Ameliorative effects of N-acetylcysteine on fluoride-induced oxidative stress and DNA damage in male rats’ testis

Impact of fluoride exposure on reproductive health: Insights into molecular mechanisms and health implications

While the benefits of fluoride in preventing dental caries are well-established, concerns about its potential toxicity at high intake levels are rising. This review investigates the link between chronic fluoride exposure and reproductive health outcomes at the molecular level, focusing on population growth and child sex ratios in the fluorosis-affected and non-fluorosis regions. The exploration of the detrimental effects of fluoride on both male and female reproductive systems is necessary. In males, hormonal variations, alterations in spermatogenesis, capacitation, and sperm motility using molecular markers, epigenetic, transcriptomic, and proteomic data. For females, hormonal imbalances, disruptions in oocyte formation, teratogenicity (congenital disabilities), and compromised infant development due to maternal fluorosis using similar approaches. Furthermore, we explored drugs that address affected pathways, the potential benefits of vitamins and natural remedies, and lifestyle modifications to minimise adverse effects. The impact of various molecular pathways like apoptosis, autophagy, DNA damage, hormonal imbalance, inflammatory response, mitochondrial dynamics, and cell signalling pathways has been linked to reproductive toxicity induced by chronic and specific doses of fluoride. Analysing existing research and exploring potential therapeutic avenues contributes to the development of strategies to safeguard reproductive well-being in populations exposed to high fluoride levels.

Fluoride-induced testicular and ovarian toxicity: evidence from animal studies

Fluoride (F), as a natural element found in a wide range of sources such as water and certain foods, has been proven to be beneficial in preventing dental caries, but concerns have been raised regarding its potential deleterious effects on overall health. Sodium fluoride (NaF), another form of F, has the ability to accumulate in reproductive organs and interfere with hormonal regulation and oxidative stress pathways, contributing to reproductive toxicity. While the exact mechanisms of F-induced reproductive toxicity are not fully understood, this review aims to elucidate the mechanisms involved in testicular and ovarian injury. In males, F exposure at different doses has been associated with reduced testis weight, reduced sperm quality in terms of count, motility, and viability, as well as abnormal sperm morphology and disruption of seminiferous tubules by altering hormone levels (especially testosterone), impairing spermatogenesis, and inducing oxidative stress and zinc deficiency. Similarly, administration of F can impact female reproductive health by affecting ovarian function, hormone levels, oocyte quality, and the regularity of the estrous cycle. However, the impact of F exposure on LH, FSH, and GnRH levels is controversial between males and females. In both males and females, F exerts its adverse effects by triggering apoptosis, autophagy, inflammation, mitochondrial dysfunction, reduction in ATP synthesis, and modulation of important genes involved in steroidogenesis. Furthermore, genetic susceptibility and individual variations in F metabolism may contribute to different responses to fluoride exposure.

Effects of fluoride toxicity on the male reproductive system: A review

BACKGROUND

Fluoride toxicity and fluorosis is an emerging global problem. Fluoride has long been added to water for dental caries prevention; however, it has a variety of damaging consequences on human bodies. The aim of this paper is to analyse all the literature available on the effects of fluoride toxicity on male reproductive system.

METHODS

Research papers were collected using various methods of data collection like Pubmed, Scopus, and Google Scholar from 1980 to 2024, and then reviewed thoroughly.

RESULTS

Fluoride is known to cause various histopathological and biochemical alterations in the male reproductive system. It also affects fertility, semen quality, sperm number and quality,the process of spermatogenesis and spermiogenesis. Key changes caused by fluoride in male reproductive system include structural defects in the flagellum, acrosome, and nucleus of spermatids and epididymal spermatozoa. Degenerative changes in Leydig cells result in reduced testosterone production, causing regression of seminiferous tubules and structural damage to the epididymis, ultimately terminating spermatogenesis which leads to infertility. Decrease in levels of testosterone and activities of various antioxidant enzymes resulting in greater oxidative stress was also seen.

CONCLUSIONS

Fluoride has various detrimental effects on male reproductive system and overall reproductive health. This type of study is important for understanding the effects of fluoride toxicity so that health officials can guide public about safe fluoride exposure limits and the damages it can cause in higher concentrations. Studies using various natural and synthetic ameliorative substances mentioned in the text later can prove to be helpful for development of various therapeutic approaches to mitigate the effects of fluoride toxicity.

L-Cysteine Upregulates Testosterone Biosynthesis and Blood-Testis Barrier Genes in Cultured Human Leydig Cells and THP-1 Monocytes and Increases Testosterone Secretion in Human Leydig Cells

Leydig cells are the primary source of testosterone or androgen production in male mammals. The blood-testis barrier (BTB) maintains structural integrity and safeguards germ cells from harmful substances by blocking their entry into the seminiferous tubules. L-cysteine is essential to the production of glutathione, a powerful antioxidant crucial to protecting against oxidative stress-induced damage. Animal studies have demonstrated the protective effect of L-cysteine in preventing testicular damage caused by chemicals or radiation. This study examines whether L-cysteine enhances the expression of testosterone biosynthesis and the BTB genes in human Leydig cells and THP-1 monocytes. The Leydig cells and THP-1 monocytes were treated with L-cysteine for 24 h. RNA was extracted following treatment, and the gene expression was analyzed using quantitative RT-PCR. Testosterone levels in the cell supernatant were measured using an ELISA kit. L-cysteine treatment in Leydig cells significantly upregulated the expression of CYP11A1 (p = 0.03) and the BTB genes CLDN1 (p = 0.03), CLDN11 (p = 0.02), and TJP1 (p = 0.02). Similarly, L-cysteine significantly upregulated the expression of CYP11A1 (p = 0.03) and CYP19A1 (p < 0.01), and the BTB genes CLDN1 (p = 0.04), CLDN2 (p < 0.01), CLDN4 (p < 0.01), CLDN11 (p < 0.01), and TJP1 (p = 0.03) in THP-1 monocytes. Further, L-cysteine supplementation increased the testosterone secretion levels in human Leydig cells. The findings suggest that L-cysteine supplementation could be used as an adjuvant therapy to promote the integrity of the BTB genes, testosterone biosynthesis and secretion, and the maintenance of testicular functions, which in turn mitigates the risk of male infertility.

Micro- and Macronutrients in Endometrial Cancer-From Metallomic Analysis to Improvements in Treatment Strategies

Endometrial cancer is reported to be one of the most prevalent cancers of the female reproductive organs worldwide, with increasing incidence and mortality rates over the past decade. Early diagnosis is critical for effective treatment. Recently, there has been a growing focus on the role of nutrition and micronutrient and macronutrient status in patients with gynecologic cancers, including endometrial cancer. In the following paper, we have conducted an in-depth narrative literature review with the aim of evaluating the results of metallomic studies specifically concerning the micro- and macronutrient status of patients with endometrial cancer. The main objective of the paper was to analyze the results regarding the nutritional status of endometrial cancer patients and describe the role of chosen elements in the onset and progression of endometrial carcinogenesis. Further, we have focused on the evaluation of the usage of the described elements in the potential treatment of the abovementioned cancer, as well as the possible prevention of cancer considering proper supplementation of chosen elements in healthy individuals. Calcium supplementation has been proposed to reduce the risk of endometrial cancer, although some studies offer conflicting evidence. Deficiencies in phosphorus, selenium, and zinc have been inversely associated with endometrial cancer risk, suggesting they may play a protective role, whereas excessive levels of iron, copper, and cadmium have been positively correlated with increased risk. However, the molecular mechanisms by which these elements affect endometrial carcinogenesis are not fully understood, and current findings are often contradictory. Further research is needed to clarify these relationships and to evaluate the potential of nutritional interventions for the prevention and treatment of endometrial cancer.

The Protective Role of L-Cysteine in the Regulation of Blood-Testis Barrier Functions-A Brief Review

Blood-testis barrier (BTB) genes are crucial for the cellular mechanisms of spermatogenesis as they protect against detrimental cytotoxic agents, chemicals, and pathogens, thereby maintaining a sterile environment necessary for sperm development. BTB proteins predominantly consist of extensive tight and gap junctions formed between Sertoli cells. These junctions form a crucial immunological barrier restricting the intercellular movement of substances and molecules within the adluminal compartment. Epithelial tight junctions are complex membrane structures composed of various integral membrane proteins, including claudins, zonula occludens-1, and occludin. Inter-testicular cell junction proteins undergo a constant process of degradation and renewal. In addition, the downregulation of genes crucial to the development and preservation of cell junctions could disrupt the functionality of the BTB, potentially leading to male infertility. Oxidative stress and inflammation may contribute to disrupted spermatogenesis, resulting in male infertility. L-cysteine is a precursor to glutathione, a crucial antioxidant that helps mitigate damage and inflammation resulting from oxidative stress. Preclinical research indicates that L-cysteine may offer protective benefits against testicular injury and promote the expression of BTB genes. This review emphasizes various BTB genes essential for preserving its structural integrity and facilitating spermatogenesis and male fertility. Furthermore, it consolidates various research findings suggesting that L-cysteine may promote the expression of BTB-associated genes, thereby aiding in the maintenance of testicular functions.

