Excess iodine supplementation aggravates the toxic effects induced by perchlorate on the male reproductive system in rats

Objective: To investigate the toxicity of excess iodine and perchlorate co-exposure on male reproductive system in rats. Methods: Eighteen male Wistar albino rats were divided into three groups. Group 1 received no treatment and served as the control group. Group 2 received perchlorate alone (130 mg/kg body weight), and group 3 received perchlorate (130 mg/kg body weight) plus excess iodine (0.7 mg potassium iodine/100 g body weight) for 45 days. Urinary perchlorate and iodine excretion pattern, testicular iodine concentration, serum testosterone levels, epididymal sperm count, key enzymes of steroidogenic pathway, reactive oxygen and nitrogen species including total antioxidant profiles in testis with electron microscopic ultrastructure analysis of spermatozoa were evaluated. Results: Co-exposure of perchlorate and excess iodine reduced their excretion pattern, reflecting accumulation with reactive oxygen species generation. It was accompanied by higher lipid peroxidation level with imbalance in the pro-/antioxidant status, inhibiting the activities of Δ5 3 β-hydroxysteroid dehydrogenase (HSD) and 17 β-HSD rate limiting enzyme activities, and causing reduced synthesis of testosterone, parallel to reduction in testicular and accessory sex organs weight, epididymal sperm-count with deformed ultrastructure of sperm. Perchlorate alone was not a reproductive toxicant; however, in combination with excess-iodine, acute effects were noticed, resulting in a severe deterioration of testicular and spermatozoal structure and function. Conclusions: This study provides a novel insight on the augmentation of the relatively moderate repro-toxic effects of perchlorate to a more severe form in presence of excess iodine on male reproductive physiology, which justifies further investigations.