[Serotonin formation in the hypothalamus of thyroidectomized rats under the influence of exogenous somatotropin]

The content of serotonin in hypothalamus of thyroidectomized rats is twice as low on the 5th day and twice as high on the 14th day after the operation as in the intact animals. Specific radioactivity of serotonin after subarachnoid administration of tryptophan-14C an hour before killing is twice as high on the 5th day and twice as low on the 14th day. Exogenous somatotropin prevents from the mentioned changes on the 5th day. A conclusion is drawn that the changes in serotonin metabolism in the hypothalamus of rats after thyroidectomy is mainly determined by the changes in the level of somatotropin in the organism.