Thyroid organotypic rat and human cultures used to investigate drug effects on thyroid function, hormone synthesis and release pathways
- Drug Safety Evaluation, Allergan Inc., 2525 Dupont Dr, Irvine CA 92612 (United States)
- Vitron Inc., Tucson, AZ (United States)
Drug induced thyroid effects were evaluated in organotypic models utilizing either a rat thyroid lobe or human thyroid slices to compare rodent and human response. An inhibition of thyroid peroxidase (TPO) function led to a perturbation in the expression of key genes in thyroid hormone synthesis and release pathways. The clinically used thiourea drugs, methimazole (MMI) and 6-n-propyl-2-thioruacil (PTU), were used to evaluate thyroid drug response in these models. Inhibition of TPO occurred early as shown in rat thyroid lobes (2 h) and was sustained in both rat (24–48 h) and human (24 h) with ≥ 10 μM MMI. Thyroid from rats treated with single doses of MMI (30–1000 mg/kg) exhibited sustained TPO inhibition at 48 h. The MMI in vivo thyroid concentrations were comparable to the culture concentrations (∼ 15–84 μM), thus demonstrating a close correlation between in vivo and ex vivo thyroid effects. A compensatory response to TPO inhibition was demonstrated in the rat thyroid lobe with significant up-regulation of genes involved in the pathway of thyroid hormone synthesis (Tpo, Dio1, Slc5a5, Tg, Tshr) and the megalin release pathway (Lrp2) by 24 h with MMI (≥ 10 μM) and PTU (100 μM). Similarly, thyroid from the rat in vivo study exhibited an up-regulation of Dio1, Slc5a5, Lrp2, and Tshr. In human thyroid slices, there were few gene expression changes (Slc5a5, ∼ 2-fold) and only at higher MMI concentrations (≥ 1500 μM, 24 h). Extended exposure (48 h) resulted in up-regulation of Tpo, Dio1 and Lrp2, along with Slc5a5 and Tshr. In summary, TPO was inhibited by similar MMI concentrations in rat and human tissue, however an increased sensitivity to drug treatment in rat is indicated by the up-regulation of thyroid hormone synthesis and release gene pathways at concentrations found not to affect human tissue. -- Highlights: ► Novel model of rat thyroid or human thyroid slices to evaluate pathways of injury. ► TPO inhibition by MMI or PTU altered hormone synthesis and release genes. ► Rat thyroid was more sensitive to the drug effects than human tissue.
- OSTI ID:
- 22215286
- Journal Information:
- Toxicology and Applied Pharmacology, Vol. 260, Issue 1; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0041-008X
- Country of Publication:
- United States
- Language:
- English
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