The grasshopper mouse, which lives in the southwestern portion of the United States and Mexico, is practically immune to pain. Among other benefits, the adaptation expands the species' choice of prey to include more dangerous threats like scorpions.
Curious about the mechanisms that protect grasshopper mice and eager to see if their natural defenses could be translated into safer pain killing medicine, scientists studied the unique mouse and released their findings this week, according to USA Today.
"Some people might say, 'Why would you study grasshopper mice and bark scorpions?' " said Ashlee Rowe, an evolutionary neurobiologist from Michigan State who led the study. "There's a whole lot of things animals can do that we can't. ... There's potential for applying it to human biomedical problems, for sure."
Researchers found that the structure of grasshopper mice's nerve cells gives them the ability to withstand multiple bites from a scorpion, an experience victims have compared to "being branded" and one that could kill a small child, according to USA Today. The authors of the study believe this rare ability could potentially lead to more natural pain killing medicine with fewer side effects.
Rowe and colleagues tested the grasshopper mice against regular house mice by injecting each with a low dose of scorpion poison. The regular mice responded by licking the entry point for up to three and a half minutes -- licking being a natural response to pain -- while the grasshopper mice licked its wound for just nine seconds. The fact that the grasshopper showed some response to the injected area means they experience pain, but only for a short period.
Researchers repeated the experiment but replaced scorpion venom with a pain inducing chemical. Results remained the same, indicating that mice aren't just protected from scorpion bites, but pain in general.
Studying the scorpion venom-nerve cell interaction in more detail, researchers discovered that the venom's toxin bonds with portions of the nerve cell, which lessens pain signals to the nervous system.
Allan Basbaum of the University of California, San Francisco, who was not part of the study, called the results "provocative," but felt the effects of the toxin may affect other areas of the grasshopper mouse's system not mentioned in this study.
Rowe agrees with that assessment, but believes the interaction demonstrated in her study is accurate and integral to the grasshopper mouse's unique abilities.
The mice "make a living in the desert. They do stuff we can't do," she said. "I have a lot of respect for this animal."
