Perchlorate Inhibition of Iodide Uptake in Normal and Iodine-deficient Rats

Abstract

Perchlorate-induced inhibition of thyroidal iodide uptake was measured in normal and iodine-deficient female Sprague-Dawley rats. Rats that were made iodine-deficient by long-term restriction of iodine in the diet absorbed a gavage dose of ¹³¹I to the thyroid in proportionally greater amounts than rats fed a normal diet. Furthermore, the iodine-deficient rats maintained their high rates of absorption even when challenged by levels of perchlorate in their drinking water sufficient to produce pronounced inhibition of ¹³¹I uptake in rats fed a normal diet. Every dose of perchlorate used in this study (1.1, 5.6, and 28 mg/L) produced significant inhibition of iodide uptake in normally fed rats, but only the highest level of perchlorate (28 mg/L) significantly inhibited thyroidal uptake of ¹³¹I in the iodine-deficient rats. Taken together, these results demonstrate that iodide-deficient animals exhibit increased resistance to the inhibition of iodine absorption resulting from perchlorate exposure.

The authors thanks Pat Beall, Terry Hanna, Bethany Hope, Mark Michie, Lorus Miller, Heidi Paulus, Robert Sunderland, and Martha Thompson for their assistance with blood draws, necropsies, RAIU assays, and routine animal care. Funding for this work was provided by the U.S. Army Environmental Center.

The views, opinions, and/or findings presented in this publication should not be construed as official Department of Defense position, policy or decision unless designated by other official documentation.