Effects of chemical and thermal stress on acetylcholinesterase activity in the brain of the bank vole, Myodes glareolus

Synergistic effect of nickel and temperature on gene expression, multiple stress markers, and depuration: an acute toxicity in fish

Aquatic animals are prone to extinction due to metal pollution and global climate change. Even though the fish and their products are also unsafe for human consumption, their exports have been rejected due to inorganic and organic contaminants. Nickel (Ni) is a metal that induces toxicity and accumulates in the aquatic ecosystem, posing health threats to humans, animals, and fish. In light of the above, our present investigation aimed to determine the median lethal concentration (96 h-LC50) of nickel alone and concurrent with high temperature (34 °C) (Ni + T) using static non-renewable bioassay toxicity test in Pangasianodon hypophthalmus. The groups treated under exposure to Ni reared under control condition (25-28.9 °C) and Ni + T exposure group reread under 34 °C. In this study, chose the definitive dose of Ni and Ni + T as 17, 18, 19, and 20 mg L-1 after the range finding test. The median lethal concentration of Ni and Ni + T was determined as 19.38 and 18.75 mg L-1, respectively at 96 h. Oxidative stress viz. catalase (CAT), superoxide dismutase (SOD), glutathione-s-transferase (GST), and glutathione peroxidase (GPx) in the liver, gill, and kidney were noticeably elevated with Ni and Ni + T during 96 h. Whereas, the CAT, GPx, and SOD gene expressions were significantly upregulated with Ni and Ni + T. Trilox equivalent anti-oxidant capacity (TEAC), cupric reducing anti-oxidant capacity (CUPRIC), ferric reducing ability of plasma (FRAP), ethoxy resorufin-O-deethylase (EROD), and acetylcholine esterase (AChE) were reduced due to exposure to Ni and Ni + T. Cellular metabolic stress and lipid peroxidation were highly affected due to Ni and Ni + T exposure. The immunological status, as indicated by total protein, albumin, globulin, A:G ratio, and nitro blue tetrazolium chloride (NBT), was severely affected by the toxicity of Ni and Ni + T. Moreover, the gene expression of interleukin (IL), tumor necrosis factor (TNFα), toll-like receptor (TLR), and total immunoglobulin (Ig) was remarkably downregulated following exposure to Ni and Ni + T. HSP 70, iNOS expression, ATPase, Na + /K + -ATPase, cortisol, and blood glucose was significantly elevated with Ni and Ni + T in P. hypophthalmus. The bioaccumulation of Ni in fish tissues and experimental water was determined. The kidney and liver tissues were highly accumulated with Ni, whereas DNA damage was reported in gill tissue. Interestingly, depuration study revealed that at the 28th day, the Ni bioaccumulation was below the maximum residue limit (MRL) level. Therefore, the present study revealed that Ni and Ni + T led to dysfunctional gene and metabolic regulation affecting physiology and genotoxicity. The bioaccumulation and depuration results also indicate higher residual occurrence of Ni in water and aquatic organisms for longer periods.

Effect of Chronic Administration of Nickel on Affective and Cognitive Behavior in Male and Female Rats: Possible Implication of Oxidative Stress Pathway

Nickel (Ni) toxicity has been reported to produce biochemical and behavioral dysfunction. The present study was undertaken to examine whether Ni chronic administration can induce alterations of affective and cognitive behavior and oxidative stress in male and female rats. Twenty-four rats, for each gender, divided into control and three test groups (n = 6), were injected intraperitoneally with saline (0.9% NaCl) or NiCl2 (0.25 mg/kg, 0.5 mg/kg and 1 mg/kg) for 8 weeks. After treatment period, animals were tested in the open-field, elevated plus maze tests for anxiety-like behavior, and forced swimming test for depression-like behavior. The Morris Water Maze was used to evaluate the spatial learning and memory. The hippocampus of each animal was taken for biochemical examination. The results showed that Ni administration dose dependently increased anxiety-like behavior in both tests. A significant increase in depression-like symptoms was also exhibited by Ni treated rats. In the Morris Water Maze test, the spatial learning and memory were significantly impaired just in males treated with 1 mg/kg of Ni. With regard to biochemical analysis, activity of catalase (CAT) and superoxide dismutase (SOD) were significantly decreased, while the levels of nitric oxide (NO) and lipid peroxidation (LPO) in the hippocampus were significantly increased in the Ni-treated groups. Consequently, chronic Ni administration induced behavioral and biochemical dysfunctions.

