Distribution of nickel in body fluids and organs of rats chronically exposed to nickel sulphate

Nickel chloride induces anticancer biological responses in hepatocellular carcinoma cell lines

Nickel has long been known to have a toxic effect in humans and has been defined as a human carcinogen. However, recent studies have suggested that nickel chloride (NiCl₂) may also possess anticancer properties. The liver is one of the target organs for nickel, and thus, the present study aims to evaluate the effect of NiCl₂ on anticancer biological responses in hepatocellular carcinoma (HCC) cell lines. Both HuH-7, a well-differentiated HCC cell line, and Mahlavu cell line, a poorly differentiated HCC cell line, were exposed to NiCl₂. It was determined that NiCl₂ decreased cell viability in both cell lines in a dose- and time-dependent manner. Nickel chloride exposure at IC50 doses were observed to suppress the ability of HCC cells to produce colonies and also induce apoptosis of HCC cells by increasing Cleaved Caspase-3 protein levels. It was found that NiCl₂ exposure affected cellular morphology, increased the LC3-II protein levels, and induced autophagy in parallel to increased apoptosis in HCC cells. It was also observed that NiCl₂ suppressed cell migration, decreased the size and viability of HCC tumor spheroids generated in 3D cell cultures, and disrupted the spheroid structure of the tumor cells depending on E-cadherin expression levels. Furthermore, it was observed that all anticancer biological responses induced by NiCl₂ occurred independently of the AKT signaling pathway. In conclusion, our results suggested that NiCl₂ induced anticancer biological responses in HCC cell lines. Moreover, this study provided important new molecular and cellular biological basic data about the action mechanisms of NiCl₂ in HCC.

Vitamin C pretreatment protects from nickel-induced acute nephrotoxicity in mice

Nickel is an abundant carcinogenic and nephrotoxic metal whose activity leads to renal impairment. Previous studies have shown a protective effect of simultaneous vitamin C administration on acute and chronic nickel toxicity. However, very little research relating to the effect of vitamin C pretreatment in preventing nickel-induced acute nephrotoxicity is available. Therefore, the present study aimed to determine the efficiency of vitamin C (VC) pretreatment in preventing acute renal toxicity of nickel. Mice were pretreated orally with vitamin C (16.6 mg kg-1 body weight, b.w.) for seven consecutive days, prior to intraperitoneal (i.p.) administration of nickel chloride at different doses (3, 5, and 10 mg Ni kg-1 b.w.) for an exposure period of 24 hours. Thereafter, animals were killed and kidney tissue and blood samples were taken for histological examination and biochemical marker analyses. Vitamin C pretreatment alone did not alter the levels of serum kidney markers (creatinine, urea, and uric acid). However, treatment with Ni alone showed a significant increase in the levels of serum creatinine, urea, and uric acid with marked necrotic epithelial cells and infiltration by inflammatory cells in kidney sections as compared to the control group. Pretreatment with vitamin C and treatment with Ni at all doses tested for 24 hours showed a significant decrease in the levels of serum creatinine, urea, and uric acid, as well as an improvement in histological changes compared to those previously seen in the group treated with Ni alone. It is concluded that vitamin C pretreatment effectively improved renal function and tissue damage caused by nickel.

Urinary nickel: measurement of exposure by inductively coupled plasma argon emission spectrometry

Nickel is a rare earth metal and is widely used in modern industry. Its overexposure in human beings can provoke significant effects including lung, cardiovascular and kidney diseases. As an index of occupational exposure, urine is widely used for the monitoring of nickel concentration because it is a minimally invasive method. Recent studies have used atomic absorption spectrometry to measure nickel concentration. In this study, we introduced novel inductively coupled plasma argon emission spectrometry (ICPAES) which enables us to measure multiple elements simultaneously with smaller volume and with lower detection limits compared to conventional atomic absorption emission spectrometry, and we established the new measuring method by determining the appropriate wavelengths for nickel concentration. Furthermore, using the established new measuring method, we investigated the correlation between a single oral administration of nickel and urine elimination in rats. As a result, different concentrations of nickel standard solutions were measured by ICPAES, and among five specific wavelengths of nickel, 221.647 and 231.604 nm were chosen because they had the highest inclines of both signal to background ratio and emission intensity in simple linear regression analysis. Next, by using healthy human urine samples that had not been exposed to nickel, 231.604 nm was determined to be the most appropriate wavelength because it did not present abnormal intensity due to obstacle wavelength. Male Wistar rats received an oral administration of nickel ranging from 0.025 to 250 mg/kg, which is equivalent to 0.0015-15% of LD50, and during the following 24 h, urine samples were collected and the nickel concentration was measured by ICPAES. With a single oral administration of nickel, there was an increase in urine nickel concentration in a dose-dependent manner and the appropriate equation was developed. Acute renal failure was not observed in this dosage of oral nickel administration by analysing NAG, b2-microglobulin, urine albumin and urine protein. It was concluded that the obtained nickel reference values using ICPAES would be useful for the early diagnosis of nickel intoxication and in the assessment of the exposure to nickel.

