A landmark discovery by University of Otago researchers represents a substantial step forward in treating infertility.
It could lead to novel infertility treatments for couples who struggle to conceive.
The finding is the final piece in the puzzle of understanding how the brain achieves normal fertility in humans and other mammals.
Normal fertility in humans depends on the key cellular location of signalling between a protein named kisspeptin, and its receptor, Gpr54, the research team led by Otago neuroscientist Professor Allan Herbison discovered.
Kisspeptin had been found to be crucial for fertility in humans and, in a subsequent major breakthrough, Prof Herbison showed that the protein was also vital for ovulation to occur.
In the latest research, Prof Herbison and colleagues studied mice that lacked the Gpr54 receptor. The mice did not undergo puberty and were infertile. When the mice were exposed to the gene, their fertility could become normal.
This showed a substantial step forward in enabling new treatments for infertility and new classes of contraceptives to be developed, Prof Herbison said.
"Infertility is a major issue affecting millions of people worldwide. It's currently estimated that up to 20 per cent of New Zealand couples are infertile, and it is thought that up to one-third of all cases of infertility in women involve disorders in the area of brain circuitry we are studying.
"Our new understanding of the exact mechanism by which kisspeptin acts as a master controller of reproduction is an exciting breakthrough which opens up avenues for tackling what is often a very heartbreaking health issue.
"Through detailing this mechanism we now have a key chemical switch to which drugs can be precisely targeted," he said.
Researchers found that the kisspeptin-Gpr54 signalling occurred in only a small population of nerve cells in the brain called gonadotropin-releasing hormone neurons.
The findings also suggested kisspeptin may be valuable in treating diseases such as prostate cancer that are influenced by sex steroid hormone levels in the blood, Prof Herbison said.
The research findings represented a long-standing collaborative effort with the laboratory of Professor Gunther Schutz, of Heidelberg University in Germany, he said.
The findings feature in the journal Nature Communications.
Kisspeptin was originally named after the Hershey Kiss chocolate by United States researchers based in Hershey, Pennsylvania. At the time they were unaware it had a role in fertility.
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