Is hibernation facilitated by an inhibition of arousal?

Seasonal hibernation is a poorly understood phenomenon and the details of h ow hibernation induction, maintenance and arousal are controlled are, for t he most part, enigmatic. Hibernating golden-mantled ground squirrels, Sperm ophilus lateralis, were treated with MK-801, a non-competitive antagonist o f the NMDA-type glutamate receptor, as part of a larger investigation of th e role of these receptors in the control of breathing in this species. Drug treatment prompted arousal from hibernation at a dose of 5.0 mg/kg, but no t at a dose of 0.5 mg/kg. We have previously demonstrated that similar trea tment prevents sleep and sleep-like states of cortical arousal in unanesthe tized and anesthetized squirrels. As removal of NMDA-type glutamatergic act ivation resulted in arousal, the data suggest that arousal is normally acti vely inhibited; glutamatergic inhibition facilitates stable hibernation and NMDA-type glutamatergic blockade results in a disinhibition of arousal mec hanisms, resulting in arousal from hibernation. The similarity between the present results and those pertaining to sleep in non-hibernating squirrels supports the theoretical homology between hibernation and sleep. This resea rch was supported by the Natural Sciences and Engineering Research Council of Canada, and results have: been submitted, for peer-reviewed publication in primary literature.