Altered sperm chromatin structure in mice exposed to sodium fluoride through drinking water

The role of taurine in male reproduction: Physiology, pathology and toxicology

Taurine, a sulfur-containing amino acid, has a wide range of biological effects, such as bile salt formation, osmotic regulation, oxidative stress inhibition, immunomodulation and neuromodulation. Taurine has been proved to be synthesized and abundant in male reproductive organs. Recently, accumulating data showed that taurine has a potential protective effect on reproductive function of male animals. In physiology, taurine can promote the endocrine function of the hypothalamus-pituitary-testis (HPT) axis, testicular tissue development, spermatogenesis and maturation, delay the aging of testicular structure and function, maintain the homeostasis of the testicular environment, and enhance sexual ability. In pathology, taurine supplement may be beneficial to alleviate pathological damage of male reproductive system, including oxidative damage of sperm preservation in vitro, testicular reperfusion injury and diabetes -induced reproductive complications. In addition, taurine acts as a protective agent against toxic damage to the male reproductive system by exogenous substances (e.g., therapeutic drugs, environmental pollutants, radiation). Related mechanisms include reduced oxidative stress, increased antioxidant capacity, inhibited inflammation and apoptosis, restored the secretory activity of the HPT axis, reduced chromosomal variation, enhanced sperm mitochondrial energy metabolism, cell membrane stabilization effect, etc. Therefore, this article reviewed the protective effect of taurine on male reproductive function and its detailed mechanism, in order to provide reference for further research and clinical application.

A systematic review on fluoride-induced epigenetic toxicity in mammals

Fluoride, one of the global groundwater contaminants, is ubiquitous in our day-to-day life from various natural and anthropogenic sources. Numerous in vitro, in vivo, and epidemiological studies are conducted to understand the effect of fluoride on biological systems. A low concentration of fluoride is reported to increase oral health, whereas chronic exposure to higher concentrations causes fluoride toxicity (fluorosis). It includes dental fluorosis, skeletal fluorosis, and fluoride toxicity in soft tissues. The mechanism of fluoride toxicity has been reviewed extensively. However, epigenetic regulation in fluoride toxicity has not been reviewed. This systematic review summarizes the current knowledge regarding fluoride-induced epigenetic toxicity in the in vitro, in vivo, and epidemiological studies in mammalian systems. We examined four databases for the association between epigenetics and fluoride exposure. Out of 932 articles (as of 31 March 2022), 39 met our inclusion criteria. Most of the studies focused on different genes, and overall, preliminary evidence for epigenetic regulation of fluoride toxicity was identified. We further highlight the need for epigenome studies rather than candidate genes and provide recommendations for future research. Our results indicate a correlation between fluoride exposure and epigenetic processes. Further studies are warranted to elucidate and confirm the mechanism of epigenetic alterations mediated fluoride toxicity.

Vitamin C and E supplementation can ameliorate NaF mediated testicular and spermatozoal DNA damages in adult Wistar rats

OBJECTIVE

Present study was designed to explore the efficacy of vitamin C and E (VC&VE) against fluoride mediated testicular, epididymal and spermatozoal anomalies.

MATERIALS AND METHODS

Thirty two adult Wistar rats were divided into four groups. Group-I was control; Group-II received sodium fluoride (NaF) at 15 mg/kg/day dose; Group-III was provided with VC (200 mg/kg/day) and VE (400 mg/kg/day) plus NaF; Group-IV received only VC&VE. Structural integrity and oxidative stress markers (superoxide dismutase, catalase, malondialdehyde and protein carbonyl) of testis and epididymis were assessed. Spermatozoal parameters (count, motility, viability and hypo-osmotic swelling) were evaluated. Testicular functional maker enzymes (acid phosphatase, alkaline phosphatase and lactate dehydrogenase) were also assessed. Integrity of testicular and spermatozoal DNA were evaluated. Testicular fluoride content was measured.

