Levels of Trace Elements in Muscle and Kidney Tissues of Sheep with Fluorosis

The Footprints of Mitochondrial Fission and Apoptosis in Fluoride-Induced Renal Dysfunction

Fluoride (F) is widely distributed in the environment and poses serious health risks to humans and animals. Although a good body of literature demonstrates a close relationship between F content and renal system performance, there is no satisfactory information on the involved intracellular routes. Hence, this study used histopathology and mitochondrial fission to explore fluorine-induced nephrotoxicity further. For this purpose, mice were exposed to the F ion (0, 25, 50, 100 mg/L) for 90 days. The effects of different F levels on renal pathomorphology and ion metabolism were assessed using hematoxylin and eosin (H&E), periodic acid-Schiff stain (PAS), periodic acid-silver methenamine (PASM), Prussian blue (PB), and alkaline phosphatase (ALP) staining. The results showed that F could lead to glomerular atrophy, tubular degeneration, and vacuolization. Meanwhile, F also could increase glomerular and tubular glycoproteins; made thickening of the renal capsule membrane and thickening of the tubular basement membrane; led to the accumulation of iron ions in the tubules; and increased in glomerular alp and decreased tubular alp. Concomitantly, IHC results showed that F significantly upregulated the expression levels of mitochondrial fission-related proteins, including mitochondrial fission factor (Mff), fission 1 (Fis1), and mitochondrial dynamics proteins of 49 kDa (MiD49) and 51 kDa (MiD51), ultimately caused apoptosis. To sum up, excessive fluorine has a strong nephrotoxicity effect, disrupting the balance of mitochondrial fission and fusion, interfering with the process of mitochondrial fission, and then causing damage to renal tissue structure and apoptosis.

Fluoride regulates the differentiation and atrophy through FGF21/ERK signaling pathway in C2C12 cells

Excess intake of fluoride leads to a serious health issue called fluorosis. Fluorosis patients exhibit the symptom of muscle damage, but the specific mechanism remains unclear. Fibroblast growth factor 21 (FGF21) is a novel myokine that is involved in the regulation of myogenic differentiation, but whether fluoride induces skeletal muscle damage via FGF21 signaling has not been reported yet. In the current study, C2C12 cells were used to investigate the impact of fluoride on myogenic development and the involved regulatory role of FGF21/ERK signaling pathway. The expressions of the markers of myoblasts development and FGF21/ERK signaling pathway-related molecules were detected after fluoride treatment. The results indicated that fluoride notably inhibited the expressions of myogenic regulatory genes MyoD, MyoG and MyHC in C2C12 cells. In addition, fluoride increased the expressions of muscle atrophy-related markers MuRF1 and MAFbx. We proved that fluoride significantly inhibited the expression of FGF21 based on the RNA-seq results, and detected the expressions of downstream molecules FGFR1, KLB, Raf, MEK and ERK. Moreover, FGF21 pretreatment reversed the adverse effect of fluoride on the C2C12 cells and alleviated the atrophy of myotubes. Taken together, these findings indicated that fluoride suppressed differentiation and aggravated atrophy via FGF21/ERK signaling pathway in C2C12 cells. Our study has provided new evidence for the role of FGF21/ERK in fluoride-induced skeletal muscle damage and FGF21 may be one of the potential targets for prevention and treatment of fluorosis.

Redox and biometal status in Wistar rats after subacute exposure to fluoride and selenium counter-effects

This study aimed to investigate the effect of 150 mg/L sodium fluoride (NaF) on redox status parameters and essential metals [copper (Cu), iron (Fe), and zinc (Zn)] in the blood, liver, kidney, brain, and spleen of Wistar rats and to determine the protective potential of selenium (Se) against fluoride (F^-) toxicity. Male Wistar rats were randomly distributed in groups of five (n=5) receiving tap water (control) or water with NaF 150 mg/L, NaF 150 mg/L + Se 1.5 mg/L, and Se 1.5 mg/L solutions ad libitum for 28 days. Fluorides caused an imbalance in the redox and biometal (Cu, Fe, and Zn) status, leading to high superoxide anion (O^{2 .-}) and malondialdehyde (MDA) levels in the blood and brain and a drop in superoxide dismutase (SOD1) activity in the liver and its increase in the brain and kidneys. Se given with NaF improved MDA, SOD1, and O^{2 .-} in the blood, brain, and kidneys, while alone it decreased SH group levels in the liver and kidney. Biometals both reduced and increased F- toxicity. Further research is needed before Se should be considered as a promising strategy for mitigating F^- toxicity.

