Strange rats don't know how to hurt

It was hairless, had huge teeth, buried itself in the ground, and had no sense of acid or chili. The only cold-blooded mammal known on this earth is the East African mole.

" They are the sweetest, sweetest creatures I've ever worked with. They look scary but very gentle, " said neurobiologist Thomas Park at the University of Illinois, Chicago, USA. .

Scientists still know that mole rats are sensitive, possibly to replace their almost blind eyes. After studying the skin, Park and colleagues accidentally discovered that this rodent lacks Substance P - causing a burning sensation in mammals.

(Photo: Nature.com) The team found that when the moles were unconsciously immersed in a mild acid dose, similar to lemon juice, like the spicy capsaicin ingredient in chili, they didn't show pain. What pain.

"It's so surprising that they are insensitive to acid, " Park said. " All animals tested, from fish, frogs, lizards, birds to other mammals, are sensitive to acids ."

To test the possibility of deeper pain, the team used a virus carrying the gene containing Substance P implanted in a hind leg of a mole rat. The team found that DNA restored the ability to sense the pain of rats on capsaicin in chili. " They pulled their legs back and licked ," Park said. Other legs are still completely insensitive to the heat of capsaicin.

However, the moles are still completely unresponsive to acid, even when genes contain Substance P. This proves that there is a fundamental difference in the rat's nervous system reacting to Such pain.

The group hypothesizes that the mole rats have developed the ability to be insensitive to acids to adapt to underground living conditions. They often emit high levels of CO ₂ , and in such narrow space conditions will accumulate more acid in the air. So animals must become insensitive to acid.