In the subterranean depths of East Africa, the naked mole-rat (Heterocephalus glaber) lives in crowded burrows where carbon dioxide is suffocating and oxygen often drops to levels fatal to any other vertebrate. For any conventional mammal, just three or four minutes without oxygen triggers an irreversible neurological catastrophe: neurons deplete their energy and die, unable to metabolize glucose. However, this rodent has developed an unusual biochemical trick: it can survive up to eighteen minutes in absolute anoxia without suffering the slightest brain damage.
International research published in the journal Science in 2017 revealed the mystery behind this feat. When air runs out completely, the naked mole-rat's cells switch off traditional glycolysis and activate a metabolic pathway typical of the plant kingdom:
- Massive release of fructose: The animal floods its bloodstream with fructose using GLUT5 transporters, which are heavily present in its brain and heart.
- Bypassing cellular blockage: In the absence of oxygen, the normal breakdown of glucose is halted by the inhibition of the enzyme phosphofructokinase. Fructose bypasses this cellular block and allows it to continue generating ATP (chemical energy) anaerobically.
- Suspended animation state: The rodent drastically slows its vital signs, reducing its heart rate from 200 to barely 50 beats per minute.
As soon as a hint of fresh air returns, the animal begins moving again as if nothing had happened. This mechanism opens fascinating avenues for medical research to prevent strokes in humans.
Source: Science (Park et al., 2017: 'Fructose-driven glycolysis supports anoxia resistance in the naked mole-rat')
