Naked mole-rats resist the accumulation of hypoxia-induced oxidative damage

Abstract

Naked mole-rats are among the few mammals with the ability to endure severe hypoxia. These unique rodents use metabolic rate depression along with various molecular mechanisms to successfully overcome the challenges of oxygen-limitation, which they experience in their underground borrows. While studies have reported that naked mole-rats exhibit inherently higher levels of oxidative damage across their lifespan as compared to mice, it has yet to be determined whether naked mole-rats are vulnerable to oxidative damage during periods of low oxygen exposure. To investigate this phenomenon, we examined cellular oxidative damage markers of macromolecules: DNA oxidation determined as 8-oxo-2’deoxyguanosine (8-OHdG8) levels, RNA oxidation as 8-hydroxyguanosine (8-OHG), protein carbonylation, and lipid peroxidation in normoxic (control), acute (4 h at 7% O2), and chronic (24 h at 7% O2) hypoxia-exposed naked mole-rats. Brain appears to be the most resilient to hypoxia-induced oxidative damage, with both brain and heart exhibiting enhanced antioxidant capacity during hypoxia. Levels of DNA and RNA oxidation were minimally changed in all tissues and no changes were observed in protein carbonylation. Most tissues experienced lipid peroxidation, with liver displaying a 9.6-fold increase during hypoxia. Concomitantly, levels of DNA damage repair proteins were dynamically regulated in a tissue-specific manner, with white adipose displaying a significant reduction during hypoxia. Our findings show that naked mole-rats largely avoid hypoxia-induced oxidative damage, possibly due to their high tolerance to redox stress, or to reduced oxidative requirements made possible during their hypometabolic response when oxygen supply is limited.