Ascorbic acid inhibits cadmium-induced disruption of the blood-testis barrier by regulating oxidative stress-mediated p38 MAPK pathways

Mechanisms of Heavy Metal Cadmium (Cd)-Induced Malignancy

The environmental pollution of cadmium is worsening, and its significant carcinogenic effects on humans have been confirmed. Cadmium can induce cancer through various signaling pathways, including the ERK/JNK/p38MAPK, PI3K/AKT/mTOR, NF-κB, and Wnt. It can also cause cancer by directly damaging DNA and inhibiting DNA repair systems, or through epigenetic mechanisms such as abnormal DNA methylation, LncRNA, and microRNA. However, the detailed mechanisms of Cd-induced cancer are still not fully understood and require further investigation.

Curcumin protects against cadmium-induced germ cell death in the testis of rats

Introduction

Cadmium (Cd) has been shown to disrupt the reproductive system. In this study, we evaluated the protective effects of Curcumin (Cur) against Cd-induced reproductive toxicity.

Methods

Exploring the role of Cur in Cd-treated rat models.

Results

The study demonstrated that Cd treatment impaired the seminiferous epithelium, leading to increased apoptosis of germ cells. Interestingly, pretreatment with Cur ameliorated the histological damage and decreased the germ cell apoptosis induced by Cd. Furthermore, after Cd exposure, B-cell lymphoma-2 expression was significantly decreased while Bax expression was increased. Pretreatment of rats with Cur protected against germ cell apoptosis by improving the expression of B-cell lymphoma-2 and reducing Bax. Additionally, Cd treatment increased reactive oxygen species, resulting in a decrease in antioxidant enzymes. However, pretreatment of rats with Cur followed by Cd administration led to a substantial decrease in reactive oxygen species levels and increased activities of antioxidant enzymes. Ultrastructural investigations revealed that damage to the mitochondrial structure was significantly ameliorated by Cur pretreatment in Cd-treated rats. Notably, Cur significantly activated the peroxisome proliferator-activated receptor gamma coactivator 1a/Sirtuins-3 signaling pathway.

Conclusions

Overall, our data suggest that Cd induces germ cell apoptosis through mitochondrial-induced oxidative stress, but Cur pretreatment offers strong protection against Cd-induced reproductive toxicity.

Cross-talk between Vimentin and autophagy regulates blood-testis barrier disruption induced by cadmium

The blood-testis barrier (BTB) plays a vital role in mammalian spermatogenesis by separating the seminiferous epithelium into an adluminal and a basal compartment. Cadmium (Cd) is a toxic heavy metal that is widely present in the environment. We observed that Cd can induce BTB disruption, leading to apoptosis of testicular cells. However, the molecular mechanisms contributing to BTB injury induced by Cd have not yet been fully clarified. Vimentin (Vim) is an important desmosome-like junction protein that mediates robust adhesion in the BTB. In this study, we investigated how Vim responds to Cd. We found that Cd treatment led to a significant decrease in Vim expression, accompanied by a marked increase in LC3-II expression and a higer number of autophagosomes. Interestingly, we also observed that Cd-induced autophagy was associated with decreased Vim activity and enhanced apoptosis of testicular cells. To further investigate the role of autophagy in Vim regulation under Cd exposure, we treated cells with an autophagy inhibitor called 3-MA. We found that 3-MA treatment enhanced Vim expression and improved the disruption of the BTB under Cd exposure. Additionally, the inhibition of Vim confirmed the role of autophagy in modulating Vim expression. These results reveal a previously unknown regulatory mechanism of Cd involving the interplay between a heavy metal and a protein.

Defective autophagic flux aggravates cadmium-induced Sertoli cell apoptosis

The male reproductive dysfunction accounts for 50% of infertile couples in the world. Cadmium (Cd) is one of the most harmful heavy metals to both the environment and inhabitants. Accumulating data suggest that Cd could cause male infertility. Sertoli cell (SC) is a somatic cell of testis and a key regulator of spermatogenesis by providing physical and nutritional support for developing sperm. Many studies showed that Cd induced dysfunction of SCs was directly related to male reproductive damage. However, the mechanism of SCs injury caused by Cd remains to be clarified. We found that Cd treatment caused a significant increase of apoptosis in SCs cells, accompanied by a marked increase in the production of ROS. These results were associated with the formation of mitochondria-containing autophagosomes and increased expression of LC3-II in vitro. Interestingly, our results showed that Cd did not promote but inhibited the fusion of mitochondria-containing autophagosomes with lysosomes by reducing the function of lysosomes. Together, this study provides insight into the negative effects of Cd, which interferes with autophagic flux and induces the apoptosis of SCs.

Cadmium exposure induces pyroptosis of TM4 cells through oxidative stress damage and inflammasome activation

Cadmium (Cd) is a harmful metal that seriously affects the male reproductive system, but the mechanism of how Cd exposure damages Sertoli cells is not fully understood. This study used TM4 cells to explore the mechanism of Cd damage to Sertoli cells. We found that Cd was concentration- and time-dependent on TM4 cell viability. Cd exposure increased intracellular reactive oxygen species (ROS) levels, lactate dehydrogenase (LDH), and Interleukin-1β (IL-1β) release in TM4 cells, decreased mitochondrial function, and increased pyroptosis. N-acetylcysteine (NAC), MCC950 and BAY 11-7082 (BAY) alleviate the release of IL-1β and LDH induced by Cd. NAC reduced Cd induced increases in ROS, NLRP3, Caspase-1, Heme oxygenase-1(HO-1), superoxide dismutase (SOD2), and increased mitochondrial function. The activation of GSDMD is the main causes of pyroptosis, and NAC significantly inhibit its activation and formation. Our results suggest that Cd exposure induces a toxic mechanism of GSDMD-mediated pyroptosis in TM4 cells by increasing ROS levels and activating the inflammasome.

Nickel induces blood-testis barrier damage through ROS-mediated p38 MAPK pathways in mice

Nickel (Ni) is an essential common environmental contaminant, it is hazardous to male reproduction, but the precise mechanisms are still unknown. Blood-testis barrier (BTB), an important testicular structure consisting of connections between sertoli cells, is the target of reproductive toxicity caused by many environmental toxins. In this study, ultrastructure observation and BTB integrity assay results indicated that NiCl2 induced BTB damage. Meanwhile, BTB-related proteins including the tight junction (TJ), adhesion junction (AJ) and the gap junction (GJ) protein expression in mouse testes as well as in sertoli cells (TM4) were significantly decreased after NiCl2 treatment. Next, the antioxidant N-acetylcysteine (NAC) was co-treated with NiCl2 to study the function of oxidative stress in NiCl2-mediated BTB deterioration. The results showed that NAC attenuated testicular histopathological damage, and the expression of BTB-related proteins were markedly reversed by NAC co-treatment in vitro and vivo. Otherwise, NiCl2 activated the p38 MAPK signaling pathway. And, NAC co-treatment could significantly inhibit p38 activation induced by NiCl2 in TM4 cells. Furthermore, in order to confirm the role of the p38 MAPK signaling pathway in NiCl2-induced BTB impairment, a p38 inhibitor (SB203580) was co-treated with NiCl2 in TM4 cells, and p38 MAPK signaling inhibition significantly restored BTB damage induced by NiCl2 in TM4 cells. These results suggest that NiCl2 treatment destroys the BTB, in which the oxidative stress-mediated p38 MAPK signaling pathway plays a vital role.

Melatonin or vitamin C attenuates lead acetate-induced testicular oxidative and inflammatory damage in mice by inhibiting oxidative stress mediated NF-κB signaling

Lead (Pb) acts as an environmental endocrine disruptor and has negative effects in animals; excessive accumulation of lead causes reproductive dysfunction in male animals. Oxidative stress plays a vital role in Pb-induced injury. However, the mechanisms underlying chronic testicular toxicity of Pb remain unclear. In this study, we aimed to determine the effects of lead acetate on reproductive function in male mice, identify the underlying mechanisms, and test counter measures to alleviate the toxic effects. Male mice were dosed with lead acetate (500 mg/L) in free drinking water for 12 weeks, and administered melatonin (5 mg/kg) or vitamin C (500 mg/kg) by intraperitoneal injection. Blood from the eyeball, testicles, and sperm from the caudal epididymis were collected after 12 weeks and analyzed. Pb exposure reduced sperm count and motility, increased sperm malformation (P < 0.01), disrupted testicular morphology and structure, and decreased the expression of steroid hormone synthesis-related enzymes and serum testosterone concentration (P < 0.01). Pb also increased the number of inflammatory cells and the levels of the pro-inflammatory cytokines TNF-α and IL-6 (P < 0.01), and activated NF-κB signaling. Furthermore, the ROS yield and oxidation indicators LPO and MDA were significantly increased (P < 0.01), and the antioxidant indicators T-AOC, SOD, and GSH were significantly reduced (P < 0.01). Treatment with melatonin or vitamin C reversed the effects of lead acetate; vitamin C was more effective in restoring SOD activity (P < 0.01) and enhancing ZO-1 protein levels (P < 0.01). Thus, long-term exposure to lead acetate at low concentrations could adversely affect sperm quality and induce inflammatory damage by oxidative stress mediated NF-κB signaling. Vitamin C could act as a protective agent and improve reproductive dysfunction in male animals after lead accumulation.

