Page 98 - University of Pretoria Research Review 2017

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Death and
resurrection
in a long-lived
mammal
Nigel Bennett and Heike Lutermann, Mammal Research Institute, Department of Zoology and Entomology
If the naked mole-rat is completely deprived of oxygen, it stops breathing, its heart rate drops and it ultimately dies. But, death in this unusual mammal is temporary and if within a certain time it is provided with oxygen again, it comes back to life!
Professor Nigel Bennett and Dr Heike Lutermann of the Mammal Research Institute in the Department of Zoology and Entomology have recently published an exciting study looking into anoxia in mole-rats in the journal Science*. Professor Thom Park of the University of Illinois in the USA, the principal investigator of
this study, commented: ‘This was a challenge so big that it took three labs on three continents to solve
it’. Professor Gary Lewin of the Max Delbrück Centre for Molecular Medicine at the University of Berlin, Germany, was the other lead investigator in the study.
While naked mole-rats are adapted to the high levels
of carbon dioxide (hypercapnia) in their underground castles of clay, this study observed the results when mole-rats had no access to oxygen at all. During these periods, the naked mole-rat reduces its heart rate to the extent that it almost appears to have stopped, but it keeps it pumping just enough to circulate blood.
The research team discovered that when the naked mole-rat is deprived of oxygen, it uses internal pathways, used by no other mammal, to survive. It alters its metabolic systems to function more like a plant than an animal, releasing fructose into the blood, which is then taken up by the cells in the brain. It is the brain that contains cells that can make use of fructose, enabling cellular functions to continue. Aerobic energy production stops and the animal operates on anaerobic systems, relying on fructose for energy instead of glucose. Once oxygen is present they revert back to their usual pathways.
Nigel Bennett and Heike Lutermann
Can you imagine putting 70 small rodents into a small container, sealing the container shut and subsequently burying it over a metre underground? The result would be 70 dead rodents. In fact, if any animal is deprived of oxygen for too long the result is fatal, but there is an exception – the naked mole-rat.
* Park TJ, Reznick J, Peterson BL, Blass G, Omerbasic D, Bennett NC, Henning P, Kuich JL, Zasada C, Browe BM, Hamann W, Applegate DR, Radke MH, Kosten T, Lutermann H, Gavaghan V, Eigenbrod O, Begay V, Amaroso VG, Govind V, Minshall RD, St J Smith E, Larson J, Gotthardt M, Kempa S, Lewin GR (2017). Fructose driven glycolysis supports anoxia resistance in the naked mole-rat. Science 356: 307-311