RESULT

Fluoride induced structural changes and alterations of oxidative stress markers were observed in testis and epididymis. Spermatozoal potentials were altered and reduced activities of testicular functional marker enzymes were observed. Fluoride caused testicular and spermatozoal DNA damages. VC&VE supplementation resulted in protectionfrom all fluoride mediated alterations and helped in attenuating testicular fluoride accumulation.

CONCLUSION

Antioxidant properties of VC&VE ameliorated fluoride mediated reproductive damages but only supplementation did not exhibit any notable effect compared to control rats.

The cholinergic system, intelligence, and dental fluorosis in school-aged children with low-to-moderate fluoride exposure

Disruption of cholinergic neurotransmission can affect cognition, but little is known about whether low-to-moderate fluoride exposure affects cholinergic system and its effect on the prevalence of dental fluorosis (DF) and intelligence quotient (IQ). A cross-sectional study was conducted to explore the associations of moderate fluoride exposure and cholinergic system in relation to children's DF and IQ. We recruited 709 resident children in Tianjin, China. Ion selective electrode method was used to detect fluoride concentrations in water and urine. Cholinergic system was assessed by the detection of choline acetyltransferase (ChAT), acetylcholinesterase (AChE) and acetylcholine (ACh) levels in serum. Compared with children in the first quartile, those in fourth quartile the risk of either developing DF or IQ < 120 increased by 19% and 20% for water and urinary fluoride. The risk of having both increased by 58% and 62% in third and fourth quartile for water fluoride, 52% and 65% for urinary fluoride. Water fluoride concentrations were positively associated with AChE and negatively associated with ChAT and ACh, trends were same for urinary fluoride except for ACh. The risk of either developing DF or having non-high intelligence rose by 22% (95%CI: 1.07%, 1.38%) for the fourth quartile than those in the first quartile of AChE, for having the both, the risk was 1.27 (95%CI: 1.07, 1.50), 1.37 (95%CI: 1.17, 1.62) and 1.44 (95%CI: 1.23, 1.68) in second, third and fourth quartiles. The mediation proportion by AChE between water fluoride and either developing DF or IQ < 120 was 15.7%. For both to exist, the proportion was 6.7% and 7.2% for water and urinary fluoride. Our findings suggest low-to-moderate fluoride exposure was associated with dysfunction of cholinergic system for children. AChE may partly mediate the prevalence of DF and lower probability of having superior and above intelligence.

Environmental fluoride exposure disrupts the intestinal structure and gut microbial composition in ducks

Fluorine (F) and its compounds produced from industrial production and coal combustion can cause air, water and soil contamination, which can accumulate in animals, plants and humans via food chain threatening public health. Fluoride exposure affects liver, kidney, gastrointestinal and reproductive system in humans and animals. Literature regarding fluoride influence on intestinal structure and microbiota composition in ducks is scarce. This study was designed to investigate these effects by using simple and electron microscopy and 16S rRNA sequencing techniques. Results indicated an impaired structure with reduced relative distribution of goblet cells in the fluoride exposed group. Moreover, the gut microbiota showed a significant decrease in alpha diversity. Proteobacteria, Firmicutes and Bacteroidetes were the most abundant phyla in both control and fluoride-exposed groups. Specifically, fluoride exposure resulted in a significant decrease in the relative abundance of 9 bacterial phyla and 15 bacterial genera. Among them, 4 phyla (Latescibacteria, Dependentiae, Zixibacteria and Fibrobacteres) and 4 genera (Thauera, Hydrogenophaga, Reyranella and Arenimonas) weren't even detectable in the gut microbiota of the ducks. In summary, higher fluoride exposure can significantly damage the intestinal structure and gut microbial composition in ducks.

