Effect of nickel on oxygen free radical metabolism. Inhibition of superoxide dismutase and enhancement of hydroxydopamine autoxidation

The relationship between plasma nickel concentrations and type 2 diabetes mellitus risk: A protective effect within a specific range

BACKGROUND

Nickel is considered an essential nutrient for certain microbial, plant, and animal species, but its role in human health remains controversial. Some studies have reported the relationship between nickel and type 2 diabetes mellitus (T2DM), but the results are not consistent and the mechanism is not clear, which needs further exploration.

AIM

To investigate the possible correlation between nickel and T2DM.

METHODS

We conducted a case-control study of 192 patients with T2DM and 189 healthy controls at a hospital in central China. Plasma concentrations of nickel and six other trace elements were measured with inductively coupled plasma mass spectrometry. Logistic regression models, restricted cubic spline models (RCS), and Bayesian kernel machine regression (BKMR) were used to evaluate the relationship between plasma nickel and T2DM and its metabolic risk factors, as well as the presence or absence of interactions between nickel and other elements.

RESULTS

The T2DM group exhibited considerably lower plasma nickel levels than the control group (P < 0.001). Whether using a crude or adjusted model, logistic regression analysis finds a negative correlation between nickel levels and the risk of T2DM (P trend < 0.001). According to the RCS, the risk of T2DM reduces with rising nickel levels when the value is below 6.1 μg/L; nickel has a negative linear correlation with fasting plasma glucose (FPG), an inverse U-shaped connection with superoxide dismutase (SOD), and a positive linear correlation with malondialdehyde (MDA) (all P overall < 0.05). The plasma nickel concentration was positively correlated with zinc, vanadium, and chromium (r = 0.23, 0.11, and 0.19, respectively; all P < 0.05) and negatively correlated with copper (r = - 0.11, P < 0.05). In the BKMR model, interactions of nickel with zinc on T2DM and SOD, nickel with chromium on T2DM and homeostasis model assessment of β cell (HOMA-β), and nickel with copper on FPG, homeostasis model assessment of insulin (HOMA-IR), and MDA were observed.

CONCLUSION

Nickel may have a dual effect on the risk of T2DM, with a protective range of less than 6.1 μg/L. Potential interactions between nickel, copper, zinc, and chromium existed in their associations with T2DM and its metabolic risk factors.

A Molecular Mechanism to Explain the Nickel-Induced Changes in Protamine-like Proteins and Their DNA Binding Affecting Sperm Chromatin in Mytilus galloprovincialis: An In Vitro Study

Nickel is associated with reproductive toxicity, but little is known about the molecular mechanisms of nickel-induced effects on sperm chromatin and protamine-like proteins (PLs). In the present work, we analyzed PLs from Mytilus galloprovincialis by urea-acetic acid polyacrylamide gel electrophoresis (AU-PAGE) and SDS-PAGE and assessed their binding to DNA by Electrophoretic Mobility Shift Assay (EMSA) after exposing mussels to 5, 15, and 35 µM NiCl2 for 24 h. In addition, a time course of digestion with MNase and release of PLs from sperm nuclei by the NaCl gradient was performed. For all exposure doses, in AU-PAGE, there was an additional migrating band between PL-III and PL-IV, corresponding to a fraction of PLs in the form of peptides detected by SDS-PAGE. Alterations in DNA binding of PLs were observed by EMSA after exposure to 5 and 15 µM NiCl2, while, at all NiCl2 doses, increased accessibility of MNase to sperm chromatin was found. The latter was particularly relevant at 15 µM NiCl2, a dose at which increased release of PLII and PLIII from sperm nuclei and the highest value of nickel accumulated in the gonads were also found. Finally, at all exposure doses, there was also an increase in PARP expression, but especially at 5 µM NiCl2. A possible molecular mechanism for the toxic reproductive effects of nickel in Mytilus galloprovincialis is discussed.

Mechanisms underlying reproductive toxicity induced by nickel nanoparticles identified by comprehensive gene expression analysis in GC-1 spg cells

