Abstract

Objective To observe the effects of fluoride on thyroid morphology,thyroid peroxidase and serum thyroid hormones.

Methods One – month ablactating SD rats were randomly divided into three groups:the control group, low-fluoride group, middle-fluoride group, high-fluoride group, fed with water containing different fluoride concentration by adding NaF respectively. Rats were sacrificed after being fed for six months. The morphology of thyroid was observed through light microscope. The TPO activity was measured with upgrade guaiacol method. Radio-immunoassay was used to detect serum thyroid hormones.

Results The major changes included increased follicles with colloid accumulation in high fluoride groups. With the dose of fluoride increasing, TPO activity significantly decreased as compared with the control group (P0.05). FT4 levels of the high-fluoride group were significantly lower compared with the control group (P0.05).

Conclusions Chronic fluoride excess leads to definite histological changes in rat thyroid, inhibiting TPO activity so that level of thyroid hormone is decreased, which shows that fluoride can cause goiter, and cause abnormal changes of thyroid metabolism function.

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