Alteration of testicular biochemistry during protein restriction in nickel treated rats

Association between the urinary nickel and the diastolic blood pressure in general population

AIM

To investigate the association of the level of nickel and blood pressure (BP) level in a general population.

METHODS

A total of 2201 participants were enrolled from the National Health and Nutrition Examination Surveys (NHANES) 2017-2018. Urinary nickel level was measured using inductively coupled-plasma mass spectrometry. Multivariable linear regressions were performed to explore the associations between nickel and systolic BP and diastolic BP. Restricted cubic splines were used to explore the nonlinearity.

RESULTS

Per one-fold increase of nickel was associated with a 0.67-unit decrease of diastolic BP (β -0.67, 95 % confidence interval [CI] [-1.15, -0.18]; p = 0.007). Comparing with the lowest quartile, the highest quartile decreased 2.21-unit diastolic BP (β -2.21, 95 % CI [-3.84, -0.59]; p = 0.007). Restricted cubic spline confirmed the relationship was linear. Subgroup analysis found that the association was only significant in population without hypertension.

CONCLUSIONS

The urinary nickel, as a long-term exposure biomarker, was associated with the diastolic BP in individuals without hypertension.

In vitro assessment of the impact of nickel on the viability and steroidogenesis in the human adrenocortical carcinoma (NCI-H295R) cell line

Nickel is a ubiquitous environmental pollutant, which has various effects on reproductive endocrinology. In this study, human adrenocortical carcinoma (NCI-H295R) cell line was used as an in vitro biological model to study the effect of nickel chloride (NiCl2) on the viability and steroidogenesis. The cells were exposed to different concentrations (3.90; 7.80; 15.60; 31.20; 62.50; 125; 250 and 500 microM) of NiCl2 and compared with control group (culture medium without NiCl2). The cell viability was measured by the metabolic activity assay. Production of sexual steroid hormones was quantified by enzyme linked immunosorbent assay. Following 48 h culture of the cells in the presence of NiCl2 a dose-dependent depletion of progesterone release was observed even at the lower concentrations. In fact, lower levels of progesterone were detected in groups with higher doses (>/=125 microM) of NiCl2 (P<0.01), which also elicited cytotoxic action. A more prominent decrease in testosterone production (P<0.01) was also noted in comparison to that of progesterone. On the other hand, the release of 17beta-estradiol was substantially increased at low concentrations (3.90 to 62.50 microM) of NiCl2. The cell viability remained relatively unaltered up to 125 microM (P>0.05) and slightly decreased from 250 microM of NiCl2 (P<0.05). Our results indicate endocrine disruptive effect of NiCl2 on the release of progesterone and testosterone in the NCI-H295R cell line. Although no detrimental effect of NiCl2 (</=62.50 microM) could be found on 17beta-estradiol production, its toxicity may reflect at other points of the steroidogenic pathway.

Effect of L-Ascorbic Acid on Nickel-Induced Alteration of Cardiovascular Pathophysiology in Wistar Rats

Nickel, a widely used heavy metal is suspected as a cardiotoxic element. The aim of the present study was to assess the possible protective role of l-ascorbic acid on nickel-induced alterations of cardiovascular pathophysiology in male albino rats. Twenty-four albino rats (b.wt. 170-250 g) were randomized into four groups: control; l-ascorbic acid (50 mg/100 g b.wt., orally); NiSO₄ (2.0 mg/100 g b.wt., i.p.); NiSO₄ with l-ascorbic acid. Cardiovascular electrophysiology, serum and cardiac tissue malondialdehyde (MDA), nitric oxide (NO), ascorbic acid, serum α-tocopherol and serum vascular endothelial growth factor (VEGF) were evaluated. Histopathology of cardiac and aortic tissues was also assessed. NiSO₄-treated rats showed a significant increase in heart rate, LF/HF ratio and blood pressure (SBP, DBP and MAP). A significant increase of serum MDA, NO and VEGF in NiSO₄ treatment with a concomitant decrease of serum ascorbic acid and α-tocopherol as compared to their respective controls were also observed. Simultaneous supplementation of l-ascorbic acid with NiSO₄ significantly decreased LF/HF ratio, BP and oxidative stress parameters, whereas ascorbic acid and α-tocopherol concentration was found to be increased. Histopathology of cardiac and aortic tissues showed nickel-induced focal myocardial hypertrophy and degeneration in cardiac tissue with focal aneurism in aortic tissues. Supplementation with l-ascorbic showed a protective action in both cardiac and aortic tissues. Results indicated the possible beneficial effect of l-ascorbic acid on nickel-induced alteration of the cardiovascular pathophysiology in experimental rats.

