Histopathological and enzymological studies on the effects of chronic lead nitrate intoxication in the digestive system of a freshwater teleost, Channa punctatus.

The effect of lead nitrate on the digestive system of a teleost fish, Channa punctatus has been studied after 125 days of exposure to a sublethal concentration (6.8 mg/liter). The results show that considerable degenerative changes are produced in the histological structure of liver, intestine, and pyloric caeca. In the liver, the damage is in the form of liver cord disarray, necrosis, inflammation of portal areas, hardening of connective tissue, shrinkage of nuclei, and septa formation around blood vessels. No fatty infiltration or glycogen depletion has been observed. Lipofuscin granules accumulated in the cytoplasm of hepatocytes. In the intestine and pyloric caeca flattening of villi at a number of places, inflammation, and necrosis are the most conspicuous changes. The activities of alkaline phosphatase and aminotripeptidase are inhibited in the liver. In stomach, alkaline phosphatase is inhibited but an elevation in amylase activity was noted. Acid phosphatase showed an increase in the intestine and pyloric caeca while aminotripeptidase and glycylglycine dipeptidase were inhibited.