Fluoride and aluminium disturb neuronal morphology, transport functions, cholinesterase, lysosomal and cell cycle activities

Trace Elements Levels in Major Depressive Disorder-Evaluation of Potential Threats and Possible Therapeutic Approaches

The multifactorial etiology of major depressive disorder (MDD) includes biological, environmental, genetic, and psychological aspects. Recently, there has been an increasing interest in metallomic studies in psychiatry, aiming to evaluate the role of chosen trace elements in the MDD etiology as well as the progression of symptoms. This narrative review aims to summarize the available literature on the relationship between the concentration of chosen elements in the serum of patients with MDD and the onset and progression of this psychiatric condition. The authors reviewed PubMed, Web of Science, and Scopus databases searching for elements that had been investigated so far and further evaluated them in this paper. Ultimately, 15 elements were evaluated, namely, zinc, magnesium, selenium, iron, copper, aluminium, cadmium, lead, mercury, arsenic, calcium, manganese, chromium, nickel, and phosphorus. The association between metallomic studies and psychiatry has been developing dynamically recently. According to the results of current research, metallomics might act as a potential screening tool for patients with MDD while at the same time providing an assessment of the severity of symptoms. Either deficiencies or excessive amounts of chosen elements might be associated with the progression of depressive symptoms or even the onset of the disease among people predisposed to MDD.

Aluminium in the Human Brain: Routes of Penetration, Toxicity, and Resulting Complications

Aluminium (Al) is the most ubiquitous metal in the Earth's crust. Even though its toxicity is well-documented, the role of Al in the pathogenesis of several neurological diseases remains debatable. To establish the basic framework for future studies, we review literature reports on Al toxicokinetics and its role in Alzheimer's disease (AD), autism spectrum disorder (ASD), alcohol use disorder (AUD), multiple sclerosis (MS), Parkinson's disease (PD), and dialysis encephalopathy (DE) from 1976 to 2022. Despite poor absorption via mucosa, the biggest amount of Al comes with food, drinking water, and inhalation. Vaccines introduce negligible amounts of Al, while the data on skin absorption (which might be linked with carcinogenesis) is limited and requires further investigation. In the above-mentioned diseases, the literature shows excessive Al accumulation in the central nervous system (AD, AUD, MS, PD, DE) and epidemiological links between greater Al exposition and their increased prevalence (AD, PD, DE). Moreover, the literature suggests that Al has the potential as a marker of disease (AD, PD) and beneficial results of Al chelator use (such as cognitive improvement in AD, AUD, MS, and DE cases).

Effects of chronic fluorosis on the brain

This article reviews the effects of chronic fluorosis on the brain and possible mechanisms. We used PubMed, Medline and Cochraine databases to collect data on fluorosis, brain injury, and pathogenesis. A large number of in vivo and in vitro studies and epidemiological investigations have found that chronic fluorosis can cause brain damage, resulting in abnormal brain structure and brain function.Chronic fluorosis not only causes a decline in concentration, learning, and memory, but also has mental symptoms such as anxiety, tension, and depression. Several possible mechanisms that have been proposed: the oxidative stress and inflammation theory, neural cell apoptosis theory, neurotransmitter imbalance theory, as well as the doctrine of the interaction of fluorine with other elements. However, the specific mechanism of chronic fluorosis on brain damage is still unclear. Thus, a better understanding of the mechanisms via which chronic fluorosis causes brain damage is of great significance to protect the physical and mental health of people in developing countries, especially those living in the endemic areas of fluorosis. In brief, further investigation concerning the influence of fluoride on the brain should be conducted as the neural damage induced by it may bring about a huge problem in public health, especially considering growing environmental pollution.

Fluorosilicic acid and cotinine, separately and in combination, induce genotoxicity and telomeric reduction in human osteoblast cell line MG63