Mitigative Effects of l-Arginine and N-Acetyl Cysteine against Cisplatin-Induced Testicular Dysfunction and Toxicity through the Regulation of Antioxidant, Anti-inflammatory, and Antiapoptotic Markers: Role of miR-155 and miR-34c Expression

Testicular dysfunction is a common adverse effect of cisplatin (CIS) administration as a chemotherapeutic drug. The current study has outlined the role of micro-RNAs (miR-155 and 34c) in CIS-induced testicular dysfunction and evaluated the protective effect of N-acetyl cysteine (NAC) and/or l-arginine (LA). Seven groups of Albino rats were used for this study. The control (C) group received physiological saline; the CIS group was injected CIS (7 mg/kg IP, once) on day 21 of the experiment; the NAC group was administered NAC (150 mg/kg intragastric, for 28 days); and the LA group was injected LA (50 mg/kg IP, for 28 days). NAC+CIS, LA+CIS, and NAC+LA+CIS groups received the above regime. CIS significantly reduced serum testosterone, LH, and FSH concentrations with decline of testicular enzyme activities. CIS caused significant elevation in testicular oxidative-stress biomarkers, inflammation-associated cytokines, and apoptosis markers, along with overexpression of miR-155 and low miR-34c expression. Additionally, marked testicular degenerative changes were observed in the examined histological section; a significant decrease in the expression of PCNA with significant increase in expressions of F4/80 and BAX was confirmed. The administration of NAC or LA upregulated testicular functions and improved histopathological and immunohistochemical changes as well as miRNA expression compared with the CIS-administered group. Rats receiving both NAC and LA showed a more significant ameliorative effect compared with groups receiving NAC or LA alone. In conclusion, NAC or LA showed an ameliorative effect against CIS-induced testicular toxicity and dysfunction through the regulation of antioxidant, anti-inflammatory, and antiapoptotic markers and via modulating miR-155 and miR-34c expression.

The Impact of Vitamin D and L-Cysteine Co-Supplementation on Upregulating Glutathione and Vitamin D-Metabolizing Genes and in the Treatment of Circulating 25-Hydroxy Vitamin D Deficiency

Vitamin D receptors are expressed in many organs and tissues, which suggests that vitamin D (VD) affects physiological functions beyond its role in maintaining bone health. Deficiency or inadequacy of 25(OH)VD is widespread globally. Population studies demonstrate that a positive association exists between a high incidence of VD deficiency and a high incidence of chronic diseases, including dementia, diabetes, and heart disease. However, many subjects have difficulty achieving the required circulating levels of 25(OH)VD even after high-dose VD supplementation, and randomized controlled clinical trials have reported limited therapeutic success post-VD supplementation. Thus, there is a discordance between the benefits of VD supplementation and the prevention of chronic diseases in those with VD deficiency. Why this dissociation exists is currently under debate and is of significant public interest. This review discusses the downregulation of VD-metabolizing genes needed to convert consumed VD into 25(OH)VD to enable its metabolic action exhibited by subjects with metabolic syndrome, obesity, and other chronic diseases. Research findings indicate a positive correlation between the levels of 25(OH)VD and glutathione (GSH) in both healthy and diabetic individuals. Cell culture and animal experiments reveal a novel mechanism through which the status of GSH can positively impact the expression of VD metabolism genes. This review highlights that for better success, VD deficiency needs to be corrected at multiple levels: (i) VD supplements and/or VD-rich foods need to be consumed to provide adequate VD, and (ii) the body needs to be able to upregulate VD-metabolizing genes to convert VD into 25(OH)VD and then to 1,25(OH)2VD to enhance its metabolic action. This review outlines the association between 25(OH)VD deficiency/inadequacy and decreased GSH levels, highlighting the positive impact of combined VD+LC supplementation on upregulating GSH, VD-metabolizing genes, and VDR. These effects have the potential to enhance 25(OH)VD levels and its therapeutic efficacy.

Kisspeptin-10 Improves Testicular Redox Status but Does Not Alter the Unfolded Protein Response (UPR) That Is Downregulated by Hypothyroidism in a Rat Model

Hypothyroidism compromises the testicular redox status and is associated with reduced sperm quality and infertility in men. In this regard, studies have demonstrated the antioxidant potential of kisspeptin in reproductive and metabolic diseases. In this study, we evaluate the effects of kisspeptin-10 (Kp10) on the testicular redox, as well as mediators of the unfolded protein response (UPR) in adult rats with hypothyroidism. Adult male Wistar rats were randomly separated into the Control (n = 15), Hypo (n = 13) and Hypo + Kp10 (n = 14) groups, and hypothyroidism was induced with 6-propyl-2-thiouracil (PTU) for three months. In the last month, half of the hypothyroid animals received Kp10. Testis samples were collected for enzymatic, immunohistochemical and/or gene evaluation of mediators of oxidative stress (TBARs, lipid hydroperoxides (LOOH), ROS, peroxynitrite, SOD, CAT and GPX), endoplasmic reticulum stress (GRP78, ATF6, PERK, CHOP, HO-1 and sXBP1) and antiapoptocytes (BCL-2). Hypothyroidism increased apoptosis index, TBARS and LOOH concentrations, and reduced testicular gene expression of Sod1, Sod2 and Gpx1, as well as the expression of Grp78, Atf6, Ho1 and Chop. Treatment with Kp10, in turn, reduced testicular apoptosis and the production of peroxynitrite, while increased SOD1 and GPX ½ expression, and enzymatic activity of CAT, but did not affect the lower expression of UPR mediators caused by hypothyroidism. This study demonstrated that hypothyroidism causes oxidative stress and dysregulated the UPR pathway in rat testes and that, although Kp10 does not influence the low expression of UPR mediators, it improves the testicular redox status, configuring it as an important antioxidant factor in situations of thyroid dysfunction.

Effect of syringic acid on oxidative stress, autophagy, apoptosis, inflammation pathways against testicular damage induced by lead acetate

BACKGROUND

Heavy metals are one of the environmental pollutants. Lead (Pb) is one of the most common of these heavy metals. In this study, it was aimed at investigating the effects of syringic acid (SA) against testicular toxicity in rats administered lead acetate (PbAc).

METHODS

In the present study, a total of 35 Sprague-Dawley rats, 7 in each group, were used. The rats were divided into 5 groups, with 7 male rats in each group. Rats were given PbAc and SA orally for 7 days. The effects of PbAc and SA on epididymal sperm quality and apoptosis, inflammation, oxidative stress and histopathological changes in testicular tissue were determined.

RESULTS

While PbAc disrupted the seminiferous tubules and produced atrophic images, SA corrected these histological abnormalities. PbAc adminisration significantly reduced the levels of SOD, GSH, GPx, CAT, NRF-2 and NQO1 and significantly increased the levels of MDA and 8-OHdG in the testicular tissue of rats, while SA improved this situation. NF-κB, TNF-α, IL-1β, NLRP3, RAGE, ATF6, PERK, IRE1, CHOP, and GRP78 genes expression levels increased with PbAc administration, however these levels decreased with SA administration. In addition, PbAc increased the levels of apoptotic markers Bax, Caspase-3 and APAF-1 and decreased the level of Bcl-2, while SA improved this situation. It was observed that PbAc significantly reduced sperm quality in rats, while SA positively affected sperm quality.

CONCLUSION

As a result, SA administered against PbAc-induced testicular dysfunction in rats can provide effective protection at doses of 25 mg/kg/bw and 50 mg/kg/bw.

