| Abstrakt: |
The interference of hyperthyroidism with the response of castrate female rats to estrogenic hormones was first reported by Reiss and Perény.1These authors came to the conclusion that there is an antagonism between the two hormones. Their observation has been confirmed later by Weichert and Boyd2and Van Horn.3The latter advanced the explanation that the increased metabolism obtained by thyroid feeding brings about a more rapid elimination of the estrogenic substance.In all these experiments, a rather large dose of thyroid has been employed over a relatively long period, producing a considerable and sustained increase of metabolism. The present investigation was suggested by the idea that quantities of thyroid, too small to produce an appreciable increase of metabolism, might have a reversed action on the estrin effect, sensitizing the animal to estrogens. This expectation was admissible in view of the fact that thyroid at low dosage exerts an anabolic effect in contrast to the catabolic action at medication with larger quantities. This latter contention is based on the clinical observation that emaciated patients frequently gain weight when small doses of thyroid are given. Our own observation in thyroidectomized rats is also in agreement with this view. The repair of loss in weight suffered through the operation is extremely slow for a long time, but rapid gain follows medication with minute doses of thyroid. Whether or not the non-thyroxine fraction of the thyroid gland might act differently than the thyroxine fraction in this respect, was a second question to be investigated.Female rats 80 days of age and of established estrous cycle were castrated and after allowance of a reasonable time for recovery tested for absence of estrus. For priming, a safe excess of urinary estrin was used and thereafter the minimum effective dose was determined. The total quantity of estrin given to induce estrus in a group of rats was termed a unit, Injections were given 6 times, 3 each on 2 consecutive days. Vaginal smears were taken repeatedly on the fourth and fifth day. Only perfect estrus was counted as positive response; proestrus reaction was not counted. |
