A Harvard zoologist last week proved the existence of a new female sex hormone. It had taken him 20 years. The new hormone, named relaxin by its discoverer, may be of interest to at least half the human race—for it may eventually help to make childbirth easier.
Relaxin’s discoverer is gentle, publicity-shy Professor Frederick Lee Hisaw, 52. He found the hormone during long, painstaking studies of the sex life of the pocket gopher, a small prairie animal that lives in burrows like a mole.
As a researcher at Kansas State Agricultural College in the early ’20s, Dr. Hisaw noticed a puzzling fact about the pocket gopher: the animal, for turning around in its narrow burrow, has a very narrow pelvis, and its compressed pubic bones come together in a bridge (called the symphysis), which leaves an opening much too small for the female to deliver her young. But when a female becomes pregnant, the symphysis somehow dissolves, the opening widens.
The Act. Dr. Hisaw thought a hormone in the ovaries might account for this change. He tested his theory by injecting extracts from a female’s ovaries into castrated male pocket gophers. Sure enough, the males lost their symphyses.
When Dr. Hisaw published these findings under the title, “The Influence of the Ovary on the Resorption of the Pubic Bones of the Pocket Gopher,” nobody paid much attention. But endocrinologists began to get interested when Dr. Hisaw and fellow researchers found the relaxing substance in the blood of pregnant guinea pigs, rabbits, sows, dogs, cats, mares, women. In non-burrowing animals, relaxin dissolved no bone (as in the pocket gopher) but relaxed the pelvic ligaments and widened the pelvic canal, thus making birth easier. Hisaw found that even virgin female animals were relaxed by relaxin.
It remained to be proved that Dr. Hisaw had actually discovered a new hormone. He had found relatively large amounts of the relaxing substance (whose presence was proved by its effect on guinea pigs) in the corpus luteum (a yellow mass in the ovary) and in the placenta of various animals. But he had failed to determine its chemical composition. And his theory seemed to be knocked into a cocked hat when several European investigators succeeded in relaxing animals with injections of the well-known ovarian hormones, estrogen and progesterone.
The Actor. Last week, however, Dr. Hisaw and his assistants reported in Endocrinology that the relaxing material could not possibly be estrogen or progesterone, that it must indeed be a new hormone. The proof was partly chemical: they produced a concentrated ovarian extract from which estrogen and progesterone (which are soluble in alcohol) had been removed; the extract nonetheless had a strong relaxing effect. But the most significant evidence was a contrast in speed between relaxin and progesterone. Relaxin acted within six hours, while progesterone took two to four days to produce the same effect. Estrogen seemed to be needed to help the reaction in both cases. Hisaw’s conclusion: relaxin is a separate hormone produced in the female reproductive organs by progesterone.
Relaxin seems to be a protein compound, insoluble in most solvents. Though the pure hormone has not yet been isolated, Hisaw has produced highly concentrated doses. A conscientious scientist who never lets himself get ahead of his facts, Dr. Hisaw refuses to predict what use, if any, may be made of relaxin.
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