Skeletal fluorosis is a severe case in which bone deformations and bone tissue weakening occur due to excessive fluorine deposition. Recently, data on smoking have been published that smoke constituents can indirectly influence bone mass and interfere in the metabolism of fluorides in humans. Thus, the present in vitro study aimed to assess the genetic instability in human osteoblast MG63 cells exposed to fluorosilicic acid (FA) and cotinine (COT), separately and in combination, in concentrations found in human plasma. For this, cell cytotoxicity was performed by MTT assay; DNA damage was performed by alkaline comet assay (CA), modified by repair endonucleases (+FPG); micronuclei test (MN) using CBMN-Cyt assay; and telomere length (TL) by qPCR in MG63 cells. No cytotoxicity was observed for all concentrations tested in this study. Alkaline CA results showed a significant increase in DNA damage at all FA concentrations (0.03125-0.300 mg/L), in the two highest concentrations of COT (125 and 250 ng/mL), and the highest concentration of FA+COT (0.300 mg/L+250 ng/mL). Alkaline CA+FPG test was used to detect oxidized nucleobases, which occurred at the two highest concentrations of FA, COT, and FA+COT. Micronuclei test showed an increase in the frequency of MN at all concentrations of FA (0.075-0.300 mg/L) except in the lowest concentration (0.03125 mg/L), in the two highest concentrations of COT (125 and 250 ng/mL), and all concentrations of FA+COT. There was no significant difference in nuclear division index, binucleated cells, nucleoplasmic bridge, and nuclear bud. A TL reduction was observed in cells treated with the highest concentrations of FA alone (0.300 mg/L) and FA+COT (0.300 mg/L+250 ng/mL). Finally, our study showed that FA and COT (mainly alone) at concentrations found in human plasma induced oxidative damage and genetic instability in human osteoblast cells.

Selenium abates manganese-induced striatal and hippocampal toxicity via abrogation of neurobehavioral deficits, biometal accumulation, oxidative stress, inflammation, and caspase-3 activation in rats

Excessive exposure to manganese (Mn) is associated with neurotoxicity characterized by oxidative stress, inflammation, and apoptosis induction. Selenium (Se) has been shown to possess antioxidant, anti-inflammatory, and anti-apoptotic properties in humans and animals. The present study investigated the neuroprotective mechanism of Se in rats sub-chronically treated with Mn at 30 mg/kg body weight or orally co-treated with Se at 0.2 and 0.4 mg/kg body weight for 35 consecutive days. Locomotive and exploratory profiles were recorded and computed with the aid of ANY-Maze (a video-tracking software) for 5-min trial, in a novel apparatus. The ANY-Maze analysis showed that Se significantly (p < 0.05) abated Mn-induced locomotive impairment evidenced by increased in maximum speed, total time traveled, absolute turn angle, number of line crossing, rotation and forelimb grip and decreased total time immobile, grooming, and negative geotaxis as verified by the enhanced track plot density. Furthermore, the striatum and hippocampus of the rats were excised and the levels of Mn and Se, oxidative stress markers, proinflammatory cytokines including acetylcholinesterase and caspase-3 activities were assayed. The result shows that Se abates Mn-mediated accumulation of Mn. Also, Se ameliorated Mn-induced decrease in antioxidant enzymes as well as glutathione level and increase in acetylcholinesterase activity, lipid peroxidation, proinflammatory cytokines (i.e., interleukin (IL)-6, IL-1β, tumor necrosis factor alpha), and caspase-3 activation in the striatum and hippocampus of the rats. Collectively, Se abated Mn-induced striatal and hippocampal toxicity via abrogation of neurobehavioral deficits, biometal accumulation, oxidative stress, inflammation, and caspase-3 activation in rats. Se may serve as a neuroprotective agent against Mn-mediated neurotoxicity.

Evaluation of Cerebellar Function and Integrity of Adult Rats After Long-Term Exposure to Aluminum at Equivalent Urban Region Consumption Concentrations

High amounts of aluminum (Al) are found in soil and water. It is highly bioavailable, which makes it an important agent of environmental imbalance. Moreover, Al is considered a neurotoxic agent that is associated with several neurodegenerative diseases. Thus, this study investigated the effects of long-term Al chloride (AlCl₃) exposure on motor behavior, oxidative biochemistry, and cerebellar tissue parameters. For this, adult Wistar rats were divided into three groups: Al-D1 (8.3 mg kg^-1 day^-1), Al-D2 (5.2 mg kg^-1 day^-1), and control (distilled water); all groups were orally exposed for 60 days by intragastric gavage. After the exposure period, animals performed the open field, elevated plus maze, rotarod, and beam walking tests. Then, the blood and cerebellum were collected to evaluate Al levels and biochemical and morphological analyses, respectively. Our results demonstrate that animals exposed to Al doses presented a higher Al level in the blood. In the spontaneous locomotor activity, Al exposure groups had traveled a lower total distance when compared with the control group. There was no statistically significant difference (p > 0.05) between exposed and control groups when anxiogenic profile, forced locomotion, fine motor coordination/balance, pro-oxidative parameter, and density Purkinje cells were compared. Thus, aluminum exposure in equivalent doses to human consumption in urban regions did not promote significant changes in the cerebellum or motor parameters.

