Summary
There is evidence that iodoarachidonates are mediators of iodide in thyroid autoregulation,
however, their occurrence in vivo has not yet been demonstrated. We therefore tried to identify δ-iodolactone (5-Hydroxy-6-iodo-8,11,14-eicosatrienoic
δ-lactone, IL-δ) in thyroid tissue from a patient with Graves' disease treated with
high doses of iodide. Lipids were extracted from thyroid tissue, purified by reversed
phase chromatography and analyzed by gas chromatography - tandem mass spectrometry
(GC-MSMS). The retention time in gas chromatography and fragmentation pattern in tandem
mass spectrometry were determined with biochemically synthesized non-deuterated and
deuterated IL-δ. According to retention time (13.44 min) and specific fragments (m/z
303, m/z 259) the occurrence of IL-δ could be demonstrated in the extract of iodide
treated goiter. In vitro, potassium iodide (40 μM) as well as IL-δ (1.0 μM) significantly
inhibited the proliferation of human thyroid follicular cells induced by phorbol ester
TPA (12-O-tetradecanoylphorbol 13-acetate). These results demonstrate for the first
time that Il-δ is present in iodide treated human thyroid. As cell proliferation is
under negative control of IL-δ, a crucial role in thyroid involution following iodide
treatment may be possible.
Key words
Iodide - Iodolactone - GC-MS - Thyroid Growth - Autoregulation
