Histological Alterations in the Thyroid Follicular Cells Induced by ‎Lead Acetate Toxicity in Adult Male Albino Rats

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Lead exposure can cause multiple systemic toxicities, particularly affecting the ‎hematopoietic, nervous, and renal systems. Experimental studies have shown that ‎lead has potent endocrine-disrupting activity. However, its effects on the thyroid ‎structure and functions are not well elucidated and the published studies are ‎controversial. The aim of this study was to evaluate the changes occur in thyroid ‎tissue, optically and ultrastructurally, and hormonal changes induced by low-dose ‎sub-chronic lead acetate toxicity. Twenty adult male albino rats were divided into ‎two groups, each containing 10 animals; group I (normal control) received distilled ‎water as placebo and group II (Lead acetate group) was treated with 100 mg/kg BW ‎of lead acetate by oral gavage for 8 weeks. The results showed that lead acetate ‎treatment caused biochemical changes that are consistent with hypothyroidism i.e. ‎low T4 and T3 levels and a significant increase in TSH. Microscopic examination of ‎thyroid sections in Lead-acetate treated group revealed that the majority of the ‎thyroid follicles were irregular and enlarged, others were distended with vacuolated ‎colloids, and some of them were small with no colloid, congested blood vessels, ‎prominent mast cells, and exfoliated cells in the lumen of the follicles. In conclusion, ‎lead acetate exposure resulted in subclinical hypothyroidism associated with evident ‎morphological alterations in the thyroid tissue‎‎.