Effects of Arsenic on Estrogen and Its Receptor in Rats

Objective To examine the effects of arsenic on estrogen and its receptor as well as the relationships among the indicators of estrogen receptor (ER) signaling pathway in rats.

Methods Female SD rats were divided into four groups with six rats each and were exposed to NaAsO₂ (0, 0.625, 2.500, and 10.000 mg/kg) by oral perfusion, once a day, for three consecutive months respectively. The concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), and ER in serum were determined by enzyme-linked immunosorbent assay.

Results The levels of FSH in the control, low arsenic, middle arsenic, and high arsenic groups were (26.05±2.10), (18.23±1.58), (10.22±1.58), and (2.07±0.79) IU/L, respectively; the levels of LH were (39.43±1.65), (10.33±2.08), (1.95±0.29), and (0.60±0.23) IU/L, respectively; the levels of E2 were (54.92±5.14), (40.68±3.01), (9.20±1.92), and (9.03±1.02) ng/L, respectively; the levels of ER were (41.06±2.14), (24.32±2.21), (22.16±3.16), and (9.06±2.06) ng/L, respectively. With the increasing of arsenic, the expression levels of FSH and LH gradually decreased (P < 0.01). The expression levels of E2 and ER were of significant differences between groups treated with different doses of arsenic (P < 0.01) except the E2 in the middle and high arsenic groups (2.500, 10.000 mg/kg) and the ER in the low and middle arsenic groups (0.625, 2.500 mg/kg). There were dose-effect relationships of arsenic exposure with FSH, LH, E2, and ER. Arsenic and urinary arsenic were negatively associated with FSH, LH, E2, and ER (P < 0.05). E2 was positively associated with FSH, LH, and ER (P < 0.05).

Conclusion Estrogen and its receptor participate in the process of reproductive system damage caused by arsenic. The expression levels of the ER pathway indicators are inhibited by arsenic. Therefore, arsenic is probably an endocrine disrupting chemical.