Cadmium-induced apoptosis is mediated by the translocation of AIF to the nucleus in rat testes

PBA alleviates cadmium-induced mouse spermatogonia apoptosis by suppressing endoplasmic reticulum stress

OBJECTIVE

Endoplasmic reticulum (ER) stress mediates Cd-caused germ cell apoptosis in testis. The effects of 4-phenylbutyric acid (PBA), a classical chaperone, were investigated on Cd-induced apoptosis in mouse GC-1 spermatogonia cells.

METHODS

The cells were pretreated with PBA before Cd exposure. TUNEL and flow cytometry assays were applied to determine apoptosis. Some key biomarkers of ER stress were analyzed using RT-PCR and western blot.

RESULTS

as expected, the apoptotic cells exposed to Cd apparently increased. The mRNA and protein expression levels of GRP78 and ATF6α, were elevated in the Cd groups. Additional experiments displayed that Cd notably increased IRE1α and JNK phosphorylation, and upregulated XBP-1 mRNA and protein expression. Moreover, p-eIF2α and CHOP expressions were clearly elevated in the Cd groups. Interestingly, PBA almost completely inhibited ER stress and protected spermatogonia against apoptosis induced by Cd.

CONCLUSION

PBA alleviated Cd-induced ER stress and spermatogonia apoptosis, and may have the therapeutic role in Cd-induced male reproductive toxicity.

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.

Identification of testis development-related genes by combining Iso-Seq and RNA-Seq in Zeugodacus tau

Introduction: Zeugodacus tau (Walker) is an invasive pest. An effective method to control this pest is the sterile insect technique (SIT). To better apply this technique, it is necessary to understand testis development progression. Methods: Differentially expressed genes (DEGs) during testis development were analyzed by PacBio Iso-Seq and RNA-seq. Results: RNA-Seq library of Z. tau testes on day 1, 6, and 11 post eclosion were constructed. We identified 755 and 865 differentially expressed genes in the comparisons of T6 (testes on day 6) vs. T1 and T11 vs. T1, respectively. The KEGG pathway analysis showed that the DEGs were significantly enriched in retinol metabolism, vitamin B6 metabolism, and ascorbate and aldarate metabolism pathways. Knockdown of retinol dehydrogenase 12-like (rdh12-like), pyridoxal kinase (pdxk) and regucalcin (rgn), the representative gene in each of the above 3 pathways, reduced the hatching rate of Z. tau offspring. In addition, we identified 107 Drosophila spermatogenesis-related orthologous genes in Z. tau, of which innexin 2 (inx2) exhibited significantly up-regulated expression throughout testis development, and the knockdown of this gene reduced offspring hatching rate. Discussion: Our data indicated that rdh12-like, pdxk, rgn, and inx2 genes were related to testis development, and they were conserved in tephritid species. These results suggested that this gene might have the same function in tephritid. The findings provide an insight into testis development and spermatogenesis in tephritid species.

The Antioxidant Activity of Betanin protects MRC-5 cells Against Cadmium Induced Toxicity

Cadmium (Cd) can induce both acute and chronic effects in the lungs depending on the time and the exposure route. Betanin is a component derived from the roots of red beets and it is well-known for its antioxidant and anti-apoptosis effects. The current study aimed to survey the protective effects of betanin on cell toxicity induced by Cd. Different concentration of Cd alone and in combination with betanin was assessed in MRC-5 cells. The viability and oxidative stress were measured using resazurin and DCF-DA methods respectively. Apoptotic cells were assessed by PI staining of the fragmented DNA and western blot analysis detected the activation of caspase 3 and PARP proteins. Cd exposure for 24 h declined viability and increased ROS production in MRC-5 cells compared to the control group (p < 0.001). Also, Cd (35 μM) elevated DNA fragmentation (p < 0.05), and the level of caspase 3-cleaved and cleaved PARP proteins in MRC-5 cells (p < 0.001). Co-treatment of cells with betanin for 24 h significantly enhanced viability in concentrations of 1.25 and 2.5 μM (p < 0.001) and 5 μM (p < 0.05) and declined ROS generation (1.25 and 5 μM p < 0.001, and 2.5 μM p < 0.01). As well as, betanin reduced DNA fragmentation (p < 0.01), and the markers of apoptosis (p < 0.001) compared to the Cd-treated group. In conclusion, betanin protects lung cells against Cd-induced toxicity through antioxidant activity and inhibition of apoptosis.

Cadmium-induced impairment of spermatozoa development by reducing exosomal-MVBs secretion: a novel pathway

Cadmium is a heavy environmental pollutant that presents a high risk to male-fertility and targets the different cellular and steroidogenic supporting germ cells networks during spermatogenesis. However, the mechanism accounting for its toxicity in multivesicular bodies (MVBs) biogenesis, and exosomal secretion associated with spermatozoa remains obscure. In the current study, the light and electron microscopy revealed that, the Sertoli cells perform a dynamic role with secretion of well-developed early endosomes (Ee) and MVBs pathway associated with spermatozoa during spermatogenesis. In addition, some apical blebs containing nano-scale exosomes located on the cell surface and after fragmentation nano-scale exosomes were directly linked with spermatozoa in the luminal compartment of seminiferous tubules, indicating normal spermatogenesis. Controversially, the cadmium treated group showed limited and deformed spermatozoa with damaging acromion process and mid-peace, and the cytoplasmic vacuolization of spermatids. After cadmium treatment, there is very limited biogenesis of MVBs inside the cytoplasm of Sertoli cells, and no obvious secretions of nano-scale exosomes interacted with spermatozoa. Interestingly, the cadmium treated group demonstrated relatively higher formation of autophagosomes and autolysosome, and the autophagosomes were enveloped by MVBs that later formed the amphisome which degraded by lysosomes, indicating the hypo-spermatogenesis. Moreover, cadmium declined the exosomal protein cluster of differentiation (CD63) and increased the autophagy-related proteins microtubule-associated light chain (LC3), sequestosome 1 (P62) and lysosomal-associated membrane protein 2 (LAMP2) expression level were confirmed by Western blotting. These results provide rich information regarding how cadmium is capable of triggering impaired spermatozoa development during spermatogenesis by reduction of MVBs pathway through high activation of autophagic pathway. This study explores the toxicant effect of cadmium on nano-scale exosomes secretion interacting with spermatozoa.