Ascorbic acid enhances chondrocyte differentiation of ATDC5 by accelerating insulin receptor signaling

Chondrogenesis is strictly regulated by several factors, including cytokines, hormones, and extracellular matrix proteins. Mouse teratocarcinoma-derived lineage cells, differentiate into chondrocytes in the presence of insulin. Although ascorbic acid promotes chondrogenic differentiation, the detailed regulative mechanisms underlying its role in chondrogenesis remain unclear. Therefore, in this study, we evaluated the effects of ascorbic acid on insulin-induced chondrogenic differentiation of ATDC5 cells and the underlying intracellular signaling. The results revealed that insulin-stimulated collagen deposition, matrix formation, calcification, and expression of chondrogenic differentiation marker genes in ATDC5 cells. This enhancement by insulin was amplified with the addition of ascorbic acid. Molecular analysis revealed that the activation of insulin-induced phosphoinositide 3-kinase (PI3K)/Akt signaling was enhanced in the presence of ascorbic acid. In contrast, Wnt/β-catenin signaling was suppressed during chondrocyte differentiation via upregulation of the Wnt agonist, secreted Frizzled-related protein 1 (sFRP-1) and 3 (sFRP-3). Notably, ascorbic acid upregulated the expression of insulin receptors and their substrates (IRS-1 and IRS-2). Furthermore, ascorbic acid reversed the suppression of IRS-1 and IRS-2 protein by insulin. These results indicate that ascorbic acid positively regulates the chondrogenic differentiation of ATDC5 cells via enhancement of insulin signaling. Our findings provide a substantial basis for further elucidation of the regulatory mechanisms of chondrocyte differentiation and the pathophysiology of OA, thus aiding in development of effective treatment strategies.

3,5,6-Trichloro-2-pyridinol confirms ototoxicity in mouse cochlear organotypic cultures and induces cytotoxicity in HEI-OC1 cells

The metabolite of organophosphate pesticide chlorpyrifos (CPF), 3,5,6-Trichloro-2-pyridinol (TCP), is persistent and mobile toxic substance in soil and water environments, exhibiting cytotoxic, genotoxic, and neurotoxic properties. However, little is known about its effects on the peripheral auditory system. Herein, we investigated the effects of TCP exposure on mouse postnatal day 3 (P3) cochlear culture and an auditory cell line HEI-OC1 to elucidate the underlying molecular mechanisms of ototoxicity. The damage of TCP to outer hair cells (OHC) and support cells (SC) was observed in a dose and time-dependent manner. OHC and SC were a significant loss from basal to apical turn of the cochlea under exposure over 800 μM TCP for 96 h. As TCP concentrations increased, cell viability was reduced whereas reactive oxygen species (ROS) generation, apoptotic cells, and the extent of DNA damage were increased, accordingly. TCP-induced phosphorylation of the p38 and JNK MAPK are the downstream effectors of ROS. The antioxidant agent, N-acetylcysteine (NAC), could reverse TCP-mediated intracellular ROS generation, inhibit the expressive level of cleaved-caspase 3 and block phosphorylation of p38/JNK. Overall, this is the first demonstration of TCP damaging to peripheral sensory HCs and SC in organotypic cultures from the postnatal cochlea. Data also showed that TCP exposure induced oxidase stress, cell apoptosis and DNA damage in the HEI-OC1 cells. These findings serve as an important reference for assessing the risk of TCP exposure.

Vitamin C as a Potential Prophylactic Measure Against Frozen Shoulder in an In Vivo Shoulder Contracture Animal Model

BACKGROUND

Frozen shoulder is a common, painful, and movement-restricting condition. Although primary frozen shoulder is idiopathic, secondary frozen shoulder can occur after trauma or surgery. Prophylactic and therapeutic options are often unsatisfactory. Vitamin C (ascorbic acid) is a potent physiological antioxidant and likely inhibits the activation of nuclear factor κB, which plays a decisive role in inflammatory reactions.

HYPOTHESIS

Because of its anti-inflammatory effects, vitamin C may be valuable in the prevention of secondary frozen shoulder.

STUDY DESIGN

Controlled laboratory study.

METHODS

An in vivo shoulder contracture model was conducted by fixation of the right proximal limb of Sprague-Dawley rats. A treatment group (n = 8) receiving vitamin C orally was compared with a control group (n = 9) without vitamin C. The primary outcome was capsular thickness at the shoulder joint measured on magnetic resonance imaging (MRI) examination. Further histological examination was performed but was not statistically analyzed because of variability of the cutting plane through the glenoid.

RESULTS

Vitamin C treatment resulted in less thickening of the axillary fold of the operated shoulder at 2 of the 3 locations measured on MRI compared with untreated controls (insertion to the glenoid, P = .074; insertion to the humerus, P = .006; middle of the axillary recess, P = .008). The observed structural changes in histological examination corroborated the significant changes obtained from the MRI measurements.

CONCLUSION

Prophylactic vitamin C seemed to reduce the thickening of the axillary recess in secondary frozen shoulder in this preclinical study.

CLINICAL RELEVANCE

Vitamin C may be helpful as a noninvasive therapeutic measure to prevent secondary frozen shoulder (eg, within the context of surgery in the shoulder region or immobilization) or to treat primary frozen shoulder at an early stage. Further studies are required to evaluate the effect of this treatment in humans and the necessary dosage in humans.

Association between aldehyde exposure and sex steroid hormones among adults

Exogenous and endogenous exposure to aldehydes is seen worldwide. Aldehydes are closely associated with human diseases, especially reproductive toxicity. However, the effect of aldehyde exposure on sex steroid hormones among adults remains uninvestigated. A total of 851 participants aged over 18 years were included in this cross-sectional analysis based on data from National Health and Nutrition Examination Survey (NHANES) 2013-2014. Serum aldehyde concentrations were quantified following an automated analytical method. Sex steroid hormones including total testosterone, estradiol, and sex hormone binding globulin (SHBG) were detected. Multivariate linear regression models, forest plots, generalized additive model (GAM), and smooth curve fitting analysis were used to assess the associations between quartiles of aldehydes and sex steroid hormones levels after adjusting for potential confounders. Butyraldehyde and propanaldehyde were found to be negatively associated with estradiol and SHBG in females and males, respectively. β values with 95% confidence intervals (95% CIs) were - 20.59 (- 38.30 to - 2.88) for Q2 vs. Q1 of butyraldehyde and - 8.13 (- 14.92 to - 1.33) and - 7.79 (- 14.91 to - 0.67) for Q2 vs. Q1 and Q4 vs. Q1 of propanaldehyde. No significant associations were observed between other aldehydes and sex hormones. In premenopausal women, isopentanaldehyde was inversely associated with serum total testosterone levels (Q4 vs. Q1: OR =  - 7.95, 95% CI: - 15.62 to - 0.27), whereas propanaldehyde was positively associated with serum estradiol concentration (Q3 vs. Q1: β = 28.88, 95% CI: 0.83 to 56.94). Compared with Q1, Q3 of isopentanaldehyde was associated with 3.53 pg/mL higher concentration of estradiol in postmenopausal women (β = 3.53, 95% CI: 0.08 to 6.97). Moreover, in males under 40 years, butyraldehyde and heptanaldehyde were inversely proportional to total testosterone levels and heptanaldehyde and butyraldehyde were negatively associated with estradiol and SHBG. Decreased total testosterone, elevated estradiol, and decreased SHBG levels were found in higher quartiles of benzaldehyde, hexanaldehyde and isopentanaldehyde, and propanaldehyde, respectively, in males aged over 60 years. In male participants aged 40-60 years, only hexanaldehyde was observed to be correlated with higher serum estradiol levels. In conclusion, our current research presented the association between six serum aldehydes and sex hormones. Of note, stratification analyses were conducted in participants with different menopausal statuses and age among males and females. Sex- and age-specific effect of aldehyde exposure on alterations in sex hormone levels were observed. Further studies are warranted to confirm the causal relationship and explore the underlying mechanisms.

