2013: Long Term F and thyroid function - rats

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2013: Long Term F and thyroid function - rats

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Liu Hongliang, Yu Linyu, Cui Yushan, Zeng Qiang, Zhao Liang, Hou Changchun, Wang Aiguo - "Influence of Long Term Excessive Fluoride Intake on the Morphology and Function of Thyroid in Rats" Journal of Environmental Hygiene 3(5): 390-393, 397 (2013)

OBJECTIVE : To investigate the effects of long-term intake of excess fluoride on thyroid morphology and function in rats.


120 Wistar rats were randomly divided into control group (tap water, fluoride ion concentration 0.344 mg/L), low fluoride group (5 mg/L), middle fluoride group (10 mg/L) and high fluoride group (20 mg). /L) 4 groups. Five male and female rats were sacrificed in each group at the end of the second, fourth and eighth months of drinking water. Thyroid weight was weighed, thyroid tissue morphology was observed under light microscope, and serum thyroid stimulating hormone (TSH), total tetraiodothyronine (TT 4 ), and free tetraiodothyronine were detected by radioimmunoassay. The levels of FT 4 ), total triiodothyronine (TT 3 ), and free triiodothyronine (FT 3 ) were compared and the differences between the groups were compared.


Compared with control group, at the end of exposure 4,8, TSH high fluoride group was significantly decreased ( P less than 0.05); TT exposure fluoro groups 4 the FT and 4 levels of exposure at the end of 2 were significantly increased ( P Less than 0.05), then showed a downward trend; there was no significant change in TT 3 and FT 3 levels during the exposure ( PMore than 0.05). At the end of 2 months of exposure, the thyroid gland of the exposed group showed hyperplastic follicles, the gelatin decreased, a few follicles became larger, and the follicular epithelial cells were flattened; with the prolonged exposure time, follicular hyperplasia was more active. The follicular cavity becomes smaller, and some giant thyroid follicles are also visible in some thyroid glands.


Long-term intake of excess fluoride can lead to abnormal thyroid morphology and function, and exposure time may be an important factor.
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