Abstract
Arousal from hibernation with a rapid increase of the energy metabolism suggests being exposed to a strong oxidation stress whenever the animal awakes, therefore being considered to have an innate anti-oxidation mechanism to prevent pathological troubles. To elucidate the state of the oxidation stress, endogenous anti-oxidants were quantified along the time course of hibernation. Very slow flow (3.5 μL/h) brain microdialysis enabled temperature independent sampling of the brain extracellular fluid (ECF) during hibernation, arousal and cenothermia in Syrian hamsters (Mesocricetus auratus). Brain tissue and dialysates were analyzed to provide the first profile of ECF changes in levels of ascorbic acid (AA), glutathione (GSH) and uric acid (UA) during hibernation and the transition to cenothermia. Brain tissue content of AA and GSH were unchanged between hibernation and cenothermia, however arousal was associated with substantial oxidation of AA from the brain ECF and plasma compartments. ECF-GSH increased during arousal. Brain tissue UA content was decreased 50% during hibernation. ECF-UA levels were unchanged in hibernation and cenothermia, however transiently increased 100% during arousal. The results suggest that arousal from hibernation is a suitable experimental model for examination of the mechanisms by which non-pathological tissue integrity is maintained in the face of the generation of free radicals during increasing metabolism, temperature and cerebral reperfusion. [J Physiol Sci. 2006;56 Suppl:S102]
