Does Viagra Aid Or Hinder Fertility?
This just in: researchers say that Viagra can have an adverse affect on a man's fertility. A study on the subject, performed by Queen's University in Belfast, also says that IVF may be hampered by the use of the erection-enabling drug in IVF clinics. According to Dr. Sheena Lewis, "The message we want to get across is that caution should be taken when using recreational drugs if you are hoping to start a family."
Acrosome Reaction
On the other hand, the scientists plan to tell the members of the British Fertility Society that Viagra seems to improve sperm motility (movement), though at the same time, the drug tends to undermine the timing of the acrosome reaction, a chemical process integral to egg fertilization. In the acrosome reaction, digestive enzymes are released that serve to dissolve the protective outer layer of the egg. This reaction allows the sperm to penetrate the egg.
It seems that Viagra speeds up the acrosome reaction so that the digestive enzymes are released by the sperm long before they reach the egg. That means that once the sperm reaches the egg, it hasn't got any enzymes left to break down that outer egg layer. When this mishap in timing occurs, sperm are said to become "reacted."
After testing 45 samples of semen, researchers discovered that the samples that came from men treated with Viagra contained 79% more sperm that was fully reacted. These results tally with earlier research on mice. In the mouse study, the presence of Viagra meant that many fewer eggs had been fertilized. Only a small number of the resulting embryos continued to develop.
Serious Impact
Dr. Lewis says that the acrosome reaction involves channeling charged calcium atoms, or ions. She says that this process has an influence on many of the workings of the cells and may therefore have a serious impact on early embryo development. Lewis comments that when Viagra first came out on the market in 1998, its intended target population was men with erectile dysfunction. It was thought this population would be represented by older men, way past any desire in fathering children. But now, says Lewis, the drug has become popular as a sexual enhancement aid.
Co-author of the study, Dr. David Glenn comments, "Nearly half of licensed fertility units in the UK currently use Viagra to assist patient semen production. Our study raises questions about the drug's use in assisted reproduction."
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