A specific manipulation of receptors in the nervous system in the neurotransmitter dopamine impairs chronic pain in male mice, but not in female mice, according to scientists, who suggest that this may mean that pain begins differently for men and women at the cellular level.

“For the same magnitude of pain in a male and a female, the mechanisms that drive pain seem to be remarkably separate,” says Dr Ted Price, who conducted the study together with Dr Salim Megat and colleagues the Pain Neurobiology Research Group at The University of Texas at Dallas.

“We’ve made a cellular change that completely reverses the genesis of the chronic pain in only the male. What we’re learning is that different types of cells drive the development of pain,” adds Price, an associate professor of neuroscience in the School of Behavioral and Brain Sciences, in a media release from The University of Texas at Dallas.

Their study, published in the Journal of Neuroscience, focused on a newly discovered pain mechanism related to D5 dopamine receptors—one of five identified classes of receptors for the neurotransmitter. Mice genetically engineered to lack these D5 receptors showed significantly reduced pain responses—but only the males.

“It’s extraordinarily specific for males,” Price states. “If we see the same results in human tissues, it will support the idea that you could make a D5 antagonist drug to treat pain in men.”

The accelerating movement of research demonstrating profound differences between males and females may soon yield a new model for pain relief medication, Price adds.

“It leads me to believe that it’s fairly likely we’ll want to make male- and female-specific drugs for chronic pain,” Price states. “If not that, we may need to develop diagnostics to look at an individual’s cell types that are prolonging pain, so we can tailor the therapeutic based on the underlying mechanism. We just don’t do that right now.”

Price admits that, in one respect, his own research findings frustrate him, due to which sex they favor.

“Discovering D5 receptors as a pain relief target upsets me in a way. Most chronic pain patients are women, not men, so I would prefer to develop something that was certain to work in females,” he shares, in the release.

He’s hoping that adding his research to the mounting evidence of sex dimorphism can help bring change in how pain alleviation is viewed—and eventual relief to chronic pain sufferers regardless of their sex, the release concludes.

[Source(s): University of Texas at Dallas, Science Daily]