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

Bioactive Compounds Protect Mammalian Reproductive Cells from Xenobiotics and Heat Stress-Induced Oxidative Distress via Nrf2 Signaling Activation: A Narrative Review

Oxidative stress occurs when there is an imbalance between the production of reactive oxygen species (ROS) and the body's antioxidant defenses. It poses a significant threat to the physiological function of reproductive cells. Factors such as xenobiotics and heat can worsen this stress, leading to cellular damage and apoptosis, ultimately decreasing reproductive efficiency. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway plays a crucial role in defending against oxidative stress and protecting reproductive cells via enhancing antioxidant responses. Dysregulation of Nrf2 signaling has been associated with infertility and suboptimal reproductive performance in mammals. Recent advancements in therapeutic interventions have underscored the critical role of Nrf2 in mitigating oxidative damage and restoring the functional integrity of reproductive cells. In this narrative review, we delineate the harmful effects of heat and xenobiotic-induced oxidative stress on reproductive cells and explain how Nrf2 signaling provides protection against these challenges. Recent studies have shown that activating the Nrf2 signaling pathway using various bioactive compounds can ameliorate heat stress and xenobiotic-induced oxidative distress and apoptosis in mammalian reproductive cells. By comprehensively analyzing the existing literature, we propose Nrf2 as a key therapeutic target for mitigating oxidative damage and apoptosis in reproductive cells caused by exposure to xenobiotic exposure and heat stress. Additionally, based on the synthesis of these findings, we discuss the potential of therapies focused on the Nrf2 signaling pathway to improve mammalian reproductive efficiency.

Testicular niche repair after gonadotoxic treatments: Current knowledge and future directions

The testicular niche, which includes the germ cells, somatic cells, and extracellular matrix, plays a crucial role in maintaining the proper functions of the testis. Gonadotoxic treatments, such as chemotherapy and radiation therapy, have significantly improved the survival rates of cancer patients but have also been shown to have adverse effects on the testicular microenvironment. Therefore, repairing the testicular niche after gonadotoxic treatments is essential to restore its function. In recent years, several approaches, such as stem cell transplantation, gene therapy, growth factor therapy, and pharmacological interventions have been proposed as potential therapeutic strategies to repair the testicular niche. This comprehensive review aims to provide an overview of the current understanding of testis damage and repair mechanisms. We will cover a range of topics, including the mechanism of gonadotoxic action, repair mechanisms, and treatment approaches. Overall, this review highlights the importance of repairing the testicular niche after gonadotoxic treatments and identifies potential avenues for future research to improve the outcomes for cancer survivors.

Riboflavin Attenuates Fluoride-Induced Testicular Injury via Interleukin 17A-Mediated Classical Pyroptosis

Male reproductive toxicity of fluoride is of great concern worldwide, yet the underlying mechanism is unclear. Pyroptosis is a novel mode of inflammatory cell death, and riboflavin with anti-inflammatory properties has the potential to protect against fluoride damage. However, it is unknown whether pyroptosis is involved in fluoride-induced testicular injury and riboflavin intervention. Here, we first found that riboflavin could alleviate fluoride-caused lower sperm quality and damaged testicular morphology by reducing pyroptosis based on a model of ICR mice treated with NaF (100 mg/L) and/or riboflavin supplementation (40 mg/L) via drinking water for 13 weeks. And then, together with the results of in vitro Leydig cell modelsm it was confirmed that the pyroptosis occurs predominantly through classical NLRP3/Caspase-1/GSDMD pathway. Furthermore, our results reveal that interleukin-17A mediates the process of pyroptosis in testes induced by fluoride and riboflavin attenuation according to the results of our established models of riboflavin- and/or fluoride-treated IL-17A knockout mice. The results not only declare a new mechanism by which fluoride induces testicular injury via interleukin 17A-mediated classical pyroptosis but also provide evidence for the potential clinical application of riboflavin as an effective therapy for fluoride toxicity.