Diabetes-Induced Autophagy Dysregulation Engenders Testicular Impairment via Oxidative Stress

Testes produce sperms, and gamete generation relies on a proper niche environment. The disruption of hierarchical regulatory homeostasis in Leydig or Sertoli cells may evoke a sterile phenotype in humans. In this study, we recapitulated type 2 diabetes mellitus by using a high-fat diet- (HFD-) fed mouse model to identify the phenotype and potential mechanism of diabetes-induced testicular impairment. At the end of the study, blood glucose levels, testosterone structure, testicular antioxidant capacity, and testosterone level and the expression of hypoxia-inducible factor- (HIF-) 1α, apoptosis-related protein cleaved-caspase3, and autophagy-related proteins such as LC3I/II, p62, and Beclin1 were evaluated. We found that long-term HFD treatment causes the development of diabetes mellitus, implicating increased serum glucose level, cell apoptosis, and testicular atrophy (P < 0.05 vs. Ctrl). Mechanistically, the results showed enhanced expression of HIF-1α in both Sertoli and Leydig cells (P < 0.05 vs. Ctrl). Advanced glycation end products (AGEs) were demonstrated to be a potential factor leading to HIF-1α upregulation in both cell types. In Sertoli cells, high glucose treatment had minor effects on Sertoli cell autophagy. However, AGE treatment stagnated the autophagy flux and escalated cell apoptosis (P < 0.05 vs. Ctrl+Ctrl). In Leydig cells, high glucose treatment was adequate to encumber autophagy induction and enhance oxidative stress. Similarly, AGE treatment facilitated HIF-1α expression and hampered testosterone production (P < 0.05 vs. Ctrl+Ctrl). Overall, these findings highlight the dual effects of diabetes on autophagy regulation in Sertoli and Leydig cells while imposing oxidative stress in both cell types. Furthermore, the upregulation of HIF-1α, which could be triggered by AGE treatment, may negatively affect both cell types. Together, these findings will help us further understand the molecular mechanism of diabetes-induced autophagy dysregulation and testicular impairment, enriching the content of male reproductive biology in diabetic patients.

Analyses of widely targeted metabolic profiling reveals mechanisms of metabolomic variations during Tibetan sheep (Ovis aries) testis development

In mammals, the testis is the organ with the highest transcriptional activity. After gene transcription, translation, and post-translational protein modification, the transcriptional results are finally presented at the metabolic level. Metabolites not only essential for cell signaling and energy transfer, but also directly influenced by the physiological and pathological changes in tissues and accurately reflect the physiological changes. The fact that the testes are oxygen-deprived organs can explain why Sertoli cells and germ cells may use distinctive metabolic pathways to obtain energy in their different stages of development. Therefore, studying metabolic changes during testis development can better elucidate metabolic profile of the testis, which is essential to revealing characteristic metabolic pathways. The present study applied a widely targeted UPLC-MS/MS-based metabolomics approach with large-scale detection, identification and quantification to investigate the widespread metabolic changes during Tibetan sheep testis development. Firstly, a total of 847 metabolites were detected in the sheep testis, and their changes along with the three testis-development stages were further investigated. The results indicated that those metabolites were clustered into amino acids and their derivatives, carbohydrates and their derivatives, organic acids and their derivatives, benzene and substituted derivatives, alcohols and amines, lipids, nucleotides and their derivatives, bile acids, coenzymes and vitamins, hormones and hormone-related compounds, etc. Among them, the most abundant metabolites in the testis were amino acids and lipid metabolites. The results showed that most of the lipids, carbohydrates with their derivatives, as well as alcohol and amines metabolites were high in sexually immature sheep while organic acids, amino acids and nucleotides showed a continuously increasing trend along with testis development stages. Among them, the content of metabolites with antioxidant effects increased along with testis development, while those related with energy synthesis was downregulated with age. Further correlation analyses of each metabolite-metabolite pair emphasized the cross talk between differential metabolisms across testis development, suggesting a significant correlation between lipids and other metabolites. Finally, based on KEGG pathway analysis, we found that the metabolic pathways in Tibetan sheep testis development were mainly clustered into energy metabolism, gonadal development, and anti-oxidative stress. Reactive oxygen species (ROS) are by-products of normal cellular metabolism and are inevitable during testicular energy metabolism. Thus, the anti-oxidative stress function is a key process in maintaining the normal physiological function of testis. These results contributed to a broader view of the testis metabolome and a comprehensive analysis on metabolomic variation among different testis-development stages, providing a theoretical basis for us to understand the sheep testis metabolic mechanism.

Coenzyme Q10 enhances testicular functions and sexual behavior through regulating steroidogenic-related gene expression and inflammatory pathways of Japanese quail (Coturnix japonica) aganist cadmium

A progressively essential bird of high economic significance for meat production and commercial egg is the Japanese quail, and so more experiments are necessary to improve the productivity of these birds under stressful encounters. The current work was performed to define the influences of Coenzyme Q10 (CoQ10) on growth, sexual behavior, and testicular characteristics (size of the gonad, traits of spermatic features, levels of plasma testosterone, steroidogenic-related gene expression) of Japanese quail (Coturnix coturnix japonica) aganist cadmium (Cd) administration. Chicks of quail (n = 250), 14 days old of age were distributed into 4 groups: basal ration (Group 1), basal ration and CoQ10 at 100 mg/kg ration (Group 2), basal ration and Cd at 50 mg/kg ration (Group 3), and CoQ10 + Cd (Group 4). Several parameters relating to productive performance, such as weight of the body, weight gain, feed intake, and the conversion ratio of feed, were evaluated. Constant visual scanning of the quails was performed to observe their sexual behaviors. Sperm characteristics, plasma testosterone levels, and testicular inflammatory markers of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were also determined. Oxidative-antioxidant redox status in the testes was evaluated by analyzing MDA level, GPx, and SOD activities. Steroidogenic-related gene expression in the testes (CYP17A1, StAR, 3β-HSD, and Cyp19) was also examined. In addition, testicular apoptosis was assessed by monitoring the alterations in the local expression of stress-induced (HSP70), proteins of anti-apoptotic marker (Bcl-2), and pro-apoptotic markers (caspase-3 and Bax). Cd administration hurts body performance, sexual behavior, and testicular efficiency parameters. Interestingly, CoQ10 supplementation improved reproductive performance. Moreover, it significantly increases the % of birds exhibiting sexual behavior and enhances testicular functions, which were damaged by Cd administration, by enhancing plasma testosterone level, antioxidative enzyme activity, and sperm quality traits while reducing the MDA and pro-inflammatory markers. Furthermore, downregulation of pro-apoptotic factor expression, though it increased the expression of the anti-apoptotic protein, was recorded. Correspondingly, CoQ10 revealed a marked upregulation in the expression of steroidogenic-related genes. Conclusion: It is established that the consumption of CoQ10 in the ration of Japanese quail, following a Cd adminstration, improves productive performance, sexual behavior, and several testicular function parameters as a potent antioxidant.

Cadmium exposure induces pyroptosis in testicular tissue by increasing oxidative stress and activating the AIM2 inflammasome pathway

High doses of cadmium (Cd) cause irreversible injury to the reproductive system, especially testicular tissue. Studies have shown that pyroptosis is involved in Cd-induced tissue damage, but whether pyroptosis is involved in damage to testicular tissue following Cd exposure remains unclear. To investigate the mechanism of pyroptosis in testicular injury induced by Cd exposure, we used 8-week-old male C57BL/6J mice subjected to consecutive 7 days of intraperitoneal injection of cadmium chloride (CdCl₂) at concentrations of 0, 1.0 and 3.0 mg/kg. The results indicated that 3.0 mg/kg CdCl₂ significantly decreased serum testosterone levels, sperm concentration and sperm motility, while increased LDH and IL-1β levels. Testicular HE staining indicated that Cd exposure damaged the interstitial cells and increased the atypical residual bodies. Fluorescence results indicated that 3.0 mg/kg CdCl₂ increased ROS levels, DNA damage, and the number of TUNEL-positive seminiferous tubule cells in testicular tissue. Transcriptome analysis showed that Cd exposure mainly induced inflammatory and chemokine signaling pathways in testicular tissue, with upregulated mRNA levels of Aim2, and reduced mRNA levels of Nlrp3. Further analysis showed that 3.0 mg/kg CdCl₂ increased the expression of testicular HO-1, SOD2, γH2AX and PARP-1, as well as the pyroptosis-related factors GSDMD, GSDME, Caspase-1, ASC and IL-1β. In conclusion, our results provide a possible mechanism by which Cd exposure activates the AIM2 pathway by increasing oxidative stress injury to induce pyroptosis in testicular tissue. This provides a new perspective on testicular damage caused by Cd exposure.

