The Effect of Vitamin E and Metallothionein on the Antioxidant Capacities of Cadmium-Damaged Liver in Grass Carp Ctenopharyngodon idellus

Cadmium induced bioaccumulation, histopathology, gene regulation in fish and its amelioration - A review

Different anthropogenic activities as well as natural sources contribute enormously towards various heavy metal contaminations in aquatic habitats. Cadmium (Cd) is one of most prevalent and toxic heavy metals with a long half life. Unlike terrestrial animals, exposure of Cd in fishes may happen not only through feeds but also from its habitat water. Bioaccumulation of Cd in fishes occurs in many tissues, but mainly in gill, liver, kidney, skin, and muscle. The concentrations of Cd in fish tissues depend upon the extent and duration of Cd exposure, species and age of fishes, dietary minerals and antioxidant concentrations, and habitat water quality. Specific histopathological observations in liver, kidney, and gill are useful to understand the effects of Cd, which could help to determine the ameliorating methods to be adopted. Exposure of Cd exerts several adverse effects on general growth and development, reproductive processes, osmoregulation, morphological and histological structures, stress tolerance, and endocrine system, mainly due to changes in biological functions induced by differential expressions of several genes related to oxidative stress, apoptosis, inflammation, immunosuppressions, genotoxicity, Cd chelation and carbohydrate metabolism. Chronic biomagnifications of Cd exceeding the permitted level may be harmful not only to the fishes itself but also to humans through food chains. Amelioration of such toxic heavy metal that has been categorized as a potent carcinogenic in humans is of utmost importance. Main modes of amelioration encompas reducing oxidative damages by promoting the antioxidative defenses, decreasing Cd absorption, increasing excretion through excretory system and improving the tolerance of fishes to Cd toxicity. Many amelioration measures such as use of minerals (for example, zinc, calcium, and iron), vitamins (vitamin C, A, and E), different herbs, probiotics and other agents (taurine, bentonite, chitosan, zeolite, and metallothionein) have been explored for their effective roles to reduce Cd bioaccumulation and toxicity symptoms in fishes. The present review discusses bioaccumulation of Cd, histopathological alterations, oxidative stress, synergism-antagonism, and gene regulation in different tissues, and its amelioration measures in fishes.

Ameliorative Effects of Vitamins A, C, and E on Sperm Parameters, Testis Histopathology, and Oxidative Stress Status in Zinc Oxide Nanoparticle-Treated Rats

One of the most often utilized nanoparticles (NPs) in several technologies is zinc oxide (ZnO) NPs. However, these NPs are said to have harmful effects on the reproductive system. Thus, we designed this study to specify the potential preventive activity of vitamins (Vits) A, C, and E, as antioxidants, against toxicity of ZnO NPs in the testes of rats. A total of 54 Wistar rats were arranged in 9 groups of 6 and then orally received water (control 1), olive oil (control 2), Vit A (1000 IU/kg), Vit C (200 mg/kg), Vit E (100 IU/kg), ZnO (200 mg/kg), ZnO+Vit A, ZnO+Vit C, and ZnO+Vit E. To determine the amount of testicular injury, sperm analysis and histological evaluation were performed. In addition, oxidative stress status was examined using colorimetric and qRT-PCR methods. Our findings suggest that ZnO NPs cause adverse effects on sperm parameters and testicular histology. Furthermore, oxidative biomarkers (malondialdehyde and total oxidant capacity) were enhanced in the ZnO group. By contrast, the gene expression and activities of antioxidant enzymes (SOD, GPx, and CAT) noted a remarkable decrease in the ZnO group regarding control (p < 0.05). However, oxidative markers were remarkably mitigated after combined treatment of ZnO NPs and Vits A, C, or E compared to the rats given ZnO NPs (p < 0.05). Additionally, compared to the ZnO NP group, the rats receiving Vits+ZnO NPs exhibit increased antioxidant enzyme activity and mRNA expression (p < 0.05). The findings demonstrate the abovementioned Vits' ameliorative effects on toxicity incurred by ZnO NPs.

The role of well-known antioxidant vitamins in the prevention of cadmium-induced toxicity

Long-term exposure to cadmium (Cd) leads to the development of a number of conditions associated with liver and kidney damage, reproductive and cardiovascular disorders, in addition to visual impairment, blindness and hearing loss, among others. Cadmium has been classified as a human carcinogen by the International Agency for Research on Cancer. The toxicity of Cd is related to its pro-oxidant properties and the associated increase in oxidative stress. Antioxidant ingredients may be helpful in preventing the adverse effects of Cd. The effect of well-known antioxidant vitamins (E, C, A and β-carotene) in the prevention of Cd-induced toxicity is presented in this study. Numerous studies in animal models have shown that the effects of vitamins: E, C, A, and β-carotene were effective in reducing Cd concentrations in organs and tissues and reduced Cd-induced changes in liver, kidney, and reproductive, circulatory, nervous, immune, and respiratory systems. In contrast, the limited number of human studies does not allow to accurately determine the role of these nutrients in reducing Cd-induced toxicity, indicating the need for further studies clarifying the role of antioxidant vitamins in reducing Cd-induced toxicity. However, it seems reasonable to promote the consumption of natural food products that are sources of antioxidant vitamins in groups of people with occupational and environmental exposure to Cd. Int J Occup Med Environ Health. 2022;35(4):367-92.

Transcription profiling of cadmium-exposed livers reveals alteration of lipid metabolism and predisposition to hepatic steatosis

1. Cadmium (Cd) is a ubiquitous environmental toxicant that can cause liver steatosis and nonalcoholic fatty liver disease (NAFLD) on long-term exposure.2. Sixteen Sprague Dawley rats were randomly divided into two groups, and were administered normal saline and 5 mg/(kg·d) cadmium chloride by gavage. In vitro, BRL3A cells, a rat normal liver cell line, were treated with different concentrations of Cd to verify the sequencing results.3. The RNA-seq revealed 146 upregulated genes and 127 downregulated genes in the Cd intervention group. The key genes of lipid metabolism were significantly overexpressed, such as Cyp1a1 and Pla2g2d. The GO enrichment analysis showed that the 'sterol biosynthetic process' was the most obvious difference. The KEGG analysis showed that six of the top 10 differential pathways were related to lipid metabolism. The expression of the essential genes in BRL3A was consistent with the sequencing results. The protein-protein interaction (PPI) yielded that Cyp1a1 is in the central region of the differentially expressed gene network.4. The chronic Cd exposure is still an important environmental health problem with a probable tendency to cause NAFLD. It may possibly act by affecting the lipid metabolism in the liver, especially the synthesis and decomposition of unsaturated fatty acids.