HORMONES 



adrenal medulla, and thyroxine, the hormone of the thyroid, are 

 phenolic substances. 



(2) Proteins. — To the proteins belong the hormones of the 

 hypophysis (two gonadotropins, thyrotropin, adrenocorticotropin, 

 lactogenic hormone and growth-promoting factor from the anterior 

 lobe, and the vasopressor, oxytocic and melanic-expanding principles 

 of the posterior lobe); the hormone of the pancreas (insulin), and the 

 hormone of the parathyroid (parathormone). 



(J) Steroids. — To the steroid family belong the hormones 

 isolated from the ovarium and corpus luteum, testicle, and adrenal 

 cortex, twenty-eight steroids having been isolated so far from the 

 adrenal cortex (Reichstein, 1943). They all have in common a cyclo- 

 pentanoperhydrophenanthrene ring system. 



Attempts to prepare the nonprotein hormones synthetically 

 have followed closely the determination of their chemical constitution. 

 Besides, several synthetic substances of constitution similar to, but not 

 identical with, the natural hormones have been prepared, and their 

 pharmacologic action tested. Many vasoconstrictor and bronchodila- 

 tor substances have thus been obtained which are more efficient than 

 adrenalin for some therapeutic uses. Several synthetic estrogens (di- 

 ethylstilbestiol, hexestrol, etc.) have also been obtained which are now 

 largely used instead of natural estrogens to treat ovarian insufficiency. 

 Desoxycorticosterone, a substance which is able to maintain adrenalec- 

 tomized animals in normal condition, has been prepared by partial 

 synthesis. Probably a wide field for pharmacological investigation of 

 corticoadrenal hormones will soon be opened, since Reichstein (1943) 

 announced a method of preparing steroids containing an atom of oxy- 

 gen linked to carbon atom 1 1 . Steroid hormones are usually prepared 

 by partial synthesis, starting from stigmasterol, a product of soybeans. 



The active substances extracted from an endocrine gland do not 

 always represent the circulating natural hormone. Thus, while thy- 

 roxine increases the oxygen consumption if given to the whole animal, 

 it does not have such an action upon isolated tissues. Furthermore, 

 whereas only from 25 to 50% of organically bound iodine is extract- 

 able from the thyroid in the form of thyroxine, all the iodine compounds 

 of the thyroid are able to increase the rate of metabolism. These and 

 other reasons make it dubious that thyroxine is a constituent of the 

 thyroid hormone or the hormone itself. 



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