Fluctuation of Brain Tissue Oxygen Partial Pressure: A Biochemical Landmark in the Arctic Ground Squirrel's Spontaneous Arousal

摘要

Hibernation in the Arctic Ground Squirrel (AGS) is a regulated, adaptive response to arctic environmental conditions. Problem statement: Regional brain Blood Flow (rCBF) has been observed to increase dramatically during arousal in hibernators. However, the real time dynamic change in P_tO_2 during arousal has not been studied, we hypothesized that P_tO_2 is Interdependent of T_(brain) and a key component in the arousal process. Approach: Simultaneous in vivo measurements of P_tO_2 and brain temperature (T_(brain)) in conjunction with oxygen consumption (V02) were conducted in the striatum of non-sedated, non-anesthetized Arctic ground squirrels during spontaneous arousal from hibernation. Results: A dramatic fluctuation of brain tissue oxygen partial pressure (P_tO_2) is associated with the complex phenomena of spontaneous arousal. In this study, we observed that: (1) a Pt02 elevation precedes changes in T_(brain) and V_(02); (2) P_tO_2 changes do not correlate with changes in V_(02) during arousaland (3), endogenous O_2 shift from O_2 enriched blood to brain in hibernating AGS induces an arousal with the pharmaceutical chemical, efaproxiral (RSR-13). Conclusion: The four turning points of P_tO_2 appearing at different T_(brain) during arousal suggest that changes in P_tO_2 are T_(brain) interdependent and support the concept that arousal from hibernation is complex process invoking different feedbacks.