This Week in Sex: New Research on Sperm and Egg Attraction, Viagra and Skin Cancer, and Facebook and Body Image


This Week in Sex is a weekly summary of news and research related to sexual behavior, sexuality education, contraception, STIs, and more.

Why Are Sperm and Egg Attracted to Each Other?

So we all know the basic story of fertilization. A man has sperm. A woman has eggs. The man and woman have intercourse. His sperm swim up to her egg, one lucky sperm gloms on, and voila, we have a zygote.

Well apparently it’s not only not that simple, but no one knew exactly what happened between the two until now because researchers had not yet determined exactly what drew the sperm to the egg and how they attached to each other.

Half of the puzzle was figured out in 2005, when Japanese scientists found a molecule jutting out of the surface of mammalian sperm that docked on to the surface of eggs. They named the molecule Izumo after a Japanese marriage shrine.

Since then, scientists around the world have been trying to elucidate the other side of the equation—the protein on the egg’s surface that sticks to Izumo. An article just published in the most recent issue of Nature says that they finally can explain it. A team of researchers at the Wellcome Trust Sanger Institute in the United Kingdom discovered that a protein called folate receptor 4 is responsible for hooking on to Izumo and beginning the process of fertilization. They propose renaming the protein Juno after the Roman goddess of fertility and marriage. Juno has another role as well—it disappears from the surface of the egg within 30 to 40 minutes of fertilization, which prevents more than one sperm from getting into the egg. A zygote with more than one sperm would have too many chromosomes and could not develop normally.

What is particularly interesting about these findings is the discovery that without Juno, fertilization cannot happen. Female mice without Juno were healthy but could not reproduce. Researchers believe this has immediate implications for infertility treatment. Women having trouble getting pregnant could be tested for the presence of Juno. Those who don’t have it could skip other types of fertility treatments and go straight to intracytoplasmic sperm injection, in which a single sperm cell is injected directly into an egg. It’s still not clear, however, how many women are lacking Juno.

The researchers also believe that this discovery could lead to new forms of contraception that block Juno and/or Izumo, thereby preventing fertilization.

Viagra May Increase Men’s Risk of Melanoma

Since it was introduced in 1998, 23 million prescriptions have been written for the little blue pill that can help with erectile dysfunction (ED). Immediate side effects of Viagra and other similar ED medications include headaches, flushing, indigestion, nasal congestion, dizziness, and vision problems such as seeing a blue haze, increased brightness, or temporary loss of vision. Of course, the most famous side effect might be the erection lasting four hours or longer, which is warned about in every commercial. That is actually a painful and dangerous condition known as priapism. It is a rare side effect of ED drugs, but can happen when they are taken recreationally by men who do not have erectile issues.

Until now, studies suggested that there was no risk of long-term health conditions caused by these drugs. But a new study published online in JAMA Medicine demonstrates a link between Viagra use and the most dangerous kind of skin cancer, melanoma. (The study did not look at other similar ED drugs, such as Cialis or Levitra, because they did not exist when the data was first being collected.)

Researchers analyzed data from more than 25,000 men participating in the Health Professionals Follow-Up Study. They found that men who had used sildenafil, better known as Viagra, were twice as likely to develop melanoma as men who had not. This finding held up even after controlling for known melanoma risk factors, including family history of the cancer, sun exposure, and UV intensity in the state in which the men lived. There was no link between erectile dysfunction itself and melanoma.

The researchers caution that their findings show a correlation but do not prove that Viagra causes melanoma and that more research has to be done before experts would suggest changes to the guideline for prescribing Viagra.

There is, however, a scientific explanation for how Viagra could increase melanoma risk. Viagra belongs to a class of medication called PDE5 inhibitors, which also includes Cialis and Levitra. By blocking the PDE5 enzyme, the medications help the smooth muscles in the penis relax and increase blood flow. In his article for Everyday Health, Dr. Adam Friedman explains that inhibiting the PDE5 enzyme, which is also done by a mutation found in many melanoma tumors, enhances melanoma cells’ ability to invade and metastasize. He concludes, “The punchline: It is possible that by inhibiting this enzyme, Viagra may promote development of primary melanoma tumors.”

Again, this has not been proven, and no one is suggesting that men stop taking Viagra because of this one study. However, Dr. Abrar Qureshi, a professor of dermatology at Brown University and co-author of the new study, told NBC News, “But people who are on the medication and who have a high risk for developing melanoma may consider touching base with their primary care provider.”

Is Facebook Bad for Your Self-Image?

New research presented last week at the International Communication Association conference suggests that in addition to being a time-suck, Facebook may actually be damaging to some users’ self-image.

Researchers surveyed more than 800 college women to assess their Facebook habits and their body image. Respondents were asked how often they visited the site, how long they typically spent there, what they looked at, and what they were thinking about as they looked. For example, one question asked, “When looking at someone else’s photos on Facebook, how much attention do you pay to: 1) how they dress, and 2) their body?” They were then asked how they felt about their own body, including what their current weight was and what they ideally would like to weigh. Other questions touched on eating habits and school success.

On average, respondents spent 80 minutes on Facebook reading their news feed and looking at photos. Their average weight was about 149 pounds, but most respondents wanted to weigh 20 pounds less than they actually did. Women who spent more time on Facebook were more likely to feel bad about their own bodies and compare themselves to others. This was especially true for women who felt like they needed to lose weight. Women who wanted to gain or maintain their weight did not feel bad about themselves after using Facebook.

Of course, the study does not prove that Facebook causes low self-image but it did suggest that spending time on the site could exacerbate body image issues. Petya Eckler, lead author of the study, pointed out to HealthDay, “Women tend to present their ideal self on Facebook, not necessarily their actual, true self.”

We all know at this point that pictures of models in magazines are retouched to make them look thinner, but Eckler says friends may do that as well by using Photoshop or other apps, such as Skinneepix, that are specifically designed to “shave pounds” off of pictures. Comparing themselves to these idealized photos of friends can make women feel inferior. Eckler worries that this can ultimately lead to an eating disorder. “Feeling negatively about yourself and increased body comparison is sort of the first step towards disordered eating,” said Eckler.

This doesn’t necessarily mean that we should all log off of the social networking site. But we should become more knowledgeable consumers of photographs, and remember that comparing ourselves to possibly retouched photos of others—even photos of friends—is not really fair.

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Follow Martha Kempner on twitter: @MarthaKempner