Riboflavin alleviates fluoride-induced ferroptosis by IL-17A-independent system Xc-/GPX4 pathway and iron metabolism in testicular Leydig cells

Fluoride is widely found in groundwater, soil, animal and plant organisms. Excessive fluoride exposure can cause reproductive dysfunction by activating IL-17A signaling pathway. However, the adverse effects of fluoride on male reproductive system and the mechanisms remain elusive. In this study, the wild type and IL-17A knockout C57BL/6J mouse were treated with 24 mg/kg·bw·d sodium fluoride and/or 5 mg/kg·bw·d riboflavin-5'-phosphate sodium for 91 days. Results showed that fluoride caused dental fluorosis, increased the levels of ROS in testicular Leydig cells and GSSG in testicular tissue, and did not affect the iron and serum hepcidin levels in testicular tissue. Riboflavin alleviated above adverse changes, whereas IL-17A does not participate in the oxidative stress-mediated reproductive toxicity of fluoride. Based on this, TM3 cells were used to verify the injury of fluoride on Leydig cells. Results showed that fluoride increased mRNA levels of ferroptosis marker SLC3A2, VDAC3, TFRC, and SLC40A1 and decreased Nrf2 mRNA levels in TM3 cells. The ferroptosis inhibitor Lip-1 and DFO were used to further investigate the relationship between male reproductive toxicity and ferroptosis induced by fluoride. We found that the fluoride-induced decrease in cell viability, increase in xCT, TFRC, and FTH protein expression, and decrease in GPX4 protein expression, can all be rescued by Lip-1 and DFO. Similar results were also observed in the riboflavin treatment group. Moreover, riboflavin mitigated fluoride-induced increases in ROS levels and SLC3A2 protein levels. In all, our work revealed that riboflavin inhibited ferroptosis in testicular Leydig cells and improved the declined male reproductive function caused by fluoride. This study provides new perspectives for revealing new male reproductive toxicity mechanisms and mitigating fluoride toxicity damage.

Fluoride exposure confers NRF2 activation in hepatocyte through both canonical and non-canonical signaling pathways

Due to the high abundance in the Earth's crust and industrial application, fluoride is widely present in our living environment. However, excessive fluoride exposure causes toxicity in different organs. As the most important detoxification and excretion organ, liver is more easily involved in fluoride toxicity than other organs, and oxidative stress is considered as the key mechanism related with fluoride hepatotoxicity. In this study, we mainly investigated the role of nuclear factor erythroid-derived 2-like 2 (NRF2, a core transcription factor in oxidative stress) in fluoride exposure-induced hepatotoxicity as well as the related mechanism. Herein, liver cells (BNL CL.2) were treated with fluoride in different concentrations. The hepatotoxicity and NRF2 signaling pathway were analyzed respectively. Our results indicated that excessive fluoride (over 1 mM) resulted in obvious toxicity in hepatocyte and activated NRF2 and NRF2 target genes. The increased ROS generation after fluoride exposure suppressed KEAP1-induced NRF2 ubiquitylation and degradation. Meanwhile, fluoride exposure also led to blockage of autophagic flux and upregulation of p62, which contributed to activation of NRF2 via competitive binding with KEAP1. Both pharmaceutical activation and genetic activation of NRF2 accelerated fluoride exposure-induced hepatotoxicity. Thus, the upregulation of NRF2 in hepatocyte after fluoride exposure can be regarded as a cellular self-defense, and NRF2-KEAP1 system could be a novel molecular target against fluoride exposure-induced hepatotoxicity.

Attenuation of fluoride-induced hepatorenal oxidative stress by ferulic acid in vivo: An approach with in-silico analysis and interaction informatics of ferulic acid

BACKGROUND

Chronic fluoride toxicity induces oxidative strain and lipid peroxidation and imparts deleterious effects on human metabolic organs.

AIM

The present study aimed to expose the defensive impact of ferulic acid against sodium fluoride (NaF) induced hepatorenal dysfunction at the biochemical and antioxidative systems.

METHODS

In-vivo. Rats were arbitrarily separated into five groups as control, sodium fluoride-treated (200 ppm kg ^-1), vitamin C -as a positive control, and FA co-administered groups with 10 mg kg ^-1 and 20 mg kg ^-1 body weight for 56 days. In the present investigation, we measured antioxidant enzymes, superoxide dismutase, catalase, and lactate dehydrogenase by electrozymographic and spectrophotometric methods. Biochemical assessment of TBARS, conjugated diene, and different serum biomarkers was done for liver and kidney functionality tests. In-silico. An in-silico study was conducted through a molecular docking experiment to evaluate the binding potentiality of FA by employing AutoDock Vina [version 1.5.6] to overcome the abnormality in the activities of catalase, and superoxide dismutase in NaF promoted toxicity of hepatorenal system. In-vitro. An in vitro biochemical experiment was conducted to support the in-silico study.

