Comparison of cadmium toxicity on kidneys and on testes of rats

In order to find out the critical organ in chronic cadmium (Cd) intoxication, the Cd toxicity on kidneys and testes was compared. 3-month-old male Sprague-Dawley rats were given 0, 15.0, 37.5 or 93.8 ppm Cd in drinking water for 12 wk. The urinary excretion of low molecular weight proteins (LMWP), activity of urinary alkaline phosphatase (ALP), serum testosterone (T) level and LDH-X activity of testes homogenates were measured. By the end of the treatmant, each male was mated to two females for the assessment of male fertility. The male rats were sacrificed; the kidneys, testes, epididymides and prostates were weighed. Cd contents were measured by AAS, and the morphological changes were examined. The sperm counts and sperm morphology were also examined. The results show that the urinary LMWP excretion and ALP activity increased only in the 93.8 ppm Cd group (P0.05). The serum T level show significant decrease in both the 37.5 and 93.8 ppm Cd groups(P0.05). The LDH-X activity in the testes was inhibited significantly in all the Cd treated groups (P0.01). No significant effect on male fertility was observed. Under a light microscope, a lot of protein casts were present in the collecting tubules in the 93.8 ppm Cd group. Neither renal tubular necrosis nor glomerular changes were found. No histological changes in the testes, epididymides and prostates were observed. Under an electron microscope, ultra- structural changes were observed in both 37.5 and 93.8 ppm Cd groups, and the injury was extensive in high dose group. The injuries occurred on proximal convoluted tubule cells of the kidneys, mainly on the spermatocytes and Leydig′s cells of the testes.