Erections: what we learned from mice could help with sexual health in men
Have you ever wondered how a penile erection works but never dared to ask? Imagine a dry sponge inside a condom. Now pour water onto the sponge—this represents blood flowing in. That’s essentially how an erection happens.
This “sponge” is scientifically known as the corpora cavernosa, and erections depend on the influx and trapping of blood. Smooth muscle cells regulate this blood flow, determining the firmness of the penis. In a recent study, my colleague and I explored the role of penile fibroblasts, the most abundant cells in the human penis, yet previously understudied.
Unlocking the Role of Fibroblasts in Erections
We discovered that penile fibroblasts help smooth muscle cells relax. Using a technique that makes cells light-sensitive, we activated fibroblasts by shining blue light on the penises of mice.
The result? Light-induced fibroblast activation relaxed smooth muscle cells and increased blood flow. The more fibroblasts present, the easier it was to achieve and maintain an erection.
Interestingly, the number of fibroblasts isn’t fixed. We identified specific signaling molecules that regulate fibroblast numbers in the penis. By either increasing or decreasing these molecules, we could control fibroblast levels and, consequently, penile blood flow.
However, too much of a good thing can be problematic. Mice with excessive penile fibroblasts experienced prolonged erections lasting several hours—a condition known as priapism in men, which requires urgent medical intervention.
Can Erections Be Trained?
In humans, much of “erectile training” happens naturally during sleep. On average, men experience three to five erections per night, a process called nocturnal penile tumescence.
To study the effects of training, we artificially modified the frequency of erections in mice by stimulating a brain region responsible for initiating them. Using a designer drug, we could turn erections on and off, revealing fascinating insights.
More Erections, More Blood Flow
Surprisingly, we found that frequent erections led to an increase in fibroblast numbers, improving blood flow and making erections easier to sustain. This suggests that erectile function strengthens with regular stimulation—whether spontaneous or intentional.
However, as men age, nocturnal erections become less frequent. Aging is one of the primary risk factors for erectile dysfunction (ED).
When we examined older mice, their penises had fewer fibroblasts than those of younger mice. Additionally, when young mice were deprived of regular erections for an extended period, they experienced a decline in fibroblast numbers and blood flow, mirroring age-related changes.
One possible interpretation? A lack of “training” negatively impacts erectile function over time.
Implications for Erectile Health
While spontaneous nighttime erections are a natural convenience, our study suggests that actively stimulating erections could help maintain healthy penile function. Age-related declines in nocturnal erections might be a future target for ED treatments, potentially compensated for by intentional stimulation.
By unveiling a previously unknown mechanism of fibroblast-driven erection control, our research opens doors for new ways to understand, maintain, and enhance sexual health.