Sodium fluoride causes oxidative damage to silkworm (Bombyx mori) testis by affecting the oxidative phosphorylation pathway

Bombyx mori was used to study the molecular mechanism of fluoride induced reproductive toxicity. In our previous study, we confirmed the physiological and biochemical effects of NaF on reproductive toxicity, and we found that the molecular mechanism of NaF induced reproductive damage may be associated with the oxidative phosphorylation pathway. To further study the function of NaF exposure on the oxidative phosphorylation pathway in the testis in Bombyx mori, and the relationship between oxidative phosphorylation and oxidative stress, we measured the changes in the main ROS (O2- and H2O2) in the testis, the activity of the main electron transport chain complex enzymes in the oxidative phosphorylation pathway and the transcription levels of the corresponding genes; we additionally performed pathological observations of the silkworm testis after exposure to 200 mg/L NaF solution for different times. The content of O2- and H2O in the silkworm gonads increased significantly at 24 h, 72 h and 120 h after NaF stress. The activity of mitochondrial complexes I, III, IV and V in the silkworm testis was significantly greater than that in the control group. RT-PCR analysis suggested that the mRNA transcription levels of NADH-CoQ1, Cyt c reductase, Cyt c oxidase and ATP synthase genes were up-regulated significantly. Histopathological investigation showed that the damage to the silkworm testis was more severe with increasing NaF exposure times. These results indicated that NaF stress affects the NADH respiratory chain of the mitochondrial electron transport chain and increases the activity of related enzyme complexes, thus destroying the balance of the electron transport chain. Subsequently, the content of ROS in cells significantly increases, thus resulting in oxidative stress reactions in cells. These results enable better understanding of the testis-damaging molecular toxicological mechanism of NaF.

ITRAQ-based proteomics reveals the potential mechanism of fluoride-induced myocardial contraction function damage

Fluorosis is a worldwide public health problem, and its adverse effects on the heart have been confirmed by many studies. Abnormal myocardial contractions are often associated with impairment of cardiac function as a cause or consequence. We designed two-part experiments to search for biomarkers and clarify the underlying molecular mechanism of fluoride on myocardial contraction. First, we used Pressure-volume Loop analysis to evaluate changes in myocardial function indexes with multiple fluoride exposure levels in mice (0, 30, 70, and 150 mg/L) exposed for 4 weeks. The results showed that fluoride exposure affects the heart pump function and reduces cardiac contractility. Then, we established a rat model of fluoride exposure (0, 30, 60, and 90 mg/L) for 6 months to carry out proteomic analysis of fluoride-induced myocardial contractile injury. Hematoxylin-eosin (H&E) staining was used to determine the severity of myocardial injury, and myocardial tissue samples were submitted for isobaric tags for relative and absolute quantitation (ITRAQ) analysis. A total of 1607 proteins were successfully identified with 294 differentially expressed proteins (DEPs) in fluoride treated groups. According to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, 12 DEPs were confirmed to be involved in pathways related to myocardial contraction. Furthermore, we constructed a protein-protein interaction (PPI) network for these 12 core DEPs to illustrate the role and location of each DEP in the myocardial contraction pathway. The results of this study are helpful for identify a potential mechanism and biomarkers of fluoride-induced myocardial contraction function damage, moreover, which can provide a new insight into the heart toxicity of fluoride in animals at the proteomics level.

Intestinal fungal dysbiosis in mice induced by fluoride

To explore the effects of fluoride on intestinal fungi in mice, the internal transcriptional spacer (ITS) region in colon feces of mice exposed to 100 mg sodium fluoride (NaF)/L of distilled water for 60 days were sequenced. Results showed that, there were 305 operational taxonomic units (OTUs) unique to the control group, 154 OTUs to the fluoride group, and 295 OTUs were detected in both groups. There was no significant difference in relative species abundance between the two groups at phylum levels. Compared with control group, Ustilaginomycetes class, showed a significant change in fluoride group. At the genus level, Epicoccum, Penicillium, Microdochium, Plectosphaerella and Pluteus were significantly affected by fluoride exposure. Among them, there was a strong positive correlation between Penicillium and Pluteus (+0.43). Therefore, it showed that fluoride can influence the relative species abundance of intestinal fungi in mice, mainly at the genus levels. It can provide some new ideas about the harmful effects of fluorosis on intestinal fungal homeostasis.

