THE PITUITARY BODY 



physectomized; obesity in all) and Aschner and Porges (one 

 dog) reported in 191 2 that hypophysectomy lowered the 

 basal metabolic rate. According to Houssay (1934), the basal 

 metabolism of the dog is reduced to about 15 per cent below 

 normal as a result of hypophysectomy. This is due to a re- 

 duced thyroid function. Hypophysectomy, in one series of 

 dogs, was followed by a lowered basal metabolic rate ( — 12 

 per cent) ; subsequent thyroidectomy caused a further reduc- 

 tion (to —22 per cent) similar to that following thyroidec- 

 tomy alone ( — 24 per cent). Hypophysectomy after thy- 

 roidectomy was found not to alter the basal metabolic rate. 

 Foster and Smith (1926) were the first to observe that re- 

 placement therapy by pituitary homo-implants raised the 

 basal metabolic rate of the hypophysectomized animal (rat) 

 to normal. In the hypophysectomized dog, Houssay and 

 Artundo (1933) and Strieck (1933) showed further that ante- 

 rior pituitary extracts usually caused no increase in the basal 

 metabolic rate unless the thyroid was intact. 



Numerous experiments have been performed with non- 

 hypophysectomized animals. Siebert and Smith (1930) were 

 the first to demonstrate that a crude extract of the anterior 

 pituitary markedly raised the metabolic rate only if the thy- 

 roid was intact. Treatment of young normal guinea pigs for 

 a period of 10 days raised the metabolism as much as 60 per 

 cent. When the injections were continued for a period of 4 

 weeks, the metabolism progressively fell to a normal level 

 just as the thyroid's microscopic appearance again resembled 

 that of an untreated animal. Verzar and Wahl (1931) re- 

 ported that thyroid stimulation by an anterior-lobe extract 

 could be demonstrated by an increased oxygen consumption 

 in guinea pigs 20-36 hours after the injection of the extract. 

 Guinea pigs and rats which had received injections of ante- 

 rior-lobe extract were markedly more sensitive to atmos- 

 pheres low in oxygen tension than similarly treated animals 

 which had previously been thyroidectomized (Houssay and 



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