Effect of perchlorate on ovarian morphology and histology, estrous cyclicity, steroidogenic enzyme activities and hormonal profiles in adult female rats

Perchlorate contamination is widespread for its industrial uses and natural occurrence. It is also used as an antithyroid drug. Perchlorate competitively inhibits iodide transport at the level of sodium-iodide symporter (NIS) in the thyroid gland, affecting thyroid hormone synthesis, resulting in alteration of thyroid gland structure and functions. Thyroid hormones are vital for proper functioning of the female reproductive system, since they modulate the metabolism and development of ovary and uterus. This study investigates the effect of perchlorate exposure for consecutive four weeks on the morphological and functional status of reproductive organs in adult female rats following parameters as the estrous cyclicity, histology of ovary and uterus, activities of steroidogenic enzymes, serum estradiol and estriol levels. Results revel irregular estrous cyclicity that ultimately ceased presenting a persistent estrous stage, hypertrophied ovary with corpora lutea of different sizes, large and inflated uterine lumen with proliferated endometrium comprising numerous secretory glands in the perchlorate exposed reproductive organs. The activities of steroidogenic enzymes (Δ⁵ 3β HSD and 17β HSD) were augmented that have heightened serum estriol level while the estradiol level was weakened. Therefore, an apparent hypertrophied and hyperfunctioning condition of ovary and uterus developed resembling pseudopregnancy on exposure of this iodide blocker