Exposure of Fluoride with Streptozotocin-Induced Diabetes Aggravates Testicular Damage and Spermatozoa Parameters in Mice

Diabetes mellitus is the most common chronic disease worldwide that causes numerous complications, including male infertility. The prevalence of DM is 451 million people and estimated that would increase to 693 million in 2045. Fluorosis caused by drinking water contaminated with inorganic fluoride is a public health problem in many areas around the world. Previous studies have shown that fluoride exposure damages the male reproductive function. This study aimed to evaluate the fluoride sub-chronic exposure on the spermatozoa function in streptozotocin (STZ)-induced diabetic mice. After confirming diabetes by measuring blood glucose levels, the male mice received 45.2 ppm of fluoride added or deionized water. We evaluated several parameters in diabetic mice exposed to fluoride: standard quality analysis, the mitochondrial transmembrane potential (ψm), the caspase activity in spermatozoa, urinary fluoride excretion, and histological evaluation in the testes. After 60 days of fluoride-exposure, diabetic mice, significantly decreased sperm quality (motility, viability, and concentration). Spermatozoa from fluoride-exposure in diabetic mice presented a significant decrease in ψm and a significant increase in activity caspase 3/7. Urinary fluoride excretion was decreased in diabetic mice exposed to fluoride. Subchronic fluoride exposure of mice with STZ-induced diabetes aggravated testicular damage and the spermatozoa function.

Positive PCNA and Ki-67 Expression in the Testis Correlates with Spermatogenesis Dysfunction in Fluoride-Treated Rats

The present study aimed to evaluate the effect of fluoride (F) on spermatogenesis in male rats. F^- at 50 and 100 mg/L was administered for 70 days, after which the testicular and epididymis tissues were collected to observe the histopathological structure under a light microscope. The ultrastructure of the testis and sperm was also examined via transmission electron microscopy. The apoptosis of spermatogenic cells was measured through terminal deoxynucleotidyl transferase dUTP nick end labeling staining. The expression of proliferation factors, namely, proliferating cell nuclear antigen (PCNA) and Ki-67, in the testicular and epididymis tissues, were assayed through immunohistochemistry. F^- at 50 and 100 mg/L significantly damaged the structure of the testis and epididymis, and the testis and sperm ultrastructure exhibited various changes, including mitochondrial swelling and vacuolization, and apsilated and raised sperm membrane. F treatment significantly increased spermatogenic cell apoptosis in the testis. PCNA (P < 0.01) and Ki-67 (P < 0.01) also presented positive expression in the testis. By comparison, no significant changes occurred in the epididymis. In summary, excessive F intake results in spermatogenesis dysfunction by damaging the testicular structure and inducing spermatogenic cell apoptosis in male rats. The positive expression level of PCNA and Ki-67 was a good response to spermatogenesis dysfunction.

Effects of sodium fluoride on the reproductive development of Bombyx mori

Bombyx mori was used as a model to evaluate the reproductive toxicity of NaF in insects. Significant reduction in cocoon quality, survival rate, fecundity, and hatchability were observed upon NaF treatment groups. Fluoride determination indicated that F^- has a cumulative effect on the gonad of silkworm. High-performance liquid chromatography revealed that the testosterone content of males was decreased in NaF-treated groups, and enzyme-linked immunosorbent assay showed that the estradiol content was decreased in NaF-treated females. Ultrastructural observation of testicles of silkworm larvae revealed mitochondrial turgescence, endoplasmic reticulum destruction, the appearance of vacuoles and lysosomes, and apoptosis and necrosis of cells in NaF-treated groups. Altered tail length and tail DNA content in Comet assays further confirmed DNA damage in NaF-treated larvae. We demonstrated reproductive toxicity of fluoride toward silkworm at physiological and biochemical levels, and the results provide a theoretical basis for revealing the reproductive toxicity of fluoride in terrestrial insects.