RESULTS

Superoxide dismutase and catalase were decreased in the intoxicated rat. Ferulic acid (FA) as an antioxidant remarkably defended the NaF-mediated deterioration of the antioxidative status in the hepatorenal system, lowering lipid peroxidation products, malondialdehyde, and conjugated diene. Serum biomarkers, ALT, AST, ALP, urea, and creatinine increased in the intoxicated group than in control. Ferulic acid significantly neutralized the ill effects of NaF on serum lipid profile. In-silico analysis hypothesized the strong interaction of FA with the active side of catalase and superoxide dismutase that prevented the binding of NaF at the active site of these mentioned enzymes and this was further validated by in-vitro assay.

CONCLUSION

However, FA modulates free radical generation and protected these metabolic organs against sodium fluoride-induced injury.

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

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

Nanosized Titanium Dioxide Induced Apoptosis and Abnormal Expression of Blood-Testis Barrier Junction Proteins Through JNK Signaling Pathway in TM4 Cells

Nanosized titanium dioxide (nano-TiO₂) has been widely used in consumer products. It can cross the blood-testis barrier (BTB), and it has adverse effects on the male reproductive system. However, the specific mechanism has not been fully elucidated. The purpose of this study was to understand the role of the JNK signaling pathway in the apoptosis and abnormal expression of BTB junction proteins induced by nano-TiO₂ in TM4 cells. After different concentration of nano-TiO₂ treatments, the cell viability, apoptosis, mitochondrial membrane potential (Δψm), BTB junction proteins (Claudin-11, ZO-1, β-catenin), apoptosis-related proteins (Bax, Bcl-2, cleaved caspase-9, cleaved caspase-3), and phosphorylated (p)-JNK protein were examined. The results showed that cell viability, apoptosis rates, Δψm, and apoptosis-related protein levels changed in a concentration-dependent manner. Cell viability decreased significantly from 100 μg/mL nano-TiO₂ group. Apoptosis rates increased significantly from 150 μg/mL nano-TiO₂ group, and Δψm decreased significantly from 150 μg/mL nano-TiO₂ group. The protein levels of Bax, cleaved caspase-9, and cleaved caspase-3 increased significantly from 150 μg/mL nano-TiO₂ group, and the protein level of Bcl-2 decreased significantly from 100 μg/mL nano-TiO₂ group. The protein level of p-JNK increased significantly from 100 μg/mL nano-TiO₂ group. Abnormal expression of ZO-1 and β-catenin started from 150 μg/mL nano-TiO₂ group, and abnormal expression of Claudin-11 started from 100 μg/mL nano-TiO₂ group. Cells were treated with JNK inhibitor SP100625 to determine whether the changes of the above indicators in the concentration of 150 μg/mL nano-TiO₂ group can be reversed. We found that SP100625 at 20 μM significantly reversed these effects. These results highlighted that nano-TiO₂ could activate the JNK signaling pathway to induce mitochondria-mediated apoptosis and abnormal expression of BTB junction proteins in TM4 cells.

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.

Clofibrate, a Peroxisome Proliferator-Activated Receptor-Alpha (PPARα) Agonist, and Its Molecular Mechanisms of Action against Sodium Fluoride-Induced Toxicity

Sodium fluoride (NaF) is one of the neglected environmental pollutants. It is ubiquitously found in the soil, water, and environment. Interestingly, fluoride has been extensively utilized for prevention of dental caries and tartar formation, and may be added to mouthwash, mouth rinse, and toothpastes. This study is aimed at mitigating fluoride-induced hypertension and nephrotoxicity with clofibrate, a peroxisome proliferator-activated receptor-alpha (PPARα) agonist. For this study, forty male Wistar rats were used and randomly grouped into ten rats per group, control, sodium fluoride (NaF; 300 ppm) only, NaF plus clofibrate (250 mg/kg) and NaF plus lisinopril (10 mg/kg), respectively, for 7 days. The administration of NaF was by drinking water ad libitum, while clofibrate and lisinopril were administered by oral gavage. Administration of NaF induced hypertension, and was accompanied with exaggerated oxidative stress; depletion of antioxidant defence system; reduced nitric oxide production; increased systolic, diastolic and mean arterial pressure; activation of angiotensin-converting enzyme activity and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB); and testicular apoptosis. Treatment of rats with clofibrate reduced oxidative stress, improved antioxidant status, lowered high blood pressure through the inhibition of angiotensin-converting enzyme activity, mineralocorticoid receptor over-activation, and abrogated testicular apoptosis. Taken together, clofibrate could offer exceptional therapeutic benefit in mitigating toxicity associated with sodium fluoride.