Chronic exposure to environmentally relevant concentration of fluoride impairs osteoblast's collagen synthesis and matrix mineralization: Involvement of epigenetic regulation in skeletal fluorosis

Globally, 200 million people are suffering from toxic manifestations of Fluoride(F), dental and skeletal fluorosis; unfortunately, there is no treatment. To unravel the pathogenesis of skeletal fluorosis, we established fluorosis mice by treating environmentally relevant concentration of F (15 ppm NaF) through drinking water for 4 months. As in skeletal fluorosis, locomotor disability, crippling deformities occur and thus, our hypothesis was F might adversely affects collagen which gives the bone tensile strength. This work inevitably had to be carried out on osteoblast cells, responsible for synthesis, deposition, and mineralization of bone matrix. Isolated osteoblast cells were confirmed by ALP activity and mineralized nodules formation. Expression of collagen Col1a1, Col1a2, COL1A1 was significantly reduced in treated mice. Further, a study revealed the involvement of epigenetic regulation by promoter hypermethylation of Col1a1; expressional alterations of transcription factors, calcium channels and other genes e.g., Cbfa-1, Tgf-β1, Bmp1, Sp1, Sp7, Nf-Kb p65, Bmp-2, Bglap, Gprc6a and Cav1.2 are associated with impairment of collagen synthesis, deposition and decreased mineralization thus, enfeebling bone health. This study indicates the possible association of epigenetic regulation in skeletal fluorosis. However, no association was found between polymorphisms in the Col1a1 (RsaI, HindIII) and Col1a2 (RsaI, HindIII) genes with fluorosis in mice.

Pomegranate peel extract, N-Acetylcysteine and their combination with Ornipural alleviate Cadmium-induced toxicity in rats

Cadmium is a major environmental pollutant and a highly toxic metal. It was aimed to determine the effects of pomegranate peel extract (PPE), N-acetylcysteine (NAC) alone and along with Ornipural on cadmium-induced toxicity. Forty-six Wistar Albino male rats were divided into 6 groups and the groups were formed into healthy control, Cadmium group (5 mg/kg/day, oral), Cadmium + Pomegranate peel extract (500 mg/kg, oral), Cadmium + N-acetylcysteine (100 mg/kg, oral), Cadmium + Pomegranate peel extract (500 mg/kg, oral) + Ornipural (1 mL/kg, subcutaneous) and Cadmium + N-acetylcysteine (100 mg/kg, oral) + Ornipural (1 mL/kg, subcutaneous). Cadmium accumulated heavily in both liver and kidney tissue. The administration of N-acetylcysteine and pomegranate peel extract alone reduced cadmium levels in both tissues. N-acetylcysteine treatment prevented the increase in ALT and MDA levels by cadmium damage. N-acetylcysteine + Ornipural treatment inhibited the increase in liver 8-OHdG level in the liver. N-acetylcysteine and N-acetylcysteine + Ornipural treatments prevented the reduced serum MMP2 level. N-acetylcysteine and Pomegranate peel extract + Ornipural treatments significantly reduced the increased liver iNOS level in the liver. In conclusion, NAC therapy may be a successful treatment option for cadmium toxicity. However, further research is needed on the effects of PPE and Ornipural combinations for the treatment of cadmium toxicity. In future studies, various doses of these treatment options (with chelators) should be investigated for cadmium toxicity.

Effect of Fluoride on the Expression of 8-Hydroxy-2'-Deoxyguanosine in the Blood, Kidney, Liver, and Brain of Rats

Excessive exposure of fluoride not only leads to damage on bone, but also has an adverse effect on soft tissues. Oxidative DNA damage induced by fluoride is thought to be one of the toxic mechanisms of fluoride effect. However, the dose-response of fluoride on oxidative DNA damage is barely studied in organisms. This study investigated the concentration of fluoride in rat blood, kidney, liver, and brain as well as the dose-time effect of fluoride on the expression of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the above tissues. Rats were exposed to 0 mg/L, 25 mg/L, 50 mg/L, and 100 mg/L of fluorine ion and treated for one and three months. The results showed that the accumulation of fluoride in soft tissues was very different. At the first month, blood fluoride was increased, liver and brain fluoride showed a U-shaped change, and kidney fluoride was not significant. At the third month, blood fluoride was altered with an inverted U-shaped change, kidney and brain fluoride increased, but liver fluoride decreased. Both the exposure concentration and the time of exposure had a significant effect on the expression of 8-OHdG in the above tissues. However, the effect patterns of fluoride on these tissues were notably different at different times. At the first month of fluoride treatment, blood, kidney, and liver 8-OHdG decreased with the increasing fluoride concentration. At the third month, blood 8-OHdG showed a U-shaped change, but kidney 8-OHdG altered with an inverted U-shaped change. Liver 8-OHdG increased, while brain 8-OHdG decreased at the third month. Correlation analysis showed that only blood 8-OHdG was significantly inversely correlated with blood fluoride and dental fluorosis grade in both the first and third months. Liver 8-OHdG was negatively and significantly correlated with liver fluoride. There was a weak but nonsignificant correlation between kidney and brain 8-OHdG and fluoride in both tissues. Additionally, blood 8-OHdG was positively correlated with kidney and liver 8-OHdG at the first month and positively correlated with brain 8-OHdG at the third month. Taken together, our data suggests that concentration and time of fluoride exposure had a significant effect on 8-OHdG, but the effect patterns of fluoride on 8-OHdG were different in the tissues, which suggests that the impact of fluoride on 8-OHdG may be a tissue-specific, as well as a non-monotonic positive correlation.

N-acetylcysteine rescues meiotic arrest during spermatogenesis in mice exposed to BDE-209

Deca-bromodiphenyl ethers (BDE-209) has been widely used in electronic devices and textiles as additives to flame retardants. Growing evidence showed that BDE-209 exposure leads to poorer sperm quality and male reproductive dysfunction. However, the underlying mechanisms of BDE-209 exposure caused a decline in sperm quality remains unclear. This study aimed to evaluate the protective effects of N-acetylcysteine (NAC) on meiotic arrest in spermatocytes and decreased sperm quality in BDE-209-exposed mice. In the study, mice were treated with NAC (150 mg/kg BW) 2 h before administrated with BDE-209 (80 mg/kg BW) for 2 weeks. For the in vitro studies, spermatocyte cell line GC-2spd cells were pretreated with NAC (5 mM) 2 h before treated with BDE-209 (50 μM) for 24 h. We found that pretreatment with NAC attenuated the oxidative stress status induced by BDE-209 in vivo and in vitro. Moreover, pretreatment with NAC rescued the testicular histology impairment and decreased the testicular organ coefficient in BDE-209-exposed mice. In addition, NAC supplement partially promoted meiotic prophase and improved sperm quality in BDE-209-exposed mice. Furthermore, NAC pretreatment effectively improved DNA damage repair by recovering DMC1, RAD51, and MLH1. In conclusion, BDE-209 caused spermatogenesis dysfunction related to the meiotic arrest medicated by oxidative stress, decreasing sperm quality.

Fluoride-Induced Sperm Damage and HuR-Mediated Excessive Apoptosis and Autophagy in Spermatocytes

It is critical to determine the mechanism underlying fluoride (F)-induced damage of the testes to develop appropriate strategies for monitoring and intervention. In the present study, exposure to 50 mg/L sodium fluoride (NaF) for 90 days damaged the normal structure of the testes and quality of the sperm, particularly the spermatocytes, and triggered overexpression of human antigen R (Elavl1/HuR) according to western blotting and immunofluorescence. Furthermore, 0.5 mM NaF exposure for 24 h exposure increased the proportion of apoptosis and expression of caspase-3 and caspase-9 in mouse spermatocytes (GC-2spd cell line), whereas inhibition of HuR reduced apoptosis and the expression of caspase-3 and caspase-9. Additionally, inhibition of HuR alleviated F-induced autophagy based on observation of the autophagy bodies, detection of autophagy activity, and analysis of the expression of the LC3II/LC3I and p62 proteins. These results reveal that excessive F can lead to overexpression of HuR, resulting in high levels of apoptosis and autophagy in spermatocytes. These findings improve the understanding of the mechanisms underlying F-induced male reproductive toxicity, and HuR may be explored as a treatment target for certain conditions. Excessive fluoride can induce overexpression of HuR in testis and result in excessive apoptosis and autophagy in spermatocytes as well as male reproductive damage, such as a decreased sperm count, decreased sperm motility, and increased deformity rate.

