Effects of cadmium and polychlorinated biphenyls (Clophen A50) on steroid metabolism and cytochrome P-450 monooxygenase system in the sea star Asterias rubens L

Abstract

A study was made on the effects of long-term cadmium or PCB exposure on the steroid metabolism and the cytochrome P-450 monooxygenase system of the sea star Asterias rubens. Sea stars were exposed to 25 μg/l cadmium or fed with PCB (Clophen A50)-exposed mussels containing 26 μg σ 8-PCBs/g lipid, which was six times higher than the PCB levels in control mussels. Twelve weeks of exposure resulted in cadmium and PCB levels in the pyloric caeca which were comparable to those found in sea stars collected from the Western Scheldt (SW Netherlands) or in animals that had been fed with mussels from this heavily polluted estuary. Cadmium and PCB exposure caused significant reductions in the levels of progesterone and testosterone in the pyloric caeca of male and female sea stars. Steroid levels in the gonads had not changed after cadmium exposure, whereas after twelve weeks of PCB exposure elevated levels of testosterone were found in testes and ovaries. Both cadmium and PCBs caused a decrease in the content of cytochrome P-450 and cytochrome b 5 in pyloric caeca musomes. Benzo[ a]pyrene hydroxylase activity was elevated by PCB exposure but had not changed after exposure to cadmium. Microsomal NADPH-cytochrome c reductase and steroid conversion activities were not significantly influenced by cadmium or PCB exposure, although a slight reduction of steroid metabolism was observed.