Estimations of blood sugar in decerebrate animals.

Abstract

Figures for blood sugar following decerebration have been given by J. Mellanby, 1 but he used an injection of starch for decerebration and the actual area of brain damage remained very uncertain. He found a hyperglycemia lasting as long as six and a half hours and supposed that this high sugar level might be maintained indefinitely. On the other hand, Bazett and Penfield found a disappearance of sugar from the urine in decerebrate cats within two days.

A few observations on blood sugar have been made on cats decerebrated aseptically by a scooping out method under chloroform anesthesia. The blood has been obtained from a cut in the ear and the sugar estimated by Maclean's method. In one such animal a blood sugar of 0.256 per cent was obtained 24 hours after operation, and the urine secreted during the night contained sugar. In another animal the blood sugar 24 hours after operation was found to be 0.19 per cent. In both of the above animals the pituitary was left intact. In an animal decerebrated acutely with the Sherrington guillotine and chloroform anesthesia in which the whole of the hypophysis was removed and also any accessory pituitary tissue in the pharynx a blood sugar of 0.37 per cent was obtained one half hour after decerebration and the level gradually fell until 7 hours after operation it was 0.20 per cent and finally reached 0.165 eleven and a half hours after the operation. At this time the animal began to have difficulty in breathing from tracheal mucus, and his general condition became much worse and with this change the blood sugar rose again reaching a level of 0.38 per cent just before death, 21 hours after operation. The initial fall of blood sugar could not therefore, have been due to a lack of available glycogen. These few figures confirm the data obtained by Mellanby, but indicate that if he had carried on his experiments for a longer time the blood sugar might have fallen, and that the high blood sugar cannot be considered as maintained at a constant high level.

In further experiments animals have been decerebrated aseptically by a scoop method under anesthesia induced by chloretone given in alcohol and water by stomach tube in a dosage of 0.17 gm. per kilo, the resultant anesthesia king loccasionally supplemented by a little chloroform. In these animals the hemorrhage at time of operation has been much less than with chloroform anesthesia. The chloretone has maintained its effects for 24 to 48 hours or even longer, although some rigidity has usually developed within 6 to 8 hours. In some animals the pituitary has been left intact, in others it has been remolved at the time of operation and in sow experiments an attempt has been made to remove pituitary, but at autopsy it has been found to have been only partially removed.