Seasonal variation of gut Cyanophyta contents and liver GST expression of mud carp (Cirrhina molitorella) and Nile tilapia (Oreochromis niloticus) in the tropical Xiangang Reservoir (Huizhou, China)

Effect of hexavalent chromium exposure on the liver and kidney tissues related to the expression of CYP450 and GST genes of Oreochromis niloticus fish: Role of curcumin supplemented diet

The present study evaluated the adverse effects of the hexavalent chromium (Cr (VI)) at sub-lethal concentrations and the ameliorative potential of curcumin (CUR) over a sub-chronic exposure period on Oreochromis niloticus. Fish were exposed to Cr (VI) (4.57 mg/L) and CUR (0.02% in diet or 200 mg/kg diet), individually or in combination for 60-days. The growth rate during the period of experiment, condition factor, body composition, hepatosomatic index (HSI), hematological parameters, oxidative stress, apoptotic and DNA damage, branchial, hepato- and nephrotoxicity were estimated in this study. Moreover, the changes in mRNA expression of Cytochromes (CYP450) and glutathione S-transferase (GST) in kidney and liver tissues were assessed by qRT-PCR. Additionally, the concentration of metallothionine in the liver, histological investigation, and lesion scoring to the branchial, hepatic, renal and gill tissues were applied. The results revealed that Cr (VI) exposure caused a significant decline in most hematological variables and growth rate with down-regulation of CYP450 and GST expression. Histologically, Cr (VI) induced diverse forms of cell injury, vascular, and inflammatory alterations with upregulation of caspase-3 and downregulation of Bcl₂ expression in the examined tissues. Additionally, it elevated the levels of serum MDA and 8-hydroxy-2' -deoxyguanosine than control. CUR-supplementation resulted in a significant improvement in most indices, amelioration of histological alterations and up-regulation of CYP450 and GST expression. These results may conclude that dietary supplements with CUR could be useful for modulation of the growth with protective effects to the branchial, hepatic, and renal tissues in response to Cr (VI) exposure, thereby presenting a promising feed additive for Nile tilapia in aquaculture.