EFFECTS OF FLUORIDE AND ARSENIC ON SERUM THYROID HORMONE IN RATS

Our previous study suggested that learning and memory were increasingly disturbed by exposure to high fluoride and high arsenic. The purpose of this study was to investigate the impact of high fluoride and high arsenic on the thyroid hormone status of the rats, thereby to find out potential pathway leading to reduction in learning and memory ability. T3, T4 and TSH levels in serum were measured by radioimmunoassay and results revealed that serum T3 level was significantly increased (p<0.05) by excessive F or As, especially in the HiF+HiAs group (p<0.01); T4 level were significantly affected by excessive F or As in a time-dependent manner; TSH level was significantly increased by excessive F or As. These results suggest that serum thyroid hormone level were significantly affected by excessive F or As, which may be one of the causes that lead to a reduction in the learning and memory of rats.