Apoptotic and Oxidative Mechanisms in Liver and Kidney Tissues of Sheep with Fluorosis

This study was planned to determine the molecular basis and causes of damage to the kidney and the liver, which are the most affected tissues in sheep exposed to chronic fluoride. For this purpose, liver and kidney tissues were obtained from sheep with signs of fluorosis in the age range of 4-6 years. The control group consisted of clinically healthy sheep without fluorosis. The apoptotic and oxidative genes expression of target genes was determined using the real qRT-PCR method. According to the control gene (Gapdh) that was detected that in the liver, the apoptotic genes caspase-8, caspase-9, and Bim increased and caspase-3, Bcl-2, and Bak decreased, while in the kidney, caspase-3 and Bax and caspase-8, Bcl-2, Bcl2l-1, Bim, and Bak decreased. According to the 2-ΔCt values of the oxidative stress genes, it was determined that Cygb, Gstp1, and Ncf1 genes increased significantly in the fluorosis group and Gpx1, sod1, and sod2 genes decreased significantly. In the kidney tissue, Cygb and Gpx1 increased in the fluorosis group, while sod1, sod2, Gstp1, Ncf1 and Ccs, and Nos2 were found to decrease significantly. As a result, it was shown that apoptosis and oxidative mechanisms are activated in the liver and the kidney tissues of sheep with fluorosis and these parameters have an important role in understanding the molecular basis of tissue damage in fluorosis.

Protective role of maize purple plant pigment against oxidative stress in fluorosis rat brain

In fluorosis-endemic areas, exposure to high levels of fluoride causes neurotoxicity such as lowered intelligence and cognitive impairment. Oxidative damage is critical to pathophysiologic processes of fluoride intoxication, and neurotoxicity of fluoride may be associated with oxidative stress. In previous studies, maize purple plant pigment (MPPP), which was rich in anthocyanins, showed a strong scavenging activity in vitro and in vivo. The present study aimed to determine whether treatment with MPPP can alleviate fluoride-induced oxidative damage in rat brain. After 3 months of experiment, brain tissues were assayed for oxidative stress variables, histological and Western blotting examinations. Our results showed that MPPP reduced the elevated malondialdehyde levels, increased superoxide dismutase activity, and further attenuated histopathological alterations and mitigated neuronal apoptosis. Importantly, MPPP also reversed changes in Bax and Bcl-2. Therefore, it was speculated that MPPP protects brain tissue from fluoride toxicity through its antioxidant capacity.

Beyond the Mind-Serum Trace Element Levels in Schizophrenic Patients: A Systematic Review

The alterations in serum trace element levels are common phenomena observed in patients with different psychiatric conditions such as schizophrenia, autism spectrum disorder, or major depressive disorder. The fluctuations in the trace element concentrations might act as potential diagnostic and prognostic biomarkers of many psychiatric and neurological disorders. This paper aimed to assess the alterations in serum trace element concentrations in patients with a diagnosed schizophrenia. The authors made a systematic review, extracting papers from the PubMed, Web of Science, and Scopus databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Among 5009 articles identified through database searching, 59 of them were assessed for eligibility. Ultimately, 33 articles were included in the qualitative synthesis. This review includes the analysis of serum levels of the following trace elements: iron, nickel, molybdenum, phosphorus, lead, chromium, antimony, uranium, magnesium, aluminum, zinc, copper, selenium, calcium, and manganese. Currently, there is no consistency regarding serum trace element levels in schizophrenic patients. Thus, it cannot be considered as a reliable prognostic or diagnostic marker of schizophrenia. However, it can be assumed that altered concentrations of those elements are crucial regarding the onset and exaggeration of either psychotic or negative symptoms or cognitive dysfunctions.

