Seasonal dependence of the activity of antioxidant defence enzymes in the ground squirrel (Citellus citellus): The effect of cold

The effects of hibernation on the contractile and biochemical properties of skeletal muscles in the thirteen-lined ground squirrel, Ictidomys tridecemlineatus

“…Secondly, a well-developed antioxidant capacity is crucial to deal with a rapid increase in ROS production caused when the rate of oxygen consumption increases by as much as 30-fold when animals rewarm during interbout arousal (Boyer and Barnes, 1999). The findings of the current study are interesting as previous work on thirteen-lined ground squirrels found that antioxidant enzyme activities, including superoxide dismutase, glutathione peroxidase and glutathione reductase, were not upregulated during hibernation in brain, heart and liver tissues when compared with summer levels (Page et al, 2009), although antioxidant enzyme activities do increase in liver tissue during hibernation in other ground squirrel species (Buzadzić et al, 1992). However, there is evidence that levels of antioxidant metabolites are elevated; for example, ascorbate levels rise 3-to 5-fold in plasma during torpor and ascorbate is redistributed from plasma to liver and spleen tissues, at the same time as oxygen consumption peaks, during arousal from torpor in Arctic ground squirrels (Tøien et al, 2001;Drew et al, 2002).…”

The impact of cold acclimation and hibernation on antioxidant defenses in the ground squirrel (Spermophilus citellus): An update

“…Considering that heat production is highly energy demanding, it necessarily requires an increased metabolic rate that, in turn, results in elevated generation of ROS. Generally, maintenance of cellular homeostasis under conditions of increased ROS production is achieved by a proportional increase in tissue AD [1,24,[45][46][47][48]. Thus, although there is little evidence of tissue-specific metabolic reprogramming in euthermic hibernators during cold exposure, the increased content of SOD2 in …”

Could human cold adaptation decrease the risk of cardiovascular disease?

“…UCP are closely connected to many physiological processes, including their involvement in an antioxidative capacity (Blanc et al, 2003;Nubel and Ricquier, 2006). The supposition that prolonged or repeated cold stress could induce oxidative stress was first verified in animal models (Buzadzic et al, 1992;Spasic et al, 1993); a finding even confirmed in humans (Siems and Brenke, 1992). Oxidative stress is defined as an imbalance between the production of reactive oxygen species (ROS) and their insufficient decomposition by the antioxidant system, resulting in macromolecular damage and disruption of redox signalling and control.…”