Neuroprotection supports signal processing in the hippocampus of Syrian hamsters, a facultative hibernator

Studies on several species of mammalian seasonal hibernators (those hibernating only in winter) show that their neurons are more tolerant to hypoxia than those in non-hibernating species. Such tolerance has not been studied in facultative hibernators [e.g., Syrian hamsters (Mesocricetus auratus)], which can hibernate at any time of year. We tested the hypotheses that, when exposed to hypoxia, hamster hippocampal pyramidal cells more effectively support signal processing than do rat hippocampal neurons and this protection is enhanced in slices from hibernating versus non-hibernating hamsters and as temperature decreases. Population spike amplitudes (PSAs) were recorded from CA1 pyramidal cells. Slices were perfused in oxygenated artificial cerebral spinal fluid (O2ACSF) to establish a baseline. Oxygen was then replaced by nitrogen (N2ACSF) for 15 min, followed by a 30-min recovery period in O2ACSF. Three minutes after slices were returned to O2ACSF, PSAs recovered to 62.4 ± 6.8% of baseline in 15 slices from 8 non-hibernating hamsters but only to 22.7 ± 5.6% in 17 slices from 5 rats. Additionally, PSA recovery was greater in slices from hibernating than non-hibernating hamsters and recovery increased as temperature decreased. These significant differences (P ≤ 0.05) suggest Syrian hamsters are a useful model for studying naturally occurring neuroprotective mechanisms.

► Euthermic hamster CA1 neurons are more tolerant to hypoxia than rat CA1 neurons. ► This tolerance is enhanced in neurons from hibernating versus euthermic hamsters. ► Tolerance is also greater at lower temperatures. ► Neuroprotective adaptations allow neuronal viability/function at low temperatures. ► These adaptations may contribute to survival during hibernation bouts.