Preclinical evidences of aluminum-induced neurotoxicity in hippocampus and pre-frontal cortex of rats exposed to low doses

Aluminum (Al) is a neurotoxicant agent implicated in several behavioral, neuropathological and neurochemical changes associated with cognitive impairments. Nevertheless, mechanisms of damage and safety concentrations are still very discussed. Thus, the main purpose of this study was to investigate whether two aluminum low doses were able to produce deleterious effects on cognition of adult rats, including oxidative stress in hippocampus and prefrontal cortex, two important areas for cognition. For this, thirty adult Wistar rats were divided into three groups: Al1 (8.3 mg/kg/day), Al2 (32 mg/kg/day) and Control (Ultrapure Water), in which all three groups received their solutions containing or not AlCl₃ by intragastric gavage for 60 days. After the experimental period, the short- and long-term memories were assessed by the object recognition test and step-down inhibitory avoidance. After euthanizing, prefrontal cortex and hippocampus samples were dissected for Al levels measurement and evaluation of oxidative biochemistry. Only Al2 increased Al levels in hippocampal parenchyma significantly; both concentrations did not impair short-term memory, while long-term memory was affected in Al1 and Al2. In addition, oxidative stress was observed in prefrontal and hippocampus in Al1 and Al2. Our results indicate that, in a translational perspective, humans are subjected to deleterious effects of Al over cognition even when exposed to low concentrations, by triggering oxidative stress and poor long-term memory performance.

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.

Histomorphological evaluations on the frontal cortex extrapyramidal cell layer following administration of N-Acetyl cysteine in aluminum induced neurodegeneration rat model

Aluminum is a potent neurotoxin used in animal models of neurodegenerative diseases like Alzheimer's disease (AD), in which oxidative stress mediates tissue pathogenesis in vivo. N-acetyl cysteine (NAC) is a glutathione precursor with reported antioxidant and neuroprotective potentials. Recent therapy for combating AD is known to provide only symptomatic relief thus necessitating the discovery of new drugs and their mechanism of action. This study was aimed to demonstrate the in vivo neuroprotective effect of NAC against aluminum (Al3+)-induced neuro-degeneration in rats (a model for AD). Twenty- five (25) adult male Wistar rats used for this study were divided into 5 groups: Group A = Control, B = Aluminum chloride (200 mg/kg), C = 1000 mg/kg of NAC + Aluminum chloride (200 mg/kg), D = 1000 mg/kg of NAC, E = Aluminum chloride (200 mg/kg) was orally administered daily for 3 weeks and discontinued for one week. Frontal Cortex harvested for histological analysis using Haematoxylin and Eosin stain, Cresyl Fast Violet stain for Nissl granules and Glial fibrillary acidic protein immunohistochemistry specific for astrocytes. Aluminum significantly induced oxidative stress, coupled with marked neurons necrosis, chromatolysis and gliosis in the frontal cortex, upon NAC administration, there was neuro anti-inflammatory response as seen in the significant reduction in astrocytes expression, neuronal cell death and Nissl body aggregation which attenuates neuropathological deficits induced by Al3+. It was shown that aluminum is a neurotoxin mediating AD-like oxidative stress, NAC has a therapeutic potential associated with its potent in vivo interaction with astrocytes in response to Al3+ neuro-inflammation seen in positive expression of Nissl granules and glial cells in addition to possibility of endogenous glutathione neuroprotection after withdrawal of stress mediator in neurodegeneration. Graphical abstract.

Removal of fluoride from fertilizer industry effluent using carbon nanotubes stabilized in chitosan sponge

Adsorption of fluoride from fertilizer industry effluent using carbon nanotubes stabilized in chitosan sponge as adsorbent was evaluated. The effluent was produced in the washing of acid gases during the reaction in fertilizer production and all assays were performed using this hazardous material. Adsorbent characterization and ions interactions were elucidated from differential scanning calorimetry, thermal gravimetric analyses, X-ray diffraction, scanning electron microscopy dispersive energy X-ray spectroscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The effluent presented pH 3 and its value not changed in the adsorption assays, maintaining the conditions of the process. The kinetics assays of fluoride from industry effluent were performed in different stirring rates from 100 to 300 rpm. It was observed that adsorption was initially fast reaching the equilibrium at 300 rpm in 20 min. The adsorption capacity was around 975.4 mg g^-1, showing the potential of the hybrid material to remove fluoride from a real matrix. The high adsorption capacity was attributed to the chitosan functional groups and the high interaction area promoted by sponge form and the carbon nanotube. Reuse and regeneration of the CNT-CS were investigated and 5 cycles were obtained. The adsorption capacity kept similar values in all cycles.

