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Significance of SIMS microscopy for the radioiodine detection in animal and human thyroid tissue *
Author(s) -
Briançon Colette,
Jeusset Josette,
Francese Cecilia,
Omri Frédérique,
Halpern Sylvain,
Fragu Philippe
Publication year - 1992
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1016/0248-4900(92)90010-x
Subject(s) - thyroid , in vivo , iodine , microgram , follicular cell , lumen (anatomy) , in vitro , radiochemistry , endocrinology , medicine , biology , chemistry , nuclear medicine , biochemistry , microbiology and biotechnology , organic chemistry
Summary— We defined the SIMS conditions for radioiodine detection in animal and man thyroid follicles, in tissue sections (3 μm) chemically fixed and resin embedded. Two radioisotopes were tested: 125 I and 129 I, of high (14 mCi 125 I μg −1 ) and low specific activity (1.07 10 −6 mCi 129 I μg −1 ). In animal study, Wistar rats fed a normal iodine diet (10 μg 127 I day −1 ) were injected ip 24 h before sacrifice either with 125 I (7 10 −3 μg) or with 129 I at a dose identical to iodine diet (10 μg) or 3 times higher (30 μg). No SIMS signal of 125 I was obtained in vivo due to its too low concentration, while radioiodine distribution was evidenced with both doses of 129 I. Local concentration of previously stored 127 I in follicular lumen was not modified, when compared to control (4.14 ± 0.03 μg/mg, m ± SE), by 125 I or 129 I at a dose of 10 μg, but was nearly doubled with 129 I at a dose of 30 μg, proof of a pharmacological effect on thyroid iodine regulation. In human study 129 I was excluded due to its long half‐life (1.6 10 7 years), and 125 I was tested only in vitro on two surgical specimens of normal perinodular thyroid tissue maintained in mini‐organ culture for 48 h in presence of 100 μCi/ml of 125 I. The 125 I was detectable, its concentration was 1000‐fold higher than that of 127 I (1.5 ± 0.004 μg/mg). For both in vivo and in vitro studies, a positive correlation exists between newly organified radioiodine ( 125 I or 129 I) and previously stored iodine ( 127 I). In conclusion, the radioisotope 129 I used at a dose of 10 μg is well adapted for SIMS detection in vivo of thyroid exchangeable iodine, but only in animal, while 125 I isotope is especially adapted for in vitro study in man.