Functional aspects of cadmium and selenium interactions in insect digestive tract. Enzyme studies

Effects of cadmium and selenium on some digestive and cytoplasmic enzymes activities in midgut of the cockroach ( gromphadorhina portentosa) were evaluated after 7 weeks of intoxication. Activities of digestive enzymes were insignificantly lower in groups reared on food suplemented with cadmium (0.4 μmol Cd/g dry food) or selenium (0.01 μmol Se/g dry food). Significant differences relative to control groups were stated only in males, in the cases of α-amylase, cellobiase, sucrase and α-galactosidase. Activities of aminotransferases were significantly lower, when compared to control, only in females from Cd and Se groups. Alkaline phosphatase activity was very low or not detected in all examined groups, while that of acid phosphatase was lower in Cd and Cd + Se (0.4 μmol Cd + 0.01 μmol Se/g dry food) groups in comparison to control. Also, activity of carboxylesterase was significantly lower after Cd or Se intoxication. There were no differences, both in males and females, in this enzyme activity between control and Cd + Se groups. The results confirmed toxic effects of cadmium on enzymatic activity of the digestive tract in the cockroach, but they also indicated toxicity of selenium at the given dose. Simultaneous administration of cadmium and selenium reduced toxic effects exerted by these elements given separately.