Cholinesterase and Glutamic Decarboxylase Levels in the Brain of the Hibernating Hamster

Abstract

LITTLE information is available concerning the biochemistry of the brain of the hibernating animal although a considerable amount of data has been reported concerning the electrophysiology. Hibernating animals respond to stimuli with cries, positional changes and arousal¹; but conspicuous activity was reported to be absent in the electrocorticogram of the golden hamster (Mesocricetus auratus) during arousal until body temperatures reached 19°–21° (ref. 2). Recordings from sub-cortical areas showed electrical activity at lower temperatures to be largely confined to the limbic system³, while in the awakening European hamster (Cricetus cricetus) there was a sequence of increasing electrical activity with rising body temperature from mesencephalon to neocortex⁴. Cortical and sub-cortical neuronal activity has been recorded in the ground squirrel during deep hibernation, but only at 10 per cent of the amplitude found in the awakened brain¹. It therefore seemed of interest to determine whether changes in enzyme systems of particular significance to the nervous system, such as cholinesterase and glutamic decarboxylase, occurred in the hibernating brain concomitantly with these electrophysiological phenomena.