Regulation of Antioxidant Defenses, DNA Damage Repair, the Immune Response, and Neuroprotection During Hibernation in the Thirteen-Lined Ground Squirrel

The results show that hibernation is a complex, multi-faceted process that employs specific adaptations of damage prevention/repair pathways to protect squirrel tissues from damage during prolonged torpor but over the transitional states to/from torpor and does so expertly while conserving energy until such a time that repair mechanisms may be fully initiated

Kama Szereszewski

2019

Scholarcy highlights

  • Hibernation is a complex, yet fascinating, phenomenon that many mammals use to cope with the extreme challenges of winter
  • Global antioxidant capacity was measured in a group of selected tissues, relative expression levels of 5 antioxidant enzymes was assessed via multiplex analysis, and the relative protein expression of PRDX isoforms was determined over the course of the torpor-arousal cycle in liver and brown adipose tissue of hibernating ground
  • The results of this study reveal that IRF3 is an important transcription factor which induces the expression of these genes in a tissue-specific and time-specific manner, and is likely a key player in maintaining the “fat but fit” state of the hibernating ground squirrel
  • The predicted s-humanin amino acid sequence was determined and aligned with the sequences from other mammals obtained from the NCBI data bank: golden-mantled ground squirrel, Norway rat, little brown bat, David’s myotis bat, domestic dog, cow, Swinhoe’s striped squirrel, Siberian chipmunk, naked mole rat and the red squirrel
  • We suggest that because ground squirrels must maintain superior neuronal plasticity and synaptogenesis over multiple torpor bouts, that this region has likely prioritized for neuroprotection, compared to the brainstem region whose functions are known to be suppressed during torpor
  • In order to achieve a metabolic rate drop to <5% of euthermic levels during hibernation, virtually all but the most important metabolic processes are suppressed. During this time, oxygen perfusion of tissues is less than 10% of euthermic rates and heart rate is slowed
  • Despite the global suppression of energy-expensive processes and control mechanisms that characterizes torpor, many pathways remain active, but others, as described in this study, show mechanisms that finetune their response so that pro-survival mechanisms are still maintained, but energyexpensive processes are preferentially suppressed until arousal
  • The ground squirrel is able to protect its tissues and macromolecules from damage

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