Ultrastructural analysis of cadmium-induced toxicity and its alleviation by antioxidant quercetin in caprine testicular germ cells in vitro

Increasing evidence has demonstrated that cadmium (Cd), a common environmental toxicant, has been associated with testicular toxicity. Quercetin, an efficient flavonoid, has been shown to exert cytoprotective effect in numerous pathological processes. The current study has employed ultrastructural analysis to examine the Cd-induced toxicity in goat testicular tissue along with the ameliorative action of quercetin in a dose- and time-dependent manner in-vitro. Results of transmission electron microscopy (TEM) revealed that at lower selected concentrations (10 and 50 µM), Cd induced apoptosis-mediated cytotoxicity in testicular tissue as supported by presence of various morphological attributes of apoptosis in testicular germ cells such as condensed and marginated chromatin followed by breakdown of chromatin material, swollen mitochondria, and vacuolization. At 100 µM concentration, along with apoptosis, Cd-induced cytotoxicity in testicular tissue was associated with induction of necrosis also. However, the simultaneous supplementation of antioxidant quercetin has markedly abrogated the testicular cytotoxicity as shown by restoration of Cd-evoked aberrant ultrastructure of testicular germ cells in a dose- and time-dependent manner, providing a basis for future studies to involve quercetin in management of Cd-induced reproductive toxicity in males.

Apoptosis-Inducing Factor 2 (AIF-2) Mediates a Caspase-Independent Apoptotic Pathway in the Tropical Sea Cucumber (Holothuria leucospilota)

Apoptosis, also known as programmed cell death, is a biological process that is critical for embryonic development, organic differentiation, and tissue homeostasis of organisms. As an essential mitochondrial flavoprotein, the apoptosis-inducing factor (AIF) can directly mediate the caspase-independent mitochondrial apoptotic pathway. In this study, we identified and characterized a novel AIF-2 (HlAIF-2) from the tropical sea cucumber Holothuria leucospilota. HlAIF-2 contains a conserved Pyr_redox_2 domain and a putative C-terminal nuclear localization sequence (NLS) but lacks an N-terminal mitochondrial localization sequence (MLS). In addition, both NADH- and FAD-binding domains for oxidoreductase function are conserved in HlAIF-2. HlAIF-2 mRNA was ubiquitously detected in all tissues and increased significantly during larval development. The transcript expression of HlAIF-2 was significantly upregulated after treatment with CdCl₂, but not the pathogen-associated molecular patterns (PAMPs) in primary coelomocytes. In HEK293T cells, HlAIF-2 protein was located in the cytoplasm and nucleus, and tended to transfer into the nucleus by CdCl₂ incubation. Moreover, there was an overexpression of HlAIF-2-induced apoptosis in HEK293T cells. As a whole, this study provides the first evidence for heavy metal-induced apoptosis mediated by AIF-2 in sea cucumbers, and it may contribute to increasing the basic knowledge of the caspase-independent apoptotic pathway in ancient echinoderm species.

Low-dose heavy metal mixture (lead, cadmium and mercury)-induced testicular injury and protective effect of zinc and Costus afer in wistar albino rats

The study evaluated the protective effect of Costus afer on low-dose heavy metal mixture (LDHMM)-mediated effects in the testis of albino rats. The weight-matched animals were divided into six groups: normal control, metal mixture of (PbCl₂  + CdCl₂ + HgCl₂ ), combination of metal mixture + Costus afer at 750 mg/kg, combination of metal mixture + Costus afer at 1,500 mg/kg, combination of metal mixture + Costus afer at 2,250 mg/kg and combination of metal mixture + (ZnCl₂ ). LDHMM reduced (p < .05) the antioxidant biomarkers (superoxide dismutase, SOD; catalase, CAT; and glutathione, GSH) and increased (p < .05) the lipid peroxidation marker (malondialdehyde, MDA) and lead, cadmium and mercury concentrations in the testis. Treatment with LDHMM increased (p < .05) abnormal sperm morphology and plasma prolactin (PRL) level and decreased epididymal sperm count, viability, follicle-stimulating hormone (FSH), luteinising hormone (LH) and testosterone. LDHMM exposure caused deleterious changes in the testis. Treatment of rats with Costus afer (750, 1,500 and 2,250 mg/kg) dose-dependently reduced (p < .05) the LDHMM-mediated toxicity. Treatment with Costus afer also reversed the testicular weight and LDHMM decrease in antioxidant biomarkers. Costus afer may be a defensive modulator of LDHMM-mediated testicular lesions.

p53- and ROS-mediated AIF pathway involved in TGEV-induced apoptosis

We previously demonstrated that transmissible gastroenteritis virus (TGEV) could induce apoptosis through caspase signaling. However, apoptosis was not completely prevented by caspases inhibitors, suggesting that there may be a caspase-independent pathway involved in TGEV-induced cell apoptosis. In this study, we investigated the regulation of apoptosis-inducing factor (AIF) on TGEV-induced apoptotic pathway. Results indicated that AIF translocated from the mitochondria to nucleus during TGEV infection, and the AIF inhibitor, N-phenylmaleimide (NP), significantly attenuated the apoptosis. In addition, the translocation of AIF was inhibited by Veliparib (ABT-888), an inhibitor of poly (ADP-ribose) polymerase (PARP). And the reactive oxygen species (ROS) scavenger, pyrrolidinedithiocarbamic (PDTC), redistributed AIF in the mitochondria and nucleus in TGEV-infected cells. Moreover, the protein levels in nucleus and the mRNA levels of AIF were inhibited in the presence of the p53 inhibitor, pifithrin-α (PFT-α) or in TGEV-infected p53-/-cells. Furthermore, TGEV-induced apoptosis was blocked by combination of three or more inhibitors, such as pan caspase inhibitor Z-VAD-FMK, NP, ABT-888, PDTC, PFT-α, to treat PK-15 cells. Taken together, these results suggest that the p53- and ROS-mediated AIF pathway and caspase-dependent pathway were involved in TGEV-induced apoptosis.

In utero single low-dose exposure of cadmium induces rat fetal Leydig cell dysfunction

Cadmium chloride (Cd) is a potent endocrine disruptor and may cause the malformation in the male reproductive tract. However, the effects of a single in utero exposure to low doses of Cd on fetal Leydig cell development are still unknown. The objective of this study is to investigate the effects of a single in utero exposure to low doses of Cd on rat fetal Leydig cell development. Adult 64-day-old Sprague-Dawley dams received a single intraperitoneal injection of 0, 0.25, 0.5, and 1.0 mg/kg Cd on gestational day 12. Cd dose-dependently reduced testosterone production of fetal testis, lowered fetal Leydig cell numbers, downregulated protein expression levels of Leydig (LHCGR, SCARB1, STAR, CYP11A1, HSD3B1, and CYP17A1), and Sertoli cells (HSD17B3, DHH, and FSHR). In conclusion, our results demonstrated that a single in utero exposure to low doses of Cd blocked fetal Leydig cell development.

