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

Localization and expression of phospholipase A2 and polyunsaturated fatty acid profile in the testis tissues of Hu sheep

The fatty acid content and the localization and expression of phospholipase A2 (PLA2) in the testis of Hu sheep were investigated. A total of 18 six-month-old Hu sheep were divided into small group (S, with left testis weight < 50 g), medium group (M, with left testis weight among 90-110 g), and large group (L, with left testis weight >160 g), which had six individuals each. The expression of PLA2 in testicular tissues of different sizes was analyzed by immunohistochemistry, RT-qPCR, and Western blot. The fatty acid profile was detected by gas chromatography. Immunohistochemical labeling determined that PLA2 protein was expressed in the Leydig and Sertoli cells of testis, and the immunohistochemical average optional density in the S group was significantly greater than the L group (P < 0.05). RT-qPCR and Western blot analysis showed that PLA2 in the S group was greater than that in the L group (P < 0.05). Docosahexaenoic acid, ω-3 polyunsaturated fatty acid (PUFA), and total PUFA content in the testis of the L group were significantly less than those of the S and M groups (P < 0.01). This study showed that PLA2 content in the S group was greater than that in the L group.

Metabolic effects of long-term cadmium exposure: an overview

Cadmium (Cd) is a toxic non-essential heavy metal. Chronic low Cd exposure (CLCE) has been associated with distinct pathologies in many organ systems, including liver and kidney damage, osteoporosis, carcinogenicity, or reproductive toxicity. Currently, about 10% of the global population is at risk of CLCE. It is urgent to find robust and effective biomarkers for early diagnosis of Cd exposure and treatment. Metabolomics is a high-throughput method based on mass spectrometry to study the dynamic changes in a series of endogenous small molecular metabolites (typically < 1000 Da) of tissues, cells, or biofluids. It can reflect the rich and complex biochemical changes in the body after exposure to heavy metals, which may be useful in screening biomarkers to monitor exposure to environmental pollutants and/or predict disease risk. Therefore, this review focuses on the changes in metabolic profiles of humans and rodents under long-term Cd exposure from the perspective of metabolomics. Furthermore, the relationship between the disturbance of metabolic pathways and the toxic mechanism of Cd is discussed. All these information will facilitate the development of reliable metabolic biomarkers for early detection and diagnosis of Cd-related diseases.

Long-term environmental cadmium exposure induced serum metabolic changes related to renal and liver dysfunctions in a female cohort from Southwest China

Cadmium (Cd), a toxic heavy mental, has been reported to be correlated with increased incidences of multiple diseases. Only a few studies have paid attention to screen the urine metabolites related to long-term environmental Cd exposure in humans. Research on the Cd exposure-related serum metabolic alternations and biological mechanisms linking Cd exposure to adverse health risks in humans is scanty. In this study, we investigated the serum Cd exposure-related metabolic alternations in a cohort of 101 non-smoking females (two polluted groups and one control group) and 18 Cd exposure-related metabolites were identified. A total of 16 clinical indicators of renal and hepatic functions and bone health were measured. Five health effect biomarkers including serum creatinine, alkaline phosphatase, total bilirubin, direct bilirubin and albumin to globulin ratio that are related to impaired renal and hepatic functions showed significant differences among the three groups and had close correlations with Cd levels. We identified intermediate metabolites that were associated with both Cd exposure and health effect biomarkers using a "meet-in-the-middle" approach. Fourteen Cd exposure-related metabolites in the metabolism of glycerophospholipids, sphingolipids, arachidic acid, linoleic acid and amino acids, were identified to be the intermediates of Cd exposure and the health effect biomarkers. Our findings provided evidence for the linkage of long-term environmental Cd exposure and the renal and hepatic insufficiency.

Resolvin D1 protects against cadmium chloride-induced memory loss and hippocampal damage in rats: A comparison with docosahexaenoic acid

BACKGROUND

Intoxication with cadmium (Cd) ions leads to hippocampal damage and cognitive impairment. However, omega-3 polyunsaturated fatty acids (n-3 PUFAs) exert neuroprotective effects in different animal models of neurodegeneration.

PURPOSE

This study compared the neuroprotective effect of the n-3 PUFA, docosahexaenoic acid (DHA), and its downstream metabolite, resolvin D1 (RVD1), on hippocampal damage and memory deficits in cadmium chloride (CdCl₂)-treated rats.

RESEARCH DESIGN

Control or CdCl₂ (0.5 mg/kg)-treated rats were subdivided into three groups (n = 18/each) and treated for 6 weeks as follows: (1) fed control diet, (2) fed DHA-rich diets (0.7 g/100 g), or (3) treated with RVD1 (0.2 μg/kg, i.p).