Primary concept of nickel toxicity - an overview

Toxic metals, including excessive levels of essential metals tend to change biological structures and systems into either reversible or irreversible conformations, leading to the derangement of organ functions or ultimate death. Nickel, a known heavy metal is found at very low levels in the environment. Nickel is available in all soil types and meteorites and also erupts from volcanic emissions. In the environment, nickel is principally bound with oxygen or sulfur and forms oxides or sulfides in earth crust. The vast industrial use of nickel during its production, recycling and disposal has led to widespread environmental pollution. Nickel is discharged into the atmosphere either by nickel mining or by various industrial processes, such as power plants or incinerators, rubber and plastic industries, nickel-cadmium battery industries and electroplating industries. The extensive use of nickel in various industries or its occupational exposure is definitely a matter of serious impact on human health. Heavy metals like nickel can produce free radicals from diatomic molecule through the double step process and generate superoxide anion. Further, these superoxide anions come together with protons and facilitate dismutation to form hydrogen peroxide, which is the most important reason behind the nickel-induced pathophysiological changes in living systems. In this review, we address the acute, subchronic and chronic nickel toxicities in both human and experimental animals. We have also discussed nickel-induced genotoxicity, carcinogenicity, immunotoxicity and toxicity in various other metabolically active tissues. This review specifically highlighted nickel-induced oxidative stress and possible cell signaling mechanisms as well.

Reproductive toxicology of nickel - review

The goal of this minireview is to summarize our current knowledge on the reproductive toxicity of soluble nickel salts. We made an attempt to present the most relevant data obtained from in vivo and in vitro experiments performed on mammals, mammalian primary cell cultures and cell lines. Nickel has been demonstrated to disturb the mammalian reproductive functions at several levels of regulation. The results of previous investigations indicate that the hormonal effects may play an important role in the reproductive toxicology of nickel both at the neuroendocrine and gonadal levels in the hypothalamic-pituitary-gonadal (HPG) axis. At the molecular level, it may be important that nickel may substitute certain other metals in metal dependent enzymes, leading to an altered protein function. It readily crosses the cell membrane via calcium channels and competes with calcium for specific receptors. Nickel can cross-link aminoacids to DNA, lead to formation of reactive oxygen species (ROS), moreover mimic hypoxia. These changes may lead to the activation of some signaling pathways, subsequent transcription factors and eventually to alterations in gene expression and cellular metabolism. These events are likely to be involved in the reproductive toxicity of nickel.

Hepatoprotective Role of Zinc in Lead-Treated, Protein-Deficient Rats

The current study was designed to evaluate the hepatoprotective role of zinc after lead (Pb) treatment of protein-deficient (PD) rats. The animals were subjected to seven different treatment groups: G-1 (normal control, 18% protein), G-2 (protein-deficient, 8% protein), G-3 (Pb-treated, 100 mg/kg body weight of lead acetate), G-4 (Zn-treated, zinc sulfate at a dose level of 227 mg/L drinking water), G-5 (PD + Pb-treated), G-6 (PD + Zn-treated), and G-7 (PD + Pb + Zn-treated). Serum albumin levels and total serum protein contents were estimated to assess the severity of protein deficiency at the end of 8 weeks in all the treatment groups. Also, the study explored the role of zinc on antioxidative defense system enzymes in liver of protein-deficient rats subjected to lead toxicity treatment. Further, the study was extended to elucidate the levels of zinc and lead in liver tissue after different treatments of rats using positron-induced X-ray emission technique (PIXE). The current study indicated a significant change in the levels of various antioxidative enzymes and serum albumin as well as total protein contents of protein-deficient rats subjected to lead treatment. A significant increase in the levels of malondialdehyde (MDA), catalase, and glutathione peroxidase (GPx) was seen after 8 weeks of lead treatment of protein-deficient rats. On the contrary, levels of albumin, total protein content, superoxide dismutase (SOD), GSH, were found to be decreased. Interestingly, zinc supplementation has tended to normalize the altered levels of these enzymes to a significant extent. The levels of zinc in liver tissue was found to be decreased significantly in protein-deficient as well as lead-treated rats. However, hepatic zinc concentration was increased to a significant extent in protein-deficient rats supplemented with zinc when compared with protein-deficient rats. Further, the presence of lead was also observed in livers of lead-treated animals. In conclusion, the study revealed the antioxidative role of zinc in hepatotoxic conditions induced by subjecting the rats to protein-deficient diet and lead treatment.