Prospects for the Role of Ferroptosis in Fluorosis

As a strong oxidant, fluorine can induce oxidative stress resulting in cellular damage. Ferroptosis is an iron-dependent type of cell death caused by unrestricted lipid peroxidation (LPO) and subsequent plasma membrane rupture. This article indicated a relationship between fluorosis and ferroptosis. Evidence of the depletion of glutathione (GSH) and increased oxidized GSH can be found in a variety of organisms in high fluorine environments. Studies have shown that high fluoride levels can reduce the antioxidant capacity of antioxidant enzymes, while increasing the contents of reactive oxygen species (ROS) and malondialdehyde (MDA), resulting in oxidative stress and fluoride-induced oxidative stress, which are related to iron metabolism disorders. Excessive fluorine causes insufficient GSH, glutathione peroxidase (GSH-Px) inhibition, and oxidative stress, resulting in ferroptosis, which may play an important role in the occurrence and development of fluorosis.

A comprehensive review on endemic and experimental fluorosis in sheep: Its diverse effects and prevention

Fluoride is a natural element widely distributed in the environment and plays an important role in the growth of humans and animals. However, in many species, high concentrations of fluoride induce several problems, such as dental, skeletal, and non-skeletal fluorosis. Sheep living in endemic areas are sensitive to the chronic toxicity of fluoride, and they have been found to suffer not only from teeth and bone problems but also from other organs. Studies indicating the chronic harmful effects of fluoride on teeth, bones, blood biochemical parameters, kidney, liver, heart, reproductive system and growth in sheep have been clearly summarized in this review. Besides, this work also includes updated progress in terms of prevention or reduction of fluoride toxicity in this species.

In Vitro Evaluation of the Apoptotic, Autophagic, and Necrotic Molecular Pathways of Fluoride

Prolonged exposure to high doses of fluoride causes chronic poisoning called fluorosis, which affects many tissues and causes serious health problems. This study was planned to investigate the apoptotic, autophagic, and necrotic molecular pathways of fluoride. Sodium fluoride (NaF) was administered to normal rat kidney epithelial (NRK-52E) cells. The NaF IC₅₀ value was determined using the MTT assay. The expression of the genes in the autophagic, apoptotic, and necrotic pathways was determined by real-time PCR. It was determined that there were significant changes in NaF-induced molecular pathways depending on the time. There were no increases in apoptotic and necrotic pathway markers except for Atg3, an autophagy gene, at the 3rd and the 12th hours. However, there was an induction in all cell death signaling pathways at 24 h. The molecular mechanisms demonstrated NaF-induced cellular death in the NRK-52E cell line. It was concluded that these molecular mechanisms were activated with NaF, and different mechanisms accelerated the cellular death at the 24th hour.

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.

Temporal changes in metal concentrations in Andean condor feathers: a potential influence of volcanic activity

Geothermal activities (e.g., volcanic eruptions) represent one of the most important natural sources of metal emissions (heavy metals and metalloids). They can be one of the main risks for the ecosystems in regions like North of Argentiniean Patagonia, a sparsely populated area, close to an extensive network of active volcanoes on the Andes Range. The 2011 eruption of the Puyehue-Cordon Caulle volcanic complex (PCCVC) has been the largest volcanic event of the last decades. The effects of exposure to ashes on wildlife and humans have been sparsely studied, and only one biomonitoring study has used higher trophic species. The exposure to metals of the species in Patagonia has been poorly studied. The main objectives of our study were to assess metal screening and to evaluate a possible relation between the levels of metals in the Andean condor (Vultur gryphus) population and the volcanic activity of the area. We investigated the effects of the eruption of the PCCVC in 2011, using samples of molt primary feathers of the Andean condor, collected in nine roosts around Bariloche, Argentina (maximum distance 85 km). Data available suggest the molt of the primary feathers of the Andean condor has a duration of 6 years. We carried out sampling before (2007, 2009) and after (2017) the volcanic eruption (2011). The feathers sampled in 2017 should have been developed in 2011-2012, reflecting the environmental situation of the period immediately following the eruption of the PCCVC. For the first time, we have screened metals in 48 molted primary feathers of Andean condor, showing the levels of 9 metals and metalloids (Si, Cr, Cu, Zn, As, Se, Cd, Pb, Hg). Si, Zn, As, and Cd showed higher levels in the feathers sampled after the eruption. The levels of Cr and Pb (although apparently not related to the volcanic eruption) in some samples are compatible with potential adverse effects in living organisms. The screening results represent an important database (the first for this species) that can be used in in future studies for comparative purposes. HIGHLIGHTS: •We present the first database of metals in condor feathers, which may be useful for future studies. •Volcanic eruptions might represent an important source of metal and metalloid emissions in this area. •The Andean condor from Argentine Patagonia could be affected by volcanic activity in the area. •Andean condor feathers may be good biomonitoring units of this contamination. •Pb pollution does not seem to be related to the volcano's eruption.