Principles of fluoride toxicity and the cellular response: a review

Fluoride is ubiquitously present throughout the world. It is released from minerals, magmatic gas, and industrial processing, and travels in the atmosphere and water. Exposure to low concentrations of fluoride increases overall oral health. Consequently, many countries add fluoride to their public water supply at 0.7-1.5 ppm. Exposure to high concentrations of fluoride, such as in a laboratory setting often exceeding 100 ppm, results in a wide array of toxicity phenotypes. This includes oxidative stress, organelle damage, and apoptosis in single cells, and skeletal and soft tissue damage in multicellular organisms. The mechanism of fluoride toxicity can be broadly attributed to four mechanisms: inhibition of proteins, organelle disruption, altered pH, and electrolyte imbalance. Recently, there has been renewed concern in the public sector as to whether fluoride is safe at the current exposure levels. In this review, we will focus on the impact of fluoride at the chemical, cellular, and multisystem level, as well as how organisms defend against fluoride. We also address public concerns about fluoride toxicity, including whether fluoride has a significant effect on neurodegeneration, diabetes, and the endocrine system.

Inorganic fluoride and functions of brain

Although actively disputed and questioned, it has been proposed that chronic exposure to inorganic fluoride (F^-) is toxic for brain. The major question for this review was whether an excessive F^- intake is causally related to adverse neurological and cognitive health conditions in human beings and animals. The paper systematically and critically summarizes the findings of the studies showing positive associations between F^- intoxication and various intellectual defects, as well as of those which attempted to clarify the nature of F^- neurotoxicity. Many works provide support for a link between pre- and postnatal F^- exposure and structural and functional changes in the central nervous system responsible for neurological and cognitive disorders. The mechanisms suggested to underlie F^- neurotoxicity include the disturbances in synaptic transmission and synaptic plasticity, premature death of neurons, altered activities of components of intracellular signaling cascades, impaired protein synthesis, deficit of neurotrophic and transcriptional factors, oxidative stress, metabolic changes, inflammatory processes. However, the majority of works have been performed on laboratory rodents using such F^- doses which are never exist in the nature even in the regions of endemic fluorosis. Thus, this kind of treatment is hardly comparable with human exposure even taking into account the higher rate of F^- clearance in animals. Of special importance are the data collected on humans chronically consuming excessive F^- doses in the regions of endemic fluorosis or contacting with toxic F^- compounds at industrial sites, but those works are scarce and often criticized due to low quality. New, expertly performed studies with repeated exposure assessment in independent populations are needed to prove an ability of F^- to impair neurological and intellectual development of human beings and to understand the molecular mechanisms implicated in F^--induced neurotoxicity.

Ethanol Exacerbates Manganese-Induced Neurobehavioral Deficits, Striatal Oxidative Stress, and Apoptosis Via Regulation of p53, Caspase-3, and Bax/Bcl-2 Ratio-Dependent Pathway

This study investigated the effects of ethanol (EtOH) on manganese (Mn)-induced striatal toxicity in rat by evaluating the neurobehavioral changes, biochemical and molecular events in rats exposed to Mn alone at 30 mg/kg, or their combination with EtOH at 1.25- and 5-g/kg body weight for 35 consecutive days. Locomotive and exploratory profiles were assessed using a video tracking software (ANY-Maze software) during a 5-min trial in a novel environment. Subsequently, acetylcholinesterase (AChE) activity, oxidative stress markers, histological morphology, and expression of apoptotic proteins (p53 and Bax and caspase-3) and anti-apoptotic protein (Bcl-2) were assessed in the striatum. Results showed that Mn, EtOH, and their combination induced locomotor and motor deficits. Track plot analysis indicated that EtOH exacerbated the Mn-induced reduction in exploratory profiles of exposed rats. Similarly, exposure of rats to Mn, EtOH, or combination of Mn and EtOH resulted in decreased activities of anti-oxidant enzymes, diminished level of reduced glutathione, downregulated Bcl-2 expression, increased AChE activity, enhanced hydrogen peroxide and lipid peroxidation levels, and upregulated expressions of p53, Bax, and caspase-3. Moreover, potentiation of Mn-induced striatal toxicity by EtOH co-exposure was dose dependent. Taken together, it seems that EtOH exacerbates Mn-induced neurobehavioral deficits, oxidative stress, and apoptosis induction via the regulation of p53, caspase-3, and Bax/Bcl-2 ratio-dependent pathway in rat striatum.

