Studies on the goiter inhibiting action of iodolactones

The thyroid gland synthetizes 6-delta-iodolactone, a compound shown to inhibit goiter growth in vivo and cell proliferation in culture. The present studies were performed to characterize this effect further with the aim of exploring the possible therapeutic action of iodolactones. Prevention assay: rats were treated simultaneously with a goitrogen, methylmercaptoimidazole, and either 6-delta-iodo-lactone or 14-iodo-omega-lactone, a synthetic derivative, given either i.p. or p. o. Both compounds caused a significant decrease in thyroid weight irrespective of the route of administration, but oral administration was less effective. A dose-response relationship was observed, the minimal effective dose (i.p.) being 3 μg/day. Involution assay: goiter was first induced with methylmercaptoimidazole and then the iodolactones were injected. Both compounds caused a significant involution, which was dose-related. Acute (10 days) administration of the iodolactones did not produce significant changes in several serum parameters (total T3 and T4, cholesterol, total protein, urea and acetylcholinesterease). These results give further support to the potential therapeutic application of iodolactones.