Exploring Nrf2 as a therapeutic target in testicular dysfunction

Testicular dysfunction, a major contributory factor to infertility, has received a lot of attention over the recent years. Several studies have linked abnormal sperm function and morphology with an enhanced generation of reactive oxygen species (ROS) and oxidative stress. The nuclear factor erythroid-derived 2 (Nrf2) is a transcriptional response to cellular stresses (intrinsic or extrinsic) that regulates the oxidative status, mitochondrial dysfunction, inflammation, and proteostasis. In this review, the therapeutic role of Nrf2 was explored. To do so, scientific data were retrieved from databases such as Elsevier, Wiley, Web of Science, Springer, PubMed, Taylor and Francis, and Google Scholar using search terms such as "Nrf2" and "testis," "sperm," "testicular function," and "testosterone." It has been noted that Nrf2 influences the physiology and pathology of testicular dysfunction, especially in the spermatogenic process, by regulating cellular resistance to oxidative stress, inflammation, and environmental toxicants. However, numerous compounds serve as activators and inhibitors of testicular Nrf2. Nrf2 activators might play a therapeutic role in the prevention and treatment of testicular dysfunction, while molecules that inhibit Nrf2 might induce dysfunction in testis components. Nrf2 activators protect cells against oxidative damage and activate Nrf2/KEAP1 signaling which promotes its movement to the nucleus, and increased Nrf2 function and expression, along with their downstream antioxidant gene. Nrf2 inhibitors facilitate oxidative stress via interfering with the Nrf2 signal pathway. The Nrf2 activation could serve as a promising therapeutic target for testicular dysfunction. This review explored the effect of Nrf2 on testicular function while highlighting potential activators and inhibitors of Nrf2.

Evaluation of the toxicological effects of atrazine-metolachlor in male rats: in vivo and in silico studies

The types and mechanisms of atrazine-metolachlor toxicity, an herbicide composed of atrazine (ATR) and metolachlor (MET), need to be further investigated. This study evaluated the toxic actions of ATR-MET by in vivo and in silico methods. Here, varying doses of ATR-MET were orally administered to rats once daily for twenty-one days using normal saline as control. Molecular docking was used to characterize the binding of ATR and MET with androgen receptor (AR) to predict their potential endocrine-disrupting effects, using testosterone as benchmark. ATR-MET-induced-testicular toxicity (reduced sperm motility, count, and daily sperm production and increased live/dead ratio) was accompanied with testicular oxidative stress (diminished level of reduced glutathione, activities of glutathione-S-transferase, superoxide dismutase and catalase and increased level of malondialdehyde). Furthermore, ATR-MET induced cardiovascular toxicity (increased levels of plasma total cholesterol, HDL-cholesterol, LDL-cholesterol, and triglycerides) with concomitant induction of renal toxicity (increased plasma creatinine and urea levels), and hepatotoxicity (increased plasma bilirubin, alkaline phosphatase, acid phosphatase, alanine aminotransferase and aspartate aminotransferase). Binding energy and amino acid interactions from in silico study revealed that MET possessed endocrine-disrupting capacity. In conclusion, exposure to atrazine-metolachlor could promote cardiovascular, renal, hepatic, as well as reproductive impairment in experimental male albino rats.

Role of oxidative stress-mediated cell death and signaling pathways in experimental fluorosis

Free radicals and other oxidants have enticed the interest of researchers in the fields of biology and medicine, owing to their role in several pathophysiological conditions, including fluorosis (Fluoride toxicity). Radical species affect cellular biomolecules such as nucleic acids, proteins, and lipids, resulting in oxidative stress. Reactive oxygen species-mediated oxidative stress is a common denominator in fluoride toxicity. Fluorosis is a global health concern caused by excessive fluoride consumption over time. Fluoride alters the cellular redox homeostasis, and its toxicity leads to the activation of cell death mechanisms like apoptosis, autophagy, and necroptosis. Even though a surfeit of signaling pathways is involved in fluorosis, their toxicity mechanisms are not fully understood. Thus, this review aims to understand the role of reactive species in fluoride toxicity with an outlook on the effects of fluoride in vitro and in vivo models. Also, we emphasized the signal transduction pathways and the mechanism of cell death implicated in fluoride-induced oxidative stress.

Testicular toxicity of cisplatin in rats: ameliorative effect of lycopene and N-acetylcysteine

Lycopene (LP) and N-acetylcysteine (NAC) protective effects were assessed for testicular toxicity mediated by cisplatin (CP) in rats. Forty-nine rats were divided into 7 groups (n = 7); these groups included the control group (saline, PO), LP (10 mg/kg, PO), NAC (150 mg/kg, PO), CP (7.5 mg/kg, IP) on the 27th day of the study, LP + CP, NAC+CP, and LP + NAC + CP. Serum levels of testosterone were decreased following CP injection. Malondialdehyde (MDA) has been increased with considerable glutathione (GSH), and dismutase superoxide (SOD) and catalase (CAT) decline in the testis tissues after CP injection. CP caused severe alterations in testicular tissues and elevated caspase-3 expression. Besides that, LP and/or NAC administration improved CP-induced testicular toxicity and apoptosis, probably via their antioxidant properties.

Long-Term Wi-Fi Exposure From Pre-Pubertal to Adult Age on the Spermatogonia Proliferation and Protective Effects of Edible Bird’s Nest Supplementation

Children are vulnerable to the radiofrequency radiation (RFR) emitted by Wi-Fi devices. Nevertheless, the severity of the Wi-Fi effect on their reproductive development has been sparsely available. Therefore, this study was conducted to evaluate the Wi-Fi exposure on spermatogonia proliferation in the testis. This study also incorporated an approach to attenuate the effect of Wi-Fi by giving concurrent edible bird’s nest (EBN) supplementation. It was predicted that Wi-Fi exposure reduces spermatogonia proliferation while EBN supplementation protects against it. A total of 30 (N = 30) 3-week-old Sprague Dawley weanlings were divided equally into five groups; Control, Control EBN, Wi-Fi, Sham Wi-Fi, and Wi-Fi + EBN. 2.45 GHz Wi-Fi exposure and 250 mg/kg EBN supplementation were conducted for 14 weeks. Findings showed that the Wi-Fi group had decreased in spermatogonia mitosis status. However, the mRNA and protein expression of c-Kit-SCF showed no significant decrease. Instead, the reproductive hormone showed a reduction in FSH and LH serum levels. Of these, LH serum level was decreased significantly in the Wi-Fi group. Otherwise, supplementing the Wi-Fi + EBN group with 250 mg/kg EBN resulted in a significant increase in spermatogonia mitotic status. Even though EBN supplementation improved c-Kit-SCF mRNA and protein expression, the effects were insignificant. The improvement of spermatogonia mitosis appeared to be associated with a significant increase in blood FSH levels following EBN supplementation. In conclusion, the long-term Wi-Fi exposure from pre-pubertal to adult age reduces spermatogonia proliferation in the testis. On the other hand, EBN supplementation protects spermatogonia proliferation against Wi-Fi exposure.

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.

Sperm quality parameters and oxidative stress: Exploring correlation in fluoride-intoxicated rats

Background:

Assessment of male fertility needs evaluation of sperm quality parameters, namely sperm count, viability, motility and morphology.

Aims:

The present study aimed to analyse and correlate oxidative stress with sperm quality parameters.

Settings and Design:

The male Wistar albino rats, weighing between 100 and 150 g, were employed in the present study under the Committee for the Purpose of Control and Supervision of Experiments on Animals guidelines with ethical clearance from the Institutional Ethical Committee. These rats were categorised into four groups with six rats in each as control and test animals.

Materials and Methods:

Young male Wistar albino rats, weighing between 100 and 150 g, were divided into four groups of six rats each. The first group of rats served as control (n = 6) and was maintained under normal laboratory condition and was provided with clean drinking water, whereas rats in the second (n = 6), third (n = 6) and fourth (n = 6) groups were orally intubated with sodium fluoride of 100 ppm, 200 ppm and 300 ppm, respectively, for 40 days.

Statistical Analysis Used:

After the treatment period of 40 days, animals were sacrificed and alterations in sperm quality parameters were analysed by complete randomised design SAS 9.4 and Statistical Package for the Social Sciences (SPSS) IBM 17 and judged significant if P < 0.05.

Results:

In the experiment, a negative correlation emerged between sperm motility, viability, count versus malondialdehyde (MDA) levels, whereas the level of MDA has a positive correlation with sperm abnormalities. Sperm motility, viability and count were positively correlated with activities of superoxide dismutase and catalase, whereas decreased activities of antioxidants were related to increased sperm morphological abnormalities.

Conclusion:

These results suggest that MDA causes a decline in sperm motility, count and viability and an increase in morphological abnormalities via oxidative damage of membrane lipids.

