Sex is influenced by spinal cord - rodent study

Researchers in Portugal and France discovered that the spinal cord plays a crucial role in sexual behaviour in mice and rats, opening new ways for treating sexual dysfunction in humans. 

Scientists previously believed that spinal cord nerve cells were only responsible for triggering ejaculation, while the brain was the main player in more complex sexual behaviours like arousal, courtship and copulation.  

Researchers at EARA member Champalimaud Centre for the Unknown and the University of Bordeaux initially focused on a muscle beneath the penis responsible for ejaculation. Using genetically altered mice, they discovered that specific spinal cord nerve cells (Gal+ neurons) control this muscle's contractions. 

In another study using mice and rats, researchers used optogenetics, a technique that makes specific cells respond to light, to selectively stimulate Gal+ neurons, triggering ejaculation. In mice, however, Gal+ neurons also required additional signals from the brain. The spinal cord also appeared to "remember" recent ejaculation, as stimulation could not trigger a second ejaculation immediately after the first. 

The destruction of Gal+ neurons in both species also showed different responses, with rats showing more negative alterations than mice. 

"Rats may be good models for studying premature ejaculation," notes Constanze Lenschow, leading author of the study published in Nature Communications. "But mice might actually be better for understanding how human sexuality works, how arousal builds and how ejaculation is regulated."