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Influence of nicotinamide on the radiosensitivity of normal and goitrous thyroid in the rat.
- Source :
-
Thyroid : official journal of the American Thyroid Association [Thyroid] 2001 Nov; Vol. 11 (11), pp. 1003-7. - Publication Year :
- 2001
-
Abstract
- Radioiodine is used to treat thyroid cancer and hyperthyroidism. In order to reduce radiation hazard to the patient and to people in contact with the patient it would be desirable to obtain the same therapeutic effect with lower activities of the radioisotope. This could be achieved by the simultaneous administration of a compound that increases tissue radiosensitivity. In this study we analyzed the use of nicotinamide (NA) as a radiosensitizer to radioiodine, to increase 131I efficacy. NA administered during 30 days to Wistar rats failed to alter thyroid weight. The influence of NA on radiothyroidectomy induced by increasing doses of 131I was examined in otherwise nontreated rats. NA produced a significant increase in the ablation caused by radioiodine. Goiter was then induced by the administration of methylmercaptoimidazol (MMI) to rats, followed by the treatment with radioiodine with and without simultaneous administration of NA. Thyroid weight per 100 g of body weight ratio was not changed by NA alone; 131I administration caused a 25% decrease in goiter size, while 131I plus NA produced a reduction of the ratio of 46% (p < 0.01 vs. NA). No changes were observed in adenosine diphosphate (ADP)-ribosilation of thyroid nuclear protein in NA-treated rats. Thyroid blood flow (determined by 86Rb uptake) was increased by 84% by NA. In conclusion, nicotinamide has a significant radiosensitizing effect to 131I both in normal and goitrous rats. This action is because of an increase in thyroid blood flow, which probably enhances tissue oxgenation.
- Subjects :
- Adenosine Diphosphate Ribose metabolism
Animals
Antithyroid Agents pharmacology
Cell Nucleus drug effects
Female
Iodine Radioisotopes pharmacokinetics
Methimazole pharmacology
Rats
Rats, Wistar
Regional Blood Flow drug effects
Rubidium Radioisotopes pharmacokinetics
Thyroid Gland blood supply
Thyroid Gland drug effects
Goiter radiotherapy
Niacinamide pharmacology
Radiation Tolerance drug effects
Subjects
Details
- Language :
- English
- ISSN :
- 1050-7256
- Volume :
- 11
- Issue :
- 11
- Database :
- MEDLINE
- Journal :
- Thyroid : official journal of the American Thyroid Association
- Publication Type :
- Academic Journal
- Accession number :
- 11762708
- Full Text :
- https://doi.org/10.1089/105072501753271671