The public around the world is increasingly concerned about male reproductive health. The impact of nickel nanoparticles (Ni NPs) on male reproductive toxicity including sperm production, motility and fertilizing capacity has been confirmed by our previous researches. In the current study of Ni NPs-inducing toxicity, the expression profiles of piRNAs and their predicted target genes associated with male infertility, were obtained. The results showed that piR-mmu-32362259 was the highest differential expression multiples in both the testis tissues of male mice and GC-1 cells similarly. Notably, piR-mmu-32362259 target gene was significantly enriched in the PI3K-AKT signaling pathway. All these results suggest that piR-mmu-32362259 may affect the occurrence and development of injury in the mouse spermatogenesis process by regulating the PI3K-AKT signaling pathway. In order to verify the result, piR-mmu-32362259 low-expression lentivirus was used to transfect GC-1 cells to establish a stable transfected cell model. The effects of piR-mmu-32362259 on the viability, cycle and apoptosis as well as related protein expression levels of GC-1 cells induced by Ni NPs were detected using CCK8, flow cytometry and western blot assay, respectively. The results showed that low expression of piR-mmu-32362259 could not only alleviate the decrease of GC-1 cell viability, affect the cell cycle and reduce the apoptosis rate, but also significantly affect the expression levels of key proteins and their downstream molecules of PI3K/AKT/mTOR signaling pathway. Collectively, our current results provide a theoretical basis for further exploring the molecular regulatory mechanism of male reproductive toxicity induced by Ni NPs.

Nickel has biochemical, physiological, and structural effects on the green microalga Ankistrodesmus falcatus: An integrative study

In recent years, the release of chemical pollutants to water bodies has increased due to anthropogenic activities. Ni(2+) is an essential metal that causes damage to aquatic biota at high concentrations. Phytoplankton are photosynthesizing microscopic organisms that constitute a fundamental community in aquatic environments because they are primary producers that sustain the aquatic food web. Nickel toxicity has not been characterized in all of the affected levels of biological organization. For this reason, the present study evaluated the toxic effects of nickel on the growth of a primary producer, the green microalga Ankistrodesmus falcatus, and on its biochemical, enzymatic, and structural levels. The IC50 (96h) was determined for Ni(2+). Based on this result, five concentrations were determined for additional tests, in which cell density was evaluated daily. At the end of the assay, pigments and six biomarkers, including antioxidant enzymes (catalase [CAT], glutathione peroxidase [GPx], superoxide dismutase [SOD]), and macromolecules (proteins, carbohydrates and lipids), were quantified; the integrated biomarker response (IBR) was determined also. The microalgae were observed by SEM and TEM. Population growth was affected starting at 7.5 μg L(-1) (0.028 μM), and at 120 μg L(-1) (0.450 μM), growth was inhibited completely; the determined IC50 was 17 μg L(-1). Exposure to nickel reduced the concentration of pigments, decreased the content of all of the macromolecules, inhibited of SOD activity, and increased CAT and GPx activities. The IBR revealed that Ni(2+) increased the antioxidant response and diminished the macromolecules concentration. A. falcatus was affected by nickel at very low concentrations; negative effects were observed at the macromolecular, enzymatic, cytoplasmic, and morphological levels, as well as in population growth. Ni(2+) toxicity could result in environmental impacts with consequences on the entire aquatic community. Current regulations should be revised to protect primary producers.

Nickel sulfate induces location-dependent atrophy of mouse olfactory epithelium: protective and proliferative role of purinergic receptor activation

Exposure to nickel sulfate (NiSO(4)) leads to impaired olfaction and anosmia through an unknown mechanism. We tested the hypothesis that ATP is released following NiSO4-induced injury and that ATP promotes regenerative cell proliferation in the olfactory epithelium (OE). Male Swiss Webster mice were intranasally instilled with NiSO(4) or saline followed by ATP, purinergic receptor antagonists, or saline. We assessed the olfactory epithelium for NiSO(4)-induced changes using histology and immunohistochemistry 1-7 days postinstillation and compared results to olfactory bulb ablation-induced toxicity. Intranasal instillation of NiSO(4) produced a dose- and time-dependent reduction in the thickness of turbinate OE. These reductions were due to sustentacular cell loss, measured by terminal dUTP nick-end labeling (TUNEL) staining at 1-day postinstillation and caspase-3-dependent apoptosis of olfactory sensory neurons at 3 days postinstillation. A significant increase in cell proliferation was observed at 5 and 7 days postinstillation of NiSO(4) evidenced by BrdU incorporation. Treatment with purinergic receptor antagonists significantly reduced NiSO(4)-induced cell proliferation and posttreatment with ATP significantly increased cell proliferation. Furthermore, posttreatment with ATP had no effect on sustentacular cell viability but significantly reduced caspase-3-dependent neuronal apoptosis. In a bulbectomy-induced model of apoptosis, exogenous ATP produced a significant increase in cell proliferation that was not affected by purinergic receptor antagonists, suggesting that ATP is not released during bulbectomy-induced apoptosis. ATP is released following NiSO(4)-induced apoptosis and has neuroproliferative and neuroprotective functions. These data provide therapeutic strategies to alleviate or cure the loss of olfactory function associated with exposure to nickel compounds.