Co-exposure to fluoride and arsenic disrupts intestinal flora balance and induces testicular autophagy in offspring rats

While numerous studies have shown that fluoride or arsenic exposure may damage the reproductive system, there are few reports of co-exposure to fluoride and arsenic. In addition, the literature on autophagy and intestinal flora composition in reproductive toxicity studies of co-exposure to fluoride and arsenic is insufficient. In this study, we developed a rat model of fluoride and arsenic exposure via drinking water from pre-pregnancy to 90 days postnatal. Sprague-Dawley rats were randomly divided into sterile water control group, fluoride group (100 mg/L NaF), arsenic group (50 mg/L NaAsO₂) and combined exposure group (100 mg/L NaF+50 mg/L NaAsO₂). Our results showed that fluoride and arsenic exposure caused a reduction in testicular weight and significant pathological damage to tissue. We found that the levels of follicle-stimulating hormone, luteinizing hormone, and testosterone were reduced to varying degrees. Meanwhile experiments showed that fluoride and arsenic exposure can modulate autophagic flux, causing increased levels of Beclin1 and LC3 expression and decreased p62 expression. Analogously, by performing 16S sequencing of rat feces, we found 24 enterobacterial genera that differed significantly among the groups. Furthermore, the flora associated with testicular injury were identified by correlation analysis of hormonal indices and autophagy alterations with intestinal flora composition at the genus level, respectively. In summary, our study shows that fluoride and arsenic co-exposure alters autophagic flux in the testis, causes testicular injury, and reveals an association between altered intestinal flora composition and testicular injury.

The role of Nrf2 pathway in alleviating fluorine-induced apoptosis by different selenium sources in the chicken duodenum and jejunum

In order to evaluate the alleviative effects and molecular mechanisms of sodium selenite (SS) and selenomethionine (SM) on excessive apoptosis induced by high fluorine (HF) in the duodenum and jejunum of broilers, 720 1 day old Lingnan Yellow broilers were randomly divided into 4 groups (each group assigned 180 chickens with 6 replicates) and offered either a control diet or test diets (800 mg/kg F, HF group; 800 mg/kg F + 0.15 mg selenium (Se)/kg as SS (SS group) or SM (SM group)) for 50 days. High F intake significantly increased (P < 0.05) apoptosis rates of duodenum and jejunum by inducing oxidative stress and leading to mitochondrial damage. Selenomethionine supplementation effectively alleviated mitochondrial damage and severe apoptosis of duodenum and jejunum caused by HF through decreasing oxidative stress parameters. Selenomethionine added group significantly increased (P < 0.05) nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA and nuclear Nrf2 protein levels as well as Nrf2 downstream antioxidant enzymes expressions in the duodenum and jejunum when compared with the HF group. Selenomethionine was superior to SS in activating the Nrf2 pathway and reducing the apoptosis rate of duodenum. It was concluded that dietary SM supplementation could ameliorate F-induced excessive apoptosis by inducing the Nrf2 pathway. Our findings will bring a promising tactics for the utilization of SM as an efficient antioxidant additive for reducing the intestinal damage caused by fluorosis in poultry.

Synergistic protective effects of lycopene and N-acetylcysteine against cisplatin-induced hepatorenal toxicity in rats

Cisplatin (CP) is one of the most frequently used chemotherapy agents. The objective of this design was to determine the ameliorative effect of lycopene (LP) and/or N-acetylcysteine (NAC) in rats with hepatic and renal toxicity induced by CP. Rats were divided randomly into 7 groups (7 rats/group): control vehicle group (saline only), the LP group (10 mg/kg, orally), the NAC group (150 mg/kg, orally), the CP group (7.5 mg/kg, IP on day 27), the LP-CP group, the NAC-CP group, and the LP-NAC-CP group. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (APK), and levels of urea, creatinine, and lipids (cholesterol, triglycerides, and low-density lipoprotein-cholesterol) increased after CP injection in the serum. Moreover, CP decreased levels of protein, albumin, and HDL cholesterol. Meanwhile, malondialdehyde significantly increased with a decrease in reduced glutathione, superoxide dismutase, and catalase in the liver and kidney tissues. CP also induced some pathological lesions and increased the expression of caspase-3 in the liver and kidney tissues. Administration of LP and NAC alone or in combinations ameliorated hepatorenal toxicity and apoptosis induced by CP.

Effects of Fluoride on Oxidative Stress Markers of Lipid, Gene, and Protein in Rats

Endemic fluorosis is a systemic chronic disease caused by excessive intake of fluoride. It is widely accepted that oxidative stress is closely related to fluorosis; however, molecular mechanism of oxidative stress in fluorosis remains unclear. This study investigated the effects of fluoride (F) on oxidative stress markers of lipid, gene, and protein in rats for revealing molecular mechanism of oxidative stress in fluorosis. The results showed concentration and exposure time of fluoride both had a significant effect on MDA and 8-OHdG. Fluoride concentration significantly impacted AGEs level, but exposure time did not. AOPP was not statistically different among the groups. AGEs decreased with the increase of fluoride in the rats with 3 months of fluoride treatment. The correlation analysis showed the degree of dental fluorosis was significantly negatively correlated with 8-OHdG at 1 month and 3 months, and negatively correlated with AGEs at 3 months. In the rats with 100 mg/L of fluoride treatment, MDA was significant positively correlated with 8-OHdG, and negatively correlated with AGEs. 8-OHdG was significantly negatively correlated with AGEs in the control group and 100 mg/L fluoride group. Taken together, fluoride had different effects on oxidative stress markers of lipid, gene, and protein. Excessive fluoride could increase MDA content, and decrease 8-OHdG and AGEs. These findings suggest that oxidative stress involved in molecular pathogenesis of fluorosis is complicated, and needs to furtherly study in the future.

Edible Bird's Nest Supplementation Improves Male Reproductive Parameters of Sprague Dawley Rat

Edible bird’s nest (EBN) is reported to have a positive in vitro proliferative effect and contain male reproductive hormones. Spermatogonia cells proliferate during spermatogenesis under male reproductive hormones stimulation that include testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH). Characterization of EBN through liquid chromatography-mass spectrometry (LCMS) has found testosterone as a base peak. Six types of amino acids, estradiol and sialic acid were among the major peaks that have been characterized. Based on the presence of these reproductive components, this study evaluated different doses of EBN on sperm parameters and male reproductive hormones of Sprague Dawley rats. Sixteen Sprague Dawley rats at the age of eight weeks were randomly and equally divided into four groups, which are Control, 10 mg/kg BW/d 50 mg/kg BW/d, and 250 mg/kg BW/d EBN group. The rats were fed with EBN enriched pellet daily and water ad-libitum. Rats were sacrificed and the organ was weighed for organ coefficients after eight weeks of treatment. Sperm concentration, percentage of sperm motility, and sperm viability were evaluated. Meanwhile, ELISA method was used to measure testosterone, FSH, and LH. Findings showed that there were no significant differences in organ coefficient between groups. Supplementation of 250 mg/kg BW/d EBN demonstrated a significant increase in sperm concentration, percentage of sperm motility as well as FSH and LH level compared to 10 mg/kg BW/d group. There was a dose-dependent increase in testosterone level but was not significant between groups. Based on these findings, EBN is concluded to have crucial effects on male reproductive parameters.

PM2.5 exposure induces reproductive injury through IRE1/JNK/autophagy signaling in male rats

Fine particulate matter (PM2.5) constitutes the most significant air pollutant that causes health risks. However, the mechanism(s) underlying PM2.5-induced male reproductive injury has not been clarified. In the present study we explored whether PM2.5 activated the inositol-requiring enzyme 1 (IRE1)/c-Jun NH 2-terminal kinase (JNK)/autophagy-signaling pathway, and whether this pathway mediated reproductive injury in male rats. We established a male Sprague-Dawley rat model of PM2.5 (1.5 mg/kg) exposure-induced reproductive injury, and observed the intervention effects of STF083010 (an IRE1 inhibitor, 1 mg/kg). After 4 weeks of exposure, reproductive injury-related indicators and IRE1-cascade protein expression were analyzed. Our results showed that sperm quality and serum testosterone level significantly decreased and apoptotic index increased after exposure to PM2.5. After STF083010 intervention, sperm quality and serum testosterone level were significantly improved, while the apoptotic index was reduced. Under light microscopy, we observed that the structure of spermatogenic cells in the PM2.5 group was loose, and that the numbers of spermatogenic cells and mature spermatozoa were reduced. After STF083010 intervention, the structural damage to spermatogenic cells was improved, and the number of cells shed was reduced. Western blotting analysis showed that the expression of IRE1, phosphorylated JNK (p-JNK), beclin-1, and microtubule-associated protein 1 light chain 3(LC3)II/LC3I proteins was significantly upregulated, and that the expression of p62 protein was significantly downregulated in the PM2.5 group. The concomitant administration of STF083010 significantly antagonized the aforementioned adverse effects. STF083010 exerted specific protective effects on reproductive injury-related effects in male rats exposed to PM2.5, with effects mediated via IRE1/JNK/autophagy signaling.