N-Acetylcysteine alleviates spinal cord injury in rats after early decompression surgery by regulating inflammation and apoptosis

OBJECTIVE

Decompression surgery in patients with spinal cord injury (SCI) has a neuroprotective effect by alleviating secondary injury and improving neurological outcomes. N-Acetylcysteine (NAC), a drug approved by the United States Food and Drug Administration, has been shown to play neuroprotective roles via attenuation of apoptosis and inflammation. The purpose of the present study was to investigate the effects of early or late decompression surgery in combination with NAC administration on acute SCI, as well as investigate the underlying mechanisms of its actions.

METHODS

In this study, an acute SCI model was established in rats. The rats were treated with decompression surgery 24/48 h post-SCI in combination with or without NAC.

RESULTS

The results showed that decompression surgery in combination with NAC lead to a better outcome than decompression alone, as demonstrated by the higher Basso, Beattie, and Bresnahan scores. Histopathological examination demonstrated that early decompression surgery in combination with NAC exerted the best therapeutic effect on spinal cord recovery, which was further confirmed by the extent of inflammation and apoptosis. Additionally, we found that NAC might compensate for a lack of late surgery.

CONCLUSIONS

Collectively, early decompression surgery and NAC could be a promising combination for the treatment of acute SCI, and its therapeutic effects may be associated with the regulation of inflammation and apoptosis.

Glycine alleviates fluoride-induced oxidative stress, apoptosis and senescence in a porcine testicular Sertoli cell line

Glycine is a well-known free radical scavenger in the cellular antioxidant system that prevents oxidative damage and apoptosis. Excessive fluoride exposure is associated with multiple types of cellular damage in humans and animals. The objective of the present study was to investigate the protective effects of glycine on sodium fluoride (NaF) exposure and the possible underlying mechanisms in a porcine testicular Sertoli cell line model. Cellular viability and proliferation were examined following NaF exposure and glycine supplementation, and glycine dramatically ameliorated the decreases in NaF-induced porcine testicular Sertoli cell viability and proliferation. Further investigations revealed that glycine decreased NaF-induced intracellular reactive oxygen species production, DNA fragment accumulation and the apoptosis incidence in the porcine testicular Sertoli cell line; in addition, glycine improved mitochondrial function and ATP production. Notably, results of the SPiDER-β-Gal analysis suggested that glycine alleviated NaF-induced cellular senescence and downregulated P53, P21, HMGA2 and P16INK4a gene expression in the porcine testicular Sertoli cell line. Collectively, the beneficial effects of glycine alleviate NaF-induced oxidative stress, apoptosis and senescence, and together with our previous findings, support the hypothesis that glycine plays an important role in protecting against NaF exposure-induced impairments in the porcine testicular Sertoli cell line.

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.

Upregulation of miR-200c-3p induced by NaF promotes endothelial apoptosis by activating Fas pathway

Fluoride has been considered as a risk factor of cardiovascular disease due to its endothelial toxicology. However, the mechanism underlying the endothelial toxicity of fluoride has not been clearly illustrated. MiR-200c-3p was strongly linked with endothelial function and its level is increased in serum of fluorosis patients, but it is unclear the role of miR-200c-3p in the fluoride induced endothelial dysfunction. In this study, we confirmed that fluoride exposure induced the apoptosis of endothelial cells both in established rats model and cultured human umbilical vein endothelial cells (HUVECs). And miR-200c-3p was found to be upregulated in NaF treated HUVECs. Fluoride stimulation increased caspase-dependent apoptosis through miR-200c-3p upregulation, with repressing expression of its target gene Fas-associated phosphatase 1 (Fap-1), which functioned as Fas inhibitor. This resulted in activation of Fas-associated extrinsic apoptosis via interaction with increased Fas, Fadd, Cleaved Caspase-8 and Cleaved Caspase-3. The activation of Fas-associated extrinsic apoptosis was abrogated by miR-200c-3p inhibitor. Furthermore, the antiapoptotic effect of downregulated miR-200c-3p was restored by Fap-1 siRNA. These results suggested a determinant role of the miR-200c-3p/Fap-1 axis in fluoride induced endothelial apoptosis.

