SOME FACTORS INFLUENCING BRAIN GLYCOGEN IN THE NEONATE CHICK

—Studies of the brain glycogen concentration in the chick during the perinatal period showed that there was an increase immediately prior to hatching. This was followed by a pronounced decrease between 1 and 2 days after hatching. The decrease was most marked in the cerebellum. During ischaemia, the rate of glycogen depletion was greater in 1-day-old chicks than in 2- and 7-day-old birds. Brain glycogen concentration exhibited a circadian rhythm which was not closely related to changes in motor activity or body temperature. Exposure to a high environmental temperature (40°C) caused a depletion of glycogen, but exposure to a low temperature (2°C) had no effect. Four hours of hyperglycaemia resulted in a lowering of brain glycogen levels whereas hypoglycaemia was without effect.