Cadmium-induced increase in uterine wet weight and its mechanism

Cadmium (Cd) increases in uterine wet weight in rodents remain unclear and there are only a few studies that examined the effects of Cd on uterine morphology. It is unknown whether Cd induces a uterotrophic effect via its interaction with the estrogen receptor (ER). In our study, we compared the effects of cadmium chloride (CaCl(2)) on uterine wet weight and morphology to those of 17beta-estradiol in Sprague-Dawley (SD) rats.

Forty-eight SD rats (23 days of age) were ectomized and randomly divided into six groups (eight rats per group): vehicle control (sterile saline solution), positive control (17beta-estradiol, 0.03 mg/kg in peanut oil), and CaCl(2) groups (0.0064, 0.032, 0.16, and 0.8 mg/kg, respectively). The animals were treated by daily intraperitoneal (i.p.) injection for 3 days. The uteri were removed and assessed for weight, morphology, and immunohistochemical analysis.

Compared to the control group, the uterine wet weight, the thickness of endomerium, the thickness of the stroma and the nucleus/cytoplasm ratio in the 17beta-estradiol-treated and 0.8 mg/kg-day CaCl(2)-treated groups changed (P<0.01 or P 0.05). The endometrial gland number, the uterine epithelial cell height, and the PCNA-positive expression in 17beta-estradiol-treated rats increased compared to that of the control (P<0.01), but not in the CaCl(2) dose groups.

These results indicate that cadmium may induce an increase in uterine wet weight. However, this effect is not similar to that caused by 17beta-estradiol, suggesting it is not via Ca-ER interactions.