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Tumor promoting effect of goitrogens on the rat thyroid
J Kanno1, C Matsuoka, K Furuta
1Department of Pathology, Faculty of Medicine, Tokyo Medical and Dental University, Japan.
Toxicologic Pathology
|January 1, 1990
Summary
This study classified goitrogens into two types based on their effects on rat thyroids: iodine deficiency-type and iodine excess-type promoters. This classification aids in assessing goitrogen risks for thyroid tumors.
Area of Science:
- Endocrinology
- Toxicology
- Carcinogenesis
Background:
- Goitrogens are known to promote thyroid tumorigenesis.
- Understanding the mechanisms of goitrogen action is crucial for risk assessment.
Purpose of the Study:
- To evaluate the tumor-promoting mechanisms of various goitrogens on rat thyroids.
- To classify goitrogens based on their distinct effects on thyroid morphology and hormone levels.
Main Methods:
- Administration of thiourea, phenobarbital sodium (PB), potassium thiocyanate (KSCN), and Rose Bengal B (FR105) to F344 male rats.
- Use of an iodine-deficient diet as a positive control.
- 25-week study duration with monitoring of thyroid morphology and hormone titers.
Main Results:
- All tested goitrogens exhibited significant tumor-promoting effects or tendencies on rat thyroids.
- Goitrogens were classified into iodine deficiency-type (thiourea, KSCN, PB) and iodine excess-type (FR105) promoters.
- Distinct morphological changes and hormonal responses were observed for each goitrogen type.
Conclusions:
- A novel classification of goitrogens based on their promoting mechanisms is proposed.
- This classification differentiates between goitrogens inducing TSH-stimulated diffuse goiter and those inducing colloid goiter.
- The proposed classification system can be valuable for evaluating the carcinogenic risk associated with goitrogen exposure.