Differential Susceptibility of Germ and Leydig Cells to Cadmium-Mediated Toxicity: Impact on Testis Structure, Adiponectin Levels, and Steroidogenesis

This study investigated the relationship between germ and Leydig cell death, testosterone, and adiponectin levels in cadmium-mediated acute toxicity. Cadmium chloride was administered in a single dose to five groups of rats: G1 (0.9% NaCl) and G2 to G5 (0.67, 0.74, 0.86, and 1.1 mg Cd/kg). After 7 days, the animals were euthanized, and the testosterone and testes were analyzed. Dose-dependent Cd accumulation in the testes was identified. At 0.86 and 1.1 mg/kg, animals exhibited marked inflammatory infiltrate and disorganization of the seminiferous epithelium. While Leydig cells were morphologically resistant to Cd toxicity, massive germ cell death and DNA oxidation and fragmentation were observed. Although numerical density of Leydig cells was unchanged, testosterone levels were significantly impaired in animals exposed to 0.86 and 1.1 mg Cd/kg, occurring in parallel with the reduction in total adiponectins and the increase in high-molecular weight adiponectin levels. Our findings indicated that Leydig and germ cells exhibit differential microstructural resistance to Cd toxicity. While germ cells are a primary target of Cd-induced toxicity, Leydig cells remain resistant to death even when exposed to high doses of Cd. Despite morphological resistance, steroidogenesis was drastically impaired by Cd exposure, an event potentially related to the imbalance in adiponectin production.

Reproductive effects of cadmium on sperm function and early embryonic development in vitro

Cadmium is a major environmental toxicant that is released into the atmosphere, water and soil in the form of cadmium oxide, cadmium chloride, or cadmium sulfide via industrial activities, such as the manufacturing of batteries and pigments, metal smelting and refining and municipal waste incineration. In the present study, we investigated the effects of cadmium exposure on sperm quality parameters, fertilization capacity and early embryonic development. Our study showed that in vitro incubation of human or mouse sperms with cadmium for a long time (up to 24 hours) could significantly decreased sperm motility in a concentration- and time-dependent manner. Exposure to cadmium in the environment for a short term (30 min) did not affect sperm motility but significantly reduced in vitro fertilization rate. We also evaluated the effects of cadmium at concentrations of 0.625 μg/ml, and 1.25 μg/ml on early embryonic development in vitro and observed that the blastocyst formation rate dramatically decreased with increasing cadmium concentration. This finding emphasizes the hazardous effects of cadmium on sperm quality as well as on natural embryo development and raises greater concerns regarding cadmium pollution.

Effects of cadmium exposure on Iberian ribbed newt (Pleurodeles waltl) testes

To characterize the histomorphologic effects of cadmium on adult newt testes, male Iberian ribbed newts (6 months post-hatching) were intraperitoneally exposed to a single dose of 50 mg/kg of cadmium, with histologic analysis of the testes at 24, 48, 72, and 96 h. Beginning 24 h after cadmium exposure, apoptosis of spermatogonia and spermatocytes was observed, and congestion was observed in the interstitial vessels of the testes. Throughout the experimental period, the rates of pyknotic cells and TUNEL and cleaved caspase-3 positivity were significantly higher in the spermatogonia and spermatocytes of cadmium-treated newts compared with control newts. There were no significant differences between cadmium-treated and control newts in phospho-histone H3 positivity in the spermatogonia and spermatocytes. These results suggest that spermatogonia and spermatocytes in adult Iberian ribbed newts are highly sensitive to cadmium. This is the first report of the histomorphologic characteristics of cadmium-induced testicular dysfunction in newts.

Bone marrow mesenchymal stem cells repair cadmium-induced rat testis injury by inhibiting mitochondrial apoptosis

Cadmium is a highly toxic metal with widespread exposure to people that can cause tissue injuries that lack effective treatment. The aim of this project was to uncover whether bone marrow mesenchymal stem cells (BMSCs) can repair cadmium-induced rat testis injury and to explore the role of mitochondrial apoptosis in this process. To this end, 21 adult male Wistar rats were randomly divided into control, model and therapy groups, 7 each, and were administered 0, 0.4 and 0.4 mg/kg body weight CdCl₂ saline solution, respectively, by intraperitoneal injection 5 times per week for 5 weeks. Then, rats in the therapy group were treated with 10⁷ BMSCs by retro-orbital injections, while the others were given equal volumes of phosphate buffered saline. Following 2-week BMSCs-treatment, the therapy rats were heavier than the model rats, despite there being no difference in testicular cadmium contents between these groups, which were both significantly higher than the control group. BMSCs were observed in the testis of the therapy rats, in which pathological changes improved significantly compared with the model group. Expression of the apoptosis-associated proteins Bim, Bax, Cytochrome C, Caspase-3, active-Caspase-3 and AIF increased, while Bcl-2 was reduced significantly in rat testes of model group compared with the other groups. Based on these findings, we conclude that cadmium can accumulate in rat testes where it caused severe tissue injury, BMSCs can be localized to the injured testicular tissue of rats and repair the tissue injury, these reparative effects may be highly related with mitochondrial apoptosis.

High-mobility group box 1 regulates cytoprotective autophagy in a mouse spermatocyte cell line (GC-2spd) exposed to cadmium

BACKGROUND

Cadmium (Cd) is an environmental and industrial pollutant that induces a broad spectrum of toxicological effects, influences a variety of human organs, and is associated with poor semen quality and male infertility. Increasing evidence demonstrates that Cd induces testicular germ cell apoptosis in rodent animals. However, the specific effect of Cd exposure on autophagy in germ cells is poorly understood.

METHODS

We investigate the role of high-mobility group box 1 protein (HMGB1), a ubiquitous nuclear protein, on Cd-evoked autophagy in a mouse spermatocyte cell line (GC-2spd).

RESULTS

Our data have shown that autophagy was significantly elevated in GC-2spd cells exposed to Cd. Furthermore, there was a reduction in rapamycin (RAP)-mediated apoptosis. In addition, Cd exposure reduced cell viability, which is an effect that could be significantly inhibited by RAP treatment. These results indicate that autophagy appears to serve a positive function in reducing Cd-induced cytotoxicity. In addition, HMGB1 increased coincident with the processing of LC3-I to LC3-II. Thus, the upregulation of HMGB1 increases LC3-II levels.

