THE THYROTROPIC HORMONE 



such patients suffer from a purely "thyrogenic" hypothy- 

 roidism. 



Mahaux (1937) found that the elevation of the basal meta- 

 bolic rate of guinea pigs, an effect ordinarily appearing about 

 48 hours after the injection of a large dose of thyrotropic 

 hormone, was absent if i mg, of thyroxine had been adminis- 

 tered. (The calorigenic action of thyroxine was allowed to 

 decay before thyrotropic hormone was administered.) Like- 

 wise using guinea pigs, Gessler (1936) reported that oestradiol 

 or its benzoate (5.0 mg.) caused a fall in the basal metabolic 

 rate of ^-'^J, per cent. The oestrogen also appeared to lessen 

 the calorigenic action of thyroid extract. Sherwood and 

 Bowers (1936) stated that the injection of oestrone or oestrin 

 may lower the basal metabolic rate of rats as much as 28-54 

 per cent. Also, the return of the rate to normal, after a 

 marked elevation had been caused by thyroid extract, was 

 accelerated by the injection of oestrin, Oestrogens appear to 

 antagonize the action of thyroid hormone, not that of thyro- 

 tropic hormone as Gessler (1937) suggested. In the dog, ac- 

 cording to Zajic (1935), the increased metabolic rate follow- 

 ing the injection of thyrotropic hormone is not accompanied 

 by any change in the respiratory quotient." 



Extracts containing thyrotropic hormone readily cause 

 exophthalmos in thyroidectomized guinea pigs (Smelser, 

 1936; Paulson, 1937); therefore, this change cannot be caused 

 by an increased secretion of thyroid hormone. Smelser even 

 found that exophthalmos is more readily produced in thy- 

 roidectomized guinea pigs. He studied anatomically the con- 

 tents of the orbit in normal animals and those with experi- 

 mental exophthalmos. The increase in the bulk of the retro- 

 bulbar tissues amounted to as much as 40 per cent, because 

 of hypertrophy of the fatty connective tissue, the dorsal 

 lacrimal gland, the extraocular muscles, etc. As in certain 

 instances of exophthalmos associated with a low basal meta- 

 bolic rate in man, a fluid containing lipoid droplets and gran- 



" See also O'Donovan (1937) and Sinha (1937). 



[185] 



