This mole rat doesn’t feel any pain from acid, chili, or even wasabi
While we humans suffer from the heat of the spicy pepper on our tongues and the burning of the wasabi as it comes out of our nose to the brain, one species of African mole rat doesn’t seem to experience any pain at all.
As discovered in 2008 By neurobiologist Gary Lewin of the Max-Delbrück Center for Molecular Medicine in Berlin, Germany, the famous naked mole rat is insensitive to capsaicin – the molecule that makes chili peppers so pungent. Now new search led by Lewin discovered that a close relative, the highveld mole rat, is not only immune to chili pepper and weak hydrochloric acid (pH 3.5), but is also resistant to allyl isothiocyanate (AITC) , a chemical that attacks proteins in the body and gives wasabi the strong mustard scent that goes so well with sushi.
Although underground rodents rarely encounter freshly prepared fish, they eat plant roots that can produce irritants – harmful substances called “ algogens ” – in an attempt to protect themselves from becoming food. However, the South African highveld mole rat has developed resistance to algogens, which includes being immune to those made by biting insects like the poisonous Natal droptail ant that share its burrow systems, which could have allowed the species to colonize habitats than other moles. rats generally avoid.
The new study compared the response of nine species of burrowing rodents to dilute hydrochloric acid, capsaicin and AITC, all of which trigger a brief burning sensation on the skin of humans and other mammals. Experiments showed that three species were insensitive to acid and two had no signs of pain after being injected with capsaicin. Only one species – the top-tier mole rat – resisted the chemical wasabi AITC.
To determine what makes highveld mole rats unique, the researchers then took tissue samples from the spinal cord and dorsal root ganglia, which contain nerve cells involved in transmitting pain signals, from various sources. rodent species. They measured and compared the activity of around 7,000 genes in these neurons and revealed two with genetic variants in the highveld mole rat. The two genes, TRPA1 and NaV1.7, encode instructions to create channels that pump charged ions into or out of a nerve cell, thereby controlling the transmission of signals along the neuron.
Although the TRPA1 ion channel is less active in many species, it has been completely deactivated during the evolution of the high-level mole rat, giving it the ability to be insensitive to the chemical AITC found in wasabi. Scientists have also shown that another ion channel, NALCN, is always open: When given a drug that blocks the NALCN channel, the animals became sensitive to AITC and the venom of the droptail ant. These results suggest that the NALCN gene is ultimately responsible for the high-level mole rat’s extraordinary resistance to pain.
Ion channels may have been identified in mole rats, but blocking the same channels in humans has obvious pharmaceutical application in the potential to create potent pain relievers. As principal investigator Gary Lewin said, “The information provided by our studies on these animals should contribute, among other things, to the development of new analgesics.”