RESULTS

Treatment with a DHA-rich diet or RVD1 significantly increased the levels of docosahexaenoic acid and RVD1, respectively, in the hippocampal of CdCl₂-treated rats without affecting the reduction in the expression of the 15-lipooxygenase-1 (ALOX15). These effects were associated with improvements in rats' memory function and hippocampal structure, as well as a redction in the hippocampal levels of reactive oxygen species (ROS), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), nuclear localization of the nuclear factor-kappa beta p65 (NF-κB p65), and expression of cleaved caspase-3. Concomitantly, hippocampi of both groups of rats showed significantly higher levels of Bcl-2, superoxide dismutase (SOD), and glutathione (GSH), as well as enhanced nuclear levels of the nuclear factor erythroid 2-related factor 2 (Nrf-2). The effects of RVD1 on all these markers in the CdCl₂-induced rats were more profound than those of DHA. Also, the increase in the nuclear protein levels of Nrf-2 and the decrease in the levels of Bax and nuclear protein levels of NF-κB p65 were only seen in the hippocampal of CdCl₂ + RVD1-treated rats.

CONCLUSION

RVD1 is more powerful than DHA in preventing CdCl₂-induced memory loss and hippocampal damage in rats.

Cadmium induces endoplasmic reticulum stress-mediated apoptosis in pig pancreas via the increase of Th1 cells

Cadmium (Cd), an environmental pollutant, causes several adverse reactions in animals. High dose of Cd has serious cytotoxicities, including the induction of programmed cell necrosis, autophagy and apoptosis, which has aroused wide public concern. The balance of cytokine network is affected by Th1/Th2 balance which is closely related to immune response and the occurrence, development, treatment and outcome of various diseases. Cd can induce severe apoptosis, but the relationship between Cd induced apoptosis and Th1/Th2 balance has not been clarified. In this study, we established a pig Cd poisoning model, exposing to CdCl₂ for 40 days (20 mg Cd/kg diet). Firstly, deviation of Th1/Th2 balance was observed by fluorescence staining, and apoptosis was observed by TUNEL staining. Then, real-time fluorescence quantitative analysis and Western blot were used to detect the expression of related proteins. The results show that Cd can interfere with the balance of Th1/Th2 and shift the balance towards Th1. In addition, through the experiments, we found that Cd exposure can increase the expression of glucose-regulated protein 94 (GRP94) and glucose-regulated protein 78 (GRP78), marker proteins of unfolded protein response (UPR). Cd exposure can increase the expression of pancreatic endoplasmic reticulum kinase (PERK), CCAAT-enhancer-binding protein homologous protein (CHOP), inositol-requiring enzyme 1 (IRE-1), activating transcription factor 6 (ATF-6), cysteinyl aspartate specific proteinase (Caspase12), indicating the three branches (ATF6, PERK and IRE-1) of endoplasmic reticulum stress (ER-stress) were activated. Moreover, we found that the expression of pro-apoptosis genes in the downstream pathway of ER-stress increased. In summary, our results indicated that Cd exposure upregulated the expression of pro-apoptosis related genes and caused apoptosis via the activation of the ER-stress signaling pathways in pancreas cells. And these negative effects were correlated with the equilibrium drift of Th1/Th2, increase in the expression and secretion of Th1 cytokines.

Current mechanistic perspectives on male reproductive toxicity induced by heavy metals

Environmental and occupational exposures to heavy metals have led to various deleterious damages to the biological system of which infertility is one of them. Infertility is a global public health concern, affecting 15% of all couples of reproductive age. Out of the 100% cases of reported infertility among couples, 40% of the cases are related to male factors; including decreased semen quality. This review focuses on the recent mechanistic perspectives of heavy metal-induced male reproductive toxicity. The associated toxic metal-mediated mechanisms of male reproductive toxicity include ion mimicry, disruption of cell signaling pathways, oxidative stress, altered gene expression, epigenetic regulation of gene expression, apoptosis, disruption of testis/blood barrier, inflammation and endocrine disruption. The current literature suggests that non-coding RNAs (ncRNAs) mediate paternal intergenerational epigenetic inheritance and thus has a direct functional importance, as well as possess novel biomarker potential, for male reproductive toxicity. To identify the specific ncRNAs with the most profound impacts on heavy metal-induced male reproductive toxicity should be thrust of further research.