Gallic and ascorbic acids supplementation alleviate cognitive deficits and neuropathological damage exerted by cadmium chloride in Wistar rats

Cadmium is a highly neurotoxic heavy metal that interferes with DNA repair mechanisms via generation of reactive oxygen species. The potentials of polyphenols and antioxidants as effective protective agents following heavy metal-induced neurotoxicity are emerging. We therefore explored the neuroprotective potentials of gallic and ascorbic acids in CdCl₂-induced neurotoxicity. Seventy-two Wistar rats were divided into six groups. Group A received distilled water, B: 3 mg/kg CdCl₂, C: 3 mg/kg CdCl₂ + 20 mg/kg gallic acid (GA), D: 3 mg/kg CdCl₂ + 10 mg/kg ascorbic acid (AA), E: 20 mg/kg GA and F: 10 mg/kg AA orally for 21 days. Depression, anxiety, locomotion, learning and memory were assessed using a battery of tests. Neuronal structure and myelin expression were assessed with histological staining and immunofluorescence. The Morris Water Maze test revealed significant increase in escape latency in CdCl₂ group relative to rats concurrently treated with GA or AA. Similarly, time spent in the target quadrant was reduced significantly in CdCl₂ group relative to other groups. Concomitant administration of gallic acid led to significant reduction in the durations of immobility and freezing that were elevated in CdCl₂ group during forced swim and open field tests respectively. Furthermore, GA and AA restored myelin integrity and neuronal loss observed in the CdCl₂ group. We conclude that gallic and ascorbic acids enhance learning and memory, decrease anxiety and depressive-like behavior in CdCl₂-induced neurotoxicity with accompanying myelin-protective ability.

Bibliometric and visual analysis of blood-testis barrier research

Background: Extensive research on the blood-testis barrier has been undertaken in recent years. However, no systematic bibliometric study has been conducted on this subject. Our research aimed to identify the hotspots and frontiers of blood-testis barrier research and to serve as a guide for future scientific research and decision-making in the field.

Methods: Studies on the blood-testis barrier were found in the Web of Science Core Collection. VOSviewer, CiteSpace, and Microsoft Excel were used to conduct the bibliometric and visual analyses.

Results: We found 942 blood-testis barrier studies published in English between 1992 and 2022. The number of annual publications and citations increased significantly between 2011 and 2022, notably in the United States. China and the United States, the US Population Council, Endocrinology, and Cheng C. Yan were the most productive countries, institution, journal, and author, respectively. The study keywords indicated that blood-testis barrier research involves a variety of compositional features (tight junctions, cytoskeleton, adherens junctions), cell types (Sertoli cells, germ cells, Leydig cells, stem cells), reproductive toxicity (cadmium, nanoparticles, bisphenol-a), and relevant mechanisms (spermatogenesis, apoptosis, oxidative stress, dynamics, inflammation, immune privilege).

Conclusion: The composition and molecular processes of the blood-testis barrier as well as the blood-testis barrier in male infertility patients are the primary research hotspots in this field. In addition, future research will likely focus on treatment and the development of novel medications that target signal pathways in oxidative stress and apoptosis to preserve the blood-testis barrier. Further studies must extend to clinical diagnosis and therapy.

Impacts of cadmium on male fertility: Lessons learnt so far

Cadmium (Cd) is one of the most dangerous heavy metals in the world. Globally, toxicities associated with cadmium and its attendant negative impact on humans and animals cannot be under-estimated. Cd is a heavy metal, and people are exposed to it through contaminated foods and smoking. Cd exerts its deleterious impacts on the testes (male reproductive system) by inducing oxidative stress, spermatogenic cells apoptosis, testicular inflammation, decreasing androgenic and sperm cell functions, disrupting ionic homeostasis, pathways and epigenetic gene regulation, damaging vascular endothelium and blood testes barrier. In association with other industrial by-products, Cd has been incriminated for the recent decline of male fertility rate seen in both man and animals. Understanding the processes involved in Cd-induced testicular toxicity is vital for the innovation of techniques that will help ameliorate infertility in males. In this review, we summed up recent studies on the processes of testicular toxicity and male infertility due to Cd exposure. Also, the usage of different compounds including phytochemicals, and plant extracts to manage Cd reprotoxicity will be reviewed.

Qiangjing tablets repair of blood-testis barrier dysfunction in rats via regulating oxidative stress and p38 MAPK pathway

Background

The blood-testis barrier (BTB) is a physical barrier of the testis to prevent various exogenous substrates from entering apical compartments and provides immune privilege for spermatogenesis, which is essential for normal spermatogenic function of testis. It has been shown that oxidative stress can damage BTB by activating the p38 MAPK pathway. In Traditional Chinese Medicine, Qiangjing tablets (QJT) improve spermatogenesis and increase pregnancy rates. Previous studies have confirmed that QJT can improve sperm quality and have obvious antioxidant effects. In this study, we explore whether QJT contributes to recovery from BTB dysfunction in rats.

Methods

BTB dysfunction was induced in rats by 1% Cyclophosphamide (CP). The CP-induced rats in the treatment group were given a dose of QJT (0.45 g/kg·d) by gavage. Testis tissues were collected for histopathological and biochemical analysis, and the testis weight was estimated. Levels of BTB-related proteins and antioxidant enzyme were analyzed in the testis tissues.

Results

QJT resolved the pathological injury of rats testis induced by CP. Furthermore, MDA levels were significantly reduced, and the levels of SOD markedly increased in the testicular tissue after QJT treatment. In addition, QJT down-regulated the expression of p38 protein in rat testis and up-regulated the expressions of key proteins ZO-1, occludin and F-actin in BTB.

Conclusion

These results demonstrate that QJT exerts protective effects on CP-induced rats with BTB dysfunction, likely by regulating the oxidative stress-mediated p38 MAPK pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03615-z.

Exposure to low-dose cadmium induces testicular ferroptosis

As an environmental pollutant, cadmium (Cd) has been widely reported to induce male infertility due to its gonadotoxicity. However, the specific mechanism of Cd-induced testicular damage remains unclear. We investigated whether Cd causes testicular injury through ferroptosis. Male C57BL/6 J mice were exposed to 0, 0.5, or 5 ppm Cd via drinking water, starting in utero, and continuing through 24 weeks post-weaning. The results showed that Cd accumulated in the testes in a dose-dependent manner. Cd exposure at a concentration of 5 ppm, but not 0.5 ppm, caused a mass loss and detachment of germ cells, as well as a decreased meiotic index and testis weight. Exposure to 5 ppm Cd caused iron accumulation, increased levels of malondialdehyde (MDA) and nitro tyrosine (3-NT), and decreased expression of Nrf2, HO-1 and SOD2. We also found that exposure to 5 ppm Cd significantly decreased the expression of SLC7A11, a marker of ferroptosis in mice, along with the expression of SLC40A1 mRNA and ferritin heavy chain (FTH) protein, whereas there was no obvious change in the mRNA expression of Tfrc, ZIP8, ZIP14, and NCOA4. These findings indicate that 5 ppm Cd exposure increased testicular ferroptosis, which may be attributed to the reduction of stored iron export.

Environmental cadmium impairs blood-testis barrier via activating HRI-responsive mitochondrial stress in mice

Cadmium (Cd) is a well-known testicular toxicant. Blood-testis barrier (BTB), a vital part of testes, which has been reported to be damaged upon Cd exposure. However, the detailed mechanism about Cd-mediated disruption of BTB remains unclear. This study aims to investigate the role of Heme-Regulated Inhibitor (HRI)-responsive mitochondrial stress in Cd-mediated disruption of BTB. Male mice are intraperitoneally injected (i.p.) with melatonin (Mel, a cellular stress antagonist, 5.0 mg/kg) before Cd treatment (i.p., 2.0 mg/kg) for 8 h, and then treated with Cd for 0-48 h. Mouse Sertoli cells are pretreated with Mel (10 μM) for 1 h, and then treated with Cd (10 μM) for 0-24 h. We find that Cd damages the BTB and reduces the Occludin protein, a crucial BTB-related protein via activating p38/matrix metalloproteinase-2 (p38/MMP2) pathway and Integrated Stress Response (ISR). Further experiments reveal that the Heme-Regulated Inhibitor (HRI)-responsive mitochondrial stress is triggered in Cd-treated Sertoli cells. Most importantly, Cd-activated p38 signaling and ISR are regulated by HRI-responsive mitochondrial stress in Sertoli cells. Unexpectedly, we find that melatonin rescues the Cd-mediated disruption of BTB through blocking HRI-responsive mitochondrial stress in testes. Overall, these data indicate that environmental cadmium exposure impairs the BTB through activating HRI-responsive mitochondrial stress in Sertoli cells.