Mineral Nutritional Status of Yaks (Bos Grunniens) Grazing on the Qinghai-Tibetan Plateau

Minerals are essentially important for supporting livestock's health, as well as productivity. This study aimed to investigate the mineral status of yaks (Bos grunniens) grazing on the Qinghai-Tibetan Plateau (QTP) and the relationship between macro and micro mineral nutrients among soil, forages, and blood in four counties of the QTP. The soil samples (n = 320), forages (n = 320), and blood serum (n = 320) were collected from four randomly selected yak farms in each location during July (warm season) and December (cold season), and were analyzed for macro minerals (P, Ca, K, Mg, Na) and micro minerals (Fe, Mn, Zn, Cu, Se). Based on this study, both of the macro and micro minerals were very variable between seasons and many of the macro and micro minerals, such as P, Mg, K, S, Na, Se, and Cu, were found to be below the requirement level for yaks in all four counties. It was significantly shown that the concentrations of both macro and micro minerals in soil and forages influenced the serum concentration of minerals, showing the deficient status of yaks.

Relationship of mineral elements in sheep grazing in the highland agro-ecosystem

Objective

Minerals are one of the important nutrients for supporting the growth of sheep grazing in the highland, northwest of China. The experiment was conducted to investigate the relationship of both macro and micro minerals in sheep grazing in the highlands of six districts located in the Qilian Mountain of China.

Methods

Samples of herbage (n = 240) and soil (n = 240) were collected at random in a “W” shape across the area designated for harvesting from 24 farms, where the sheep commonly graze in October (winter) for mineral analyses. In addition, serum samples were taken via jugular vein from 20 sheep per farm from 24 farms (n = 480 samples in total) for serum minerals analyses. Mean values of macro and micro minerals were statistically compared among districts and the correlations among soil-plant-animal were statistically analyzed and correlations were regressed, as well.

Results

The results revealed that there were variations for both macro and micro minerals among districts. Statistical analysis of the correlation coefficients between herbage and sheep were significantly different for most of the minerals but not for P, Cu, and Se. Many correlation regression coefficients were found significantly different among minerals of herbage, soil, and sheep serum especially those of K, Na, Fe, Mn, and Zn (between herbage and sheep serum), and Fe and Mn (between herbage and soil), Na, Fe, Mn, and Zn (between soil and sheep serum), respectively. The regression coefficient equations derived under this experiment for prediction of Ca (R² = 0.618), K (R² = 0.803), Mg (R² = 0.767), Na (R² = 0.670), Fe (R² = 0.865), Zn (R² = 0.950), Mn (R² = 0.936), and Se (R² = 0.630), resulted in significant R² values.

Conclusion

It is inferred that the winter herbage minerals in all the districts were below the recommended levels for macro minerals which indicated there would be some mineral deficiencies in sheep grazing the herbage in these regions. Supplemental minerals may therefore play an important role in balancing the minerals available from the herbage in winter and would lead to increased productivity in sheep on the highland areas of China. These findings could be potentially applied to the other regions for improving the livestock productivity.

Fluoride-associated ultrastructural changes and apoptosis in human renal tubule: a pilot study

The susceptibility of the kidneys to fluoride toxicity can largely be attributed to its anatomy and function. As the filtrate moves along the complex tubular structure of each nephron, it is concentrated in the proximal and distal tubules and collecting duct. It has been frequently observed that the children suffering from renal impairments also have some symptoms of dental and skeletal fluorosis. The findings suggest that fluoride somehow interferes with renal anatomy and physiology, which may lead to renal pathogenesis. The aim of this study was to evaluate the fluoride-associated nephrotoxicity. A total of 156 patients with childhood nephrotic syndrome were screened and it was observed that 32 of them had significantly high levels ( p ≤ 0.05) of fluoride in urine (4.01 ± 1.83 ppm) and serum (0.1 ± 0.013 ppm). On the basis of urinary fluoride concentration, patients were divided into two groups, namely group 1 (G-1) ( n = 32) containing normal urine fluoride (0.61 ± 0.17 ppm) and group 2 (G-2) ( n = 32) having high urine fluoride concentration (4.01 ± 1.83 ppm). Age-matched healthy subjects ( n = 33) having normal levels of urinary fluoride (0.56 ± 0.15 ppm) were included in the study as control (group 0 (G-0)). Kidney biopsies were taken from G-1 and G-2 only, who were subjected to ultrastructural (transmission electron microscopy) and apoptotic (terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling) analysis. Various subcellular ultrastructural changes including nuclear disintegration, chromosome condensation, cytoplasmic ground substance lysis, and endoplasmic reticulum blebbing were observed. Increased levels of apoptosis were observed in high fluoride group (G-2) compared to normal fluoride group (G-1). Various degrees of fluoride-associated damages to the architecture of tubular epithelia, such as cell swelling and lysis, cytoplasmic vacuolation, nuclear condensation, apoptosis, and necrosis, were observed.