Influence of cadmium exposure on plasma calcium, vitellogenin and calcitonin in vitellogenic rainbow trout |
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| Authors: | C Haux BTh Bjrnsson L Frlin Larsson LJ Deftos |
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| Institution: | C. Haux, B.Th. Björnsson, L. Förlin, Å. Larsson,L.J. Deftos |
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| Abstract: | Effects of cadmium exposure on plasma levels of calcitonin and free and protein-bound calcium were studied in vitellogenic female rainbow trout kept in brackish water (7%(.)). Fish were exposed to 100 μg cadmium litre−1 for four weeks. Exposure of female rainbow trout in the stage of vitellogenesis, with increased total plasma levels of calcium, resulted in a complex hypocalcemic response. Thus, hypocalcemia was found to be due to three different processes: (1) a decrease in the free plasma calcium, and a reduction in protein-bound calcium; due both to (2) decreased plasma levels of vitellogenin; and (3) a reduced binding of calcium to vitellogenin. These findings support the concept of an interference of cadmium with ionregulating tissues as a mechanism for hypocalcemia in rainbow trout. A direct effect on the vitellogenin-binding of calcium was also observed and reproductive function in the females was affected by decreased plasma levels of vitellogenin. In spite of the marked changes of plasma calcium in exposed fish, no significant effects on plasma calcitonin were observed, indicating a lack of a direct relationship between plasma calcium and calcitonin levels in rainbow trout. |
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