Prenatal iodine deficiency results in structurally and functionally immature lungs in neonatal rats

Maternal hypothyroidism affects postnatal lung structure. High prevalence of hypothyroxinemia (low T4, normal T3) in iodine-deficient pregnant women and associated risk for neuropsychological development along with high infant/neonatal mortality ascribed to respiratory distress prompted us to study the effects of maternal hypothyroxinemia on postnatal lung development. Female Sprague Dawley rats were given a low-iodine diet (LID) with 1% KClO4 in drinking water for 10 days, to minimize thyroid hormone differences. Half of these rats were continued on iodine-deficient diet; ID (LID with 0.005% KClO4) for 3 mo, whereas the rest were switched to an iodine-sufficient diet; IS [LID + potassium iodide (10 μg iodine/20 g of diet + normal drinking water)]. Pups born to ID mothers were compared with age-matched pups from IS mothers at postnatal days 8 (P8) and 16 (P16) (n = 6–8/group). ID pups had normal circulating T3 but significantly low T4 levels (P < 0.05) and concomitantly approximately sixfold higher thyroi...