Cadmium-induced hepatocellular injury: Modulatory effects of γ-glutamyl cysteine on the biomarkers of inflammation, DNA damage, and apoptotic cell death

Cadmium is an extremely toxic pollutant that reaches human body through intake of the industrially polluted food and water as well as through cigarette smoking and exposure to polluted air. Cadmium accumulates in different body organs especially the liver. It induces tissue injury largely through inflammation and oxidative stress-based mechanisms. The aim of the current study was to investigate the ability of γ glutamyl cysteine (γGC) to protect against cadmium-induced hepatocellular injury employing Wistar rats as a mammalian model. The results of the current work indicated that γGC upregulated the level of the anti-inflammatory cytokine IL-10 and downregulated the levels of the pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) in the cadmium-exposed rats. In addition, γGC reduced the liver tissues cadmium content in the cadmium-treated rats, suppressed the cadmium-induced hepatocellular apoptosis and oxidative modifications of cellular DNA, lipids, and proteins. Additionally, γGC enhanced the antioxidant potential of the liver tissues in the cadmium-treated rats as evidenced by a remarkable increase in the activity of the antioxidant enzymes superoxide dismutase and glutathione peroxidase and significant increase in the levels of the total antioxidant capacity and reduced glutathione as well as a significant reduction in oxidized to reduced glutathione (GSSG/GSH) ratio. Moreover, it effectively improved liver cell integrity in the cadmium-treated rats as demonstrated by a significant reduction in the serum activity of the liver enzymes (ALT and AST) and amelioration of the cadmium-evoked histopathological alterations. Together, these findings underscore, for the first time, the alleviating effects of γGC against cadmium-induced hepatocellular injury that is potentially mediated through reduction of liver tissue cadmium content along with modulation of both hepatocellular redox status and inflammatory cytokines.

Protective Effect of Agaricus blazei Polysaccharide Against Cadmium-Induced Damage on the Testis of Chicken

Cadmium (Cd) exposure can cause reproductive toxicity through oxidative stress and inflammatory response. A polysaccharide extract of the edible mushroom Agaricus blazei Murill has been isolated and exhibits antioxidant activity and immunoregulatory effect. The aim of this study was to investigate the protective role of Agaricus blazei polysaccharide (ABP) against Cd-induced damage in chicken testis through enhancing antioxidant activity and alleviating inflammatory response. One hundred twenty healthy 7-day-old Hy-Line male chickens (Harbin, China) were randomly divided into four groups, and each group consisted of 30 chickens: Normal control was fed daily with full feed and 0.2 mL distilled water per day via oral gavage; Cd-treated group was fed daily with full feed that contained 140 mg/kg CdCl₂ and 0.2 mL distilled water per day by gavage; Polysaccharide-treated group was fed daily with full feed with 0.2 mL ABP(30 mg/ml) solution per day via oral gavage; Cd/polysaccharide-treated group was fed daily with full feed containing 140 mg/kg CdCl₂ and 0.2 mL ABP(30 mg/ml) solution per day by gavage. On the 20, 40, and 60 days, the testis was immediately removed. The contents of Cd in the testis, activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), malondialdehyde (MDA) production, messenger RNA (m RNA) levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6), protein expressions of heat shock proteins (HSPs) (HSP60, HSP70, and HSP90), and the histopathological changes of the testis were determined. The results indicated that ABP improved Cd-caused testicular tissue damage by increasing the SOD and GSH-Px activities: decreasing the Cd accumulation and MDA content, mRNA levels of TNF-α, IL-1β, and IL-6, and protein expressions of HSP60, HSP70, and HSP90. Results suggest that ABP for the mitigation of damage induced by cadmium in chicken testis through enhancing antioxidant activity and alleviating Inflammatory response.

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.

Alteration of mitochondrial phospholipid due to the PLA2 activation in rat brains under cadmium toxicity

Cadmium (Cd) is a heavy metal that has received considerable environmental and occupational concern. Cd causes toxic effects due to its accumulation in a variety of tissues, including the kidney, liver and the nervous system (CNS); however, the exact mechanism is poorly understood. In the present study, we tried to explore the impact of acute cadmium exposure on rat brain phospholipids (PLs). Cd exposure significantly reduced PLs in a time dependent manner and the reduction was due to the activation of the Phospholipase A2 enzymes (sPLA2, cPLA2). The release of arachidonic acid from PLs increased during inflammatory conditions by PLA2s. The mRNA expression of cyclooxygenase2 (COX2) and subsequently the pro-inflammatory cytokines, namely, Interleukin 1 (IL-1) and IL-6, were up regulated; however, the expression of anti-inflammatory cytokine IL-10 was reduced in a time dependent manner. The expression of the Tumor necrosis factor alpha (TNF-α), Inducible nitric oxide synthase (iNOS) and Interferon gamma (INF-γ) also experienced increases in the expression. Likewise the mRNA expression of the pro-apoptotic factor, Bcl-2-associated X protein (Bax), was elevated, whereas anti-apoptosis B-cell lymphoma 2 (Bcl2) was down regulated. This present study might help to decipher the effects of cadmium toxicity on rat brain.