CHAPTER IX 



NEW OBSERVATIONS ON THE CHEMISTRY 



AND PHARMACOLOGY OF EXTRACTS 



OF THE PARS NEURALIS 



THE purpose of this chapter is to review recent in- 

 vestigations of the chemistry and pharmacology of 

 extracts of the pars neuraHs. There is no satisfactory 

 additional evidence that more than two hormones — the oxy- 

 tocic hormone and the vasopressor or diuresis-inhibiting hor- 

 mone — are secreted by the pars neuralis. The advances 

 which have been made in elucidating the cellular origin of the 

 hormones are described in chapter i. The physiological im- 

 portance of these hormones is discussed in chapter x. 



The chemistry of the active principles. — The isolation of 

 either the oxytocic or the vasopressor principle as a pure, 

 crystalline substance is a goal yet to be attained. Stehle and 

 Eraser (1935) have described new methods for separating 

 and concentrating both hormones. However, these methods 

 are too complicated for detailed review here. The authors 

 found that, after the removal of most of the impurities, both 

 of the hormones are soluble in 96 per cent methanol. Subse- 

 quent separation and concentration of the hormones was ef- 

 fected by the addition of ethyl acetate to solutions of both 

 or one hormone in methanol (96 per cent) or ethanol {ca. 98 

 per cent). The pressor hormone was concentrated to about 

 100 times the value of International Standard Powder, the 

 oxytocic hormone to about 125 times that value. Therefore, 

 the potency of the preparations of Stehle and Eraser was 

 about the same as that of the extracts of Kamm and his 

 colleagues (1928). Tests for various amino-acids in the puri- 

 fied extracts were reported. The depressor substances in the 

 posterior lobe were studied by Larson (1936), who attributed 



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