Protective Effects of Zinc on Oxidative Stress Enzymes in Liver of Protein-Deficient Rats

Persons afflicted with protein malnutrition are generally deficient in a variety of essential micronutrients like zinc, copper, iron, and selenium, which in turn affects number of metabolic processes in the body. To evaluate the protective effects of zinc on the enzymes involved in oxidative stress induced in liver of protein-deficient rats, the current study was designed. Zinc sulfate at a dose level of 227 mg/L zinc in drinking water was administered to female Sprague-Dawley normal control as well as protein-deficient rats for a total duration of 8 weeks. The effects of zinc treatment in conditions of protein deficiency were studied on rat liver antioxidant enzymes, which included catalase, glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), glutathione reduced (GSH), and glutathione-S-transferase (GST). Protein deficiency in normal rats resulted in a significant increase in hepatic activities of catalase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase and the levels of lipid peroxidation. A significant inhibition in the levels of reduced glutathione and the enzyme activity of superoxide dismutase has been observed after protein deficiency in normal rats. Interestingly, Zn treatment to protein-deficient animals lowered already raised activity catalase, glutathione peroxidase, and glutathione-S-transferase and levels of lipid peroxidation to significant levels when compared to protein-deficient animals. Also, Zn treatment to the protein-deficient animals resulted in a significant elevation in the levels of GSH and SOD activity as compared to their respective controls, thereby indicating its effectiveness in regulating their levels in adverse conditions. It has also been observed that concentrations of zinc, copper, iron, and selenium were found to be decreased significantly in protein-deficient animals. However, the levels of these elements came back to within normal limits when zinc was administrated to protein-deficient rats. This study concludes that zinc has the potential to regulate the activities of oxidative stress enzymes as well as essential hepatic elements.

Effect of antioxidants L-ascorbic acid and alpha-tocopherol supplementation in nickel exposed hyperglycemic rats

Nickel-induced hyperglycemia in rats under both acute and subchronic exposure conditions could be due to increased hepatic glycogenolysis, increased pancreatic release of glucagon, decreased peripheral utilization of glucose, or gluconeogenesis. We studied the effect of acute and subchronic nickel sulfate treatment on Wister strain male albino rats simultaneously treated with combined L-ascorbic acid and alpha-tocopherol. The simultaneous treatment with L-ascorbic acid or alpha-tocopherol appears to be beneficial for regulating glucose homeostasis in rats. A significant rise of blood glucose level was also observed with L-ascorbic acid supplementation alone, but not in the case of alpha-tocopherol supplementation alone.

Effect of nickel exposure on peripheral tissues: role of oxidative stress in toxicity and possible protection by ascorbic acid

The vast industrial use of nickel has led to environmental pollution by the metal and its by-products during production, recycling, and disposal. Nickel is a known hematotoxic, immunotoxic, hepatotoxic, pulmotoxic, and nephrotoxic agent. Allergic skin reactions are common in individuals who are sensitive to nickel. This article presents a selective review on nickel and its effect on certain metabolically active peripheral tissues of human and animals. The subtopics include nickel sources and uses, exposure pathways, transport, excretion, general health effects, and specific acute and chronic nickel toxicities in peripheral tissues like liver, lungs, and kidneys. The review particularly addresses the nickel-induced generation of reactive oxygen species and increased lipid peroxidation in various metabolically active tissues in humans and animals, and the possible role of vitamin c as a protective antioxidant.

Effect of l-ascorbic acid on antioxidant defense system in testes of albino rats exposed to nickel sulfate

We studied the effect of oral supplementation with L-ascorbic acid (50 mg/100 g body weight) on nickel sulfate (2.0 mg/100 g body weight, i.p.) induced lipid peroxidation in the testes of Wister strain male albino rats. Testicular lipid peroxide and glutathione (GSH) levels and the activities of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were estimated. Nickel sulfate treatment significantly increased the level of testicular lipid peroxide and decreased all antioxidant enzymes activities and GSH concentration. Simultaneously treatment of L-ascorbic acid exhibited a possible protective role on the toxic effect of nickel sulfate on testicular lipid peroxide and GSH concentration as well as antioxidant enzymatic defense system.

