THE THYROTROPIC HORMONE 



2. Physiological^ pharmacological^ and biochemical aspects of 

 the action of thyrotropic hormone. — The administration of suffi- 

 ciently large doses of anterior pituitary extract rich in thyro- 

 tropic hormone into a susceptible animal like the guinea pig 

 may produce a "syndrome" strikingly resembling Graves's 

 disease in man. These changes, of course, are prevented by 

 thyroidectomy. Friedgood's article (1934) contains a discus- 

 sion of the manner in which symptoms in guinea pigs may 

 develop in relation to the administration of extract toward 

 which refractoriness finally appears. The basal metabolic 

 rate rises at first but later returns to normal, whence re- 

 crudescences of an elevated rate may appear. The rate is not 

 necessarily high, although a well-pronounced thyroid hyper- 

 plasia may persist. Exophthalmos likewise is not necessarily 

 associated with an increased rate of basal metabolism and 

 may still be present after a long series of injections. Patho- 

 logical changes in organs like the heart, kidneys, and liver 

 are not like those of Graves's disease in man (Heinemann, 

 1937); however, this is not surprising. A number of authors 

 have offered evidence indicating that an increased concen- 

 tration of thyroid hormone is present in the blood after the 

 gland has been stimulated by thyrotropic hormone. Zunz. 

 and La Barre (1935) found that the concentration of thyroid 

 hormone in the serum of dogs is increased 2-4 times only 30 

 minutes after the injection of 60-80 guinea pig units of 

 thyrotropic hormone. (Thyroid hormone was estimated by 

 the method of von Euler and Holmquist.) 



Several authors have paid particular attention to the in- 

 direct effect of thyrotropic hormone on the oxygen-consump- 

 tion of man and animals under basal conditions after the ad- 

 ministration of thyrotropic hormone.'" Observations in man 



"According to O'Donovan and Collip (1937), pituitary extract may contain a 

 substance causing an elevation of the basal metabolic rate persisting only a few 

 hours after injection. The authors concluded that this substance is not thyrotropic 

 hormone but probably is related to or identical with the melanosome-dispersing 

 hormone of the pars intermedia and that it accelerates the rate of oxidation of fat. 



Kuschinsky (1935) reported that if rats were kept at 4° C, their pituitaries con- 



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