Neurotoxic effects, molecular responses and oxidative stress biomarkers in Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) exposed to verapamil

Pharmaceutical drugs and their metabolites are detected in aquatic ecosystems and have been reported to cause ecotoxicological consequences to resident aquatic organisms. The study investigated the effects of acute and long-term exposure to verapamil on activities of acetylcholinesterase and antioxidant enzymes as well as mRNA expression of stress-related genes in brain and muscle tissues of Nile tilapia, Oreochromis niloticus. The 96h LC₅₀ of verapamil to O. niloticus was 2.29mgL^-1. Exposure to sub-lethal concentrations of verapamil (0.14, 0.29 and 0.57mgL^-1) for period of 15, 30, 45 and 60days, led to inhibition of acetylcholinesterase activities in the brain and muscle of the fish. The activities of the oxidative enzymes such as the catalase, superoxide dismutase and glutathione peroxidase were also inhibited in both the tissues while there was an increase in the activities of glutathione-S-transferase and reduced glutathione in the muscle after 15 days at 0.29mgL^-1. Lipid peroxidation and carbonyl protein showed elevated level, indicating a positive correlation with both time and concentration. The activities of energy-related biomarker (Na⁺-K⁺-ATPase) in both the tissues were significantly inhibited (p<0.05) compared with the control. Transcription of catalase (cat), superoxide dismutase (sod) and heat shock proteins 70 (hsp70) were up-regulated in both the tissues after the study period. Prolonged exposure to sub-lethal verapamil can result in oxidative stress, up-regulation of stress-related genes and neurotoxicity in O. niloticus.

Modification of nickel accumulation in the tissues of the bank vole Myodes glareolus by chemical and environmental factors

In a full factorial laboratory experiment, the effects of temperature and two chemical stressors (nickel and chlorpyrifos) on the accumulation of nickel in the liver and kidney of bank voles were studied. The nine-week experiment consisted of three periods: acclimatisation (3 days), intoxication (6 weeks) and elimination (3 weeks). During the main intoxication phase the animals were orally exposed for 42 days to different doses of nickel (Ni) (0, 300 and 800mg/kg food) or chlorpyrifos (CPF) (0, 50 and 350mg/kg food) or a mixture of both chemicals. Additionally, animals from each chemical treatment were divided into subgroups assigned to three temperatures: 10, 20 or 30°C. The highest concentrations of nickel were found in the testis, but there were no statistical effects of studied factors on this tissue. The nickel concentrations were higher in the kidney than in the liver of the bank voles. Nickel levels in the livers were influenced by Ni concentration in the food during intoxication time and additionally by interactions between Ni, temperature and day of exposure during elimination. The kidney concentrations of nickel depended on the level of nickel exposure but also on the interactions of the nickel with other factors: temperature, chlorpyrifos, day of exposure. This influence was observed only during the intoxication phase. The body mass and liver and kidney masses of the animals were affected both by the nickel concentration in the food and by the temperature.

THE CAPSULE ABSTRACT

Ni in the tissues depended on the interactions between the factors: Ni, temperature and other. The body, liver and kidney masses were affected by both Ni in the food and by the temperature.

Neurotoxic effects of nickel chloride in the rainbow trout brain: Assessment of c-Fos activity, antioxidant responses, acetylcholinesterase activity, and histopathological changes

The aim of this study was to determine the biochemical, immunohistochemical, and histopathological effects of nickel chloride (Ni) in the rainbow trout brain. Fish were exposed to Ni concentrations (1 mg/L and 2 mg/L) for 21 days. At the end of the experimental period, brain tissues were taken from all fish for c-Fos activity and histopathological examination and determination of acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT) enzyme activities, lipid peroxidation (LPO), and glutathione (GSH) levels. Our results showed that Ni treatment caused a significant increase in the brain SOD activity and in LPO and GSH levels (p < 0.05), but it significantly decreased AChE and CAT enzyme activities (p < 0.05). Strong induction in c-Fos was observed in some cerebral and cerebellar regions of fish exposed to Ni concentrations when compared with the control group. However, c-Fos activity was decreased in necrotic Purkinje cells. Brain tissues were characterized by demyelination and necrotic changes. These results suggested that Ni treatment causes oxidative stress, changes in c-Fos activity, and histopathological damage in the fish brain.