CONCLUSIONS

Our data suggest that HMGB1-induced autophagy appears to act as a defense/survival mechanism against Cd cytotoxicity in GC-2spd cells.

Modulatory effect of cadmium on the expression of phospholipase A2 and proinflammatory genes in rat testis

Cadmium (Cd) is a toxic metal that is hazardous to health, and its exposure showed a significant reduction in mitochondrial phospholipid function in the rat testes. Cd induction enhanced phospholipases (PLA2 s) activities, specifically the secretory PLA2 and cytosolic PLA2 . There was a reduction in mitochondrial membrane potential and significant decline in the respiratory complexes, which was confirmed by 2D blue native gel. The mRNA expression of cyclooxygenase and proinflammatory cytokine genes interleukin (IL)-1, IL-6, tumor necrosis factor-α, inducible nitric oxide synthase, and interferon-γ increased and that of anti-inflammatory cytokine IL-10 reduced with Cd exposure in a time-dependent manner. The gene expression of the proapoptotic factor Bax was elevated, and in parallel, the antiapoptotic factor Bcl2 was down-regulated. Hence, this study explored the testes under Cd toxicity and observed alterations in PLA2 s and mitochondrial membrane composition/function and further explored the impact of these alterations on proinflammation and apoptosis. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1176-1184, 2016.

Association of maternal serum cadmium level during pregnancy with risk of preterm birth in a Chinese population

Cadmium (Cd) was a developmental toxicant that induces fetal malformation and growth restriction in mice. However, epidemiological studies about the association of maternal serum Cd level with risk of preterm birth were limited. This study was to investigate whether maternal serum Cd level during pregnancy is associated with risk of preterm birth in a Chinese population. Total 3254 eligible mother-and-singleton-offspring pairs were recruited. Maternal serum Cd level was measured by GFAAS. Based on tertiles, maternal serum Cd concentration was classified as low (LCd, <0.65 μg/L), medium (MCd, 0.65-0.94 μg/L) and high (HCd, ≥0.95 μg/L). Odds ratio (OR) for preterm birth was estimated using multiple logistic regression models. Results showed the rate of preterm birth among LCd, M-Cd and HCd was 3.5%, 3.8%, and 9.4%, respectively. Subjects with HCd had a significantly higher risk for preterm birth (OR: 2.86; 95%CI: 1.95, 4.19; P < 0.001) than did those with LCd. Adjusted OR for preterm birth was 3.02 (95%CI: 2.02, 4.50; P < 0.001) among subjects with HCd compared to subjects with LCd. Taken together, the above results suggest that maternal serum Cd level during pregnancy is positively associated with risk of preterm birth.

Ameliorative effect of propolis on the cadmium-induced reproductive toxicity in male albino rats

Propolis is a potent antioxidant and a free radical scavenger. The present study aimed to investigate protective effects of propolis extract on cadmium-induced testicular damage, apoptosis, HIF-1α expression and toxicity in rat's testis tissue. A total of 32 male rats were equally divided into four study groups namely, control, Cd (1mg/kg/day), Cd+propolis (50mg/kg/day) and propolis. The rats were decapitated under ketamine anesthesia and their testes tissues were removed. Serum testosterone, tissue malondialdehyde and HIF-1α levels, HIF-1α expression, apoptosis and histopathological damage scores were then compared. In the Cd group, the diameters of seminiferous tubules, tubular biopsy score of Johnsen and serum testosterone levels were decreased compared control group, but tissue HIF-1α and tissue MDA levels was higher than control group. The immunoreactivity of HIF-1α and the number of apoptotic cells were increased in Cd group. Furthermore, the propolis treated group showed an improved histological appearance in the Cd group. Thus, the results suggest that propolis acts as a potent protective agent against Cd-induced testicular toxicity in rats.

Maternal serum cadmium level during pregnancy and its association with small for gestational age infants: a population-based birth cohort study

The association between maternal cadmium (Cd) exposure during pregnancy and the increased risk of fetal growth restriction (FGR) remains controversial. The present study evaluated the association between maternal serum Cd level and risk of small for gestational age (SGA) infants in a Chinese population. The present study analyzed a subsample of the C-ABCS cohort that recruited 3254 eligible mother-and-singleton-offspring pairs. Maternal serum Cd level during pregnancy was measured by graphite furnace atomic absorption spectrometry. The rate and odds ratio (OR) for SGA infant were calculated. The rate for SGA infant was 10.6% among subjects with H-Cd (≥1.06 μg/L), significantly higher than 7.5% among subjects with L-Cd (<1.06 μg/L). OR was 1.45 (95% CI: 1.11, 1.90; P = 0.007) among subjects with H-Cd. Adjusted OR for SGA infants was 1.43 (95% CI: 1.09, 1.88; P = 0.007) among subjects with H-Cd. Taken together, we observe the fact that maternal Cd exposure at middle gestational stage, elevates the risk of SGA in contrast to early gestational stage. The present results might be interesting and worth more discussing, and guarantee to further studies.

The Protective Effects of Melatonin Against Oxidative Stress and Inflammation Induced by Acute Cadmium Exposure in Mice Testis

Cadmium (Cd) is widely used in daily life and was recently recognized as a possible source of human toxicity due to its ability to accumulate in organs. Previous studies have shown that Cd exposure may cause testicular toxicity through oxidative stress and an inflammatory effect. Melatonin has been demonstrated to be an effective anti-oxidant and has an anti-inflammatory effect. The aim of the present study was to investigate the toxicological effects of Cd on reproduction in male mice and the potential protective action of melatonin against these adverse effects. Adult male mice were injected intraperitoneally with Cd at a dose of 2 mg/kg body weight per day for seven consecutive days with or without melatonin pretreatment. Sex organ weight, sperm parameters including sperm quality, apoptosis, acrosome integrity, mitochondrial membrane potential, testicular morphology, serum sex hormone, inflammatory status, and oxidative stress were evaluated. The results showed that significant adverse effects were observed in the male reproductive system after Cd exposure, including alterations in sperm parameters, increased DNA damage, and sex hormone disturbance. Acute Cd exposure also significantly increased malondialdehyde (MDA) contents, decreased glutathione (GSH) and superoxide dismutase (SOD) activities, and upregulated levels of the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), and interleukin-1beta (IL-1β), in the testis. In contrast, melatonin pretreatment significantly alleviated these toxic effects, and its mechanism may involve inhibiting MDA level, restoring GSH and SOD activities, and reducing the upregulation of TNF-α and IL-1β. Our data suggest that oxidative stress and inflammation are involved in Cd-induced toxicity in the male reproductive system and that co-administration of melatonin exerts a protective effect against Cd-induced male reproductive toxicity.

