Outer space is not an environment that is very welcoming to us Earthlings. Microgravity wreaks havoc with our bones, muscles, and blood availability and distribution, and increased radiation is seen as a constant and present danger. Adding to heart and vision problems, there could be something else that might affect some of the astronauts who go to space: erectile dysfunction.
Studies of the sexual health of astronauts are actually quite limited, and what it is known is usually anecdotal and based on word of mouth. But sexual health is an important part of general health, despite the general uneasiness of space agencies to look into it.
Researchers at Florida State University simulated the effects of microgravity on a group of 43 male rats. This was done by lifting their hind legs at a 30-degree angle for four weeks. A control group of an equal number of rats was kept on the ground. Hindlimb unloading is not a perfect simulation of microgravity, but provides important insights.
The rats in both groups were then divided into three sub-groups and exposed to galactic cosmic rays (GCR) in the GCR simulator at the NASA Space Radiation Laboratory. GCRs are protons and ions moving at high speed. The rats were exposed to either high levels, low levels, or no radiation.
A year later, the team looked at signs of erectile dysfunction in the rats. They measured more oxidative stress and a narrowing of the blood vessels (endothelial dysfunction) in the tissues around the penis in the animals that had radiation exposure compared to those that didn’t – even at low doses. Microgravity also increased these two risk factors, but to a lesser extent.
Despite the limitations of the study, it is important that this is investigated in humans. The long-term effect is certainly concerning, but the team believes that this could be alleviated by taking antioxidants, although this has not been tested yet.
“[T]his work indicates that sexual health should be closely monitored in astronauts upon their return to Earth,” corresponding author Dr Justin D. La Favor said in a statement. “While the negative impacts of galactic cosmic radiation were long-lasting, functional improvements induced by acutely targeting the redox and nitric oxide pathways in the tissues suggest that the erectile dysfunction may be treatable.”
The study is published in The FASEB Journal.