Long-term exposure to fluoride as a factor promoting changes in the expression and activity of cyclooxygenases (COX1 and COX2) in various rat brain structures

BACKGROUND

Sixty percent of the mammalian brain is composed of lipids including arachidonic acid (AA). AA released from cell membranes is metabolised in the cyclooxygenase (COX) pathway to prostanoids - biologically active substances involved in the regulation of many processes including inflammation. It has been shown that long-term exposure to fluoride in pre and neonatal period is dangerous because this element is able to penetrate through the placenta and to cross the blood-brain barrier. Exposure to fluoride during the development affects metabolism and physiology of neurons and glia which results in the impairment of cognitive functions but the exact mechanisms of fluoride neurotoxicity are not clearly defined.

OBJECTIVE

The aim of this study was to determine whether exposure to fluoride during the development affects COXes activity and the synthesis of prostanoids.

MATERIAL AND METHODS

Pre- and postnatal toxicity model in Wistar rats was used. Experimental animals received 50 mg/L of NaF in drinking water ad libitum, while control animals received tap water. In cerebral cortex, hippocampus, cerebellum and striatum were measured fluoride concentration, COX1 and COX2 genes expression, immunolocalization of the enzymatic proteins and concentration of PGE2 and TXB2.

RESULTS

of this study showed statistically significant changes in the concentration of fluoride in brain structures between study group and control animals. Moreover, significant changes in the expression level of COX1 and COX2, and in the concentration of PGE2 and TXB2 were observed.

CONCLUSION

Exposure to fluoride in the prenatal and neonatal period result in the increase in COX2 activity and increase in PGE2 concentration in rats brain, which may lead to disturbances in central nervous system homeostasis.‬‬.

Effects of Fluoride on Autophagy in Mouse Sertoli Cells

Fluoride had been reported to damage the structure and function of testicular tissues and reproductive cells; however, the mechanisms underlying its toxicity remained unclear. Autophagy plays a key role in reproductive function. In this study, we aimed to investigate the effect of fluoride on autophagy in Sertoli cells. Sertoli cells were exposed to 0, 0.125, 0.25, and 0.5 mM NaF for 24 h. The results showed that fluoride exposure up-regulated Beclin1 and p62 mRNA and protein expression levels with concomitant down-regulated mRNA and protein expression levels of LC3 and Atg5. In conclusion, exposure to fluoride impaired the autophagy process in Sertoli cells, which could be one of fluoride's mechanisms in male reproductive toxicity.

Novel carbonized bone meal for defluoridation of groundwater: Batch and column study

Low cost naturally available bone meal was carbonized and its fluoride adsorption capacity was explored. Carbonized bone meal (CBM) produced at 550°C, 4 h carbonization time and a heating rate of 60°C/min, showed fluoride adsorption capacity of 14 mg g^-1. Adsorbent was characterized using scanning electron microscopy, X-ray diffraction, X-ray fluoroscence, thermogravimetric analysis and Fourier transform infrared spectroscopy to highlight its physical and chemical properties. Best fluoride uptake capacity was observed for 0.2 mm particle size, 7 g L^-1 adsorbent concentration and at pH 6.5. Fluoride uptake was endothermic and chemisorption in nature. Effective diffusivity and mass transfer coefficient were obtained as 6 × 10^-11 m² s^-1 and 9 × 10^-5 m s^-1 from shrinking core model. Sulphate and carbonate showed the highest interference effect on adsorption of fluoride by CBM. Maximum desorption was observed at basic pH (pH 12). Fixed bed study was performed and effect of different parameters (bed height, inlet flow rate and initial concentration) was investigated. Efficiency of the adsorbent using real life fluoride contaminated groundwater solution was also observed.

Perinatal Glyphosate-Based Herbicide Exposure in Rats Alters Brain Antioxidant Status, Glutamate and Acetylcholine Metabolism and Affects Recognition Memory

