Following an anoxic insult, a hippocampal neural circuit of the Syrian hamster, a hibernator, is more protected than the hippocampus of the rat, a nonhibernator

Abstract

Environmental adaptations enable the hibernating Syrian hamster to reduce its oxygen consumption to 1% of its consumption under euthermic conditions, but whether these adaptations provide the hamster with added neuroprotection under ischemic conditions is not well studied. We tested the hypothesis that, at 30oC, the hamster hippocampus can recover function after an anoxic insult more rapidly than the rat hippocampus. The response amplitude of CA1 neurons in hippocampal slices from hibernating hamsters and rats was measured every minute throughout the experiment, beginning with a 15 minute control period in oxygenated buffer (95%O2/5%CO2). Oxygen was then replaced by nitrogen (95%N2/5%CO2) for a 15 minute period (the anoxic insult). Slices were then returned to the oxygenated buffer for a 30 minute recovery period. Three minutes after the anoxic insult, the hamster response had recovered to 84.3 + 4.2 % of control (14 slices, 4 animals) while the rat response had only recovered to 28.0 + 11.5 % of control (17 slices, 5 animals). These differences are significant (P<0.05) and support the hypothesis that a neural network in hibernating hamsters recovers function more rapidly after an anoxic insult than does the network in the rat. This study was supported by an UC Davis President's Undergraduate Fellowship award to JJB.