Effects of Cadmium as a Possible Endocrine Disruptor upon the Serum Level of Sex Steroids and the Secretion of Gonadotropins from Pituitary in Adult Rats

Objective: The objective of this study is to assess the effect of cadmium (Cd) upon the female reproductive system by investigating the serum levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH) as well as sex steroids such as estradiol (E2) and progesterone (P). Materials and Methods: Sprague-Dawley (SD) female rats were daily injected subcutaneously with CdCl2 for 7 or 14 days at a dose of 0,0.5 and 1.0 mg /Kg body-weight (BW) and the serum levels of FSH, LH, E2 and P were measured by radioimmunoassay. Also, the levels of FSH and LH in the presence or absence of extraneously added gonadotropin-releasing hormone (GnRH) were determined in the similarly treated rats. Results: Although the FSH and LH levels were not changed by CdCl2 administration, the serum concentration of E2 was significantly decreased by the injection with both high and low doses of CdCl2. In some conditions the serum P level was also decreased. To examine the reactivity of pituitary cells to GnRH in CdCl2 -treated rats, we measured the serum levels of FSH and LH in the presence or absence of extraneously added GnRH and then found that although the secretion of FSH and LH was increased more or less by GnRH administration in any combinations, the increase in the serum LH level of CdCl2 -treated rats was significantly lower than that of control rats. Conclusion: Cd may decrease the reactivity of LH cells to GnRH, resulting in lower serum levels of E2 and P through the disorder of ovarian cycles.