Glyphosate-based herbicides (Gly-BHs) lead the world pesticide market. Although are frequently promoted as safe and of low toxicity, several investigations question its innocuousness. Previously, we described that oral exposure of rats to a Gly-BH during pregnancy and lactation decreased locomotor activity and anxiety in the offspring. The aim of the present study was to evaluate the mechanisms of neurotoxicity of this herbicide. Pregnant Wistar rats were supplied orally with 0.2 and 0.4% of Gly-BH (corresponding to 0.65 and 1.30 g/l of pure Gly, respectively) from gestational day (GD) 0, until weaning (postnatal day, PND, 21). Oxidative stress markers were determined in whole brain homogenates of PND90 offspring. The activity of acetylcholinesterase (AChE), transaminases, and alkaline phosphatase (AP) were assessed in prefrontal cortex (PFC), striatum, and hippocampus. Recognition memory was evaluated by the novel object recognition test. Brain antioxidant status was altered in Gly-BH-exposed rats. Moreover, AChE and transaminases activities were decreased and AP activity was increased in PFC, striatum and hippocampus by Gly-BH treatment. In addition, the recognition memory after 24 h was impaired in adult offspring perinatally exposed to Gly-BH. The present study reveals that exposure to a Gly-BH during early stages of rat development affects brain oxidative stress markers as well as the activity of enzymes involved in the glutamatergic and cholinergic systems. These alterations could contribute to the neurobehavioral variations reported previously by us, and to the impairment in recognition memory described in the present work.

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.

Screening of Human Proteins for Fluoride and Aluminum Binding

Previous studies showed that prolonged exposure to fluoride (F-) and aluminum (Al3+) ions is associated with numerous diseases including neurological disorders. They don't have any known biological function. But they can bind with proteins that interact with ions similar to them. Such unwanted interactions affect the normal biological function of the target proteins, as well as their downstream protein-protein interactions. Several studies show the detrimental effects posed by them including Alzheimer's disease. However, their target proteins have never been reported. Here, we have screened for the human protein targets subjected to F- and Al3+ interactions by using data-driven prediction tools. We have identified 20 different proteins that directly bind with them (10 interact with fluoride and 10 with aluminum). In addition, protein-protein interaction has been explored to find the proteins that indirectly interact with F- and Al3+. We have found 86 indirect targets for F- and 90 for Al3+. Furthermore, 19 common protein targets have been identified, including proteins (9 out of 19) associated with neurodegenerative disorders. However, wet lab experiments are beyond our scopes to validate the binding networks. Additional studies must be warranted.

An Evaluation of Neurotoxicity Following Fluoride Exposure from Gestational Through Adult Ages in Long-Evans Hooded Rats

At elevated levels, fluoride (F^-) exposure has been associated with adverse human health effects. In rodents, F^- exposure has been reported to induce deficits in motor performance and learning and memory. In this study, we examined Long-Evans hooded male rats maintained on a standard diet (20.5 ppm F^-) or a low F^- diet (3.24 ppm F^-) with drinking water exposure to 0, 10, or 20 ppm F^- from gestational day 6 through adulthood. At postnatal day 25, brain F^- levels were 0.048 or 0.081 μg/g and femur 235 or 379.8 μg/g for 10 and 20 ppm F^-, respectively. Levels increase with age and in adults, levels for plasma were 0.036 or 0.025 μg/ml; for the brain 0.266 or 0.850 μg/g; and for the femur, 681.2 or 993.4 μg/g. At these exposure levels, we observed no exposure-related differences in motor, sensory, or learning and memory performance on running wheel, open-field activity, light/dark place preference, elevated plus maze, pre-pulse startle inhibition, passive avoidance, hot-plate latency, Morris water maze acquisition, probe test, reversal learning, and Y-maze. Serum triiodothyronine (T3), thyroxine (T4), and thyroid stimulating hormone (TSH) levels were not altered as a function of 10 or 20 ppm F^- in the drinking water. No exposure-related pathology was observed in the heart, liver, kidney, testes, seminal vesicles, or epididymides. Mild inflammation in the prostate gland was observed at 20 ppm F^-. No evidence of neuronal death or glial activation was observed in the hippocampus at 20 ppm F^-.

Effects of Aluminium on Long-Term Memory in Rats and on SIRT1 Mediating the Transcription of CREB-Dependent Gene in Hippocampus

