The naked mole rat just keeps getting weirder. Already odd among mammals for being hairless and cold-blooded, the unsightly, burrowing rodent also doesn’t feel certain types of pain. Mole rats are immune to the burning sensation associated with chili peppers and acids and the ache of pulled muscles, researchers report 29 January in PLoS Biology, and the team has isolated the neurotransmitter responsible for chili pepper resistance. Pain insensitivity may allow the rodents to tolerate the high acidity of their burrows–the CO2 they exhale forms carbonic acid on the humid burrow walls–and the findings may even help researchers develop new analgesics.
