New Sex Hormone Found

A new human sex hormone has been found, a new study says. The naturally occurring substance could lead to the long-sought male birth control pill, researchers cautiously speculate.

Gonadotropin-inhibitory hormone (GnIH)—first identified in birds about a decade ago—was recently discovered in the hypothalamus of the human brain. The hypothalamus produces hormones that regulate sleep, sex drive, body temperature, and more.

GnIH suppresses another hormone—gonadotropin-releasing hormone (GnRH)—which spurs the release of additional hormones, which prime the body for sex and reproduction. So scientists cautiously suggest that contraceptives based on the newfound hormone could someday be possible.

"That is an idea we've toyed with," said study co-author George Bentley, a biologist at the University of California, Berkeley. But "we don't know enough about it yet."

Louis DePaolo, the U.S. National Institutes of Health's Reproductive Sciences Branch chief, agreed "it's too premature" to consider a male birth control pill.

GnIH has been known in animals since 2000, and it was known that humans have a GnIH gene, but until now it was a mystery whether humans actually produce the hormone and what its role is.

The researchers, however, extracted GnIH from five human hypthalumuses and proved that the it affects nerve cells that produce the GnRH, the fertility-boosting hormone.