The Co-Induced Effects of Molybdenum and Cadmium on the Trace Elements and the mRNA Expression Levels of CP and MT in Duck Testicles

To investigate the chronic toxicity of molybdenum (Mo) and cadmium (Cd) on the trace elements and the mRNA expression levels of ceruloplasmin (CP) and metallothionein (MT) in duck testicles, 120 healthy 11-day-old male ducks were randomly divided into six groups with 20 ducks in each group. Ducks were treated with the diet containing different dosages of Mo or Cd. The source of Mo and Cd was hexaammonium molybdate ([(NH4)6Mo7O24·4H2O]) and cadmium sulfate (3CdSO4·8H2O), respectively, in this study. After being treated for 60 and 120 days, ten male birds in each group were randomly selected and euthanized and then testicles were aseptically collected for determining the mRNA expression levels of MT and CP, antioxidant indexes, and contents of trace elements in the testicle. In addition, testicle tissues at 120 days were subjected to histopathological analysis with the optical microscope. The results showed that co-exposure to Mo and Cd resulted in an increase in malondialdehyde (MDA) level while decrease in xanthine oxidase (XOD) and catalase (CAT) activities. The mRNA expression level of MT gene was upregulated while CP was decreased in combination groups. Contents of Mo, copper (Cu), iron (Fe), and zinc (Zn) decreased in combined groups while Cd increased in Cd and combined groups at 120 days. Furthermore, severe congestion, low sperm count, and malformation were observed in low dietary of Mo combined with Cd group and high dietary of Mo combined with Cd group. Our results suggested that Mo and Cd might aggravate testicular degeneration synergistically through altering the mRNA expression levels of MT and CP, increasing lipid peroxidation through inhibiting related enzyme activities and disturbing homeostasis of trace elements in testicles. Interaction of Mo and Cd may have a synergistic effect on the testicular toxicity.

Toxic effects of cadmium on testis of birds and mammals: a review

In humans and other mammals, cadmium (Cd) causes various damages to different organs and tissues of the body. This review presents a comprehensive overview on the effect of Cd on the structure of seminiferous tubules, Leydig cells and blood vessels in the testis. The main observation of the effect of Cd is destruction of the seminiferous tubules with severe necrotic areas. Damage is to all stages of developing germ cells by inducing their structural changes and the apoptotic cell death. Sertoli supporting cells are considered the most vulnerable cells. Their damage results in cytoplasmic rearrangement and disruption of inter-Sertoli tight junctions resulting in increased permeability of the blood-testis barrier, structural changes in the Leydig cells and decreased testosterone secretion. After long time of Cd exposure an increase of the amount of interstitial connective tissue occurs. In blood vessels Cd exposure causes various morphological and physiological changes in vascular endothelial cells and smooth muscle cells. In humans and other mammals, the range of effect depends on the dose, route, ways, and duration of exposure. After necrosis of the sensitive cells Cd produced lesions in surrounding tissue and activate free cells. Atrophy of the seminiferous tubules is followed by Leydig cell regeneration and interstitial revascularization. In birds, spermatogenic cells underwent irreversible degeneration or atrophy of seminiferous tubules in the absence of significant vascular lesions.

Protective effects of grape seed extract on cadmium-induced testicular damage, apoptosis, and endothelial nitric oxide synthases expression in rats

This study aims to evaluate the protective effect of grape seed proanthocyanidin extract (GSPE) on cadmium (Cd)-induced testicular apoptosis, endothelial nitric oxide synthases (eNOS) expression, and toxicity in rats. A total of 24 male Wistar rats were divided into four groups, namely, control, Cd (2.5 mg/kg), Cd + GSPE (100 mg/kg/day), and GSPE. Spermatogenesis and mean seminiferous tubule diameter were significantly decreased in the Cd groups. Furthermore, the GSPE-treated animals showed an improved histological appearance in the Cd group. The immunoreactivity of eNOS and the number of apoptotic cells were increased in Cd group. Our data indicate a significant reduction of terminal deoxynucleotide transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end-labeling staining and a decrease in the expression of eNOS in the testes tissue of the Cd group treated with GSPE therapy. Therefore, our results suggest that GSPE acts as a potent protective agent against Cd-induced testicular toxicity in rats.

Endocrine disruptive effects of cadmium on steroidogenesis: human adrenocortical carcinoma cell line NCI-H295R as a cellular model for reproductive toxicity testing

Cadmium (Cd) is a known endocrine disruptor with the ability to affect the production of hormones involved in the regulation of reproductive processes. In this study human adrenocortical carcinoma cell line NCI-H295R was used as an in vitro biological model to study the effect of cadmium (CdCl2) on steroidogenesis. The cell cultures were exposed to different concentrations of CdCl2 (1.90, 3.90, 7.80, 15.60, 31.20 and 62.50 μM) and compared to control (medium without CdCl2). Cell viability was measured by the metabolic activity (MTT) assay for estimation of mitochondria structural integrity. Quantification of sexual steroid production directly from aliquots of the medium was performed by enzyme linked immunosorbent assay (ELISA). Following 48 h culture of the cells in the presence of CdCl2 a concentration-dependent depletion in progesterone production was observed at the lower concentrations of CdCl2. The lowest amount of progesterone was significantly detected in groups with the higher doses (≥ 31.20 μM) of CdCl2, which elicited significant (P < 0.01) cytotoxic action, too. Cadmium decreased testosterone release in the whole applied range even at the lower concentration of CdCl2. The release of 17β-estradiol decreased as well, but the decline was less pronounced compared to decrease of progesterone and testosterone. The cytotoxic effect was significantly (P < 0.01) detected at all concentrations of CdCl2 (1.90-62.50 μM) used in the study. However, the cell viability remained relatively high (>75%) up to 7.80 μM of CdCl2 and significantly (P < 0.01) decreased at 15.60 μM and higher concentrations of CdCl2. These results suggest that cadmium has endocrine disruptive effects on sexual steroid synthesis even at very low concentrations.