Effects of whole-life exposure to low-dose cadmium with post-weaning high-fat diet on offspring testes in a male mouse model

Although several studies have reported testicular impairments caused by cadmium (Cd) or obesity alone, the combined effect of Cd and obesity on the testes and its underlying mechanism remains unclear. We examined the combined effect of whole-life exposure to low-dose Cd started at preconception and post-weaning high-fat diet (HFD) on the testes of offspring mice. At weaning, male offspring parented with and without exposure to low-dose Cd were continued on the same drinking water regimen as their parents and fed with either a normal diet (ND) or HFD for 10 or 24 weeks. Whole-life exposure to Cd resulted in its accumulation in testes, and HFD induced obesity and lipid metabolism disorder. Exposure to Cd or HFD alone significantly decreased Johnsen scores, disrupted testicular structure, and increased germ cell apoptosis at both 10 and 24 weeks. However, co-exposure to Cd and HFD did not induce the toxic effects that were induced by either alone, as revealed by preserved testicular structure and spermatogenesis, lack of significant apoptosis, and increased cell proliferation. Mechanistically, the combined effects of low-dose Cd and HFD consumption were associated with the activation of the JAK/STAT pathway. These findings suggest that co-exposure to low-dose Cd and HFD did not cause Cd- or HFD-induced testicular injury, probably because of the activation of the JAK/STAT pathway to prevent germ cell apoptosis.

Differential Expression Profiles and Potential Intergenerational Functions of tRNA-Derived Small RNAs in Mice After Cadmium Exposure

Cadmium (Cd) is a toxic heavy metal and ubiquitous environmental endocrine disruptor. Previous studies on Cd-induced damage to male fertility mainly focus on the structure and function of testis, including cytoskeleton, blood-testis barrier, and steroidogenesis. Nevertheless, to date, no studies have investigated the effects of Cd exposure on sperm epigenetic inheritance and intergenerational inheritance. In our study, we systematically revealed the changes in sperm tRNA-derived small RNAs (tsRNA) profiles and found that 14 tsRNAs (9 up-regulated and 5 down-regulated) were significantly altered after Cd exposure. Bioinformatics of tsRNA-mRNA-pathway interactions revealed that the altered biological functions mainly were related to ion transmembrane transport, lipid metabolism and cell membrane system. In addition, we focused on two stages of early embryo development and selected two organs to study the impact of these changes on cell membrane system, especially mitochondrion and lysosome, two typical membrane-enclosed organelles. Surprisingly, we found that the content of mitochondrion was significantly decreased in 2-cell stage, whereas remarkably increased in the morula stage. The contents of mitochondrion and lysosome were increased in the testes of 6-day-old offspring and livers of adult offspring, whereas remarkably decreased in the testes of adult offspring. This provides a possible basis to further explore the effects of paternal Cd exposure on offspring health.

Evidence of melatonin ameliorative effects on the blood-testis barrier and sperm quality alterations induced by cadmium in the rat testis

Herein, we further document the protective action of melatonin (MLT) in mitigating cadmium (Cd) effects on adult rat testis. Cd treatment provoked testicular injury, that was documented by histological and biomolecular alterations, i.e., decrease of serum and testicular testosterone concentration and modified sperm parameters. Mainly, both the cytoarchitecture of the blood-testis barrier (BTB) and germ cell morphology were perturbed, as highlighted by impairment in structural (OCN, VANGL, Cx43) and regulative (Src and FAK) protein levels and/or activation. The study focused on the involvement of the autophagy pathway, that was enhanced especially in the Sertoli cells, probably in response to the disorganization of the BTB. Results obtained with the MLT co-treatment demonstrated that its administration decreased the level of oxidative damage caused by Cd, with reversal of all the observed changes. Moreover, the beneficial effects of MLT alone were evidenced by an increase of sperm quality, in term of motility and DNA integrity. The combined results, obtained in rat, strongly encourage to consider a role for MLT in improving also human testicular health, not only in men exposed to Cd, but also in those having fertility disorders, to ameliorate sperm quality and, consequently, reproductive success.

Protective effect of astragaloside IV on cadmium-induced spermatogenesis microenvironment damage in rats

The previous study using Sertoli cells cultured in vitro has shown that the protective effects of astragaloside IV (AsIV) on cadmium (Cd)-induced damage to Sertoli cells and its membrane proteins. Yet, it is not known if AsIV has an equivalent effect on Cd-induced damage to the spermatogenesis microenvironment in rats. Using an in vivo model, Cd-induced damage to the spermatogenesis microenvironment and the protective effects of AsIV were studied. Eighteen male Sprague Dawley (SD) rats were randomly divided into three groups (n = 6/group): Cd group, Cd&AsIV group, and control group. Cd was administered to the rats in the Cd group via i.p. at 1 mg/kg body weight once daily, Cd and AsIV was administered to the rats in the Cd&AsIV group via i.p. at 1 mg/kg body weight and 10 mg/kg body weight respectively once daily, and the same volume of saline was administered to the rats in control group via i.p. once daily. The rats in the three groups were injected continuously for 5 days. Vesicular formation in the seminiferous tubules was observed in the Cd treatment group. The average optical density of claudin-11, zonal occludin-1 (ZO-1), and connexin 43 (Cx43) decreased significantly in the Cd treatment group. The ultrastructural damage of the Sertoli cells and tight junctions were also observed by electron microscopy. AsIV treatment rescued the morphologic changes of the seminiferous tubules of the testis and the ultrastructural damage of the Sertoli cells and tight junctions. The average optical density of claudin-11, ZO-1, and Cx43 also increased significantly after AsIV treatment. Cd damages the spermatogenesis microenvironment in rats, which can be rescued by AsIV treatment. These results illustrate that AsIV may also have a protective effect on Cd-induced damage to the spermatogenesis microenvironment in rats.Abbreviations: AsIV: astragaloside IV; Cd: cadmium; SD: Sprague Dawley; ZO-1: zonal occludin-1; Cx43: connexin 43; BTB: blood-testis barrier; MAPKs: mitogen-activated protein kinases; OSP: oligodendrocyte-specific protein; Cxs: connexins; GJIC: gap junctional intercellular communication; ROS: reactive oxygen species; MDA: malondialdehyde; TGF: tumor growth factor; PBS: phosphate buffer saline; BSA: bovine serum albumin.

Riboflavin recovery of spermatogenic dysfunction via a dual inhibition of oxidative changes and regulation of the PINK1-mediated pathway in arsenic-injured rat model

Arsenic trioxide (As2O3) poisoning and associated potential lesions are of a global concern. Inversely, riboflavin (vitamin B2, VB2) as a component of flavoproteins could play a vital role in the spermatogenic enzymatic reactions. Thus, this research aimed to explore potential beneficial roles of VB2 during As2O3-injured-toxicity. Rats were randomly allocated into 4 groups (n=8/group) and challenged as follows (for 30 days continuously): Group 1 received normal saline; Group 2 was treated with 3 mg As2O3/L; Group 3 received 40 mg VB2/L; Group 4 received 3 mg As2O3/L + 40 mg VB2/L. Both As2O3 and VB2 were dissolved in deionized water. Malondialdehyde (MDA), Glutathione Peroxidase (GSH-Px), Superoxide dismutase (SOD), and Catalase (CAT) were assessed for the oxidative profile, while TAS (Total Antioxidative Status) levels were evaluated for the antioxidant system, in both serum and testicular tissue. P<0.05 was considered statistically significant. The results show that As2O3 significantly decreased the body weight, testicular weight and testis volume, semen quality and testicular cell count (p<0.05). Furthermore, MDA content in the testicular tissue of the As2O3 group rats was significantly higher in comparison to the vehicle group (p<0.05). Likewise, TAS and the activities of GSH-Px, CAT and SOD were reduced (p<0.05) when compared to the control. As(2)O(3) induced testicular damage and seminiferous tubular atrophy. Monodansylcadaverine assays mirrored the histopathology observations. Meanwhile, As2O3 upregulated the expression of mitophagy-related genes including PINK1, Parkin, USP8, LC3-I, Fis1 and Mfn2. The p38 gene, responsible to stress stimuli, was also upregulated by As2O3 administration. Meanwhile, exposure to VB2 led to a significant decrease of the expression levels of mitophagy related genes. Our study revealed that VB2 supplementation protected testicular structures against As2O3-induced injury via a dual inhibition of oxidative changes and a regulation of the PINK1-mediated pathway.

