EVALUATION OF BIOMOLECULAR INDICES OF STRESS IN CADMIUM AND HIBISCUS SABDARIFFA CALYX EXTRACT-EXPOSED AFRICAN CATFISH (Clarias gariepinus)

Abstract

Stress inducing abilities of cadmium (Cd) and possibly too of Hibiscus sabdariffa calyx aqueos extract (HSCE) in the African catfish have been examined based on the levels of three biomolecules in the blood, brain and heart. The bimolecules used as stress indices are total cholesterol (TC), triacylglycerol (TAG) and malondialdehyde (MDA). Forty catfishes divided into four experimental groups of not less than six fishes each were used for this study. Fishes in group A, the control, were Cd and HSCE-free. Group B, no Cd but exposed to HSCE (0.25% v/v). Group C, exposed to Cd (0.3 mg/l) but no HSCE. Group D, exposed to Cd (0.3 mg/l) and HSCE (0.25% v/v). The treatments were carried out for 14 days. When compared to the control, Cd alone, caused significant (p0.05) increases in serum MDA, TC and TAG levels; increase in brain MDA as well as increases in heart MDA and TAG. Relative to the Cd only group catfishes exposed to Cd and HSCE had significantly (p<0.5) reduced serum MDA, TC and TAG; brain MDA, as well as heart MDA and TC. Catalase activities were significantly (p0.05) increased in sera of HSCE only and Cd +HSCE groups relative to the control. SOD activities in the serum were significantly (p0.05) decreased in all three groups relative to the control. Catalase activities in the heart followed the same pattern found in the serum but its SOD activities were significantly (p0.05) reduced in HSCE only and Cd + HSCE groups compared to the control. These findings indicate that Cd can cause general physiological stress (evidenced by increaseD serum, brain and heart TC and TAG) and oxidative stress (evidenced by increased serum, brain and heart MDA) in the African catfish and that HSCE counteracts the Cd-induced stress