Magazine article Science News

Con(tra)ception: Hormonal Coin Toss

Magazine article Science News

Con(tra)ception: Hormonal Coin Toss

Article excerpt

Con(tra)ception: Hormonal coin toss

Two research teams at the Salk Institute in La Jolla, Calif., have discovered a reproductive hormone that may one day be useful in the treatment of certain kinds of infertility. Another reproductive hormone, also recently isolated by one of the same research groups, may have potential as a contraceptive. In an unusual demonstration of the body's thriftiness, the hormones are a matched set: Although opposite in activity, they are largely rearrangements of the same components.

The newly discovered hormones are intriguing because they act specifically on the production of follicle-stimulating hormone (FSH), which triggers the development of ova and the production of sperm. Inhibin, one of the recently isolated hormones, acts on the pituitary gland to decrease FSH secretion without affecting levels of other hormones that are often released in tandem. Because of that specificity, says Kenneth Klivington, spokesperson for the research groups, "inhibin provides a potential ideal contraceptive for both men and women."

Unexpected findings during the research on inhibin led to the discovery of a substance that works in the opposite direction, stimulating release of FSH. That substance was reported in the June 19 NATURE. Two forms were isolated at Salk -- one named follicle-stimulating hormone releasing protein (FRP) by a group led by Wylie Vale, and the other called activin by a group led by Roger Guillemin. Klivington says it may someday lead to a "choice treatment" for infertility.

Modern contraceptive technology is prone to problems. Even though birth control pills succeed in blocking fertility in women, there are side effects that ripple throughout the hormonal system; and there is no male hormonal contraceptive available at all. The problem for researchers has been the body's intricate dovetailing of the hormones that orchestrate reprodductive events.

Scientists have long known that much of the regulation occurs in a hypothalamus-pituitary-gonad hormonal loop: The hypothalamus in the brain stimulates the pituitary to secrete two hormones, FSH and lutenizing hormone (LH), which, among other things, stimulates the production of sex steroids like estrogen and testosterone. Most birth control pills for women use estrogens and other steroids, which can disturb the rest of the hormonal balance. When researchers have attempted to use FSH-inhibiting substances as male birth control, they have been unable to block the release of FSH without also inhibiting LH. …

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