High Concentration of Fluoride Can Be Increased Risk of Abortion

The presence of fluoride in drinking water can be either beneficial or harmful for human health, depending on its concentration. Most adverse effects of fluoride are observed at high concentrations (above 1.5 mg/L). This study was aimed to evaluate the effect of fluoride concentrations in drinking water on spontaneous abortion in two regions: one with low fluoride concentration and another with high fluoride concentration. The results showed that there is a relationship between the concentration of fluoride in drinking water and abortion, so that the risk of abortion increased at high concentrations of fluoride. However, further studies are needed to clarify this relationship due to the small area and population in this study.

Analysis of digital gene expression profiling in the gonad of male silkworms (Bombyx mori) under fluoride stress

Fluorine is an essential element, but excessive fluoride can cause serious effects on the respiratory, digestive, and reproductive systems. Fluorine has been suggested to cause reproductive toxicity in vertebrates, but its potential to reproductively affect invertebrates remains unknown. In the present study, the lepidopteran model insect Bombyx mori was used to assess the reproductive toxicity of NaF. The underlying molecular mechanisms were explored by RNA sequencing, and we investigated the testes transcriptomic profile of B. mori treated with NaF via a digital gene expression (DGE) analysis. Among 520 candidate genes, 297 and 223 were identified as significantly upregulated or downregulated, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were carried out on all genes to determine their biological functions and associated processes. The results indicated that numerous differentially expressed genes are involved in the stress response, detoxification, antibacterial, transport, oxidative phosphorylation, and ribosome. The reliability of the data was confirmed by a quantitative real-time polymerase chain reaction (qRT-PCR) analysis. The changed Glutathione S-transferase (GST) activity and glutathione (GSH) content in the NaF-treated groups were increased and reduced respectively. This study reveals that using RNA-sequencing for the transcriptome profiling of B. mori testes can lead to better comprehension of the male reproductive toxicity effects of NaF. Furthermore, we expect that these results will aid future molecular studies on the reproductive toxicity of NaF in other species.

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.

Taurine reverses sodium fluoride-mediated increase in inflammation, caspase-3 activity, and oxidative damage along the brain-pituitary-gonadal axis in male rats

Excessive exposure to fluoride is associated with male reproductive dysfunction in humans and animals. Taurine (2-aminoethane sulfonic acid) is a free intracellular β-amino acid with antioxidant, anti-inflammatory, and neuroprotective properties. However, the effect of taurine on fluoride-induced reproductive toxicity has not been reported. The present study investigated the influence of taurine on sodium fluoride (NaF)-induced functional changes along the brain-pituitary-gonadal axis in male rats. NaF was administered singly in drinking water at 15 mg·L^-1 alone or orally co-administered by gavage with taurine at 100 and 200 mg·(kg body mass)^-1 for 45 consecutive days. Results showed that taurine significantly prevented NaF-induced increase in oxidative stress indices as well as augmented antioxidant enzymes activities and glutathione level in the brain, testes, and epididymis of the treated rats. Moreover, taurine reversed NaF-induced elevation in inflammatory biomarkers and caspase-3 activity as well as histological damage in the brain, testes, and epididymis of the treated rats. The significant reversal of NaF-induced decreases in testosterone level and testicular activities of acid phosphatase, alkaline phosphatase, and lactate dehydrogenase by taurine was accompanied by enhancement of sperm functional characteristics in the treated rats. Taurine may be a possible chemopreventive candidate against reproductive dysfunction resulting from fluoride exposure.

