Calcium Pre-Exposure Reducing Histopathological Alteration in Nile Tilapia (Oreochromis niloticus) After Lead Exposure.

Abstract

This study was evaluated the influence of calcium to reduce the loxicily of sublethal lead concentration in Nile tilapia with emphasis on histopathological analysis. The values of 24, 48, 72 and 96 h LC50of lead to tilapia were 247.51. 197.47. 183.74 and 182.38 mg L-1, respectively. Fish were pre-exposcd to vary dosages of calcium carbonate: 0 (Gl and G2); 20 (G3 and G4) and 60 (G5 and G6) mg L-1 for 4 days. After that, fish were post-exposed to 45 mg L-1 lead,which correspond to 25% of Ihe 96 h LC50 (G2, G4 and G6) for 96 h. Histopathological changes were especially most evident in the group (G2)exposed to lead without calcium pre-exposure. The gills were observed edema,lamellar cell hyperplasia, epithelial lifting, lamellar fusion and aneurysm. There were blood congestion in sinusoids, vacuolation of hepatocytes and necrosis. Glomerulus's atrophy, tubular swelling and also necrosis were seen. However,the only observable lesion in the muscle was the infiltration of inflammatory cells and there were no histopathological changes observed in ihe brain and intesline of Ihe lead trealed fish. Fish with pre-exposed calcium (G4 and G6)showed slightly alteration when compare the only lead treatment groups. The results suggested that calcium pre-exposure may play an important role in the reduction of lead loxicitv in fish.