Role for inner ring deiodination preventing transcutaneous passage of thyroxine
| Autor: | Gianluca Gatti, Ferruccio Santini, Marco Macchia, Lucia Montanelli, Luca Chiovato, Veronica Rosellini, Giovanni Ceccarini, Paolo Vitti, Lewis E. Braverman, Aldo Pinchera, Inder J. Chopra, Joshua D. Safer, Claudia Mammoli, Enio Martino |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Adult
medicine.medical_specialty Endocrinology Diabetes and Metabolism Metabolite Thyroxine deiodinase Clinical Biochemistry Deiodinase Human skin Urine Biochemistry Iodide Peroxidase Absorption Ointments chemistry.chemical_compound Endocrinology Internal medicine Blood plasma medicine Humans Skin biology Chemistry Biochemistry (medical) Thyroid food and beverages Isoenzymes Thyroxine medicine.anatomical_structure Liposomes biology.protein Triiodothyronine Female Hormone Iodine |
| Zdroj: | Università di Pisa-IRIS |
| ISSN: | 0021-972X |
| Popis: | Creams containing thyroid hormone are commonly employed for cosmetic purposes. To verify whether T(4) applied to the skin surface can enter the bloodstream either directly or as a metabolite, a cream containing L-T(4) [3,5,3',5'-tetraiodothyronine (T(4))] was self-applied by volunteers for 2 wk. No significant variations in urinary iodide, TSH, and serum (total and free) T(4) and T(3) concentrations were observed at any time relative to pretreatment values, whereas rT(3) concentrations increased significantly 6 and 12 h after cream application. The increased rT(3) concentration led us to investigate the presence of inner ring type III deiodinase (D3) activity in human skin. Using human surgical discard skin, we found that T(4) can be carried across human epidermis in a liposome cream. Substantial inner ring deiodination was suggested by the fact that only 10% of transferred thyroid hormone remained as T(4), and T(3) was not detected. We then measured D3 activity in a surgical skin specimen. The K(m) for T(3) was 1.74 nmol/liter, and the maximum velocity was 23.5 fmol/microg microsomal protein/h. In conclusion, our study indicates that normal human skin serves as a substantial, but incomplete, barrier to T(4) passage. D3 plays an important role in augmenting T(4) blockade by inactivating T(4) to rT(3). |
| Databáze: | OpenAIRE |
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