Scientists exploring the brain's reproductive wiring have made a discovery that could end heartache for thousands of infertile couples.
It could also free millions of women worldwide from reliance on the pill and its side effects.
Researchers, led by Otago University neuroscientist Professor Allan Herbison, have found the switch that turns normal fertility signals in the brain on and off.
"These findings open up avenues for tackling what is often a really heart-breaking health issue. Infertility is a major issue affecting millions of people worldwide," Prof Herbison said.
Estimates show up to 20 per cent of New Zealand couples are infertile, while up to one-third of female infertility cases may involve disorders in the area being studied. The final piece in the puzzle was finding the trigger site between a small protein known as kisspeptin and its receptor, called Gpr54.
Mutant mice that were missing the receptor in a specific neuron were infertile and did not go through puberty - but the researchers showed the infertile mice could go back to normal fertility by placing the receptor gene only in the targeted neurons.
Kisspeptin's crucial role in fertility was discovered a decade ago but now researchers have pinpointed the exact spot the protein acts - meaning it can be targeted with drugs.
"If your kisspeptin is not working or there's a problem in the link between the brain and the ovary they will not communicate properly and you will become infertile," Prof Herbison said.
A small clinical trial was already under way in Britain testing the protein's potential to enhance IVF programmes.
Big pharmaceutical companies were also watching developments closely because the discovery could be worth millions in new drug markets.
Prof Herbison said the findings could create new classes of contraceptives and spell the end of the oral contraceptive pill, or at least provide an alternative that was not dangerous for older woman and smokers.
"When you find the molecule that controls fertility you can make the opposite, meaning we could turn fertility off in the brain."
Having a contraceptive pill that targeted the brain directly without flooding the body with hormones would also mean side effects of the traditional pill, such as blood-clotting, could also be avoided.
Clinical director of the Otago Fertility Service Professor Wayne Gillett said the breakthrough could revolutionise the way IVF was managed, making the procedure safer and more efficient by bypassing IVF's most frequent and destructive side effect - overstimulation of the ovaries.
Down the line the findings could help the obese, advance male infertility and prostate cancer treatments and, theoretically, help treat polycystic ovary syndrome, which affects up to 10 per cent of woman of reproductive age.
- © Fairfax NZ News
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