Objective: This study was conducted to evaluate the influence of pollution with lead, copper, cadmium on the gene expression pattern of liver Glutathione-S-transferase and serum lysozyme in Nile tilapia (Oreochromis. niloticus).
Design: Descriptive study.
Fish: A Total of 120 Nile tilapia fish (Oreochromis niloticus) samples were collected from Lake Manzala, and drainage water at different localities.
Procedures: lead, copper and cadmium concentrations within mid-dorsal muscle tissue, within gills, liver, and kidney were determined. Erythrocyte count, hemoglobin concentration, Packed Cell volume and other blood indices, as well as, total leukocyte count were measured. Biochemically, Alanine transaminase, Aspartate transaminase activities, total protein, creatinine, uric acid, lysozymes activity were estimated. GST gene expression was determined in the liver.
Results: The results showed that Pb, Cu and Cd were bio accumulated at a higher level in the liver, kidney and gills of Nile tilapia fish (Oreochromis niloticus) from all sampling sites. The activities of ALT and AST were increased significantly (p < 0.05), but total protein and Albumin concentrations were decreased. Creatinine and uric acid were significantly increased in all groups compared to the control group (P≤ 0.05). Hematological parameters and lysozyme activity were decreased. Up regulation of the hepatic GST expression levels in Nile tilapia exposed to the heavy metals in comparison to the control value.
Conclusion and clinical relevance: This study shows that lead, copper and cadmium were bio accumulated at higher concentration in liver, kidney, gills and muscles of Nile tilapia due to large industrial activities near locations of the sampling sites. Additionally, GST gene expression represents sensitive biomarker of aquatic pollution.