Effect of Lead Graded Doses in Mactra Corallina Gills: Antioxidants Status, Cholinergic Function and Histopathological Studies

Lead is non-essential toxic metal used in the industrial process causes severe risk to aquatic organisms. This study aimed (aims) to evaluate the effect of Pb on oxidative stress in gills of Mactra corallina. During the experiment, bivalves were randomly divided into four groups, control served as control and D1, D2 and D3 groups were exposed to Pb graded doses (1mg/L, 2.5mg/L and 5mg/L) during 5 days, respectively. Pb accumulation was significantly increased in all treated gills with doses dependent manner. The exposure of M. corallina to PbCl2 promoted oxidative stress in gills with an increase in malondialdehyde (MDA) and in metallothionein (MTs) levels. Moreover, a decline in glutathione (GSH), non-protein–SH (NPSH) and ascorbic acid (Vit C) levels were detected in all treated groups. Thus, alterations of enzymatic antioxidants systems were confirmed by a significant increase of catalase (CAT) and decreases of glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities in doses dependent manner. The cholinergic function was confirmed by a significant decrease of acetylcholinesterase (AChE) activity in the highest exposure dose. The impairment of the gill function was confirmed by the histological study