UBC Theses and Dissertations
Effect of zinc on the teratogenic action and tissue distribution of cadmium in the rat Garcia, Miren Lizaso de
The interaction of zinc and cadmium was studied in pregnant rats and their fetuses. Four experimental groups of animals were used, with each group being given one of the following treatments by intraperitoneal injection: (1) cadmium chloride (16uM/kg body weight) with 115m-cadmium, (2) cadmium chloride (16uM/kg body weight) plus zinc chloride (16uM/kg body weight) with 115m-cadmium, (3) zinc chloride (16uM/kg body weight) with 65-zinc, or (4) zinc chloride (16uH/kg body weight) plus cadmium chloride (16uM/kg body weight) with 65-zinc. In the first experiment the chemicals were administered on day 9 of pregnancy and the animals were sacrificed on day 20 of pregnancy. Fetuses were examined for gross defects and maternal tissues and fetuses were counted for radioactivity in order to determine the distribution of cadmium and zinc. . Gross abnormalities were seen in group 1 (cadmium), where 28.8 percent of the fetuses were malformed. Defects included absent tail (7.7%), dysplastic tail (10.3%), thin abdominal wall (6.4%), dysplastic neck (5.8%), dysplastic eyes (3.2%), exencephaly (1.9%), dysplastic ears (1.3%), dysplastic limbs (0.6%), and stunted body (0.6%). In group 3 (zinc), 2 malformed fetuses both with exencephaly were found in one litter. No malformations were found in groups 2 and 4 (cadmium plus zinc). In addition, fetal weight was significantly decreased in group 1 (cadmium) when compared with groups 2, 3, and 4. There were no differences in numbers of resorption sites, numbers of dead fetuses, or litter size among the four groups. There were no differences in the maternal tissue distribution of cadmium between group 1 (cadmium) and group 2 (cadmium-zinc). On the other hand, zinc accumulation was significantly increased in group 4 (zinc-cadmium) compared with group 3 (zinc), in liver, kidney, adrenal, heart, lung spleen, placenta, fetus, fat, uterus, muscle, and plasma. In the second experiment pregnant Wistar rats were given treatments 1 (cadmium) and 2 (cadmium-zinc) on day 9, and tissues were sampled on day 10, 11, and 12 of gestation. When animals give cadmium were compared with those given cadmium plus zinc, a significantly greater amount of radioactivity (115m-cadmium) was found in the uterus, uterus plus fetus, fetus, fat, and plasma on day 10 in the cadmium group. On day 11 the only differences found were increased amounts of radioactivity in the adrenals and small intestine. On day 12 radioactivity was increased only in the femur. When the 4 different sampling days (10, 11, 12, and 20) were compared, it was found that in most tissues the amount of cadmium deposited decreased with time except for the kidney, where cadmium increased, and the liver and spleen where: there was no change. The data suggest that cadmium reaches the fetus in the early hours after injection and is excreted thereafter. Simultaneous administration of zinc did not change cadmium accumulation in maternal tissues but significantly reduced the amount of cadmium reaching the fetus 24 hours post-injection. On the other hand, simultaneous administration of cadmium increased the accumulation of zinc in most of the organs investigated.
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