Cell cycle arrest and gene expression profiling of testis in mice exposed to fluoride

Exposure to fluoride results in low reproductive capacity; however, the mechanism underlying the impact of fluoride on male productive system still remains obscure. To assess the potential toxicity in testis of mice administrated with fluoride, global genome microarray and real-time PCR were performed to detect and identify the altered transcriptions. The results revealed that 763 differentially expressed genes were identified, including 330 up-regulated and 433 down-regulated genes, which were involved in spermatogenesis, apoptosis, DNA damage, DNA replication, and cell differentiation. Twelve differential expressed genes were selected to confirm the microarray results using real-time PCR, and the result kept the same tendency with that of microarray. Furthermore, compared with the control group, more apoptotic spermatogenic cells were observed in the fluoride group, and the spermatogonium were markedly increased in S phase and decreased in G2/M phase by fluoride. Our findings suggested global genome microarray provides an insight into the reproductive toxicity induced by fluoride, and several important biological clues for further investigations. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1558-1565, 2017.

Effect of dietary protein or calcium supplement on the expression of collagen I and dentine phosphoprotein of rats with dental fluorosis

This study aims to assess the roles of dietary protein (Pr) and calcium (Ca) levels associated with excessive fluoride (F) intake and the impact of Pr, Ca, and F on expression of collagen I (COL I) and dentine phosphoprotein (DPP) in rat incisors. Seventy-two rats were randomly allotted to six groups (NC, NC + F, LPrLCa, LPrLCa + F, HPrLCa + F and LPrHCa + F). F, Pr, and Ca were orally administrated to rats for 120 days. The genes and proteins expression levels were quantified. We found that levels of COL1A1 and DSPP gene were respectively decreased by 41.9% and 43.1% in the NC + F group compared with NC group, were respectively decreased by 47.9% and 40.8% in the LPrLCa + F group compared with LPrLCa group, were respectively increased by 71.8% and 39.5% in the HPrLCa + F group and increased by 26.5% and 21.1% in the LPrHCa + F group compared with LPrLCa + F group. Meanwhile, the proteins' expression display with the genes' expression changes were consistent. This study demonstrated that the gene and protein expressions of COL I and DPP were reduced by F both in normal nutrition and malnutrition, and it was reversed by Pr and Ca supplementation, with the effect of Pr being greater than that of Ca.

Fluoride exposure changed the structure and the expressions of Y chromosome related genes in testes of mice

It is known that during spermatogenesis, pluripotent germ cells differentiate to become efficient delivery vehicles to the oocyte of paternal DNA, and the process is easily damaged by external poison. In this study, the effects of fluoride on the body weight, fluoride content in femur, testosterone levels in serum and testis, sperm quality, and the expressions of Y chromosome microdeletion genes and protein levels were examined in testes of Kunming male mice treated with different concentrations of 0, 25, 50, 100 mg/L of NaF in drinking water for 11 weeks, respectively. The results showed that compared with the control group, fluoride contents in three treatment groups were significantly increased and the structure of testes was seriously injured. The testosterone contents and the sperm count were decreased. Sperm malformation ratio was distinctly elevated. The expressions of Sly and HSF2 mRNA were markedly reduced in 100 mg/L NaF group and Ssty2 mRNA expression was dramatically decreased in 50 and 100 mg/L NaF groups. Meanwhile, the protein levels of Ssty2 and Sly were significantly reduced in 50 and 100 mg/L NaF groups and HSF2 protein levels were significantly decreased in 100 mg/L NaF group. These studies indicated that fluoride had toxic effects on male reproductive system by reducing the testosterone and sperm count, and increasing the sperm malformation ratio, supported by the damage of testicular structure, as a consequence of depressed HSF2 level, which resulted in the down-regulation of Ssty2 and Sly mRNA and protein.

