Evaluation of Respiratory Toxicity Potential of Acrylamide in Zebrafish: Oxidative Stress Parameters, mRNAs Expression, and Histomorphological Changes in Gills

Anthropogenic contamination of surface water by chemicals is a worldwide concern, which affects human health and aquatic organisms including fish. Acrylamide (ACR), a Neo-Formed Contaminants (NFC) leads to serious toxic effects on the respiratory system of marine inhabitants. The mechanisms underlying ACR-induced oxidative stress and altered mRNA expressions in zebrafish are unclear. The present investigation aimed to evaluate the effects of ACR exposure for 28 days on the activity or level of antioxidant response elements (ARE), mRNA expressions of antioxidant genes and histomorphological changes in the gills of adult zebrafish. The 270 adult zebrafish were randomly allocated into 03 experimental groups viz. control group, T1 group (ACR: 8.5 mg/L) and T2 group (ACR: 17 mg/L). After 28 days of ACR exposure, Superoxide Dismutase (SOD) activity was significantly (p<0.01) decreased in the gills of zebrafish of the T2 group; and no change in Catalase (CAT) activity was observed in both the treatment groups. The levels of reduced Glutathione (GSH) were significantly (p<0.001) decreased and Malondialdehyde (MDA) were significantly (p<0.001) increased in a concentration-dependent manner. The sod and nuclear factor erythroid 2-related factor 2 (nrf2) mRNA expressions were significantly (p<0.001) downregulated in the gills of zebrafish of both treatment groups. Noticeable histomorphological alterations were recorded in the gills of zebrafish of the T2 group. Alterations in ARE activity, mRNA expressions of antioxidant genes and histopathological findings suggest ACR exposure has been shown to produce oxidative stress-mediated damage in the gills of adult zebrafish.