Cd-induced apoptosis through the mitochondrial pathway in the hepatopancreas of the freshwater crab Sinopotamon henanense

Cd is one of the most common pollutants in the environment that also induces the apoptosis. To explore the mechanism of apoptosis in the hepatopancreas, freshwater crab S. henanense were treated with 0, 3.56, 7.12, 14.25, 28.49 and 56.98 mg/L Cd for 72 h. Apoptosis was noticeable in every treatment group and necrosis was observed clearly in the high concentration Cd groups. Classical apoptotic bodies were found by transmission electronic microscopy, which revealed chromatin condensation under nuclear membrane and mitochondrial membrane rupture. An increasing number of autolysosomes, damaged rough endoplamic reticulum and Golgi complex were observed as the Cd concentration increase. Brown colored apoptotic cells were detected by the TUNEL test in all Cd-treatment groups. The apoptosis index increased following the elevation of Cd concentration and got 32.9% in the highest Cd group. Caspase-9 and caspase-3 activities increased in the lower Cd treatment groups but no changes in the higher Cd concentration groups (comparing to the control group). The activity of caspase-8 did not change significantly. No significant change in the content of mitochondrial cytochrome c (cyt c) in Cd exposed groups except the decrease in the 56.98 mg/L group. In crabs treated with 3.56, 7.12 and 14.25 mg/L Cd, hyperpolarization of mitochondrial membrane potential (Δψ_m) significantly increased. These results implied that apoptosis in the hepatopancreas induced by Cd occurrs through the mitochondrial caspase-dependent pathway. However, whether there are other apoptotic pathways needs to be studied further.

Delphinidin-3-glucoside protects against oxidized low-density lipoprotein-induced mitochondrial dysfunction in vascular endothelial cells via the sodium-dependent glucose transporter SGLT1

Delphinidin-3-glucoside (Dp) is a member of a family of bioactive compounds known as anthocyanins that occur naturally in pigmented plants and are known to ameliorate oxidative stress. Previous studies have showed that Dp decreased oxidative stress in vascular endothelial cells, however, the underlying mechanisms remain largely unknown. In the present study, we showed that pretreatment with Dp significantly suppressed oxidized low-density lipoprotein (oxLDL)-induced cell proliferation inhibition and apoptosis in primary human umbilical vein endothelial cells (HUVECs). Also, Dp pretreatment attenuated oxLDL-induced mitochondrial dysfunction via decreased reactive oxygen species (ROS) and superoxide anion generation, thereby repressing mitochondrial membrane potential and closing mitochondrial permeability transition pore. Furthermore, in vitro and in vivo data showed that Dp was transported into endothelial cells in a temperature, concentration, and time-dependent manner via the sodium-dependent glucose transporter (SGLT1). Suppression of SGLT1 by its substrate glucose, its inhibitor phlorizin or SGLT1 siRNA blocked Dp transportation. Repression of SGLT1 significantly inhibited Dp function of ameliorating mitochondrial dysfunction induced by pro-apoptotic factors (Apoptosis-inducing factor, Cytochrome c, Caspase-3 and Bax/Bcl-2 ratio). Taken together, our data indicate that Dp protects VECs via the SGLT1-ROS-mitochodria pathway. This new insight may help to elucidate the molecular mechanisms underlying the vascular protection afforded by Dp, and anthocyanins in general, in the context of prevention of endothelial dysfunction and atherosclerosis.

Effect of Ocimum basilicum extract on cadmium-induced testicular histomorphometric and immunohistochemical alterations in albino rats

The present study examined the efficacy of Ocimum basilicum (basil) extract, a natural herb, with antioxidant properties, against testicular toxicity induced by cadmium (Cd), which is one of the most important toxic heavy metals. The intoxicated rats showed significant alterations in the testicular tissue including decreased seminiferous epithelium height and changes in the arrangement of spermatogenic layers. Hypospermatogensis with cytoplasmic vacuolization and pyknotic nuclei were observed. Intertubular hemorrahage and absence of spermatozoa were noted. Decreased cell proliferation was reflected by a decrease in Ki-67 expression, whereas the increase in apoptotic rate was associated with a decrease in the Bcl/Bax ratio. Concomitant treatment with aqueous basil extract led to an improvement in histological, morphometrical and immunohistochemical changes induced by Cd. The beneficial effects of basil extract could be attributed to its antioxidant properties.

N-acetylcysteine protects against cadmium-induced germ cell apoptosis by inhibiting endoplasmic reticulum stress in testes

Cadmium (Cd) is a reproductive toxicant that induces germ cell apoptosis in the testes. Previous studies have demonstrated that endoplasmic reticulum (ER) stress is involved in Cd-induced germ cell apoptosis. The aim of the present study was to investigate the effects of N-acetylcysteine (NAC), an antioxidant, on Cd-induced ER stress and germ cell apoptosis in the testes. Male CD-1 mice were intraperitoneally injected with CdCl2 (2.0 mg kg(-1)). As expected, acute Cd exposure induced germ cell apoptosis in the testes, as determined by terminal dUTP nick-end labelling (TUNEL). However, the administration of NAC alleviated Cd-induced germ cell apoptosis in the testes. Further analysis showed that NAC attenuated the Cd-induced upregulation of testicular glucose-regulated protein 78 (GRP78), an important ER molecular chaperone. Moreover, NAC inhibited the Cd-induced phosphorylation of testicular eukaryotic translation initiation factor 2α (eIF2α), a downstream target of the double-stranded RNA-activated kinase-like ER kinase (PERK) pathway. In addition, NAC blocked the Cd-induced activation of testicular X binding protein (XBP)-1, indicating that NAC attenuates the Cd-induced ER stress and the unfolded protein response (UPR). Interestingly, NAC almost completely prevented the Cd-induced elevation of C/EBP homologous protein (CHOP) and phosphorylation of c-Jun N-terminal kinase (JNK), two components of the ER stress-mediated apoptotic pathway. In conclusion, NAC protects against Cd-induced germ cell apoptosis by inhibiting endoplasmic reticulum stress in the testes.

A common response to common danger? Comparison of animal and plant signaling pathways involved in cadmium sensing

Exposure to cadmium results in disturbances in cell homeostasis in all living organisms. The first response to stress factors, including cadmium, is activation of signal transduction pathways that mobilize cell defense mechanisms. The aim of this review is a comparison between the signaling network triggered by Cd in plants and animals. Despite differences in the structure and physiology of plant and animal cells, their cadmium signal transduction pathways share many common elements. These elements include signaling molecules such as ROS, Ca(2+) and NO, the involvement of phospholipase C, mitogen-activated protein kinase cascades, and activation of transcription factors. Undoubtedly, both animals and plants also possess specific signaling pathways. In case of animals, Wnt/β-catenin, sonic hedgehog and oestorgen signaling are engaged in the transduction of cadmium signal. Plant specific signal transduction pathways include signaling mediated by plant hormones. The role of ethylene and jasmonic, salicylic and abscisic acid in plant response to cadmium is also discussed.