Nickel-induced structural and functional alterations in porcine granulosa cells in vitro

The present study was aimed at investigating the effect of nickel chloride (NiCl2) on secretion of progesterone (P), ultrastructure and apoptosis in porcine granulosa cells. NiCl2 was added to the cells to achieve a Ni(2+) concentration of 62.5, 125, 250, 500 and 1,000 μmol/L. A control group contained no NiCl2 addition. Quantification of P was performed directly from aliquots of the media from control and treated porcine granulosa cells after 48 h of culture using radioimmunoassay. Quantification of apoptotic cells was performed using terminal deoxynucleotidyl transferase dUTP nick end labelling assay, and ultrastructural changes were analyzed using transmission electron microscopy. A concentration-dependent depletion of P production was observed significantly for 1,000 μmol/L NiCl2. The percentage of apoptotic cells was increased in all experimental groups significantly only after addition of 1,000 μmol/L NiCl2. After addition of ≥250 μmol/L NiCl2, a higher incidence of euchromatin was observed. Also, lipid droplets and vacuoles in the cytoplasm increased after addition of ≥250 μmol/L NiCl2. NiCl2 induced the decrease in numbers of mitochondria and smooth endoplasmic reticulum after treatment with ≥500 μmol/L NiCl2. Our findings suggest a negative effect of NiCl2 on steroidogenesis and apoptosis as well as ultrastructure of porcine granulosa cells.

Binding of nickel to testicular glutamate-ammonia ligase inhibits its enzymatic activity

Exposure to nickel has been shown to cause damage to the testis in several animal models. It is not known if the testis expresses protein(s) that can bind nickel. To test this, we used a nickel-binding assay to isolate testicular nickel-binding proteins. We identified glutamate-ammonia ligase (GLUL) as a prominent nickel-binding protein by mass spectrometry. Protein analysis and reverse transcriptase polymerase chain reaction showed that GLUL is expressed in the testis, predominantly in interstitial cells. We determined that GLUL has a higher affinity for nickel than for its regular co-factor manganese. We produced an enzymatically active, recombinant GLUL protein. Upon binding, nickel interferes with the manganese-catalyzed enzymatic activity of recombinant GLUL protein. We also determined that GLUL activity in testes of animals exposed to nickel sulfate is reduced. Our results identify testicular GLUL as the first testicular protein shown to be affected by nickel exposure.

Nickel-induced blood biochemistry alterations in hens after an experimental peroral administration

The purpose of this study was to determine certain blood biochemical parameters in hens of Isa Brown breed (n = 20) after nickel administration. Animals were divided into four groups (K, P1, P2, P3). Experimental hens (n = 5; in each group) received nickel (NiCl2) as peroral administration in drinking water in various doses (P1 - 0.02 g NiCl2/L; P2 - 0.2 g NiCl2/L; P3 - 2.0 g NiCl2/L of drinking water) for 28 days. The last group - K (n = 5) was the control, receiving no nickel. Biochemical parameters of mineral profile (calcium; phosphorus; magnesium; sodium; potassium) and of energy and enzymatic profile [(glucose; total cholesterol; total proteins; triglycerides; alanine aminotransferase (ALT) aspartate aminotransferase (AST) gamma glutamyl transferase (GGT) and glutamatdehydrogenase (GLDH)] were analyzed in blood serum on Day 0, 7, 14, 21 and 28 of the experiment. Average levels of mineral metabolism parameters were relatively stable apart from calcium. The evaluation registered a significant decrease in calcium during the experiment mainly in the group with highest nickel concentration in drinking water. No significant differences were detected between groups in energy and enzymatic profile apart from the concentrations of ALT on Day 7. In conclusion, there were significant associations between nickel levels and calcium and ALT in blood serum of the hens. No significant differences were detected in other biochemical parameters of mineral profile (P, Mg, Na, K) and energy and enzymatic profile (glucose, total cholesterol, total proteins, triglycerides, AST, GGT and GLDH) after nickel administration. Our results may contribute to an evaluation of reference levels of analyzed parameters, to monitor the health and nutritional status of hens. In this study also the negative effect of nickel mainly on calcium metabolism was detected.