Epidemiological investigations have shown that aluminium (Al) is an important neurotoxicant which can be absorbed by organisms via various routes. Previous studies have confirmed that exposure to Al could cause neurodegenerative diseases, decline CREB phosphorylation and then down-regulate the transcription and protein expression of its target genes including BDNF. However, recent studies revealed that CREB activation alone was far from enough to activate the expression of long-term memory (LTM)-related genes; there might be other regulatory factors involved in this process. Several studies showed that TORC1 might be involved in regulating the transcription of downstream target genes as well. Also, TORC1 could be mediated by SIRT1 during the formation of LTM. However, the role of CREB regulating system in Al-induced LTM impairment was still not utterly elucidated till now. This study was designed to establish the rat model of subchronic Al exposure to observe the neuroethology, regulatory factor levels and molecular biological alterations in hippocampal cells. The results showed that, with the increasing AlCl3 dose, blood Al content increased gradually; morphology of the hippocampus and neuronal ultrastructure were aberrant; in the Morris water maze test, the escape latency and distance travelled became longer, swimming traces turned more complicated in the place navigation test; intracellular Ca2+ , cAMP levels declined significantly in AlCl3 -treated rats, followed by abated nuclear translocation of TORC1 and decreased SIRT1, TORC1 and pCREB levels. These results indicate that SIRT1 and TORC1 might play an important mediating role in Al-induced LTM impairment.

The Influence of Fluorine on the Disturbances of Homeostasis in the Central Nervous System

Fluorides occur naturally in the environment, the daily exposure of human organism to fluorine mainly depends on the intake of this element with drinking water and it is connected with the geographical region. In some countries, we can observe the endemic fluorosis-the damage of hard and soft tissues caused by the excessive intake of fluorine. Recent studies showed that fluorine is toxic to the central nervous system (CNS). There are several known mechanisms which lead to structural brain damage caused by the excessive intake of fluorine. This element is able to cross the blood-brain barrier, and it accumulates in neurons affecting cytological changes, cell activity and ion transport (e.g. chlorine transport). Additionally, fluorine changes the concentration of non-enzymatic advanced glycation end products (AGEs), the metabolism of neurotransmitters (influencing mainly glutamatergic neurotransmission) and the energy metabolism of neurons by the impaired glucose transporter-GLUT1. It can also change activity and lead to dysfunction of important proteins which are part of the respiratory chain. Fluorine also affects oxidative stress, glial activation and inflammation in the CNS which leads to neurodegeneration. All of those changes lead to abnormal cell differentiation and the activation of apoptosis through the changes in the expression of neural cell adhesion molecules (NCAM), glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and MAP kinases. Excessive exposure to this element can cause harmful effects such as permanent damage of all brain structures, impaired learning ability, memory dysfunction and behavioural problems. This paper provides an overview of the fluoride neurotoxicity in juveniles and adults.

Effect of Choline on the Composition and Degradation Enzyme of Extracellular Matrix of Mice Chondrocytes Exposed to Fluoride

Choline has been shown to mediate damage of the chondrocyte matrix and degradation enzymes of mice exposed to fluoride (F). To test the action of choline, pregnant mice were treated with differing amounts of F and choline. Newborn mice were weaned at 21 days after birth and treated with the same doses of F and choline as they mothers for 12 weeks. Using hematoxylin-eosin (HE) staining, real-time PCR (RT-PCR), and western blotting, changes in the structure of the cartilage, the expression of mRNA and protein related to proteoglycans (PG), and degradation enzymes were detected. The RT-PCR results show that the expression of the Aggrecan (Acan), transforming growth factor beta (TGF-β1), and Aggrecanases-1 gene were abnormal in the high fluoride (HiF) group, and treatments with choline reversed this phenomenon. The western blotting results show that the protein expression of Aggrecanases-1 was significantly increased in the HiF group (p < 0.01). These findings suggest that F can change the morphology of cartilage tissue, the gene expression of the Acan, TGF-β1, Aggrecanases-1, and the protein expression of the Acan, and that choline can attenuate the effect of F. This may provide the basis for the treatment and prevention of fluorosis.

Sodium fluoride does not affect the working memory and number of pyramidal cells in rat medial prefrontal cortex

Fluoride is a chemical compound known to bring about fluorosis. It is thought to disrupt the central nervous system because of its ability to induce excitotoxicity and oxidative stress. Any damage of pyramidal cells in the prefrontal cortex would result in cognitive function and working memory regulation disorders. The present study aimed at investigating the effects of sodium fluoride (NaF) on the working memory and estimated total number of medial prefrontal cortex pyramidal cells of adult male rats. Thirty-two male Wistar rats were assigned into four groups, namely control and three treated groups receiving 5, 10 and 20 mg/kg BW, respectively, of oral NaF solution for 30 days. The working memory test was carried out using a Y-maze. The number of pyramidal cells in the medial prefrontal cortex was estimated using an unbiased stereological method. There was no significant difference among groups in the working memory and number of pyramidal neurons in the medial prefrontal cortex cells.