GSH, GPx levels as compared to control animals. Similarly, MEL treatment significantly (P < .05) up-regulated hepatic SOD and GPx activity, whereas CAT, GR, GPx, and GSH levels in renal tissues were increased while SOD and LPO remained unaffected. Buffalo epiphyseal protein treatment produced greater effects on hepatic GPx and renal CAT and GSH levels than did MEL. These findings support the conclusion that buffalo epiphyseal proteins and melatonin activate a number of antioxidant mechanisms in hepatic and renal tissues.

Pineal proteins upregulate specific antioxidant defense systems in the brain

The neuroendocrine functions of the pineal affect a wide variety of glandular and nervous system processes. Beside melatonin (MEL), the pineal gland secretes and expresses certain proteins essential for various physiological functions. It has been suggested that the pineal gland may also have an antioxidant role due to secretory product other than MEL. Therefore, the present study was designed to study the effect of buffalo (Bubalus bubalis) pineal proteins (PP) on the antioxidant defense system in the brain of female rats. The twenty-four rats were taken in present study and were divided into four groups: control (0 day), control (28 day), vehicle control and buffalo PP. The PP was injected 100 µg/kg BW intraperitoneal (i.p.) daily for 28 days. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione reductase (GR) and reduced glutathione (GSH) concentration and the levels of lipid peroxidation (LPO) in the brain tissue were measured to assess the antioxidant systems. These enzymes protect from adverse effects of free radicals and help in amelioration of oxidative stress. Buffalo pineal proteins administration did not cause any effect on brain LPO, whereas GPx, GR and GSH were significantly (p < 0.05) decreased. However, SOD and CAT activities were increased to significant levels than the control in PP treated rats. Our study herein suggested that buffalo (Bubalus bubalis) pineal proteins upregulates specific antioxidant defense systems and can be useful in control of various oxidative stress-induced neuronal diseases.

Decreased antioxidase activities and oxidative stress in the spleen of chickens fed on high-fluorine diets

Three hundred one-day-old avian broilers were divided into four equal groups of 75 animals that were fed for 42 days as follows: a control diet containing 23 mg fluorine (F)/kg and three high F diets containing 400, 800, and 1200 mg F/kg, respectively, for high F groups I, II, and III. The superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were greatly decreased, while the malondialdehyde (MDA) contents were markedly increased in high F groups II and III. At the same time, mitochondrial injury and expanded endocytoplasmic reticulum were obviously observed in high F groups II and III, and the fluoride contents both in spleen and serum were significantly increased in the three high F groups when compared with those of control group. The results showed that excess dietary F in the range of 800−1200 mg/kg caused obvious oxidative stress, which provided a possible pathway for the apoptosis of splenocytes in chickens.