Scientists from the University of California, Los Angeles, report that their study of 896 people with chronic erectile disease found that those with low levels of testosterone, a compound that promotes healthy brain development, were less likely to experience symptoms of erectile failure.
A key finding is that the men with the lowest testosterone levels also had the lowest levels of both the neurotransmitter dopamine and serotonin, which are key neurotransmitters responsible for controlling mood and arousal, and the hormone oxytocin, which promotes bonding.
“This is the first study to show a direct relationship between the level of testosterone and erectile functioning,” says senior author Daniela López-Sánchez, a research scientist in the department of psychiatry and behavioral sciences at UCSF.
“It was really interesting because testosterone is a hormone that’s a neurotransmitter.
But when you get high levels of serotonin and dopamine, they’re really not needed.
And when you’re deficient in both of those, they don’t really function.
And these people also had lower levels of the neurotransmitter oxytocini, which is associated with bonding and the feeling of being loved.”
The study, published in the journal Current Biology, also found that the people with the highest levels of dopamine and oxytocinai had lower rates of erections.
It’s possible that these chemicals may help to alleviate erectile disorders and prevent them from becoming chronic.
“If you have a lower testosterone level, you’re not going to get as many sexual responses,” says Lóñoz-Sáez.
“The way to get them back up is to have the correct level of dopamine.”
Previous studies have found that testosterone is involved in regulating the body’s reward system, and in helping us feel better when we experience stress or when we’re anxious, so it makes sense that it could play a role in reducing erectile symptoms.
But it’s also possible that people with lower testosterone levels will experience less pleasure, and that their erectile functions may improve with greater dopamine and other neurotransmitcers.
“In general, we think testosterone plays a role, but we don’t know whether it’s an optimal level,” says co-author Andrew Tarnopolsky, a UCSF postdoctoral fellow.
“And we know that testosterone levels are very sensitive to environmental factors.”
To investigate this possibility, Lóña-Sanchez and colleagues used a combination of brain imaging and behavioral testing to measure the levels of oxytocins and dopamine in 896 men.
In a previous study, researchers found that oxytocinos were associated with positive feelings and increased sexual arousal.
The men with low testosterone also had less oxytocinis in their brains, suggesting they might be less likely than their higher testosterone counterparts to experience the effects of dopamine on sexual response.
“We had already identified a relationship between low testosterone and low dopamine, but this finding was very interesting because it was the opposite,” says Tarnopsky.
“Low dopamine is linked to higher levels of sexual desire.
And so this is the only time we’ve found a relationship with oxytocino levels that is actually different than what we’d expect.”
Tarnopoloski says this study provides a promising link between testosterone and erection.
“One of the main things we’re looking at here is how testosterone and dopamine interact,” he says.
“What happens if you increase the amount of testosterone?
You increase your libido.
So we’re trying to find the link between that and erection.”
He says this link may be related to the fact that oxytocinos have been found to be involved in dopamine release.
“There is a link between the two neurotransmitts, and dopamine releases tend to happen more in the presence of testosterone,” he explains.
“That could be why it is so important to be receiving testosterone, because if you’re getting a lot of dopamine, you can actually get more testosterone and increase your sexual drive.”
He adds that it’s possible testosterone levels could be decreased by drugs like testosterone enanthate, which has been shown to lower levels in men with erectile problems.
Lóozas-Saez is now studying the relationship between testosterone levels and testosterone levels in women.
“I think the most exciting thing about this study is that it demonstrates that there is a direct link between lower testosterone and lower erectile responses,” she says.
She also hopes to learn more about how dopamine and dopamine levels differ among different types of people.
“Maybe the best way to improve erectile health is to be getting testosterone and being getting enough dopamine,” she adds.
“Hopefully, we’ll be able to identify people who are having problems and help them develop better strategies for treatment.”