Hematoxicity and hepatoxicity attributed to zinc and cadmium in the Norwegian rat

Abstract

This study was carried out to determine changes in the blood and liver of rats given oral doses of cadmium (Cd) and zinc (Zn). Thirty 3 month old rats were kept six to a compartment in a well-demarcated five compartment cage labeled A, B, C, D, and E. After 2 weeks of acclimatization, and with ad libitum administration of water and feed, group A and B rats were, respectively, exposed to 100 mg CdSO₄ and 2200 mg ZnSO₄, respectively, mixed with their feed. Group C rats were fed with a combination of 100 mg CdSO₄ and 2200 mg ZnSO₄ mixed with their feed, while group D rats were exposed to 100 mg CdSO₄ mixed with their feed for 48 h, and after they were given 2200 mg ZnSO₄ for 96 h. Group E rats served as control and were fed a normal diet. Analysis of blood samples after 5 days showed that in rats of groups A, B, C, and D, WBC count increased from 6800 to 12,400 mm⁻³ and platelets from 26,000 to 88,000 mm⁻³. Reduction in blood counts were found for RBC from 13.8 to 4.7 × 10⁶ mm⁻³, hemoglobin from 15.6 to 11.4 dL⁻¹, and PCV from 47 to 34%. ESR was the same 1.0 mm h⁻¹ in all groups. Severe damage to the liver was also shown by severe degeneration of hepatocytes and increase in Kuppfer cells. The above observations were mildest in the liver of group C rats. A reduction of body weight was observed in all treatment groups. Cd and Zn were found to be hematoxic and hepatotoxic in the Norwegian rat with Cd exhibiting greater toxicity than Zn. Toxicity of Cd was suppressed by Zn only when both metals were admistered at the same time, but a delay in intake of Zn (after 48 h) had little effect on Cd toxicity.

Keywords:

• zinc
• cadmium
• toxicity
• Norwegian rat
• liver
• hematological parameters