The effects of age on the metabolic and electrical responses to decapitation in the awake and the anesthetized rat brain.

The effects of age on the responses of the brain to decapitation (complete ischemia) were tested in the awake and anesthetized rat. The metabolic and reflected light activities were evaluated by the use of a DC fluorometer/reflectometer (one or two hemispheres) and the electrical activity was measured by electrocorticogram. In all 81 animals used in these experiments the above-mentioned parameters were measured, to enable comparison between the age groups. The rats were divided into six age groups ranging from 2 to 120 weeks and each age group was subdivided into awake and anesthetized animals. The results can be summarized as follows. (1) The rate of energy consumption was lower in the young (2 weeks) and the old rats (120 weeks) compared to the adult rats. (2) The effect of anesthetic was more pronounced in the young and the old rats than in the adult rats. (3) The electrical activity was in good correlation with the energy availability in all animals of various ages as well as in the awake and anesthetized rats.