Relationship between toxicity and cadmium accumulation in rats given low amounts of cadmium chloride or cadmium-polluted rice for 22 months.

Abstract

To clarify toxic effects of long-term oral administration of low dose cadmium (Cd) on the liver and kidney, six groups of female Sprague-Dawley rats were fed a diet containing Cd-polluted rice or CdCl2 at concentrations up to 40 ppm, and killed after 12, 18, and 22 months. With toxicological parameters, including histopathology, there was no evidence of Cd-related hepato-renal toxicity, despite a slight decrease of mean corpuscular volume and mean corpuscular hemoglobin of red blood cells with 40 ppm CdCl2. Dose-dependent accumulation of Cd was observed in the liver and kidneys with peak levels of 130 +/- 42 micrograms/g and 120 +/- 20 micrograms/g, respectively, at 18 months in animals treated with 40 ppm CdCl2. A dose-dependent increase in urinary Cd levels became evident with time. Induction of metallothionein (MT) was also observed in the liver and kidney with a high correlation to the corresponding Cd levels. In the proximal renal tubular epithelia of 40 ppm CdCl2-treated rats at 22 months, prominent accumulation of Cd was observed in secondary lysosomes associated with MT deposits in their exocytotic residual bodies. The results demonstrated that, in contrast to the case with high-dose Cd-administration, renal toxicity is not induced by long-term oral administration of low amounts of Cd, although tissue accumulation does occur. Possible protective mechanisms may be operating.

Camel's Milk Protects Against Cadmium Chloride Induced Toxicity in White Albino Rats

“…It has also been proposed that cadmium exerts a direct toxic effect on the glomerulus [47] . Also, the present studies agree with Shibutani et al [45] , who reported that cadmium can affect on renal tubules damage and then glomerular filtration impairment. In the present investigations, administration of Camel's milk with cadmium chloride significantly decreases and brought the concentration of urea in the rat's serum to near normal levels.…”

“…As a result of cadmium activity, one notices renal tubule damage and then glomerular filtration impairment [45] . This may account for the increase of urea concentration in the animals receiving cadmium chloride.…”

Effects of Long-Term Ingestion of Cadmium-Polluted Rice or Low-Dose Cadmium-Supplemented Diet on the Endogenous Copper and Zinc Balance in Female Rats

“…20,21) The metallothionein concentration in the kidneys in the 5-, 20-, and 40-ppm groups increased at every time point in a dose-dependent manner. 15) In the liver, metallothionein increased in the 20-and 40-ppm groups from 12 months, but the liver Cu concentration did not increase. Pearson correlation coefficient analysis also revealed a clear relationship between Cd and Zn, but not between Cd and Cu.…”

“…15,16) The results showed that the retention rate of Cd did not change with the dosage or the treatment period and that renal toxicity was not induced by long-term oral administration of low amounts of Cd, in contrast to the effects of high-dose Cd administration, although tissue accumulation occurs.…”

Effect of combinations of four trace elements on cadmium bioaccumulation in a few tissues of male albino rats

“…Cd is an industrial and environmental pollutant arising primarily from battery, electroplating, pigment, plastics, fertilizer industries and cigarette smoking. The accumulation of Cd is consistently increased when a certain amount is ingested continuously (Shibutani et al, 2001). When Cd enters the body, it reaches the liver within the first 6h and binds to metallothionein, which is a protein with a low molecular weight (6000-10,000 Da) and rich in cystein (Haki Kara et al, 2005 andChan andCherian, 1993).…”