The apoptotic function analysis of p53, Apaf1, Caspase3 and Caspase7 during the spermatogenesis of the Chinese fire-bellied newt Cynops orientalis

BACKGROUND

Spontaneous and stress-induced germ cell apoptosis during spermatogenesis of multicellular organisms have been investigated broadly in mammals. Spermatogenetic process in urodele amphibians was essentially like that in mammals in spite of morphological differences; however, the mechanism of germ cell apoptosis in urodele amphibians remains unknown. The Chinese fire-belly newt, Cynops orientalis, was an excellent organism for studying germ cell apoptosis due to its sensitiveness to temperature, strong endurance of starvation, and sensitive skin to heavy metal exposure.

METHODOLOGY/PRINCIPAL FINDINGS

TUNEL result showed that spontaneous germ cell apoptosis took place in normal newt, and severe stress-induced apoptosis occurred to spermatids and sperm in response to heat shock (40°C 2 h), cold exposure (4°C 12 h), cadmium exposure (Cd 36 h), and starvation stress. Quantitative reverse transcription polymerase chain reactions (qRT-PCR) showed that gene expression of Caspase3 or Caspase7 was obviously elevated after stress treatment. Apaf1 was not altered at its gene expression level, and p53 was significantly decreased after various stress treatment. Caspase assay demonstrated that Caspase-3, -8, -9 enzyme activities in newt testis were significantly elevated after heat shock (40°C 2 h), cold exposure (4°C 12 h), and cadmium exposure (Cd 36 h), while Caspase3 and Caspase8 activities were increased with Caspase9 significantly decreased after starvation treatment.

CONCLUSIONS/SIGNIFICANCE

Severe germ cell apoptosis triggered by heat shock, cold exposure, and cadmium exposure was Caspase3 dependent, which probably involved both extrinsic and intrinsic pathways. Apaf1 may be involved in this process without elevating its gene expression. But starvation-induced germ cell apoptosis was likely mainly through extrinsic pathway. p53 was probably not responsible for stress-induced germ cell apoptosis in newt testis. The intriguing high occurrence of spermatid and sperm apoptosis probably resulted from the sperm morphology and unique reproduction policy of Chinese fire-belly newt, Cynops orientalis.

Ascorbic acid protects against cadmium-induced endoplasmic reticulum stress and germ cell apoptosis in testes

Cadmium (Cd) is a testicular toxicant which induces endoplasmic reticulum (ER) stress and germ cell apoptosis in testes. This study investigated the effects of ascorbic acid on Cd-evoked ER stress and germ cell apoptosis in testes. Male mice were intraperitoneally injected with CdCl(2) (2.0 mg/kg). As expected, a single dose of Cd induced testicular germ cell apoptosis. Interestingly, Cd-triggered testicular germ cell apoptosis was almost completely inhibited in mice treated with ascorbic acid. Interestingly, ascorbic acid significantly attenuated Cd-induced upregulation of GRP78 in testes. In addition, ascorbic acid significantly attenuated Cd-triggered testicular IRE1α and eIF2α phosphorylation and XBP-1 activation, indicating that this antioxidant counteracts Cd-induced unfolded protein response (UPR) in testes. Finally, ascorbic acid significantly attenuated Cd-evoked upregulation of CHOP and JNK phosphorylation, two components in ER stress-mediated apoptotic pathway. In conclusion, ascorbic acid protects mice from Cd-triggered germ cell apoptosis via inhibiting ER stress and UPR in testes.

Melatonin alleviates cadmium-induced cellular stress and germ cell apoptosis in testes

Increasing evidence demonstrates that melatonin has an anti-apoptotic effect in somatic cells. However, whether melatonin can protect against germ cell apoptosis remains obscure. Cadmium (Cd) is a testicular toxicant and induces germ cell apoptosis. In this study, we investigated the effects of melatonin on Cd-evoked germ cell apoptosis in testes. Male ICR mice were intraperitoneally (i.p.) injected with melatonin (5 mg/kg) every 8 hr, beginning at 8 hr before CdCl(2) (2.0 mg/kg, i.p.). As expected, acute Cd exposure resulted in germ cell apoptosis in testes, as determined by terminal dUTP nick-end labeling (TUNEL) staining. Melatonin significantly alleviated Cd-induced testicular germ cell apoptosis. An additional experiment showed that spliced form of XBP-1, the target of the IRE-1 pathway, was significantly increased in testes of mice injected with CdCl(2). GRP78, an endoplasmic reticulum (ER) chaperone, and CHOP, a downstream target of the PERK pathway, were upregulated in testes of Cd-treated mice. In addition, acute Cd exposure significantly increased testicular eIF2α and JNK phosphorylation, indicating that the unfolded protein response (UPR) pathway was activated by CdCl(2). Interestingly, melatonin almost completely inhibited Cd-induced ER stress and the UPR in testes. In addition, melatonin obviously attenuated Cd-induced heme oxygenase (HO)-1 expression and protein nitration in testes. Taken together, these results suggest that melatonin alleviates Cd-induced cellular stress and germ cell apoptosis in testes. Melatonin may be useful as pharmacological agents to protect against Cd-induced testicular toxicity.

Mitochondrial pathway of apoptosis in the hepatopancreas of the freshwater crab Sinopotamon yangtsekiense exposed to cadmium

Cadmium (Cd) is one of the most common toxic metals in water. To investigate the mechanism of Cd-induced apoptosis in the hepatopancreas, freshwater crabs Sinopotamon yangtsekiense were exposed to 0, 3.56, 7.12, 14.25, 28.49 and 56.98 mg/L Cd for 48 h. After a 48 h exposure, apoptosis and necroptosis were apparent in the group exposed to 28.49 mg/L Cd and only one case of necrosis was observed in the highest concentration of Cd. Electronic microscopy revealed chromatin condensation under nuclear membrane and mitochondrial membrane rupture in 14.25 and 28.49 mg/L Cd treatment groups. Brown colored apoptotic cells were detected with the TUNEL test in all Cd-treatment groups. The AI in 56.98 mg/L group was 1.4-fold greater than that in crabs exposed to 14.25mg/L Cd. Caspase-9, caspase-3, SDH and Ca(2+)-ATPase activities increased with increasing Cd concentration. However, the activities of caspase-8 and LDH did not change significantly compared with control group. These results implied that Cd induced apoptosis in the hepatopancreas occurs through a mitochondrial pathway.

