The ability of vitamin E, selenium and water to improve and recover the hematological, biochemical and hormonal parameters of mercury-exposed catfish Clarias gariepinus (Burchell, 1822)

This study aimed to determine the toxic impacts of a sublethal dose of mercury chloride (0.10 mg/L for 30 days as exposure period) on hematological, biochemical parameters and thyroid hormones (T3 and T4) of the African catfish, Clarias gariepinus, and to evaluate the ability of vitamin E, selenium and water to improve and recover the previous parameters in mercury-treated fish (for 15 and 30 days as recovery periods). The exposure to mercury caused a significant (p<0.05) decrease in RBCs, Hb, Ht, MCH, MCHC, MCV, WBCs, lymphocytes, monocytes, neutrophils, potassium, albumin, Alb/glob ratio, triglycerides, glucose and thyroid hormones (T3 and T4) when compared with the control group. Also, exposure to mercury caused a significant increase (p<0.05) in levels of Na, urea, creatinine, ALP, AST, ALT, total proteins and globulins levels than those of the control fish. The ability of vitamin E and selenium to improve and recover the hematological and biochemical parameters and thyroid hormones (T3 and T4) studied were better than water alone. Also, the improvement was mostly better after 30 days than 15 days of recovering period. The recovery with water alone led to complete recovery only in MCHC. While, all the remaining of hematological parameters studied in addition to cholesterol and glucose levels are improved significantly (increased/decreased) to be relatively better than those of the mercury-treated fish. The levels of urea, creatinine, ALP, AST, ALT, TP, albumin, globulins and Alb/glob ratio, T3 and T4 are not improved well by the water. But, Na levels is not affected by the water. The levels of K and triglycerides are increased to high levels than that of the control fish. The recovery with vitamin E led to complete recovery in Hb, MCV, MCH, MCHC and Na to reach the control level (p<0.05); and significantly (p<0.05) improved RBCs, Hct, WBCs, neutrophils, lymphocytes and monocytes, urea, creatinine, ALP, AST, globulin, Alb/glob ratio, cholesterol, triglycerides and glucose to be better than those of the mercury-treated fish. K and albumin levels are fluctuated. While ALT, TP decreased significantly. But, T3 and T4 are not improved well by Vitamin E. The recovery with selenium led to complete recovery in MCH, neutrophils, lymphocytes, total proteins and globulins levels (p<0.05); and significantly helped improvement (increased/decreased) of RBCs, Hb, Hct, WBCs, monocytes, urea, creatinine, ALP, AST, ALT, Alb/glob ratio, cholesterol, triglycerides, glucose, T3 and T4 to be better than those of the mercury-treated fish. But, Na, and albumin are not improved well by selenium. Potassium levels showed fluctuations. ALT and TP decreased significantly to be less than that of the control values. Also, it was noted that, the improvement of T3 and T4 due to Selenium (Se) are better than vitamin E than the mercury-free water respectively.