Effect of Nano-Titanium Dioxide on Blood-Testis Barrier and MAPK Signaling Pathway in Male Mice

Some studies have found that nano-sized titanium dioxide (nano-TiO₂) has adverse effects on the male reproductive system. Blood-testis barrier (BTB), as one of the tightest blood-tissue restriction, is crucial to the male reproductive system. However, the potential effects on BTB and signaling pathway changes in testis tissue induced by nano-TiO₂ remain poorly understood. Therefore, in this study, 60 Institute of Cancer Research mice were divided randomly into four groups (per group = 15). The mice of four groups were intragastrically administered with 0, 10, 50, and 100 mg/kg BW nano-TiO₂ respectively for 30 days to analyze the changes of BTB structure, BTB-related proteins, and MAPK signal pathways. Besides, testosterone level, estradiol level, and sperm parameter (sperm count, sperm motility, and sperm malformation rate) changes were also studied in this research. The results indicated that nano-TiO₂ could induce the BTB structural damage and accompanied by the BTB main protein (ZO-1, Claudin-11, and F-actin) elevation of irritability. Nano-TiO₂ could also activate the MAPK signaling pathways (p38, JNK, and ERK) of mice testis tissue. The testosterone and estradiol levels in serum reduced. Besides when the mice were administered with nano-TiO₂, we also found the sperm motility rate decreased, and sperm malformation increased. The above changes may be associated with BTB damage and the activation of MAPK signaling pathways, thereby causing male reproductive dysfunction.

Ascorbic acid supplementation suppresses cadmium-derived alterations in the fission yeast Schizosaccharomyces pombe

Cadmium (Cd) a highly toxic environmental pollutant, that does not have any physiological function in the organism, represents a great concern for human health as it can be easily transported from its environmental sources to the food chain. Food, water, and air are the major sources of Cd exposure to the population. Cd-mediated impairments of the basic cellular properties largely depend on its ability to enhance the formation of reactive oxygen species (ROS) and thus triggers oxidative stress to the cell. With the use of fission yeast Schizosaccharomyces pombe (S. pombe) as the model organism, we have analyzed the impact of Cd on the cell growth intensity, as it represents the fundamental feature of all living organisms. Cells were incubated with different Cd concentrations for 3, 6, and 9 hours to investigate the effect of Cd on cell growth in a time and dose-dependent manner. Further possible Cd-derived alterations, as the peroxidation of membrane lipids or the functional impairment of the enzymatic antioxidant protection mechanisms, were investigated by determination of the MDA content and via catalase (CAT) activity detection. Moreover, ascorbic acid (AsA) pre-treatment was subjected to investigate the assumed positive effect of AsA against Cd toxicity. We show here on one hand that cells suffer under the influence of Cd, but on the other hand, they substantially profit from AsA supplementation. Because S. pombe is known to shares many molecular, and biochemical similarities with higher organisms, the effect of AsA in cadmium toxicity elimination might be expected to a similar extent also in other cell types.

The role of different compounds on the integrity of blood-testis barrier: A concise review based on in vitro and in vivo studies

Sertoli cells are "nurturing cells'' in the seminiferous tubules of the testis which have essential roles in the development, proliferation and differentiation of germ cells. These cells also divide the seminiferous epithelium into a basal and an adluminal compartment and establish the blood-testis barrier (BTB). BTB shields haploid germ cells from recognition by the innate immune system. Moreover, after translocation of germ cells into the adluminal compartment their nutritional source is separated from the circulatory system being only supplied by the Sertoli cells. The integrity of BTB is influenced by several organic/ organometallic, hormonal and inflammatory substances. Moreover, several environmental contaminants such as BPA have hazardous effects on the integrity of BTB. In the current review, we summarize the results of studies that assessed the impact of these agents on the integrity of BTB. These studies have implications in understanding the molecular mechanism of male infertility and also in the male contraception.

Cadmium induced inflammation and apoptosis of porcine epididymis via activating RAF1/MEK/ERK and NF-κB pathways

Cadmium (Cd) was a serious heavy metal pollutant. Cd exposure will cause damage to reproductive organs. It was largely unknown whether Cd exposure caused inflammation and apoptosis in epididymis. In this study, we established models of Cd exposure in swine, and the apoptotic level of epididymis was detected by in situ TUNEL fluorescence staining assay, the results showed that Cd exposure significantly increased TUNEL-apoptosis index. Furthermore, the results of qRT-PCR and Western blot showed that Cd activated the proto-oncogenic serine/threonine kinase-1 (RAF1)/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) signal pathway (RAF1/MEK/ERK) and led to the subsequent up-regulation of the nuclear factor-κB (NF-κB), tumor necrosis factor α (TNF-α), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), caused inflammation in epididymis. NF-κB inflammation pathway also mediated the tumor protein P53 (P53) and indirectly activated the Cytochrome c (Cytc), B-cell lymphoma-2 (Bcl-2), Bcl-2-Associated X protein (Bax), Caspase 3, Caspase 9. In summary, we believed that the RAF1/MEK/ERK pathway came into play in the apoptosis of epididymal tissues exposed to Cd by activating the NF-κB Inflammation pathway, followed by activation of the mitochondrial apoptotic pathway. This study provides more abundant data for exploring the reproductive toxicity of Cd.

Cadmium induced BEAS-2B cells apoptosis and mitochondria damage via MAPK signaling pathway

Cadmium, a heavy metal pollutant in industrial production, is found in air, water and soil, which is harmful to human health and can lead to diseases, such as asthma, lung cancer, and emphysema. In this study, the toxicity of cadmium on human bronchial epithelial cells (BEAS-2B) was investigated. Cell viability, mitochondrial membrane potential, reactive oxygen species (ROS) level, apoptosis and the related signaling pathways were detected with MTT assay, Rhodamine staining, DCFH-DA staining, Hoechst33258 staining and Western blot methods respectively. The results showed that the cell viability decreased, the mitochondrial membrane potential declined, ROS was accumulated and apoptotic rate raised in BEAS-2B cells. Meanwhile, the expression of B-cell lymphoma-2 (Bcl-2) was downregulated, while the expression of Bcl-2-associated X protein (Bax) and the cleaved caspase-3 was upregulated, which indicated mitochondria-mediated intrinsic apoptosis pathway was activated. Furthermore, the phosphorylation of JNK, ERK and p38 was enhanced respectively, which manifested that MAPK signaling pathways were activated. Therefore, it could be concluded that cadmium could increase intracellular ROS, result in cellular oxidative stress, activate JNK, ERK and p38 MAPK pathways and ultimately lead to apoptosis of BEAS-2B cells by activating mitochondria-mediated intrinsic apoptosis pathway. This study provided useful information to elucidate the toxicity of cadmium and revealed the possible mechanism for the occurrence of lung disease induced by cadmium.

Comprehensive Review of Cadmium Toxicity Mechanisms in Male Reproduction and Therapeutic Strategies

Cadmium (Cd) has been widely studied as an environmental pollutant for many years. Numerous studies have reported that Cd exposure causes damage to the heart, liver, kidneys, and thyroid in vivo. The emerging evidence suggests that Cd exposure induces damage on male reproductive system, which is related to oxidative stress, inflammation, steroidogenesis disruption, and epigenetics. Current preclinical animal studies have confirmed a large number of proteins and intracellular signaling pathways involved in the pathological process of Cd-induced male reproductive damage and potential measures for prophylaxis and treatment, which primarily include antioxidants, anti-inflammatory agents, and essential ion supplement. However, explicit pathogenesis and effective treatments remain uncertain. This review collects data from the literatures, discusses the underlying mechanisms of Cd-induced toxicity on male reproductive function, and summarizes evidence that may provide guidance for the treatment and prevention of Cd-induced male reproductive toxicity.

Chitosan-Stabilized Selenium Nanoparticles and Metformin Synergistically Rescue Testicular Oxidative Damage and Steroidogenesis-Related Genes Dysregulation in High-Fat Diet/Streptozotocin-Induced Diabetic Rats

BACKGROUND

this study examined the metformin (MF) and/or chitosan stabilized selenium nanoparticles (CH-SeNPs) efficacy to alleviate the male reproductive function impairment in a high-fat diet feed with low-dose streptozotocin (HFD/STZ) induced type 2 diabetes mellitus (T2DM) diabetic rat model.

METHODS

control non-diabetic, HFD/STZ diabetic, HFD/STZ+MF, HFD/STZ+CH-SeNPs, and HFD/STZ+MF+CH-SeNPs rat groups were used. After 60 days, semen evaluation, hormonal assay, enzymatic antioxidant, lipid peroxidation, testis histopathology, and the steroidogenesis-related genes mRNA expressions were assessed.

RESULTS

in the HFD/STZ diabetic rats, sperm count and motility, male sexual hormones, and testicular antioxidant enzymes were significantly reduced. However, sperm abnormalities and testicular malondialdehyde were significantly incremented. The steroidogenesis-related genes, including steroidogenic acute regulatory protein (StAr), cytochrome11A1 (CYP11A1), cytochrome17A1 (CYP17A1), and hydroxysteroid 17-beta dehydrogenase 3 (HSD17B3), and the mitochondrial biogenesis related genes, including peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGCα) and sirtuin (SIRT), were significantly downregulated in the HFD/STZ diabetic rats. However, CYP19A1mRNA expression was significantly upregulated. In contrast, MF and/or CH-SeNPs oral dosing significantly rescued the T2DM-induced sperm abnormalities, reduced sperm motility, diminished sexual hormones level, testicular oxidative damage, and steroidogenesis-related genes dysregulation. In the MF and CH-SeNP co-treated group, many of the estimated parameters differ considerably from single MF or CH-SeNPs treated groups.

