Calcium Homeostasis in Low and High Calcium Water Acclimatized Oreochromis Mossambicus Exposed to Ambient and Dietary Cadmium
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Date
2007
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Abstract
The effects of cadmium administered via ambient water (10 µg/l) or food (10 µgCd/fish/day) on plasma calcium, corpuscles of Stannius
and bony tissues of Oreochromis mossambicus acclimated to low calcium (0.2 mM) and high calcium (0.8 mM) water were studied for 2, 4, 14 and
35 days. In low calcium water acclimated fish, ambient cadmium induced significant hypocalcemia, while the structure and morphometry of type-1
and type-2 cells of corpuscles of Stannius were not affected on day 2 and 4. Subsequently on day 14 and 35, recovery of plasma calcium to normal
levels was observed followed by a decrease in corpuscles of Stannius index (CSI), cell size, volume of granular endoplasmic reticulum (p<0.05) of
type-1 cells in both, fish exposed to ambient or dietary cadmium. The type-2 cells were not affected. In high calcium water acclimated fish both,
ambient and dietary cadmium caused a significant reduction of plasma calcium levels on day 2 and 4. In these fish, there was a significant transient
increase in the size of corpuscles of Stannius on day 4, followed by recovery on day 14 and 35. Ultrastructural observations of corpuscles of
Stannius revealed that cadmium did not cause any cellular damage on type-1 and type-2 cells during 35 days exposure. In low or high calcium water
acclimatized tilapia exposed to ambient or dietary cadmium had no effect on the calcium and phosphate composition of the scales, operculum and
vertebrae. Thus, it is unlikely that recovery of hypocalcemia was due to the dissolution of calcium from bony tissues. This study also revealed that
cadmium does not mediate stimulation of the corpuscles of Stannius gland, and that high Ca2+ water had a protective effect against ambient and
dietary cadmium.
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Keywords
Calcium, Cadmium, Corpuscles of Stannius, Oreochromis mossambicus
Citation
Pratap, H.B. and Wendelaar Bonga, S.E., 2007. Calcium homeostasis in low and high calcium water acclimatized Oreochromis mossambicus exposed to ambient and dietary cadmium.