THE PITUITARY BODY 



cerebrated or decapitated frog. The transplantation of the 

 pars neurahs into tadpoles is followed by a reduction (shrink- 

 age, emaciation) in body size (Swingle, 1922; Allen, 1929). 

 Belehradek and Huxley (1927) found that the injection of 

 posterior-lobe extract into Amblystoma (larval and adult) was 

 followed by an increase in weight during the fifth to tenth 

 hour after injection; repeated injections, however, caused a 

 marked loss of weight. 



The effects of extracts of the pars neuralis on the metabolism 

 of carbohydrates. — Borchardt (1908) discovered that the in- 

 jection of an extract of the posterior lobe into rabbits pro- 

 duced a glycosuria. He also found that hyperglycemia was 

 present. The effects were most marked 2-6 hours after injec- 

 tion. As a result of the refinement and the more extensive 

 use of methods of investigating carbohydrate metabolism, 

 some knowledge of the mechanism of posterior-lobe hyper- 

 glycemia has been gained. However, the physiological im- 

 portance of these studies appears doubtful. The subcutane- 

 ous injection of a posterior-lobe extract into a normal 

 mammal produces, after about an hour, a moderate hyper- 

 glycemia (e.g., blood-sugar concentration of 150 mg. per 

 cent). The effect depends upon the liberation of glucose from 

 the liver and appears not to be mediated through the sympa- 

 thetic nervous system. After the hyperglycemia has sub- 

 sided, there often appears a moderate or slight hypoglycemia 

 which seems to be the result of an increased liberation of 

 insulin. In its more pronounced first stage of action pos- 

 terior-lobe extract antagonizes both the hypoglycemic and 

 the phosphate-lowering (blood) effects of insulin. 



Although either the vasopressor or the oxytocic principle 

 has been found to cause a typical hyperglycemia, the results 

 perhaps depend partly on the use of incompletely separated 

 principles. The vasopressor principle appears to be more 

 powerful in its effects both in causing hyperglycemia and in 

 antagonizing insulin. Whether the effects are due to the 



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