Fluoride induced testicular toxicities in adult Wistar rats

Fluoride is essential for the development of teeth and bone but its excessive exposure causes reprotoxic effects. We have studied the graded effects of different doses of sodium fluoride (NaF) on 24 adult Wistar rats which were randomly divided into four groups (n = 6). All the rats were given normal diet prepared in our laboratory. Control (group I) rats were received vehicle only and treated rats (group II, III, and IV) were administered NaF orally at 10, 15, and 20 mg/kg/d doses, respectively, for 30 consecutive days. Gravimetric index of testis was decreased significantly in group III and IV rats but such changes were not observed in the accessory reproductive organs. Marked alterations in number, motility, viability, and plasma membrane functional integrity of caudal spermatozoa were noted in most of the treated groups. Noticeable alterations in testicular histoarchitecture were observed in group III and IV rats. Graded Changes of testicular redox homeostasis were noted by assessment of enzymatic (superoxide dismutase [SOD], catalase, glutathione s-transferase [GST], and glutathione peroxidase [GPx]) and nonenzymatic (malondialdehyde [MDA] and protein carbonyl [PC]) markers. Changes of testicular functional markers (acid phosphatase [ACP], alkaline phosphatase [ALP], and lactate dehydrogenase (LDH) activity) were noted in group III and IV rats. DNA fragmentation assay proved the possibility of DNA damage caused by oxidative stress, as evidenced by prominent trailing pattern of fragmented testicular genomic DNA from group III and IV rats. The study concludes that fluoride-mediated oxidative stress not only impedes the structural and functional facets of testis but also results in testicular DNA damage.

Treatment of oxidative stress, apoptosis, and DNA injury with N-acetylcysteine at simulative pesticide toxicity in fish

Pesticide toxicities are common in aquatic ecosystems and affects aquatic livings negative. Therefore, it is important to strengthen the antioxidant system in aquatic organisms and to protect the organisms against these toxic chemicals. In this study, the simulative toxicity was established to the fish then the healing process was followed. For this purpose, rainbow trout Oncorhynchus mykiss exposed to cypermethrin and left to the recovery process with either N-acetyl cysteine (an antioxidant, 0.5 mM-1.0 mM concentrations) or no intervention (self-healing) for 96 h. In this context, paraoxonase (PON), arylesterase (AR), myeloperoxidase (MPO), antioxidant enzymes (SOD, CAT, GPx), acetylcholinesterase (AChE) activities as well as MDA, caspase-3 and 8-OHdG levels were measured in fish gills, liver and kidney tissues. In addition, trace element tests were performed in the tissues sampled for each group. At the result of pesticide exposure, SOD, CAT, GPx, PON, AR and AChE activities were increased but MDA, MPO, caspase-3 and 8-OHdG levels were decreased in N-acetyl cysteine (NAC) treated groups in all tissues compared to self-healing group (p < 0.05). When the element analysis of the samples was examined, tissue-based differences were observed significantly in all application groups (p < 0.05). Considering the results of the study, it was found that NAC administration at high concentration (1.0 Mm NAC) was more effective on pesticide toxicity. It was concluded that the most sensitive tissue was the kidney.

Antioxidant effects of N-acetylcysteine on the male reproductive system: A systematic review

This study aimed to evaluate the effect of N-acetyl cysteine on the male reproductive system and consensus and classification of data found from previous studies. It is undeniable that N-acetyl cysteine as a powerful antioxidant compound can medicate many diseases such as cardiovascular, kidney, liver and reproductive system disorders. With the increasing environmental pollution that has a direct adverse effect on male fertility, the use of this compound is able to positively function on human fertility health. In this study, we have been collected the main data of scientific articles (1994-2020) about N-acetyl cysteine effects. By searching in the scientific databases of PubMed, Google Scholar, Science Direct, Wiley and Web of Science, related articles were extracted. As a result, all observations have confirmed that N-acetyl cysteine can improve and normalise the spermatogenesis in the male reproduction system.

The effect of bee pollen on reproductive and biochemical parameters in methotrexate-induced testicular damage in adult rats

OBJECTIVES

Methotrexate (MTX) is an anticancer drug used in chemotherapy. MTX was known for its toxic effects involving most of the organs including testis. Bee pollen is healthy food for human and has antioxidant effect. We intended to determine protective effect of bee pollen against testicular injury caused by MTX in rats.

METHODS

Thirty-two adult Sprague Dawley male rats were used, and 4 groups were formed: control, MTX, pollen, and MTX + pollen. Rats were given pollen at a dose of 400 mg/kg with intragastric gavage for 10 days. On day 7, MTX was administered a single dose of 30 mg/kg ip. Serum testosterone and LH, tissue MDA level, and SOD and CAT enzyme activities were examined. In addition, spermatological parameters were evaluated.

RESULTS

MDA level and SOD activity increased while testosterone level decreased significantly in the MTX group compared to the control group. In the MTX + pollen group, MDA level and SOD activity decreased while testosterone level increased. There was no significant change in CAT activity and LH values. Abnormal sperm ratio decreased in the MTX + pollen group compared to the MTX group.

CONCLUSIONS

Our results suggest that bee pollen has a healing effect on reproductive parameters in testicular damage caused by MTX.

Chronic exposure to environmentally relevant concentration of fluoride alters Ogg1 and Rad51 expressions in mice: Involvement of epigenetic regulation

Chronic exposure to fluoride (F) beyond the permissible limit (1.5 ppm) is known to cause detrimental health effects by induction of oxidative stress-mediated DNA damage overpowering the DNA repair machinery. In the present study, we assessed F induced oxidative stress through monitoring biochemical parameters and looked into the effect of chronic F exposure on two crucial DNA repair genes Ogg1 and Rad51 having important role against ROS induced DNA damages. To address this issue, we exposed Swiss albino mice to an environmentally relevant concentration of fluoride (15 ppm NaF) for 8 months. Results revealed histoarchitectural damages in liver, brain, kidney and spleen. Depletion of GSH, increase in lipid peroxidation and catalase activity in liver and brain confirmed the generation of oxidative stress. qRT-PCR result showed that expressions of Ogg1 and Rad51 were altered after F exposure in the affected organs. Promoter hypermethylation was associated with the downregulation of Rad51. F-induced DNA damage and the compromised DNA repair machinery triggered intrinsic pathway of apoptosis in liver and brain. The present study indicates the possible association of epigenetic regulation with F induced neurotoxicity.

N-acetylcysteine (NAC), an anti-oxidant, does not improve bone mechanical properties in a rat model of progressive chronic kidney disease-mineral bone disorder

Individuals with chronic kidney disease have elevated levels of oxidative stress and are at a significantly higher risk of skeletal fracture. Advanced glycation end products (AGEs), which accumulate in bone and compromise mechanical properties, are known to be driven in part by oxidative stress. The goal of this study was to study effects of N-acetylcysteine (NAC) on reducing oxidative stress and improving various bone parameters, most specifically mechanical properties, in an animal model of progressive CKD. Male Cy/+ (CKD) rats and unaffected littermates were untreated (controls) or treated with NAC (80 mg/kg, IP) from 30 to 35 weeks of age. Endpoint measures included serum biochemistries, assessments of systemic oxidative stress, bone morphology, and mechanical properties, and AGE levels in the bone. CKD rats had the expected phenotype that included low kidney function, elevated parathyroid hormone, higher cortical porosity, and compromised mechanical properties. NAC treatment had mixed effects on oxidative stress markers, significantly reducing TBARS (a measure of lipid peroxidation) while not affecting 8-OHdG (a marker of DNA oxidation) levels. AGE levels in the bone were elevated in CKD animals and were reduced with NAC although this did not translate to a benefit in bone mechanical properties. In conclusion, NAC failed to significantly improve bone architecture/geometry/mechanical properties in our rat model of progressive CKD.

