B. A. HOUSSAY 



Some of the protein hormones elicit such a small antibody re- 

 sponse, as in the case of insulin, that their administration by repeated 

 injections remains effective during scores of years. Other protein hor- 

 mones become progressively less effective, which makes it necessary to 

 increase the dose each time, as in the case of the parathyroid hormone. 

 There are still other hormones (thyrotropin, gonadotropin, and in 

 different degrees all the anteropituitary hormones) whose action de- 

 creases quickly if they are administered daily and which induce the 

 formation of antihormones. Thus, if an animal is treated with daily 

 doses of thyrotropin, it shows, at the beginning, hypertrophy and hyper- 

 function of the thyroid, but after a few weeks the action disappears 

 and is followed by atrophy and hypofunction of the organ. The 

 serum is then found to contain antithyrotropin, which not only inhibits 

 the thyrotropin action but is also capable of inhibiting the action of 

 the thyroid gland as shown by injecting such serum into another 

 animal. 



Antihormones are only produced when protein hormones are 

 administered parenterally. Gollip (1934) thought that they were sub- 

 stances of physiological importance and that each hormone should have 

 its corresponding antihormone to balance its effects. But it now seems 

 that antihormones are antibodies or immunity mechanisms (Rowlands) 

 reacting to injection of antigens from another species. It is to be noted 

 that adrenalin, thyroxine, and the steroid hormones do not produce 

 antihormones and are not proteins. For some of the actions of these 

 hormones a certain habit may be produced without any demonstrable 

 antihormones. 



The natural protein hormones do not seem to be completely 

 equivalent to those which are extracted in the laboratories, for they 

 do not induce the formation of antihormones. Thus, when a rat is 

 castrated, great quantities of gonadotropins accumulate in its blood, 

 as is readily demonstrated in parabiosis experiments — that is to say, 

 experiments involving sewing two rats together side by side, after 

 opening their bellies laterally, so that their peritoneal cavities, muscles, 

 skin, and blood vessels are fused. In this way, the gonadotropin pres- 

 ent in the blood of the castrated rat passes into the circulation of the 

 normal rat, which, as a consequence, shows an intense stimulation of 

 the gonads. This stimulation persists steadily for months, while para- 

 biosis lasts, with no sign of antihormone production, in contrast to the 



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