CONCLUSIONS

the MF and CH-SeNPs combined treatment could efficiently limit the diabetic complications largely than monotherapeutic approach and they could be considered a hopeful treatment option in the T2DM.

Intratesticular Peptidyl Prolyl Isomerase 1 Protein Delivery Using Cationic Lipid-Coated Fibroin Nanoparticle Complexes Rescues Male Infertility in Mice

Male infertility is a multifactorial condition. Unexplained male infertility is often caused by spermatogenesis dysfunction. Knockout of Pin1, an important regulator of cell proliferation and differentiation, produces male infertility phenotypes such as testicular immaturity and azoospermia with spermatogonia depletion and blood-testis barrier (BTB) dysfunction. Gene therapy has been clinically considered for the treatment of male infertility, but it is not preferred because of the risks of adverse effects in germ cells. Direct intracellular protein delivery using nanoparticles is considered an effective alternative to gene therapy; however, in vivo testicular protein delivery remains a pressing challenge. Here, we investigated the direct intracellular protein delivery strategy using a fibroin nanoparticle-encapsulated cationic lipid complex (Fibroplex) to restore intratesticular PIN1. Local intratesticular delivery of PIN1 via Fibroplex in Pin1 knockout testes produced fertile mice, achieving recovery from the infertile phenotypes. Mechanistically, PIN1-loaded Fibroplex was successfully delivered into testicular cells, including spermatogonial cells and Sertoli cells, and the sustained release of PIN1 restored the gene expression required for the proliferation of spermatogonial cells and BTB integrity in Pin1 knockout testes. Collectively, testicular PIN1 protein delivery using Fibroplex might be an effective strategy for treating male infertility.

Omega-3 polyunsaturated fatty acids alleviate hydrogen sulfide-induced blood-testis barrier disruption in the testes of adult mice

Hydrogen sulfide (H₂S), a gaseous intracellular signal transducer, participates in multiple physiological and pathological conditions, including reproductive conditions, and disrupts spermatogenesis. The blood-testis barrier (BTB) plays a vital role in spermatogenesis. However, the effect of H₂S on the BTB and the underlying mechanism remain unclear. Herein, we examined the effect of H₂S and omega-3 polyunsaturated fatty acids (ω-3 PUFAs) on the BTB and testicular functions. ICR male mice were randomly divided into the following groups: control, H₂S exposure, and H₂S exposure with ω-3 PUFAs intervention. The sperm parameters (sperm concentration and sperm motility) declined in the H₂S group and improved in the ω-3 intervention group. BTB integrity was severely disrupted by H₂S, and the BTB-related gene levels (ZO-1, Occludin, Claudin 11) decreased; ω-3 supplementation could alleviate BTB disruption by upregulating BTB-related genes, and TM4 Sertoli cells had a similar trend in vitro. p38 MAPK phosphorylation was upregulated in the Na₂S treatment group and downregulated after ω-3 cotreatment. These findings suggest that H₂S can impair the BTB and that ω-3 PUFAs supplementation can attenuate H₂S toxicity in the male reproductive system. Our study elucidated the relationship between a gasotransmitter (H₂S) and the BTB and identified the potential therapeutic effect of ω-3 PUFAs.

Co-exposure to non-toxic levels of cadmium and fluoride induces hepatotoxicity in rats via triggering mitochondrial oxidative damage, apoptosis, and NF-kB pathways

Fluoride (F) and cadmium (Cd) are two common water pollutants. There is low information about their co-exposure in low doses. So, in this study, we evaluated the combination effects of non-toxic doses of F and Cd and the possible mechanism of their combined interaction. Male rats were exposed to non-toxic doses of sodium fluoride (30 mg/l) and/or cadmium chloride (40 mg/l) in drinking water for 6 weeks. Then, liver tissues were separated and several factors including oxidative stress, mitochondrial toxicity, inflammation, apoptosis, and biochemical and histopathological changes were evaluated. Cd and F alone did not induce any significant changes in evaluated factors compared to control group, while significant elevation in liver enzymes as well as histopathological changes were observed in rats treated with F+Cd. Also, a remarkable increase in oxidative stress markers including reactive oxygen species, lipid peroxidation, and protein carbonyl and also decreasing glutathione and superoxide dismutase levels were detected following co-exposure to F and Cd. Furthermore, a combination of F and Cd resulted in mitochondrial dysfunction, swelling, as well as a reduction in mitochondrial membrane potential in isolated liver mitochondria. On the other hand, TNF-α, IL-1β, and NF-kB inflammatory genes were upregulated in the liver after combined exposure to F and Cd compared to individual treatments. Also, F+Cd treatment increased the Bax expression but decreased the expression of Bcl-2 significantly. These findings suggest that Cd and F can potentiate their individual toxic effects on the liver tissue through disruption of the cellular redox status, inflammation, and apoptosis pathway.

Toxicological Effects of Cadmium on Mammalian Testis

Cadmium is a heavy metal, and people are exposed to it through contaminated foods and smoking. In humans and other mammals, cadmium causes damage to male testis. In this review, we summarize the effects of cadmium on the development and function of the testis. Cadmium causes severe structural damage to the seminiferous tubules, Sertoli cells, and blood-testis barrier, thus leading to the loss of sperm. Cadmium hinders Leydig cell development, inhibits Leydig cell function, and induces Leydig cell tumors. Cadmium also disrupts the vascular system of the testis. Cadmium is a reactive oxygen species inducer and possibly induces DNA damage, thus epigenetically regulating somatic cell and germ cell function, leading to male subfertility/infertility.

Epigenetic dysregulation of Mdr1b in the blood-testis barrier contributes to dyszoospermia in mice exposed to cadmium

Cadmium (Cd) has been reported to induce reproductive toxicity. Recent study indicated that aberrant epigenetic regulation of Multidrug resistance 1b (Mdr1b) causes xenobiotic efflux failure at the blood-testis barrier (BTB). However, whether Mdr1b dysregulation is involved in Cd-mediated dyszoospermia and the underlying mechanism remain unknown. In this study, mice were intragastrically administered 0 or 2.5 mg/kg CdCl₂ every other day for 2 months to investigate changes in spermatogenesis and epigenetic regulation of Mdr1b. Mouse Leydig cells TM3 were cultured to detect Mdr1b expression localization. We found that the Cd group revealed BTB disruption concomitant with obvious sperm abnormity and dynamic impairment. Hypermethylation and decreased nuclear factor Ya (Nfya) recruitment to the Mdr1b promoter were correlated with low sperm motility in response to Cd. In conclusion, these findings provide in vivo evidence that epigenetic dysregulation of Mdr1b in the BTB is a potential cause of dyszoospermia upon Cd exposure.

Cross-talk between autophagy and apoptosis regulates testicular injury/recovery induced by cadmium via PI3K with mTOR-independent pathway

Autophagy and apoptosis are two major modes of cell death. A balanced interplay between both is vital for phagocytic clearance of apoptotic testicular cells. Here, generating a SD rats model-treated with cadmium (Cd) to mimic environmental exposure on human, we show that autophagy and apoptosis present synchronous change trends in Cd-induced testicular injury/self-recovery. Further, the cross-talk of autophagy and apoptosis is investigated in four testicular cell lines (GC-1/GC-2/TM3/TM4 cells) respectively. Results reveal that Cd-exposure for five consecutive weeks induces reproductive toxicity in male rats. After one cycle of spermatogenesis within 8 weeks without Cd, toxic effects are ameliorated significantly. In vitro, we find that PI3K inhibitor 3-MA regulates apoptosis by inhibiting autophagy with mTOR-independent pathway in Cd-treated testicular cells. Conclusively, cross-talk between autophagy and apoptosis regulates testicular injury/recovery induced by Cd via PI3K with mTOR-independent pathway.

