272 C. N. H. LONG 



have resulted in the preparation of quantities of the synthetic hormones 

 far exceeding those ever available from natural sources. The importance 

 of this to the further conduct of research in the field of adrenal physi- 

 ology is obvious, while the potential value of these new synthetic hor- 

 mones in the treatment of human disease can now, for the first time, 

 really be explored. 



The Regulation of Adrenal Cortical Secretion 



The manner in which the activity of the adrenal cortex is adjusted 

 to the needs of the organism and the circumstances which call forth an 

 increased secretion of its hormones is a problem engaging many investi- 

 gators at the present time. As I mentioned above, one of the tenets of 

 present day endocrinology is that the endocrine glands do not act in an 

 independent and haphazard manner but adjust their secretory rate very 

 closely to the actual needs of the moment. 



The second question to be answered is : "What are the factors that 

 regulate the secretory activity of this gland?" This requires for its solu- 

 tion the development of methods that will tell us when the gland is 

 actually producing its hormone at an accelerated rate. 



A good deal of information on this problem is now available. In 1930 

 P. E. Smith (2) showed that removal of the hypophysis in the rat was 

 followed by atrophy of the adrenal cortex and that this could be pre- 

 vented by the injection of crude pituitary extracts or by implants of the 

 anterior pituitary itself. A large amount of work has since shown that 

 all conditions that cause adrenal cortical enlargement, and these are too 

 numerous to mention, fail to do so in the absence of a factor from the 

 anterior lobe of the pituitary. This factor is a protein hormone now 

 known as the adrenotrophic or corticotrophic hormone. It has recently 

 been isolated from the anterior lobe in a highly purified if not com- 

 pletely pure form by workers in two laboratories. Such a preparation 

 has been obtained from sheep glands by Li, Simpson, and Evans (3), 

 and from hog glands by Sayers, White, and myself (4). 



It is interesting to report that these two groups, working independ- 

 ently and with the pituitaries of different species, isolated a substance 

 whose biological, chemical, and physical properties agreed in a remark- 

 able manner. 



When injected into animals this trophic hormone produces all the 

 effects given by the cortical hormones themselves. Thus it has been 

 found that it brings about an increased level of liver glycogen and of 



