Erections: what we learned from mice could help with sexual health in men

By Christian Göritz, Karolinska Institutet

Have you ever wondered how penile erection works but never dared to ask? Well, imagine a dry sponge in a condom. Now pour water on the sponge (that’s the blood flowing in). There you have it.

This penis “sponge” is scientifically termed corpora cavernosa. Erections depend on the influx and trapping of blood. Smooth muscle cells regulate the blood flow into the sponge and its subsequent firmness. In a recent study, my colleague and I delved into the role of penile fibroblasts, the most abundant cells in the human penis, about which little was previously known.

We discovered that penile fibroblasts help smooth muscle cells to relax. Using a technique to render cells light-sensitive enabled us to activate fibroblasts by shining blue light from outside onto the penises of mice.

We found that light-induced activation of fibroblasts relaxed smooth muscle cells and increased blood flow. The effectiveness of this relaxation-support depends on the number of fibroblasts. More fibroblasts led to easier relaxation and increased blood flow.

We also learned that the number of fibroblasts is not static and identified the signalling molecules regulating the number of fibroblasts in the penis. By deleting or over-expressing the relevant molecules, we could increase or decrease the number of fibroblasts and in response see the corresponding changes in penile blood flow.

But we quickly learned that too many fibroblasts has negative consequences. Mice with very high numbers of penile fibroblasts showed erections that lasted for several hours. In men, this corresponds to a painful pathological condition termed priapism, which demands a visit to the hospital.

Can penile erection be trained? In humans, much of the “erectile training” occurs naturally during sleep, with men experiencing three to five erections a night, known as “nocturnal penile tumescence”.

To test the importance of training, we artificially changed the frequency of erections in mice by targeting the brain region responsible for initiating an erection.

Read Full Story https://theconversation.com/erections-what-we-learned-from-mice-could-help-with-sexual-health-in-men-222553