The aims of this study were to quantify mercury content after administration of mercury and selenium and the protective effect of selenium against inorganic mercury retention in tissues of rats. 18 female Sprague-Dawley rats were randomly divided into two main groups, and each main group was divided into three subgroups. The one subgroup was supplied with distilled water as control. Another subgroup was received 50 mg HgCl2/ I in the drinking water every second day, and the other subgroup was treated with 50 mg HgC12/ I + 5 mg Na2SeOd I in the drinking water on the days when they were not receiving mercury. The animals in main group A were exposed for 2 weeks and main group B were exposed for 2 weeks, followed by 10 weeks of non-exposure periods. All kidney cortex, kidney medulla, liver and brain were extracted. Cold Vapour Atomic Absorption Spectrophotometry and Flame Atomic Absorption Spectrophotometry were adapted to determine the total mercury content and selenium content, respectively. All the collected data were analyzed by t-test and one-way ANOVA at the level of 0.05 using statistical data analysis software SAS 6.12.
The obtained results were as follows:
1. The mercury contents in kidney were significantly reduced in mercury mixed with selenium group. On the contrary, the mercury levels in liver were significantly higher in mercury mixed with selenium group than mercury only group (p (0.05).
2. In 2nd subgroup (HgCl2+Na2SeO), comparison between group A and group B showed a reduction in the selenium content of kidney and liver by 39% and 62%, respectively, which was similar with the reductions in mercury content. In addition to, selenium supplementation increased 2 or 16 times the retention of mercury in kidney and liver, when mercuric chloride was given.
3. The Hg/Se molar ratios in the tissues have been calculated and were found to vary considerably.
Result indicated that selenium exerted a protective effect against the toxicity of mercury by reducing mercury accumulation in the kidney, though mechanisms still to be unveiled We also suggested selenium
had effect on mercury retention by forming of stable and inactive complexes of mercury and selenium in various organs such as the liver and kidney.
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