HORMONES 



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Hyperglycemic Factor of the Pancreas. Certain commercial prepara- 

 tions of both amorphous and crystalline insulin have been found to con- 

 tain an impurity which, surprisingly enough, causes an increase in blood 

 sugar levels. This substance, the hyperglycemic factor, is present in the 

 pancreas and also in the stomach lining. It appears to be a protein and 

 to act by causing breakdown of glycogen (glycogenolysis). Its physio- 

 logical role has not been clarified. 



Lipocaic. Animals which have been rendered diabetic by removal of 

 the pancreas have been observed to accumulate great amounts of fat in 

 the liver. Since the development of such fatty livers can be prevented 

 by the feeding of raw pancreatic tissue, but not by insulin, the existence 

 of another hormone in the pancreas was postulated. This substance, 

 which was named lipocaic, is probably not a hormone, since the effect 

 can be produced by pancreatic juice {i.e., the external secretion of the 

 pancreas) and can also be duplicated by choline or methionine. Preven- 

 tion of fatty livers by raw pancreas is apparently due to the presence of 

 proteolytic enzymes which make methionine more readily available from 

 food proteins. 



Hormones of the posterior pituitary 



The pituitary or hypophysis, a small endocrine organ located in the 

 center of the head, is the master gland of the whole hormone system of 

 higher animals. Its special importance is due to the large number of 

 hormones it produces and to the fact that several of these have the 

 particular function of stimulating other glands to secrete their character- 

 istic hormones. Thus the pituitary directly or indirectly influences a 

 great number of bodily processes. The gland consists of anterior and 

 posterior lobes and a small center section. Extracts of the posterior 

 lobe have three well-defined effects on the animal, namely, those of raising 

 the blood pressure (pressor effect) , stimulating the contraction of uterine 

 muscle and, to a smaller extent, of smooth muscles generally (oxytocic 

 effect), and suppressing urinary secretion (antidiuretic effect). 



The antidiuretic effect is caused by the same substance that produces 

 the pressor effect (vasopressin). Lack of it causes diabetus insipidus, 

 a disease in which the volume of urine excreted is enormously increased, 

 although sugar is not present. 



Oxytocin. The substance responsible for the oxytocic effect, oxytocin, 

 has been very highly purified, and the best preparations of it seem to be 

 substantially one substance. It is a white, amorphous, water-soluble 

 powder with the properties of a basic polypeptide. According to Pierce 

 and du Vigneaud it yields on hydrolysis one molecule each of leucine, 

 isoleucine, tyrosine, proline, glutamic acid, aspartic acid, glycine, and 

 cystine, and three molecules of ammonia. The molecular weight is close 

 to 1,000. Thus it is an eight-membered peptide. The sequence of the 



