Vol. 43 T O R R E Y A December 1943 



Animal Hormones Affecting Growth and the Several Effects of 

 Single Hormones* 



Oscar Riddle 



In higher vertebrate animals and man. the forms in which hormonal regu- 

 lation is best known, several hormones act as stimulants to growth. In some 

 cases this stimulus is fairly restricted or localized and only a single fimction or 

 special tissue is affected. But advancing information indicates that many 

 hormones affect a variety of functions and organs. For higher animals it has 

 been learned during the past 15 years that the center of hormonal regulation 

 resides in the anterior pituitary gland ; its hormones may be called '"trigger" 

 hormones. In large measure these "trigger"" hormones stimulate other hormone 

 producing glands (thyroid, gonad, adrenal) whose products may thus in turn 

 be called "target" hormones (thyroxine, estrone, testosterone, cortin). Growth 

 processes are affected by both ''trigger" and "target"' hormones; one of the 

 former, prolactin, and one of the latter, estrone (or estrogens), are here util- 

 ized as illustrations of hormones which are not only related to growth but 

 which also exhibit a variety of actions. 



Prolactin stimulates milk secretion in mammals and growth of crop-sacs 

 and production of crop-milk in pigeons. It sometimes reduces or prevents the 

 secretion of the "trigger" hormone, gonadotrophin. It releases broodiness 

 (fowl, pigeon) and maternal behavior (rats). Perhaps it prolongs the life of 

 corpus luteum cells, and stimulates their production of the hormone, proges- 

 terone. In pigeons, but not in rats, it seems to be the chief and best of hormones 

 for the promotion of bodily growth. It assists growth in dwarf mice and there 

 synergizes the action of thyrotrophin on growth. In pituitaryless pigeons pro- 

 lactin can increase body weight and intestinal and liver tissue to an extra- 

 ordinary degree, and likewise it can partially support the pancreas ; but all 

 these actions can be shared or augmented by hormone of the adrenal cortex 

 (unpublished, ]\Iiller and Riddle), while still a third hormone, thyroxine, fur- 

 ther assists in maintaining the weight of the intestine and pancreas. It is a 

 moot question whether the pituitary gland produces a single "growth hor- 

 mone"" or whether bodily growth (probably somewhat differently stimulated 

 in different species) is a summation of effects of various "trigger" and "tar- 

 get" hormones. 



Estrone, or stable estrone-like substance, has been obtained from yeast, 

 rape seed, potatoes and female willow catkins — even from petroleum and lig- 



* Presented in more detail at the 75th Anniversary Celebration of the Torrey Botanical 

 Club at the Boyce Thompson Institute for Plant Research, Inc. Wednesday, June 24, 1942. 



Only an abstract of the discussion is published here. 



96 



