Medicine: Pocket Gophers & Pregnancy

When Kansas State College hired Freddie Hisaw as an assistant professor of zoology and mammalogist in 1919, he “didn’t even know what a mammalogist was. It turned out to be a fancy name for rodent exterminator,” says Frederick Lee Hisaw, now 64, “and one of the rodents I was to exterminate was the pocket gopher. But I soon became more interested in live pocket gophers than in dead ones.”

What made the little critter (Geomys bursarius) so fascinating to Scientist Hisaw was the nature of its pregnancy. To get around in its narrow burrows the animal has to have narrow hips, and its pubic bones are compressed, leaving an opening too small to let a female deliver its young. But millions of pocket-gopher squeals testify that the female can deliver. In 1925 Dr. Hisaw discovered how: during pregnancy the female pocket gopher secretes a hormone that causes part of the pubic bones to dissolve, leaving a wider opening. Hisaw named the hormone “relaxin” (TIME, April 10, 1944)

¶Reward of Patience. Other scientists were not convinced that Dr. Hisaw had discovered anything, because relaxin proved incredibly elusive. But at the University of Wisconsin he had a graduate student named Robert Kroc, who was not only convinced but determined to put Dr. Hisaw’s discovery to use. In 1944 Kroc went to work in the laboratories of the Maltine Co., now part of New Jersey’s Warner-Chilcott Laboratories. After an expenditure of eleven years and an estimated $1,000,000, Kroc found a way to apply the pocket gopher’s hormone to the human female biology—but for a vastly different purpose.

This week Warner-Chilcott announced that all that painstaking effort has produced a new medicine to forestall premature birth. The firm released to medical centers and drug wholesalers a hormone derivative called Releasin, which has the properties of relaxin. In a human, the drug does not work as drastically as in gophers, but it has the effect of “softening” tissues in the birth canal. It does not simply make delivery easier—though it does that too. Its chief virtue is to halt premature labor so that a fetus can be carried to term, or nearly so. In 75% of 200 cases so far, Releasin has been successful in thus arresting premature labor.

From Sow Ovaries. The chief drawback now is the scarcity of the raw material. There is no way of extracting relaxin from pocket gophers, and it is present in some bigger animals in only negligible quantities. But for some reason that researchers (including Dr. Hisaw, now at Harvard) have not fathomed, the ovaries of the pregnant sow are the best source. Fortunately some sows are pregnant when slaughtered,* and from 110,000 lbs. of sow ovaries a year the laboratories extract 100 ounces of Releasin. This is enough for seven injections for each of 18,000 patients—fewer than one in ten of the U.S. women who annually go into premature labor after the sixth month, when the fetus has a chance of survival. Cost of a seven-shot course: $150 to $175, depending on hospital markups.

*Hog raisers commonly put a boar in with a herd of fattening sows; otherwise, on coming into heat, they would rush around and wear off a lot of market-value fat. The boar pacifies them and, in the bargain, creates the main source of Releasin.