Protective role of l-ascorbic acid on antioxidant defense system in erythrocytes of albino rats exposed to nickel sulfate

In this experimental study, we investigated whether L-ascorbic acid has any influence on the blood antioxidant defense system, lipid peroxidation and hematological parameters of the albino rats exposed to nickel sulfate(NiSO4). Twenty four adult rats were divided into four groups of six animals in each group. The control rats were untreated and comprised Group I. Group II rats were administered nickel sulfate (2.0 mg/100 g b.wt.; intraperitonially, i.p.). Group II rats were treated orally L-ascorbic acid (50 mg/100 g b.wt.) and Group IV rats were given both nickel sulfate and L-ascorbic acid simultaneously on alternate days until the tenth dose. The hematological parameters were assessed: red blood corpuscle counts, packed cell volume %, hemoglobin concentration, white blood corpuscle counts and platelets count decreased significantly and clotting time increased significantly in nickel treated rats. We also observed increase malondialdehyde (MDA) and decrease glutathione level (GSH) in erythrocytes of nickel treated rats. The activities of erythrocyte antioxidant enzymes like superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) were significantly increased in rats treated with nickel sulfate. Simultaneously treatment of L-ascorbic acid exhibited a possible protective role on the toxic effect of nickel sulfate on the hematological values, erythrocyte MDA and GSH concentrations as well as antioxidant enzymatic defense system.

Effect of L-ascorbic acid on nickel-induced alterations in serum lipid profiles and liver histopathology in rats

Nickel exposure greatly depletes intracellular ascorbate and alters ascorbate-cholesterol metabolism. We studied the effect of the simultaneous oral treatment with L-ascorbic acid (50 mg/100 g body weight (BW) and nickel sulfate (2.0 mg/100 g BW, i.p) on nickelinduced changes in serum lipid profiles and liver histopathology. Nickel-treated rats showed a significant increase in serum low-density lipoprotein-cholesterol, total cholesterol, triglycerides, and a significant decrease in serum high-density lipoprotein-cholesterol. In the liver, nickel sulfate caused a loss of normal architecture, fatty changes, extensive vacuolization in hepatocytes, eccentric nuclei, and Kupffer cell hypertrophy. Simultaneous administration of L-ascorbic acid with nickel sulfate improved both the lipid profile and liver impairments when compared with rats receiving nickel sulfate only. The results indicate that L-ascorbic acid is beneficial in preventing nickel-induced lipid alterations and hepatocellular damage.

Oxidative stress due to nickel toxicity in the liver of protein-deficient rats

This study was designed to determine the oxidative stress induced by nickel sulfate in the liver in the protein-deficient rats. Nickel sulfate in the dose of 800 mg/L in drinking water was administrated to Sprauge Dawley (SD) rats as well as protein-deficient rats for a total duration of 8 weeks. The effects of nickel treatment and protein deficiency separately and in combination were studied on rat liver antioxidant defense system enzymes like catalase, glutathione peroxidase (GPX), glutathione reductase (GR), superoxide dismutase (SOD), reduced glutathione (GSH), and glutathione-S-transferase (GST), as well as on lipid peroxidation (LPO). The investigations revealed a significant increase in the activity of enzymes, which include catalase, Gpx, GR and GST, and in the levels with LPO following nickel treatment in combination with protein deficiency. On the contrary, feeding to control rats resulted in a significant depression in the levels of SOD and GSH. However, nickel treatment to normal rats caused a significant increase in the activity of enzymes catalase and GST and in the levels of LPO, whereas the levels of GSH get significantly depressed. Further, nickel treatment to protein-deficient rats did not cause any additional alteration in the status of liver antioxidants as were observed in conditions of protein deficiency.

The influence of ascorbic acid on nickel-induced hepatic lipid peroxidation in rats

We studied the effect of oral ascorbic acid treatment on nickel sulfate-induced lipid peroxidation in the liver of Wistar strain male albino rats. Lipid peroxide and glutathione levels and the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) were estimated in liver. Nickel sulfate administration significantly increased the level of lipid peroxides and decreased glutathione, SOD, CAT, and GSH-Px activities in liver. The simultaneous administration of ascorbic acid with nickel sulfate resulted in a remarkable improvement of lipid peroxide, glutathione, SOD, CAT, and GSH-Px status in liver in comparison with rats treated with nickel alone. Nickel sulfate has an adverse effect on hepatic lipid peroxidation in animals, but simultaneous treatment with ascorbic acid offers a relative protection against nickel-induced hepatotoxicity.