Signaling Pathways, Chemical and Biological Modulators of Nucleotide Excision Repair: The Faithful Shield against UV Genotoxicity

The continuous exposure of the human body's cells to radiation and genotoxic stresses leads to the accumulation of DNA lesions. Fortunately, our body has several effective repair mechanisms, among which is nucleotide excision repair (NER), to counteract these lesions. NER includes both global genome repair (GG-NER) and transcription-coupled repair (TC-NER). Deficiencies in the NER pathway underlie the development of several DNA repair diseases, such as xeroderma pigmentosum (XP), Cockayne syndrome (CS), and trichothiodystrophy (TTD). Deficiencies in GG-NER and TC-NER render individuals to become prone to cancer and neurological disorders, respectively. Therefore, NER regulation is of interest in fine-tuning these risks. Distinct signaling cascades including the NFE2L2 (NRF2), AHR, PI3K/AKT1, MAPK, and CSNK2A1 pathways can modulate NER function. In addition, several chemical and biological compounds have proven success in regulating NER's activity. These modulators, particularly the positive ones, could therefore provide potential treatments for genetic DNA repair-based diseases. Negative modulators, nonetheless, can help sensitize cells to killing by genotoxic chemicals. In this review, we will summarize and discuss the major upstream signaling pathways and molecules that could modulate the NER's activity.

Nano-selenium attenuates nickel-induced testosterone synthesis disturbance through inhibition of MAPK pathways in Sprague-Dawley rats

The aim of this study was to investigate the protective effects of Nano-Se against Ni-induced testosterone synthesis disorder in rats and determine the underlying protective mechanism. Sprague-Dawley rats were co-treated with Ni (5.0 mg/kg, i.p.) and Nano-Se (0.5, 1.0, and 2.0 mg/kg, oral gavage) for 14 days after which various endpoints were evaluated. The Ni-induced abnormal pathological changes and elevated 8-OHdG levels in the testes were attenuated by Nano-Se administration. Importantly, decreased serum testosterone levels in the Ni-treated rats were significantly restored by Nano-Se treatment, particularly at 1.0 and 2.0 mg/kg. Furthermore, the mRNA and protein levels of testosterone synthetase were increased by Nano-Se compared to the Ni group, whereas phosphorylated protein expression levels of mitogen-activated protein kinase (MAPK) pathways were suppressed by Nano-Se administration in the Ni-treated rats. Overall, the results suggest that Nano-Se may ameliorate the Ni-induced testosterone synthesis disturbance via the inhibition of ERK1/2, p38, and JNK MAPK pathways.

Protective Effect of N-Acetyl Cysteine on Chlorpyrifos-Induced Testicular Toxicity in Mice

Background

Chlorpyrifos (CPF), an organophosphate pesticide, is widely used in farms in order to preserve crops and fruits. Previous studies have shown that CPF exposure might cause chronic toxicity in male genital system. The present study investigated the protective effect of N-Acetyl Cysteine (NAC), a potent antioxidant against testicular toxicity of CPF in male mice.

Materials and Methods

In this experimental study, 42 adult male mice were divided into seven groups, CPF low (0.5 mg/kg.b.w) and high (5 mg/kg.b.w) doses groups, NAC group (35 mg/kg.b.w), NAC+CPF 0/5 mg/kg.b.w, NAC+CPF 5 mg/kg.b.w, dimethyl sulfoxide (DMSO, 0.75% solution mg/kg.b.w) and control group. All treatment were done intraperitoneally. Treatment was conducted for four consecutive weeks (five days each week). However NAC was injected to NAC+CPF groups five days before initiation of the treatment procedure. One week after the last injection, mice were sacrificed using anesthetic gas to evaluate alterations in testicular histology and sperm parameters.

Results

Seminiferous tubules area and diameter were significantly diminished in the group treated with 5 mg/kg CPF (P<0.05). CPF also statistically reduced sperm parameters (count and motility) and damaged sperm morphology) at both doses (P<0.05). However, NAC significantly improved spermatogonia, spermatocytes, spermatid cell counts as well as sperm parameters in mice treated with both CPF concentrations (P<0.05).

Conclusion

According to our results, NAC may significantly ameliorate CPF-induced damages to spermatogonia, spermatocytes, spermatids cell counts and sperm parameters.

N-acetylcysteine alleviates fluoride-induced testicular apoptosis by modulating IRE1α/JNK signaling and nuclear Nrf2 activation

We previously investigated excessive fluoride exposure elicited intracellular endoplasmic reticulum (ER) stress and led to Sertoli cells dysfunction in vitro. However, the mechanisms underlying fluoride-mediated male reproductive damage in vivo remain largely unknown. Considerable evidence has now revealed ER stress is closely linked with testicular oxidative damage. Hence, we aimed to explore whether ER stress signaling was involved in the testicular protective effects of antioxidant N-acetylcysteine (NAC) against testicular apoptosis induced by fluoride. Male SD rats were oral gavaged with sodium fluoride (NaF) for 7 weeks to induce fluorosis. The animals were pretreatment with or without NAC (150 mg/Bw•d). Our results demonstrated that sub-chronic NaF exposure triggered testicular apoptosis and sex hormonal disturbance in pituitary-testicular (PT) axis, promoted oxidative stress and the expression of ER stress mediators. Antioxidant NAC, however, prevented NaF-induced testicular apoptosis accompanied by activating Nrf2-mediated antioxidant potential. Simultaneously, NAC pretreatment downregulated XBP1 splicing, reduced JNK phosphorylation and further blocked cleavage of caspase-3, all these might contribute to the inhibition of testicular cell apoptosis. Collectively, the present results suggested that prolonged administration of NAC preserved testicular function and normalized sex hormonal disruption induced by NaF via the inhibition of Nrf2-associated oxidative damage and Ire1α-JNK-mediated apoptosis in rat testis.

Sodium fluoride induced skeletal muscle changes: Degradation of proteins and signaling mechanism

Fluoride is a well-known compound for its usefulness in healing dental caries. Similarly, fluoride is also known for its toxicity to various tissues in animals and humans. It causes skeletal fluorosis leading to osteoporosis of the bones. We hypothesized that when bones are affected by fluoride, the skeletal muscles are also likely to be affected by underlying molecular events involving myogenic differentiation. Murine myoblasts C2C12 were cultured in differentiation media with or without NaF (1 ppm-5 ppm) for four days. The effects of NaF on myoblasts and myotubes when exposed to low (1.5 ppm) and high concentration (5 ppm) were assessed based on the proliferation, alteration in gene expression, ROS production, and production of inflammatory cytokines. Changes based on morphology, multinucleated myotube formation, expression of MyHC1 and signaling pathways were also investigated. Concentrations of NaF tested had no effects on cell viability. NaF at low concentration (1.5 ppm) caused myoblast proliferation and when subjected to myogenic differentiation it induced hypertrophy of the myotubes by activating the IGF-1/AKT pathway. NaF at higher concentration (5 ppm), significantly inhibited myotube formation, increased skeletal muscle catabolism, generated reactive oxygen species (ROS) and inflammatory cytokines (TNF-α and IL-6) in C2C12 cells. NaF also enhanced the production of muscle atrophy-related genes, myostatin, and atrogin-1. The data suggest that NaF at low concentration can be used as muscle enhancing factor (hypertrophy), and at higher concentration, it accelerates skeletal muscle atrophy by activating the ubiquitin-proteosome pathway.

Changes of DNA repair gene methylation in blood of chronic fluorosis patients and rats

To investigate the relationship between DNA repair gene methylation and chronic coal-burning fluorosis. The methylation rates of O⁶-methylguanine-DNA- methyltransferase gene MGMT, a DNA repair gene and mismatch repair gene MutL homolog 1 (MLH1) were analysed by methylation of specific PCR (MSP), and the levels of mRNA in the blood of the chronic fluorosis rats and the patients in the region of endemic coal-burning fluorosis were determined by real-time PCR. The levels of mRNA and protein of MGMT and MLH1 in the liver tissue of the chronic fluorosis rats were determined by real-time PCR and Western blot respectively. The results showed an increased methylation of the MGMT and MLH1 genes in the blood of the patients in the fluorosis region that correlated positively with the severity of fluorosis. The mRNA levels of MGMT and MLH1 genes from the patients in fluorosis region were lower than those of a control group, and also showed a positive correlation with the severity of fluorosis. Both the protein and mRNA levels of MGMT and MLH1 genes from the blood of rats and liver tissue in a fluoride-treated group were lower than those of a control non-fluoride treated group. These results indicate that the degree of methylation of MGMT and MLH1 genes is altered in fluorosis disease, the resulting changed expression of these repair genes may play a role in the liver damage caused by fluoride.

