When the researchers found that these rodents truly lacked this neurotransmitter -- and hence lacked the normal reaction to certain pain stimuli -- Park consulted a colleague whose expertise lay in genetics.
Exploiting a cold sore virus as a genetic ferry of sorts, the researchers tweaked the germ to carry a bit of DNA into the naked mole rats that would cause their nerves to produce substance P.
"To our shock and amazement, it worked," Park says. The naked mole rats with the genetic tweak now responded to capsaicin."
However, they were still immune to the painful sting of acid. Park and his team dug further, and what they found was that the naked mole rats' lack of substance P was only one of three adaptations that affected the way the critters sense painful stimuli.
Park says that he is hopeful the findings on naked mole rats could one day help scientists devise new ways to temper the suffering of people who battle chronic pain.
"If we can take an animal system like this and figure out they manage to modulate their experience of pain, I think it would be a giant opportunity to find out more about how we can modify pain in humans," Park says.
But as with many biological systems, cutting people's pain experience by meddling with substance P is much more difficult than it sounds. Several drug companies, including pharmaceutical giant Merck, have tried to come up with ways to block substance P to control pain. So far, the results have been mediocre at best.
One of these hopefuls, Cope says, was actually capsaicin itself. Drug developers discovered that putting the capsaicin extracted from hot chili peppers onto a painful site caused the nerve tissues to release all of their substance P in one huge gush. Once the substance P had been drained from the area, the cycle of pain was broken, at least for a while.
But there was a catch, Cope notes. It seems few people are eager to rub capsaicin onto an area of their body that already hurts.
"This is not a treatment that people are compliant with," she says. "Though it may help with chronic pain in the longer term, for the short term people did not want to make the pain worse."
Plus, as the old saying goes, Mother Nature is a miser. In short, few substances in the body do just one thing, and substance P is no exception. Park says the chemical appears so far to be involved in the function of the brain and spinal cord. So blocking it wholesale may not be a viable solution.
"It goes to show that the pain system is super complicated," Park says.
But Cope says this findings, like other advancements in pain research, are useful in assembling the jigsaw puzzle pieces of data that come together to form a greater understanding of why, exactly, we hurt the way we do.
And why, when it comes to certain types of pain, we're somewhat less macho than the average naked mole rat.
"People maybe 30 years ago thought of pain as just a symptom," Cope says. "Now we know there are different types of pain. And at some point, we may have better diagnostics and tailored treatments for different kinds of pain."