Follow-up – WAA
There appear to be fundamental differences in how males and females process painful stimuli, according to a report published by Live Science. Live ScienceIn order for a person to feel pain, sensory nerve cells called pain receptors detect painful stimuli and then send a signal to the brain for interpretation. These painful stimuli include extreme temperatures, mechanical pressure, and inflammation. How each person perceives each stimulus varies, depending on various factors, including the person’s gender.
Several studies have reported that women have a higher sensitivity to pain and a lower pain threshold than men. For example, a 2012 study that examined how men and women respond to physical stress found that women are more sensitive to mechanical pain than men. In another study, men and women were asked to indicate when they sensed a heat stimulus and rate its intensity. The study indicated that women had a lower pain threshold for heat than men.
Conflicting study results
“It is well known that females are more sensitive to pain than males,” said Jeffrey Mogil, a professor of behavioral neuroscience at McGill University who studies sex differences in pain. “It’s a finding that has been shown in hundreds of studies, but not all of them are statistically significant, and they all point in the same direction.”
However, some studies actually show the opposite. In a 2023 study, researchers recruited 22 teenagers—12 females and 10 males—to test their thermal pain sensitivity. Participants were exposed to hot and cold stimuli and then asked to rate their pain intensity. Males rated the pain intensity of both stimuli higher than females. Other studies have found no difference in how males and females respond to pain-causing heat.
“Meaningful” metrics
Frank Porreca, a professor of neuroscience at the University of Arizona, said the reason for the disagreement among scientists and in the results of scientific studies is that there are no “meaningful” measures of pain tolerance, and a person’s pain threshold and tolerance tend to vary across tests and environments. Some studies have also found that women are more reliable on the test than men, providing more consistent assessments of their pain.
Pain sensitivity by type
Porreca has been studying the mechanisms that can enhance pain, and he and his team recently discovered that male and female pain receptors are activated by different substances, meaning that the first step in pain perception is different between the sexes.
Mogil said he had not previously shown that the characteristics of pain receptors themselves depended on sex, and it was known that pain stimuli need to exceed certain thresholds to activate pain receptors. Normally, a low-intensity stimulus, such as drinking cold water, does not activate pain receptors — but if someone has a mouth ulcer, the pain receptors there will be activated. In this scenario, Porica explained, the threshold for activating pain receptors is lowered, and then it would be possible to see if this “sensitization” was sex-dependent.
To test the hypothesis, the researchers took samples of pain receptor cells from the dorsal root ganglion, a terminal near the spinal cord through which sensory information passes to the central nervous system. The researchers took cells from male and female mice, nonhuman primates and humans and exposed the cells to different substances.
Previous studies have implicated the hormone prolactin in female pain responses and a chemical messenger called orexin in male pain responses, so they seemed like the perfect agents for the experiment. The results showed that cells behaved differently when exposed to either substance across all the species sampled.
pain receptors
Prolactin lowered the threshold for activating pain receptors in females but had no effect on males. Conversely, orexin sensitizes male cells but has no effect on female cells. Both substances are naturally present in both sexes but in different concentrations.
“The pain receptors we derive from male or female animals or postmortem human donors are completely different in the processes that produce this decrease in thresholds,” Borreca said.
Inventing new treatments
He added that this discovery could help in creating pain treatments that can be improved for men and women, especially since “most pain patients in the world are women.” For example, the chronic pain condition fibromyalgia is more common among women than men in the United States.
“Regardless of which sex is more sensitive to pain, there is growing evidence that the circuits behind the scenes are different between males and females,” Mogil said.
Source: Arabic
