RAPID TEMPERATURE-CHANGES INDUCE ADENOSINE-MEDIATED DEPRESSION OF SYNAPTIC TRANSMISSION IN HIPPOCAMPAL SLICES FROM RATS (NON-HIBERNATORS) BUT NOT IN SLICES FROM GOLDEN-HAMSTERS (HIBERNATORS)

Disturbances in neuronal communication induced by rapid temperature ch anges are a risk in the context of accidental hypothermia and would be fatal for hibernators during arousal from hibernation. Therefore, we investigated the effects of rapid temperature changes on synaptically induced CA1 population spikes in hippocampal slices from golden hamste rs (hibernators) and rats (non-hibernators). Temperature was changed r amp-like by 0.3 degrees C/min, which corresponds to the rise of body t emperature in golden hamsters during arousal from hibernation. During cooling from 35 to 10-15 degrees C, the population spike amplitude inc reased, reached maximal values at 25-30 degrees C and 20-25 degrees C in hamster and rat slices, respectively, and then decreased with furth er cooling. During rewarming, hamster slices displayed the same temper ature dependence as during cooling. In contrast, in rat slices dynamic effects of the temperature change occurred. These were most obvious i n a strong depression of the spike amplitude during rewarming as compa red to cooling. Above 26-29 degrees C, the depression was superimposed by an excitatory effect. The depression was largely attenuated by the ophylline (100-200 mu M) and thus seems to be based on an increase of the concentration of endogenous adenosine, which in turn may result fr om an imbalance in energy metabolism during warming. The lack of warmi ng-related depression in hamster slices can be explained by a lower se nsitivity for adenosine as compared to rat slices. In addition, a bett er resistance of metabolic balance against rapid temperature changes m ay prevent large elevations of endogenous adenosine in the hamster hip pocampus. For hibernators, the avoidance of temperature change-induced disturbances of neuronal communication may be a prerequisite for safe arousal from hibernation. (C) 1998 IBRO. Published by Elsevier Scienc e Ltd.