PARS NEURALIS AND INTERNAL SECRETION 



The work of Pencharz, Hopper, and Rynearson (1936) in 

 the rat as well as that of Keller, Noble, and Hamilton (1936) 

 and of White and Heinbecker (1937) in the dog and that of 

 Dodds and his colleagues in the cat (1937) indicate that 

 diabetes insipidus follows the excision of the pars neuralis, 

 but that it promptly ceases if the pars glandularis is later 

 removed. Pencharz and others were unable to provoke poly- 

 dipsia in completely hypophysectomized rats by repeatedly 

 administering homo-implants (1-3 anterior lobes on alter- 

 nate days for 3 weeks). However, Keller (1937) observed a 

 dog whose diabetes insipidus disappeared as a result of 

 complete hypophysectomy. Inasmuch as the diabetes in- 

 sipidus reappeared following the administration of anterior- 

 lobe extract or the feeding of thyroid extract, Keller con- 

 cluded that the maintenance of polyuria in dogs with an 

 intact anterior lobe is due to the thyrotropic hormone. White 

 (1937), like Pencharz and his colleagues, was unable to cause, 

 by the administration of anterior pituitary extract,^ any con- 

 vincing change in the amount of urine secreted by rats from 

 which the pars neuralis or the whole pituitary had been re- 

 moved a year previously . The administration of thyroid ex- 

 tract with or without the injection of anterior-lobe extract 

 likewise was without significant effect.'' Other experiments 

 of White and Heinbecker (1937) in dogs led to the conclusion 

 that the pars glandularis secretes a diuretic principle which 

 is not thyrotopic hormone but, nevertheless, at first is in- 

 effective in the absence of the thyroid. After the removal 

 of the thyroid from the dog, the diuretic effect of anterior 

 pituitary extract gradually reappeared, perhaps, as the au- 

 thors suggest, owing to regeneration of thyroid tissue or to 

 some unknown readjustment. Hypophysectomized or nor- 

 mal dogs were about equally sensitive toward the diuretic 



^ White injected an acid extract of beef anterior lobe. 



' Farr, Hare, and Phillips (1937) stated that cats with diabetes insipidus caused 

 by lesions of the supraoptico-hypophysial tract exhibited a pronounced increase in 

 the polyuria, if a saline suspension of beef anterior lobe had been injected. ■''?vPl'?*^'" 



^ ff ^•^ <\M 