Protective effects of Salidroside on spermatogenesis in streptozotocin induced type-1 diabetic male mice by inhibiting oxidative stress mediated blood-testis barrier damage

Spermatogenic dysfunction is one of the major secondary complications of male diabetes. Salidroside (SAL) is the important active ingredients isolated from Herba Cistanche, which exhibits numerous pharmacological activities such as antioxidant, anti-diabetic, and anti-inflammatory effects. The present study was designed to determine whether SAL contributes to the recovery from spermatogenic dysfunction in streptozotocin (STZ) induced type-1 diabetic mice. SAL (25, 50, or 100 mg/kg) and Clomiphene citrate (CC, 5 mg/kg) were orally administered to male type-1 diabetic mice for 10 weeks. Testis tissues were collected for histopathological and biochemical analysis. Moreover, reproductive organ weight, sperm parameters, and testicular cell DNA damage were estimated. The results revealed that SAL significantly improved the weight of the reproductive organs, sperm parameters and testicular morphology to different degrees in type-1 diabetic mice. Furthermore, reactive oxygen species (ROS) and malondialdehyde (MDA) levels were significantly reduced, and the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), markedly increased in the testicular tissue after SAL treatment. In addition, our data also showed a marked downregulation the fluorescence expressions of p38 MAPK phosphorylation and upregulation the protein expressions of ZO-1, Occludin, Claudin-11 and N-cadherin after SAL administration (100 mg/kg) compared with the type-1 diabetic group. In conclusion, these results demonstrated that SAL exerts protective effects on type-1 diabetes-induced male spermatogenic dysfunction, which is likely mediated by inhibiting oxidative stress-mediated blood testis barrier damage.

Maternal energy insufficiency affects testicular development of the offspring in a swine model

We determined the effects of insufficient maternal energy on testicular development in offspring in a swine model. Thirty-six sows were divided into control (CON) and low-energy diet (LE) groups during gestation. We observed that the number of Sertoli, germ, and Leydig cells in the offspring of the CON group were significantly higher than those in the LE group at 28 and 120 d after birth. Furthermore, the percentage of apoptotic testis cells was significantly higher in the offspring of the LE group than in the CON group. Transcriptome analysis of differentially expressed mRNAs and long noncoding RNAs in offspring testes indicated that these RNAs were mainly involved in lipid metabolism, apoptosis, cell proliferation, and some pivotal regulatory pathways. Results revealed that AMPK-PI3K-mTOR, MAPK, and oxidative phosphorylation signaling pathways play an important role in mediating the programming effect of insufficient maternal energy on testicular development, and that this effect occurs mainly at an early stage in life. mRNA and protein expression analyses confirmed the importance of certain signaling pathways in the regulation of testicular development. This study provides insights into the influence and possible mechanism underlying the effect of inadequate maternal energy intake on testicular development in the offspring.

Protective effects of betaine on diabetic induced disruption of the male mice blood-testis barrier by regulating oxidative stress-mediated p38 MAPK pathways

BACKGROUND

Blood-testis barrier (BTB) impairments is one of the major secondary complications of diabetes. Betaine (BET) is the important active ingredients isolated from Lycium barbarum, which exhibits numerous pharmacological activities such as antioxidant, anti-diabetic, and anti-inflammatory effects. This study aimed to establish whether BET contributes to the recovery from BTB dysfunction in streptozotocin (STZ) induced diabetic mice.

METHODS

BET (200, 400, 800 mg/kg) was orally administered to diabetic mice for 8 weeks. Testis tissues were collected for histopathological and biochemical analysis, the reproductive organ weight was estimated. Antioxidant enzyme activity and BTB associated protein expressions were determined with their corresponding assay kits and western blot analysis. The results revealed that BET significantly improved the weight of the reproductive organs and testicular morphology in diabetic mice. Furthermore, reactive oxygen species (ROS) and malondialdehyde (MDA) levels were significantly reduced, and the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), markedly increased in the testicular tissue after SAL treatment. In addition, our data also showed a marked down-regulated the expressions of p38 MAPK phosphorylation and up-regulation the protein expressions of ZO-1, Occludin, Claudin-11, N-cadherin, and Connexin-43 after BET administration compared with the diabetic group. In conclusion, these results demonstrated that BET exerts protective effects on diabetes-induced BTB dysfunction, which may be through regulating oxidative stress-mediated p38 MAPK pathways.

Effects of Cadmium and /or Chromium on reproductive organs and semen profiles of male albino rats

Objective: To evaluate the potential hazards of cadmium and/or chromium on the reproductive system of adult male albino rat. Design: Randomized controlled study. Animals: Forty mature male albino rats weighing 260 ± 10 g. Procedures: Rats were allocated into four groups (ten animals each). Control group (group 1), group 2 received 4.4 mg kg-1 cadmium chloride, group 3 was given 2.5 mg kg-1 sodium dichromate and group 4 received combination of Cd (2.2 mg kg-1) and Cr (1.25mg kg-1) orally, once daily for 65 consecutive days. Results: Exposure to Cd or Cr, in particular their combination, caused a reduction in the index weights of testes, epididymis, seminal vesicle and prostate glands. They induced a reduction of sperm count and viability with an increase of abnormal sperm morphology. Interestingly, in the combination group (Cd and Cr together), the deleterious effects were more noticeable. Pathologically, both Cd and Cr produced degenerative changes in seminiferous tubules, necrosis of spermatogenic epithelium within the testis. Moreover, the interstitial tissue of epididymis showed marked edema and prostate showed necrosis and serous exudate of lining epithelium. In the interaction group, testis showed complete degenerative changes and necrosis of spermatogenic epithelium, with marked interstitial edema and hyperplastic epithelial lining of epididymal tubules. Conclusion and clinical relevance: The present results support the hypothesis that the testis is one of the most sensitive organs to Cd and/or Cr and that the exposure to any of them or to their combination lead to testicular damage and thereby male infertility.

Bone marrow mesenchymal stem cells repair Cr (VI)- injured kidney by regulating mitochondria-mediated apoptosis and mitophagy mediated via the MAPK signaling pathway

The present study aimed to explore the repair effect and mechanism of bone marrow mesenchymal stem cells (BMSCs) transplantation on injured kidneys caused by hexavalent chromium (Cr (VI)). Wistar rats were intraperitoneally injected with 0.4 mg/kg•bw Cr (VI) ion solution. After 30 days, 1 × 10⁷ BMSCs were transplanted into rats. After cell transplantation for 2 weeks, there was no significant difference in the chromium content between the model and BMSCs-therapy group by atomic absorption spectrometry. In BMSCs-therapy group, the renal organ index, the serum levels of blood urea nitrogen (BUN) and creatinine (CRE), malonaldehyde (MDA) content were significantly decreased, superoxide dismutase (SOD) activity was significantly elevated, and the pathological changes were improved compared with the model group. The results of immunohistochemical and western blot assays showed that the expressions of apoptosis-related proteins Bax, Cytochrome c, and Caspase-3, as well as autophagy-associated proteins Beclin 1, PINK1, Parkin, p-Parkin, LC3B, and the MAPK signaling pathway, including the ratio of p-p38 to p38 and p-JNK to JNK were all significantly decreased, Bcl-2 and p62 expressions, and the ratio of p-ERK to ERK were significantly elevated in BMSCs-therapy group compared with the model group. These results suggested that BMSCs repaired Cr (VI)-injured kidney through decreasing mitochondria-mediated apoptosis and mitophagy mediated by downregulating phosphorylation of p38 and JNK, upregulating phosphorylation of ERK.

The protective effect of vitamin C on phenylhydrazine-induced hemolytic anemia on sperm quality and in-vitro embryo development in mice

Background

Phenylhydrazine (PHZ) induced anemia and was shown to have harmful effects on the male reproductive system.

Objective

To investigate the protective effect of vitamin C (Vit C) on sperm parameters quality, in vitro fertilization potential and embryonic development in a mouse model of hemolytic anemia induced by PHZ.

Materials and Methods

Thirty-two NMRI adult male mice (n = 8/each) were randomly classified into four groups. Group I (control) received normal saline, Group II (PHZ) received 8 mg/100 gr body weight PHZ as initial dose, continued by 6 mg/100 gr intraperitoneally every 48 hr, Group III (Vit C) received Vit C (10 mg/kg, daily, intraperitoneally), and group IV (PHZ + Vit C) received PHZ and Vit C. After 35 days, sperm quality parameters, the percentage of sperm with DNA damage and in vitro fertilization outcomes up to blastocyst stage were evaluated.

Results

A significant (p < 0.001) reduction in all of the sperm parameters (count, motility, viability and normal morphology) were observed in group II (PHZ) compared with group I (control). In group IV (PHZ ± Vit C), these parameters and sperm DNA damage (p < 0.001) improved significantly when compared with PHZ-treated mice. Furthermore, PHZ caused a significant (p < 0.001) decrease in the fertilization rate and the percentage of pre-implantation embryos' (two cell embryo and blastocyst) formation in comparison to group I (control), and Vit C supplementation in mice of group IV improved significantly the fertilization rate (p = 0.002), but it could not improve the percentage of two cell embryos and blastocyst production.

Conclusion

The data from this study indicated that Vit C decreased the adverse effects of PHZ on the quality of sperm parameters and in vitro fertilization rate, but it is insufficient to restore the in-vitro embryonic development and fertility potential.