Inhibition of goiter growth and of cyclic AMP formation in rat thyroid by 2-iodohexadecanal

THOMASZ, L; OGLIO, R; DAGROSA, MA; JAHN, G; KRAWIEC, L; PIGNATARO, O; SARTORIO, G; PISAREV, M; JUVENAL, G

New York

Congreso; 78 th Annual Meeting, American Thyroid Association; 2007

American Thyroid Association

Introduction: Thyroid autoregulation has been related to intraglandular content of an unknown putative iodocompound. The thyroid is capable of producing different iodolipids such as 6-iodo-deltalactone (IL) and 2-iodohexadecanal (IHDA). Data from different laboratories have shown that these iodolipids inhibit several thyroid parameters. IL has an antigoitrogenic action but no data are about the action of IHDA. Objectives: to study the action of IHDA on MMI-induced goiter. Results: Administration of MMI to rats during 10 days increases thyroid weight by 86%. This effect was significantly inhibited by the simultaneous injection of 10 µg/day of IL (45 % inhibition) or IHDA (48%, p<0.005 vs MMI) while iodine or non iodinated hexadecanal was without action. Thyroidal proliferating cell nuclear antigen (PCNA) content was increased by MMI while IHDA decreased this value (c: 100%; MMI: 190 +/- 20; MMI+IL: 170 +/- 11, n.s vs. MMI; MMI+IHDA: 134 +/- 10, p<0.01 vs. MMI). Serum TSH was increased after MMI administration (c: 0,69 +/- 0,10; MMI: 7,45 +/- 0,20 ng/ml). Both iodolipids caused a partial decrease in TSH levels (MMI+IHDA: 4,23 +/- 0,72; MMI+IL: 4,09 +/- 0,61; p<0.001 vs. MMI). Treatment with MMI increased thyroidal cAMP content (c: 9,49 +/- 0,52, MMI: 18,97 +/- 1,6 pm/mg protein) while injection of IL or IHDA significantly decreased this action (MMI+IHDA: 13,73 +/- 1,45 MMI+IL: 12,99 +/- 1,61; p<0.05 vs. MMI). Administration of the iodolipids did not produce significant changes in several serum parameters (total T3 and T4, cholesterol, total protein, urea and 5-nucleotidase). Conclusion: 2-iodohexadecanal as 6-iodo-deltalactone prevents goiter growth in rats and opens a potential therapeutic application of iodolipids