Males and females differ in their experience of pain due to differences in specialised nerve cells, a recent US study in mice, monkeys and humans has found.
Women tend to be more sensitive to pain than men, and are disproportionately more affected by chronic pain. These sex differences have been widely reported in previous studies, although it was not known what exactly is responsible.
Research, led by University of Arizona Health Sciences and also involving Saint Louis University and the biotech company AnaBios, focused on the nerve cells that transmit signals to the brain to result in the perception of pain, called nociceptors, which are located near the spinal cord.
The nociceptors are activated by external stimuli, such as touching something hot, although there is a threshold to reach in order for this activation to happen.
The team tested different substances on the tissues of animals and humans to investigate these activation thresholds. They saw that between male and females, there were different thresholds to how the nociceptors were activated.
For example, when the signalling of prolactin (a hormone responsible for lactation and breast tissue development) was blocked, there was reduced nociceptor activation in females but no effect in males.
Frank Porreca, at Arizona, said: “The outcomes of our study were strikingly consistent and support the remarkable conclusion that nociceptors, the fundamental building blocks of pain, are different in males and females. This provides an opportunity to treat pain specifically and potentially better in men or women, and that’s what we’re trying to do.”