Cardiac and thermoregulatory effects of instilled particulate matter-associated transition metals in healthy and cardiopulmonary-compromised rats

Particulate matter air pollution has been associated with cardiopulmonary morbidity and mortality in many recent epidemiological studies. Previous toxicological research has demonstrated profound cardiac and thermoregulatory changes in rats following exposure to residual oil fly ash (ROFA), a combustion-derived particulate. The response to ROFA appeared biphasic, consisting of both immediate (0-6 h) and delayed (24-96 h) bradycardia and hypothermia. Other studies have demonstrated that much of the pulmonary toxicity of ROFA was caused by its constitutive transition metals, namely, Fe, Ni, and V. This study examined the contributions of these metals to the observed cardiac and thermoregulatory changes caused by ROFA in conscious, unrestrained rats. Prior to exposure, each animal was surgically implanted with a radiotelemetry device capable of continuously monitoring heart rate, electrocardiographic, and core temperature data. Individual metals were intratracheally instilled in healthy rats (n = 4 per metal species) and in rats with monocrotaline (MCT; 60 mg/kg)-induced pulmonary hypertension (n = 10 per metal species); combinations of metals were instilled in MCT-treated rats only (n = 6 per combination of metal species). Metals were administered in doses equivalent to those found in the highest dose of ROFA used in previous studies, that is, 105 microg Fe(2)(SO(4))(3), 263 microg NiSO(4), and 245 microg VSO(4). Healthy and MCT-treated rats demonstrated similar responses to metals. Fe caused little response, whereas V caused marked bradycardia, arrhythmogenesis, and hypothermia immediately following instillation and lasting approximately 6 h. Ni caused no immediate response, but induced a delayed bradycardia, arrhythmogenesis, and hypothermia that began approximately 24 h after instillation and lasted for several days. When instilled in combination, Ni appeared to exacerbate the immediate effects of V, whereas Fe attenuated them. These data suggest that the biphasic response to instilled ROFA may result from a summation of the temporally different effects of V and Ni.

Effects of trace metals on mouse B16 melanoma cells in culture

The effects of fourteen metal ions (As3+, As5+, Cd2+, Co2+, Cr3+, Cr6+, Hg2+, Li+, Mg2+, Mn2+, Ni2+, Se4+, V5+, VO2+) on the proliferation and differentiation in mouse B16 melanoma cells cultivated in vitro were analyzed. Cell number assays, melanin, and protein measurements, a 3(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide reduction test (MTT survival test), and a clonal growth assay were performed. At 10(-4)M, metal ions such as As3+, As5+, Cd2+, Cr6+, Se4+, V5+, VO2+, and, to a minor extent, Li+, Hg2+, and Co2+ significantly reduced the number of the B16 melanoma cells. For the same molar concentration, the order of the levels of cell toxicity of the metal compounds to B16 cells as measured by the MTT test was as follows: Hg2+ > Cr6+ = Cd2+ > As3+, As5+, > V5+, VO2+ > Se4+ = Ni2+ = Co2+ = Li+. An increased synthesis of melanin in B16 cells was noted after incubation with Co2+, Ni2+, Cd2+, and Li+, whereas Se4+ had, on the contrary, an inhibiting effect on melanogenesis.

Serum nickel levels of diabetic patients and healthy controls by AAS with a graphite furnace

In this study, serum nickel levels of diabetic patients and healthy controls were determined by AAS with a graphite furnace. The serum nickel concentrations were found to be 1.15 +/- 1.89 micrograms/L in healthy controls and 0.82 +/- 0.74 microgram/L in diabetics. There was, however, no statistically significant difference between the two groups (p = 0.13). The relationship of nickel levels to diabetes type and duration, diabetic complications and treatment, sex, age, and heredity was investigated. However, again no significant differences were found, nor was there any correlation between serum nickel levels and blood sugar, HBa1c, fructosamine, sialic acid levels, and age.

Metal carcinogenesis: mechanistic implications

Cancer epidemiology has identified several metal compounds as human carcinogens. Recent evidence suggests that carcinogenic metals induce genotoxicity in a multiplicity of ways, either alone or by enhancing the effects of other agents. This review summarizes current information on the genotoxicity of arsenic, chromium, nickel, beryllium and cadmium compounds and their possible roles in carcinogenesis. Each of these metals is distinct in its primary modes of action; yet there are several mechanisms induced by more than one metal, including: the induction of cellular immunity and oxidative stress, the inhibition of DNA metabolism and repair and the formation of DNA- and/or protein-crosslinks.