Researchers have now isolated that same hormone in humans that helps control reproduction, almost like an on-off switch. It is a discovery that could lead to both new forms of birth control and novel strategies to enhance fertility.
Researcher George Bentley may know more about the mating habits of European Starlings than the birds themselves. Now, a discovery at his lab at the University of California Berkeley could someday have a profound effect on human reproduction as well.
Bentley began by studying a hormone that acts like a pause button in birds, interrupting sex drive and the production of sperm and eggs. He says it kicks in when the animals are under threat.
"So if, for example, environmental conditions become really harsh all of a sudden at this time of the breeding season, then the animal can delay breeding until conditions get better," he explained.
The hormone appears to be triggered by stress, helping birds survive by conserving energy that would otherwise be spent on offspring with limited chance of living. But, Bentley's team wanted to know whether the same hormone known as GNIH might also be present in humans and if so, whether it might serve the same function
"Because some of the hormones we study in the lab are the same between all animals, from bird to rat to primate, to human, what we study in any species can be far reaching for all the other species," assistant researcher Rebecca Calisis said.
Bentley zeroed in on a section at the base of the human brain called the hypothalamus. Using antibodies to test the tissue samples, he was eventually able to isolate the same GNIH hormone.
"We didn't know if it was there. We were pretty sure it was," Bentley recalled. "When I first looked at the sections under the microscope, I was very excited. I was trembling."
He believes the hormone could potentially lead to new and healthier forms of human birth control while learning how to block it might do the opposite, helping to make fertility treatments more effective.
"If we could inhibit the inhibitor, then we could potentially activate reproductions,so there are all sorts of clinical possibilities there," he said.
His team plans to continue studying the hormone in both animals and humans, hoping to unlock its potential for influencing reproduction.
Bentley's team also believes the discovery may have value in cancer research. Since reproductive hormones often promote the growth of cancer cells, being able to interrupt them could potentially lead to cancer-blocking drugs.