Medicine: Inhibin

Females have two sex hormones. Males have been conceded but one, though male and female sex glands are analogous. Last week Dr. D. Roy McCullagh of the Cleveland Clinic Foundation reported in Science “almost but not absolutely conclusive” arguments for the presence of two testicular hormones. In a benzene solution an extract prepared from the gonads produces the well-known hormone which is responsible for the development and maintenance of the secondary male sex characteristics (beard, voice, chest hair, etc. etc.). It is called “androtin” from the Greek root andros (man). Dr. McCullagh made a water solution of the same extract, found it acted directly upon the pituitary gland (which androtin does not), and so concluded that he had found a new hormone. He called it “inhibin,” from the Latin verb inhibere (to restrain).

Many a man, including Raymond Poincaré, Woodrow Wilson and Georges Clémenceau, has suffered from enlargement of the prostate gland after middle age. The only known remedy is surgery. In rats prostatic hypertrophy can be produced by stimulating the pituitary gland to overactivity. Dr. McCullagh found that by feeding his inhibin to rats this pituitary hyperfunction could be prevented. He concluded that probably prostatic hypertrophy is caused by 1) breakdown of the testicular cells producing inhibin, the absence of which 2) causes pituitary overactivity, which in turn 3) stimulates the androtin-producing cells of the gonads to sufficient activity to bring about 4) enlargement of the prostate gland. If this is true, prostatic hypertrophy can take place only when the inhibin-producing cells fail before the androtin-producing cells of the same glands. Then enlargement of the prostate may be cured by administration of inhibin until the glands have ceased to function altogether.