Fluoride impairs ovary development by affecting oogenesis and inducing oxidative stress and apoptosis in female zebrafish (Danio rerio)

Previous studies have shown that waterborne fluoride exposure has adverse effects on the reproductive system of zebrafish. However, the underlying toxic mechanisms were still not clear. In the present study, female zebrafish were exposed to different concentrations of 0.787 (Control), 18.599, 36.832 mg/L of fluoride for 30 d and 60 d, and the effects of different doses of fluoride on ovary development, reproductive hormones, oogenesis, ROS content, antioxidant levels, and the expression of apoptosis-related genes and proteins in the ovaries of female zebrafish were analyzed. The results showed that ovarian weight and GSI were significantly decreased, FSH, LH and VTG levels were significantly reduced, the transcriptional profiles of oogenesis-related genes (tgfβ1, bmp15, gdf9, mprα, mprβ, ptg2β) were remarkably altered, ROS levels was notably increased, the SOD, CAT, GPx activities and GSH content as well as their mRNA expressions were significantly decreased, MDA content was remarkably increased, the expressions of apoptosis-related genes and proteins (caspase3, caspase8, caspase9, Fas-L, Cytochrome C, Bax and Bcl-2) were significantly changed, the ratio of Bax/Bcl-2 protein levels were notably increased. Taken together, this study demonstrated that fluoride exposure significantly affected ovarian development, decreased the reproductive hormones, affected oogenesis, induced oxidative stress, caused apoptosis through both extrinsic and intrinsic pathways in ovary of zebrafish. Indicating that oogenesis, oxidative stress, and apoptosis were responsible for the impairment of ovarian development.

Effect of in vitro sodium fluoride treatment on CAT, SOD and Nrf mRNA expression and immunolocalisation in chicken (Gallus domesticus) embryonic gonads

In this study, we examined the effect of sodium fluoride (NaF) on oxidative stress in chicken embryonic gonads. Following exposure to varying concentrations of NaF for 6 h, mRNA expression and immunolocalisation of catalase (CAT), sodium dismutase (SOD1 and SOD2) and nuclear respiratory factors (Nrf1 and Nrf) were analysed in the gonads. In the ovary, a dose-dependent increase in mRNA expression of CAT, Nrf1 and Nrf2 following NaF exposure was found, while the intensity of immunolocalised CAT, SOD2 and Nrf1 was higher in NaF-treated groups. In the testis, no effect of NaF on CAT, SOD1 and Nrf1 mRNA levels was observed; however, NaF (3.5-14.2 mM) elevated Nrf2 mRNA expression. NaF, at a dose of 7.1 mM, increased the immunoreactivity of Nrf1 and SOD2. Further experiments evaluated the ovary and testes when incubated with NaF (7.1 mM), vitamin C (Vitamin C, 4 mM) or NaF + Vitamin C. mRNA expression of all four examined genes in the whole ovary and immunoreactivity of Nrf1 and CAT in the ovarian medulla increased in each experimental group. Similar effects were observed in the testis, where mRNA expression, as well as CAT and Nrf2 immunoreactivity, increased in Vitamin C and NaF + Vitamin C-treated groups. In summary, NaF exposure generated oxidative stress which is manifested by increased expression of free radical scavenging enzymes in chicken embryonic gonads. High doses of Vitamin C did not reverse this effect.

Endoplasmic Reticulum Stress (ER Stress) and Unfolded Protein Response (UPR) Occur in a Rat Varicocele Testis Model

Using a surgically induced varicocele rat model, we show here strong evidence that the misfolded/unfolded protein response that is part of the stress response of the endoplasmic reticulum (ER) is activated in the varicocele testis (VCL), leading to the induction of apoptosis. To support this hypothesis, it is observed that the spliced variant of the X-box protein 1 (XBP1s), resulting from the activation of the inositol-requiring enzyme 1 (IRE1) membrane sensor, is significantly more represented in VCL testicular extracts. The activation of the IRE1/XBP1s pathway is also supported by the observation that the VCL testes show an increase phosphorylation of the c-Jun-kinase (JNK) known to be one intermediate of this pathway and an increased level of caspase-3, the terminal apoptotic effector, partly explaining the apoptotic status of the VCL testis.

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.