In silico prediction of microRNAs on fluoride induced sperm toxicity in mice

Fluorosis is an endemic global problem causing male reproductive impairment. F mediates male reproductive toxicity in mice down-regulating 63 genes involved in diverse biological processes - apoptosis, cell cycle, cell signaling, chemotaxis, electron transport, glycolysis, oxidative stress, sperm capacitation and spermatogenesis. We predicted the miRNAs down-regulating these 63 genes using TargetScan, DIANA and MicroCosm. The prediction tools identified 3059 miRNAs targeting 63 genes. Of the predicted interactions, 11 miRNAs (mmu-miR-103, -107, -122, -188a, -199a-5p, -205, -340-5p, -345-3p, -452-5p, -499, -878-3p) were commonly found in the three tools utilized and seven miRNAs (miR-9-5p, miR-511-3p, miR-7b-5p, miR-30e-5p, miR-17-5p, miR-122-5p and miR-541-5p) targeting six genes (Traf3, Rock2, Rgs8, Atp1b2, Cacna2d1 and Aldoa) were already validated experimentally in mice. The miRNA-mRNA network of the predicted miRNAs with its respective targets revealed the complex interaction within a biological process leading to sperm dysfunction on exposure to F. Our findings not only suggest that the predicted miRs furnish evidence, but also have the potential to serve as non-invasive biomarkers on F-induced sperm dysfunction. Our data contribute towards elucidating the function of miRNAs in the fluoride induced infertility. miRNA molecular pathways in F intoxication will open new avenues on the use of antagomirs in recovering fertility.

Effects of fluoride and aluminum on expressions of StAR and P450scc of related steroidogenesis in guinea pigs' testis

A lot of studies have shown that fluoride and aluminum have toxic effect on male reproductive system, but the mechanism of which and the interaction between fluoride and aluminum is still unknown. This study investigated the effects of fluoride (NaF) or/and aluminum (AlCl3) on serum testosterone level, gene and protein expression levels of Steroidogenic Acute Regulatory Protein (StAR) and Cytochrome P450 cholesterol side chain cleavage enzyme (P450scc) in the testes of guinea pigs. Fifty-two guinea pigs were divided randomly into four groups (Control, HiF, HiAl and HiF + HiAl). Fluoride (150 mg NaF/L) or/and aluminum (300 mg AlCl3/L) were orally administrated to male guinea pigs for 13 weeks. The results showed that F and Al reduced number and elevated abnormal ratio of sperm. Meanwhile, the concentrations of serum testosterone in all experimental groups were decreased. P450scc protein expression was significantly reduced in all treatment groups, and StAR expression was decreased remarkably in HiF group and HiF + HiAl group. The levels of StAR mRNA in three groups were reduced by 53.9%, 21.4% and 33.4%, respectively, while the expressions of P450scc mRNA were reduced by 67.8%, 17.0% and 47.8%. Therefore, we concluded that F induced the reduction in testosterone and sperm amount, and thus in lower fertility, which might occur as a consequence of depressed StAR and P450scc mRNA expression. There were no synergistic effects between F and Al, instead, Al weakened the toxicity of F to some extents. The results indicated that Al had antagonism effects on F.

Increase in the expression of inducible nitric oxide synthase on exposure to bisphenol A: a possible cause for decline in steroidogenesis in male mice

Bisphenol A (BPA) is a well-known plasticizer and xenoestrogen that is responsible for many acquired reproductive difficulties, especially in men. Despite the prevalence of BPA in society, the mechanism behind reproductive deficits remains elusive. The present study investigates the mode of BPA's action by evaluating its effect on the expression of inducible nitric oxide synthase (iNOS) and steriodogenic acute regulatoryprotein (StAR) in male mice testis. Swiss albino mice were treated with a range BPA concentrations of 0.5, 50 and 100μg/kg body weight/day intraperitoneally for 60 days. Several markers of oxidative stress and male fertility were investigated. Nitrite levels, malondialdehyde levels and testicular injury scores were elevated whereas the sperm count, serum testosterone levels and catalase activity were reduced in the BPA groups. Mechanistically, an increase in iNOS expression was observed in the testis whereas the expression of the StAR was down regulated in the BPA treated mouse. These results suggest that BPA induces oxidative stress by altering the expression of iNOS, which consequently leads to the down regulation of StAR expression in the testis of male mouse.