Prostaglandinsのラット甲状腺内ホルモン合成及び血漿TSHに及ぼす刺激効果

概要

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It is now postulated that prostaglandins (PG) are widely distributed in mammalian tissues and stimulate adenyl cyclase-cyclic AMP system in various organs. The present study was undertaken in an attempt to clarify the effect of PG on pituitary-thyroid axis in vivo. Rats were maintained on a low-iodine diet for 8 days. The animals received graded doses (10-500 μg) of PGE1, PGE2 and PGF2α ip daily from day 5 to the day of autopsy. The 4-hr thyroid 131I uptake was consistently higher in 10 μg PGE1, 10 μg PGE2 and 100 μg PGF2α-treated rats than in the controls. Higher T3/T4 ratios were found in the diagested thyroids of PG-treated rats. Serum T4 levels appeared to be increased by the PG administration. However, a single injection of PG did not affect thyroid 131I uptake in iodine-deficient animals. No change in the thyroid 131I uptake was found in iodinereplete rats chronically treated with PG. The increase in plasma TSH levels during treatment with 30 μg PGE1 and PGE2 was clearly shown. A similar result was also obtained with 100 μg PGF2α. The increase in thyroid 131I metabolism produced by the repeated administration of PG in iodine-deficient rats is due presumably to the direct stimulation on the thyroids of rats. In addition, PG elevated plasma TSH levels in such animals, probably mediated through the hypothalamic-pituitary system.
日本内分泌学会の論文