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Tired of spending hours looking for answers to your questions?
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 Chemical gender bendingby cris conti The first direct evidence that "gender bender" chemicals affect the fertilising ability of sperm has been revealed - but it is unclear whether this would boost or harm fertility. Researchers told the European Society for Human Reproduction and Embryology conference in Vienna that chemicals that mimic the effects of the female sex hormone estrogen can prime sperm into becoming prematurely active, burning out before they have a chance to meet an egg. "It's certainly very exciting work," says Chris Barratt at the University of Birmingham. "Sperm and the fertilization process may be much more sensitive to artificial estrogens than we thought." Chemicals that mimic action of estrogen abound in food and the environment. Many occur naturally in plants such as soy and hops, and are eliminated from the body within a few hours. Others take the form of synthetic chemicals such as pesticides and plasticisers, and build up in body tissues. Research had already suggested a link between environmental estrogens, testicular problems and low sperm counts, but this is the first time anyone has looked at their effect on sperm function, according to Lynn Fraser at King's College London, who led the new study. Turn on's Estrogen in semen and in the vagina is vital for fertilization because it literally turns sperm on. The hormone stimulates a sperm to swim, and triggers physical changes that prime it for meeting with an egg - a process called capacitation. Once a primed sperm docks with the egg, the cap on its head ruptures and releases a cocktail of enzymes that help it burrow inside and fertilise the egg. Normally, proteins in semen restrain this process, making sure it does not occur too soon. If it does, the sperm will be unable to enter the egg. "Once they have undergone this reaction, they cannot fertilise, no matter how much they wiggle," explains Fraser. Fraser and her team tested the effect of estrogen and three estrogen mimics - genistein, found in soya, 8-prenylnaringen, found in hops, and nonylphenol, found in paints, herbicides and pesticides. They mixed the chemicals with mouse sperm and found all the compounds triggered capacitation and enzyme release. But the estrogen mimics were far more powerful, triggering capacitation at concentrations a thousand times lower than estrogen itself. What's more, when the team tested the compounds on sperm that had already capacitated, they found that the estrogen mimics triggered the premature release of the enzymes, whereas estrogen did not. In fact, the results aren't a complete surprise because semen does contain several mood-altering hormones, including testosterone, estrogen, follicle-stimulating hormone, luteinising hormone, prolactin and several different prostaglandins. Some of these have been detected in a women's blood within hours of exposure to semen. The question many people will ask is whether oral sex could have the same mood-enhancing effects. "Since the steroids in birth control pills survive the digestion process, I would assume that the same holds true for at least some of the chemicals in semen," Gallup says. Doubled fertilization However, when researchers mixed sperm with eggs and then treated them with the compounds, the number of eggs fertilized was doubled. This could be a benefit for IVF techniques, said Fraser. "At first sight, these results might suggest that estrogens, particularly those found in the environment, could help fertility. However, the responses we have seen could have negative effects over time," said Fraser. Asked if estrogen mimics could harm fertility in real life, Fraser said: "The potential answer to that question would be yes." Premature capacitation and enzyme release of sperm might not be a serious problem for normal fertile men, but it could be for men with lower sperm counts. On the other hand, if the proteins that normally keep sperm under control still do their job, then the extra estrogen-like activity could actually make sperm more fertile by increasing the numbers primed for fertilization. Barratt agrees that the jury is out until more research is done. But he adds that human sperm is known to be more sensitive than mouse sperm to progesterone, a hormone in the same class as estrogen, meaning that estrogen mimics could in theory have an even greater effect on humans. Article Suggested By: PEA editors Suggest an article. |
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| A large chunk of Mandarin women confess to having had oral sex, but it clearly doesn't sit well in their stomachs: 77% think the act should be made illegal! A Chinese girl is worth seeking out, though...only 38% think it's immoral. Also, only 14% of the Chinese think sex with animal is wrong. |
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Penis enlargement science What's the "real" science behind these penis enlargement products? Can it be trusted? |
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Herbal Viagra Everyone knows Viagra works. What everyone doesn't know, is that herbal viagra-like substitutes while taking longer, work just as well... |
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History of Enlargement pills They are advertised everywhere. But where did they come from? We provide an in-depth look at their origins and evolution... |
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