Mancozeb induces testicular dysfunction through oxidative stress and apoptosis: Protective role of N-acetylcysteine antioxidant

Mancozeb (MZB) is one of the fungicides used in pest control programs that might affect human health including reproductive system. The aim of this study was to demonstrate the mechanisms through which MZB induces testicular tissue damage and the probable protective effect of N-acetylcysteine (NAC), a modified amino acid, with antioxidant property, against MZB toxicity in an animal model. Male albino mice ( n = 8) were exposed to different doses of MZB (250 and 500 mg/kg/day) by oral gavage without or with NAC (200 mg/kg, twice/week) for 40 days. Sub-chronic MZB dose-dependently decreased sperm motility and count. Exposure to MZB increased lipid peroxidation and protein carbonyl, while it reduced antioxidant enzymes activities, total antioxidant capacity, and glutathione content. The histopathological examination clearly showed deleterious changes in the testicular structure. At the molecular levels, the results of quantitative real time-poly chain reaction (qRT-PCR) showed that MZB upregulated oxidative stress markers inducible nitric oxide synthase (iNOS) and NADPH oxidase 4 (NOX4) and downregulated expression of the glutathione peroxidase 1 (Gpx1) gene as one of the most important antioxidant enzymes. MZB also induced apoptosis dose-dependently in the testes as determined by the terminal dUTP nick-end labeling assay and immunoblotting. NAC administration decreased the mRNA levels of both iNOS and NOX4 with a concomitant increase in Gpx1 expression. It also significantly decreased MZB-induced oxidative stress and apoptosis. Collectively, the present study showed MZB-induced oxidative damage in testes leading to apoptosis. It revealed that antioxidants such as NAC can mitigate oxidant injury induced by the dithiocarbamate pesticides in the reproductive system.

Fluoride-induced oxidative stress and apoptosis are involved in the reducing of oocytes development potential in mice

The present study was conducted to investigate the mechanisms of excessive-fluoride-induced reduction of oocyte development potential in mice. The development morphology of oocyte and the changes of pathomorphology in ovary were observed. The protein expression levels of apoptosis factors, including Bax, Bcl-2, casepase-3, casepase-9 and cytochrome c, and the mRNA expression levels of antioxidant enzymes, including SOD1, GSH-Px1, CAT and inducible nitric oxide synthase were measured by Western blot and real-time PCR, respectively. DNA damage in the ovary was analysed by single cell gel electrophoresis and TUNEL staining. Results indicated that the structure and function of ovarian cells were seriously damaged, followed, the development potential of oocyte was reduced by excessive fluoride. The expression levels of apoptosis factors were up-regulated and antioxidant enzymes were significantly down-regulated. Meanwhile, the contents of ROS, MDA, NO and iNOS were significantly increased. Whereas, the activities of SOD1, GSH-Px1 and CAT was significantly decreased compared with the control group. Simultaneously, the results of DNA analysis indicated that the tail length and tailing ratio of ovarian cells were significantly increased in the fluoride group. In summary, the results provided compelling evidence that excessive fluoride intake can reduce the development potential of oocyte by inducing oxidative stress and apoptosis in the ovary of female mice.

The MMP-9/TIMP-1 System is Involved in Fluoride-Induced Reproductive Dysfunctions in Female Mice

A total of 84 healthy female mice were kept with various concentrations of sodium fluoride (F) (0, 50, 100, 150 mg F^-/L in drinking water for 90 days) and were then mated with healthy male mice for 1 week to study the effect of excessive fluoride on female reproductive function, particularly in embryo implantation. The rate of pregnancy, litter size, and the birth weight of female mice were evaluated. Ultrastructural changes of uteri tissues were observed by transmission electron microscopy (TEM). The mRNA expression levels of MMP-9 and TIMP-1 were determined by quantitative real-time PCR. The protein expression levels of MMP-9 and TIMP-1 were analyzed by western blotting. Results showed a significant decrease of litter size in mice exposed to fluoride. TEM images of uteri tissue of mice that underwent a 150 mg/L F^- treatment for 90 days showed a vague nucleus, reduced microvilli, increased lysosomes, a dilated endoplasmic reticulum, and a vacuolization mitochondrion when compared with the control group. Following the damage of the structure, the expression levels of MMP-9 and TIMP-1 in uteri tissues were significantly unregulated in the F 150 group. These results show that MMP-9/TIMP-1 system disturbance and changes of histological structure in uteri tissue are involved in fluoride-induced reproductive dysfunctions.

Putative mechanisms of genotoxicity induced by fluoride: a comprehensive review

Genotoxicity is the ability of an agent to produce damage on the DNA molecule. Considering the strong evidence for a relationship between genetic damage and carcinogenesis, to elucidate the putative mechanisms of genotoxicity induced by fluoride are important to measure the degree of risk involved to human populations. The purpose of this article is to provide a comprehensive review on genotoxicity induced by fluoride on the basis of its mechanisms of action. In the last 10 years, all published data showed some evidence related to genotoxicity, which is due to mitochondrial disruption, oxidative stress, and cell cycle disturbances. However, this is an area that still requires a lot of investigation since the published data are not sufficient for clarifying the genotoxicity induced by fluoride. Certainly, the new information will be added to those already established for regulatory purposes as a safe way to promote oral healthcare and prevent oral carcinogenesis.

Sodium fluoride induces hypertension and cardiac complications through generation of reactive oxygen species and activation of nuclear factor kappa beta

Human exposure to sodium fluoride through its daily usage is almost inevitable. Cardiovascular and renal dysfunction has been associated with fluoride toxicity. Therefore, this study investigated the mechanism of action of sodium fluoride (NaF) induced hypertension and cardiovascular complications Forty male albino rats of an average of 10 rats per group were used. Group A received clean tap water. Toxicity was induced in Group B to D by administering graded doses of NaF through drinking water ad libitum for 10 days at 150 ppm, 300 ppm, and 600 ppm concentration respectively. Following administration of NaF, there was significant increase in systolic pressure, diastolic pressure and mean arterial pressure. Markers of oxidative stress; malondialdehyde, hydrogen peroxide, advance oxidation protein products, and protein carbonyl were significantly increased in dose-dependent pattern in the cardiac and renal tissues of rats together with significant decrease in the GST activity in NaF-treated rats compared to the control. Also serum markers of inflammation, cardiac, and renal damage including myeloperoxidase, xanthine oxidase, blood urea nitrogen, creatinine, Lactate dehydrogenase (LDH), and Creatinine kinase myocardial band (CK-MB) significantly increased indicating induction of oxidative stress, renal, and cardiac damage after exposure. Histopathology of the kidney and heart revealed aberrations in the histological architecture in NaF-treated rats. Also, immunohistochemistry showed higher expression of nuclear factor kappa beta (NF-kB) in the cardiac and renal tissues of rats administered NaF. Combining all, these results indicate NaF-induced hypertension through generation of reactive oxygen species and activation of renal and cardiac NF-kB expressions. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1089-1101, 2017.

Nonylphenol induced apoptosis and autophagy involving the Akt/mTOR pathway in prepubertal Sprague-Dawley male rats in vivo and in vitro

This research explores the detrimental effect of nonylphenol (NP) to prepubertal Sprague-Dawley male rats in vivo and in vitro. Herein, forty-two 3-week-old rats were randomly divided into six groups, which were treated with NP (0, NAC, 25, 50, 100, 100+NACmg/kg/2d for 30 consecutive days) by intraperitoneal injection. NP induced a reduction in testosterone (15.58%, 17.23%, 13.38% in 25, 50, 100mg/kg group, respectively), triggered apoptosis related to oxidative stress, and disturbed mRNA and/or protein levels of PI3K, PTEN, PDK1, p-Akt, p-mTOR, p70S6K, caspase-3, LC3B. NP induced morphological abnormality in epididymal sperm (2.00-, 3.02-fold in 50, 100mg/kg group, respectively). Pretreatment with NAC, attenuated NP-induced ROS production; recovered testosterone in serum, and ameliorated toxic effect in epididymal sperm. Sertoli cells were isolated, purified, treated with NP (0, 10, 20, and 30μM) for 12h. NP disturbed mRNA and/or protein levels of caspase-3, cleave-caspase-3, LC3B involving the PI3K/Akt/mTOR pathway. It also decreased protein levels of ABP, FSHR, N-cadherin, transferrin, vimentin; disturbed the gene levels of all, but vimentin. Pretreatment with wortmannin, alleviated an NP-induced reduction in protein levels of PI3K and PTEN. In conclusion, excess NP exposure induces apoptosis and autophagy, causes reproductive lesions involving the PI3K/AKT/mTOR pathway both in vivo and in vitro. It also triggers oxidative stress and hormonal deficiency, reduces semen quality.