The effects of cadmium on VEGF-mediated angiogenesis in HUVECs

Cadmium (Cd) is a highly toxic element that causes morphologic alterations and dysfunction in blood vessels. The altered vascular function caused by cadmium has been implicated in a range of chronic diseases, including hypertension. The effects of cadmium are a multisystem phenomenon involving inflammation, hypertrophy, apoptosis, angiogenesis and important processes involved in vascular remodeling systems. Vascular endothelial growth factor (VEGF) plays a major role in cell growth and angiogenesis under pathologic conditions. VEGF secretion is related to anti-apoptosis protein expression and attenuates apoptosis in endothelial cells. This study examined the VEGF-dependent mechanisms of angiogenesis and apoptosis in cadmium-treated endothelial cells (HUVECs). The effects and mechanisms of cadmium in endothelial cells (HUVECs) were examined by exposing the cells to different doses of cadmium chloride (2.5-40 μ m). After the cadmium treatment, the angiogenesis and apoptosis mechanisms related to VEGF in cadmium-treated HUVECs were examined. As a result, the low concentration of cadmium increased the tube formation in HUVECs. In addition, cadmium at concentrations of 5 and 10 μ m increased VEGF secretion and VEGFR2 activity, which suggest that cadmium affects the growth of blood vessels. All three MAPK pathways, namely ERK, JNK and p38, were activated by cadmium in HUVECs. However, high concentrations of cadmium caused cell damage, disrupted tube formation and inhibited VEGF expression and the activities of VEGFR2 and MAPK in HUVECs. Cadmium has dual functions through VEGF-dependent mechanisms in a dose-dependent manner. In this study, the dual effects of cadmium might alter angiogenesis and induce apoptosis through VEGF pathways in HUVECs.

Apigenin induces apoptosis in human lung cancer H460 cells through caspase- and mitochondria-dependent pathways

Apigenin (4,5,7-trihydroxyflavone), a promising chemopreventive agent presented in fruits and vegetables, has been shown to induce cell cycle arrest and apoptosis in many types of human cancer cell lines. However, there is no available information to address the effects of apigenin on human lung cancer H460 cells. In the present studies, H460 cells were treated with apigenin for different time and then were analyzed for the morphological changes, induction of apoptosis, protein levels associated with apoptosis and results in dose-dependent induction of morphological changes, decrease in the percentage of viability, induced DNA damage and apoptosis; down-modulation of the protein expression of Bid, Bcl-2, procaspase-8; up-regulation of protein levels of Bax, caspase-3, AIF, cytochrome c, GRP78 and GADD153; decreased the levels of mitochondrial membrane potential and increased the productions of reactive oxygen species (ROS) and Ca2+ in H460 cells. Taken together, this is the first systematic in vitro study showing the involvement of apoptosis regulatory proteins as potential molecular targets of apigenin in human lung cancer H460 cells.

Cadmium directly induced mitochondrial dysfunction of human embryonic kidney cells

Cadmium (Cd) is the major component of polluted environment, which has numerous undesirable effects on health. Cd could induce apoptosis of HEK293 cells, and the mitochondria may play a key role. However, the mode of action is unclear. In the present study, we aimed to evaluate the ability of the Cd to induce dysfunction of mitochondria. We examined the effect of cadmium chloride (1, 5 and 10 μM) on mitochondrial membrane permeability and potential as well as oxidative stress markers in mitochondria isolated from HEK293 cells. We found that Cd could directly increase in permeability and decrease in membrane potential of mitochondria, even resulted in mitochondrial swelling, and that Cd could inhibit the activities of ATPase, lactate dehydrogenase (LDH), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), enhanced the levels of reactive oxygen species (ROS) and lipid peroxidation (LPO). On the whole, the results show that Cd can directly lead to mitochondrial dysfunction of HEK293 cells, including increased permeability, inhibiting respiration and evoking oxidative stress. Thus, for the first time, this paper makes an overall analysis of Cd-induced changes of structure and function of isolated mitochondria. Our findings may also have general implications in Cd-induced apoptosis by mitochondria pathway.

Cadmium suppresses the proliferation of piglet Sertoli cells and causes their DNA damage, cell apoptosis and aberrant ultrastructure

OBJECTIVE

Very little information is known about the toxic effects of cadmium on somatic cells in mammalian testis. The objective of this study is to explore the toxicity of cadmium on piglet Sertoli cells.

METHODS

Sertoli cells were isolated from piglet testes using a two-step enzyme digestion and followed by differential plating. Piglet Sertoli cells were identified by oil red O staining and Fas ligand (FasL) expression as assayed by immunocytochemistry and expression of transferrin and androgen binding protein by RT-PCR. Sertoli cells were cultured in DMEM/F12 supplemented with 10% fetal calf serum in the absence or presence of various concentrations of cadmium chloride, or treatment with p38 MAPK inhibitor SB202190 and with cadmium chloride exposure. Apoptotic cells in seminiferous tubules of piglets were also performed using TUNEL assay in vivo.

RESULTS

Cadmium chloride inhibited the proliferation of Piglet Sertoli cells as shown by MTT assay, and it increased malondialdehyde (MDA) but reduced superoxide dismutase (SOD) and Glutathione peroxidase (GSH-Px) activity. Inhibitor SB202190 alleviated the proliferation inhibition of cadmium on piglet Sertoli cells. Comet assay revealed that cadmium chloride caused DNA damage of Piglet Sertoli cells and resulted in cell apoptosis as assayed by flow cytometry. The in vivo study confirmed that cadmium induced cell apoptosis in seminiferous tubules of piglets. Transmission electronic microscopy showed abnormal and apoptotic ultrastructure in Piglet Sertoli cells treated with cadmium chloride compared to the control.

CONCLUSION

cadmium has obvious adverse effects on the proliferation of piglet Sertoli cells and causes their DNA damage, cell apoptosis, and aberrant morphology. This study thus offers novel insights into the toxicology of cadmium on male reproduction.

Effect of Ni2+ and Cd2+ ions on thermally induced conformational transitions in poly(dA)-poly(dT) system

Effects of Ni(2+) and Cd(2+) ions on thermally induced conformational transitions in the poly(dA)·poly(dT) polynucleotide duplex and poly(dA)·2poly(dT) triplex under near physiological ionic conditions were studied by measurement of UV absorption melting curves and static light scattering intensity. The diagrams of conformational transitions in poly(dA)-poly(dT)-Me(2+) systems were plotted. An aggregation in these polynucleotide systems arises at certain values of the metal ions concentration and the temperature after the polymer dissociation into single strands. The phenomenon is conditioned by the aggregation of poly(dA) via the interstrand cross-linking by the dication bridges. Unlike Ni(2+), Cd(2+) induces formation of very stable aggregates which did not disintegrate even upon cooling up to room temperature.