| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1988: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1987: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
To investigate the effect of aging, dopaminergic neurons and nicotine on thyroid hormone metabolism in the pituitary and brain, the iodothyronine 5' deiodinating (5'-D) activities were determined in young euthyroid and hypothyroid rats. Bromocriptine, haloperidol or nicotine was injected intraperitoneally, and the type I and type II 5'-D activities were measured, using the method as described by Leonard et al.
1) in euthyroid rats, no significant changes in the pituitary type I and II 51-D activities were observed after the injection of bromocriptine or haloperidol.
2) In hypothyroid rats, the pituitary type II 5'-D activity was markedly elevated, as compared with the type I 5'-D activity. Moreover, both 5'-D activities tended to diminish by administration of bromocriptine, while even higher activities were found by haloperidol injection.
3) In euthyroid rats, the type I and II 5'-D activities were the highest in the pituitary, and these activities were also high in cerebral cortex and hypocampus. The regional distribution of the activities in hypothyroid rats was almost the same as that in euthyroid rats, and marked elevation of type II activity was observed in all regions of the brain as well as the pituitary.
4) There were no significant changes in type I and II activities in the pituitary and brain from euthyroid rats injected nicotine. In contrast, the type I and II activities in the pituitary, cerebral cortex and hypocampus from hypothyroid rats were elevated by the nicotine injection.
5) In conclusion, the present results suggest that the dopamine neurons might have some effect on the pituitary type II 5'-D activity in hypothyroid rats. Moreover, it was conceivable likely that the type-I and II activities in brain from hypothyroid rats might be regulated by nicotine receptor.
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