Typically, scorpion venom acts directly on sodium/potassium channels in nociceptors to create the sensation of pain. A specialized channel known as channel 1.7 is responsible for picking up the pain signal, whereas a channel called channel 1.8 carries it to the brain.
"They just turn [the nerve] on and send that signal to the brain," Rowe said.
Not so in the grasshopper mouse. In these rodents, the scorpion toxin binds to channel 1.8. [See Photos of the Amazing Grasshopper Mouse]
Cutting a wire
By binding to this transport channel, the toxin shuts it down, effectively blocking itself, Rowe and her colleagues report Friday (Oct. 25) in the journal Science.
"It's kind of like cutting a wire," Rowe said.
The finding explains why the mice seem to feel almost no pain when stung. Instead of acting as a painful stimulus, the toxin ends up acting like an analgesic.