New 'infertility molecule' found
Dr. Kirsty Horsey
Progress Educational Trust12 May 2005
Scientists from the US have discovered an 'infertility molecule' that affects whether embryos implant in the womb. Working on mice, the scientists have found that females lacking the molecule, known as a lysophosphatidic acid (LPA) receptor, have difficulty conceiving. The mice produced eggs normally, and these fertilised in the normal way, but did not implant.
Initially, the researchers, from the Scripps Research Institute in La Jolla, California, were studying the role of LPA in the brain. The research team, led by Dr Jerold Chun, bred mice without the gene for the LPA receptor, and noticed that the female mice seemed to have fertility problems. They found that the levels of prostaglandin, a fatty acid essential for the implantation of embryos, appeared to have been affected. The team, who reported their findings in the journal Nature, say that the discovery may help research into human infertility, as women have the same LPA receptors in the womb. The discovery may also potentially lead to new treatments for infertility.
In experiments with the mice that lacked the LPA receptor, Dr Chun's team found that the way embryos were spaced in the womb changed, so that the number of implanted embryos was reduced. Instead of normal implantation, the embryos were clustered, with many sharing the same placenta, leading to litters only half as large as normal. 'When you take away just one fat receptor, named LPA3, it produces a change in the ability of the mouse to properly implant embryos', said Dr Chun. He added: 'That was a surprise, because this particular signalling system had not been on anyone's radar screen in terms of influencing implantation'.
Dr Chun went on to say that similar experiments should be done in humans, as the LPA receptor molecule might help to explain why a number of failed implantations occur. In humans, immune system problems or genetic factors might affect LPA, he said, and a drug could be developed to counter this. Dr Jaime Grifo, director of the Division of Reproductive Endocrinology at New York University Medical Centre, said that 'it is not clear how operative it is in producing infertility in normal mice', adding ' the next leap is, is it present in humans in the same way, and does it have the same impact?' However, while he said that the research might explain some failed implantations, he said that in human infertility, 'most of the problems are embryonic, and not implantation problems'. But Dr Hugh Taylor, professor of obstetrics and gynaecology at Yale University School of Medicine, disagreed. 'The major hurdle is the implantation process', he said, adding 'we don't understand it. We can stimulate lots of eggs, we can force eggs to fertilise, but we can't get them to implant'.
Reproduced with permission from BioNews, an email and online sources of news, information and comment on assisted reproduction and genetics.