Arctic ground squirrel hippocampus tolerates oxygen glucose deprivation independent of hibernation season even when not hibernating and after ATP depletion, acidosis, and glutamate efflux.

Cerebral ischemia/reperfusion (I/R) triggers a cascade of uncontrolled cellular processes that perturb cell homeostasis. The arctic ground squirrel (AGS), a seasonal hibernator resists brain damage following cerebral I/R caused by cardiac arrest and resuscitation. However, it remains unclear if tolerance to I/R injury in AGS depends on the hibernation season.

Acidotoxicity via ASIC1a Mediates Cell Death during Oxygen Glucose Deprivation and Abolishes Excitotoxicity.

Ischemic reperfusion (I/R) injury is associated with a complex and multifactorial cascade of events involving excitotoxicity, acidotoxicity, and ionic imbalance. While it is known that acidosis occurs concomitantly with glutamate-mediated excitotoxicity during brain ischemia, it remains elusive how acidosis-mediated acidotoxicity interacts with glutamate-mediated excitotoxicity. Here, we investigated the effect of acidosis on glutamate-mediated excitotoxicity in acute hippocampal slices.

Habituation of Arctic ground squirrels (Urocitellus parryii) to handling and movement during torpor to prevent artificial arousal.

Hibernation is a unique physiological adaptation characterized by periods of torpor that consist of repeated, reversible, and dramatic reductions of body temperature, metabolism, and blood flow. External and internal triggers can induce arousal from torpor in the hibernator. Studies of hibernating animals often require that animals be handled or moved prior to sampling or euthanasia but this movement can induce changes in the hibernation status of the animal.

Circannual rhythm in body temperature, torpor, and sensitivity to A₁ adenosine receptor agonist in arctic ground squirrels.

A₁ adenosine receptor (A₁AR) activation within the central nervous system induces torpor, but in obligate hibernators such as the arctic ground squirrel (AGS; Urocitellus parryii), A₁AR stimulation induces torpor only during the hibernation season, suggesting a seasonal increase in sensitivity to A₁AR signaling. The purpose of this research was to investigate the relationship between body temperature (Tb) and sensitivity to an adenosine A1 receptor agonist in AGS. We tested the hypothesis that increased sensitivity in A₁AR signaling would lead to lower Tb in euthermic animals during the hibernation season when compared with the summer season.

Altered thermoregulation via sensitization of A1 adenosine receptors in dietary-restricted rats.

Rationale: Evidence links longevity to dietary restriction (DR). A decrease in body temperature (T(b)) is thought to contribute to enhanced longevity because lower T(b) reduces oxidative metabolism and oxidative stress. It is as yet unclear how DR decreases T(b).