Abstract— Prolonged (6 hr) anaesthesia with phenobarbital in mice or rats results in a doubling or tripling of brain glycogen. Increases were also observed if high levels of plasma glucose were maintained for 6 hr. In alloxan diabetes brain glycogen was not elevated in spite of the high plasma glucose concentrations. However, administration of insulin to such diabetic animals, together with enough glucose to maintain high plasma levels, resulted in at least a doubling of brain glycogen in 6 hr. Phenobarbital can still increase brain glycogen in diabetic animals. In all of the conditions associated with increased glycogen deposition, increases were found in the ratio of brain glucose to plasma glucose. Cerebral glucose‐6‐P levels were also increased whereas there were no substantial changes in levels of UDP‐glucose or glucose‐1,6‐diphosphate.

Abstract— The levels of ATP, P‐creatine, glucose, glycogen, lactate, glutamate and ammonia were measured in mouse brain after administration of the convulsive agent methionine sulphoximine (MSO). No changes were observed in ATP and P‐creatine levels either before or during the seizures. Lactate levels were unchanged until the onset of seizures (4–5 hr) at which time the levels increased an average of 65 per cent. Glucose and glycogen levels increased progressively. Just before the onset of seizures the levels had increased 95 and 62 per cent, respectively. During the seizures both substances had increased a total of 130 per cent. Comparable changes were found in cerebral cortex, cerebellum and subcortical forebrain. Through the use of quantitative histochemical methods it was found that the greatest increases in glycogen occurred in layers I and III (layers II and IV were not analysed). Progressively smaller changes were found in layers V and VI and no increase at all was found in the subjacent white matter. Glucose, in contrast to glycogen, increased to about the same degree in all cerebral layers and in subjacent white matter. The increase in glycogen after MSO administration may be related to the fact that MSO also causes an increase in the ratio of brain to serum glucose levels. This would indicate that an increase in intracellular glucose had occurred. Ammonia levels were increased 300–400 per cent in both cerebrum and cerebellum. A time study in cerebellum showed that the increase begins early and reaches maximal levels long before the onset of seizures. Glutamate levels were reduced by small but statistically significant amounts in both cerebrum and cerebellum. Administration of methionine sulphoximine completely prevented seizures and the increase in lactate, but did not prevent the increases in glycogen and glucose. The rise in ammonia was reduced but not prevented. During 20 sec of complete ischaemia (decapitation) ATP, P‐creatine and glucose fell somewhat more rapidly than normal in brain of animals undergoing MSO seizures. From the changes it was calculated that the metabolic rate had been increased about 20 per cent by the seizure. A new sensitive and specific enzymic method for determination of tissue ammonia is presented together with evised enzymic procedures for lactate and glutamate.

No abstract

No abstract

WHEN the blood supply to the brain is cut off, function may be maintained for a short time through utilization of the energy reserve. This reserve has only four major components, P-creatine, ATP, glycogen, and glucose. Consequently the rates of change of these four substances during brief periods of complete ischaemia should be a valid measure of metabolic rate. Studies of whole brain (LOWRY, PASSONNEAU, HASSELBERGER and SCHULZ, 1964) and nerve (STEWART, PASSONNEAU and LOWRY, 1965) indicate this to be true. Although this 'closed system' method of measuring metabolic rate is relatively cumbersome it avoids some of the uncertainties of other procedures based on in vitro measurements or blood flow. The closed system method should be particularly useful for application to small areas of the brain for which there are no other methods available. Even single neuronal elements should eventually be accessible to this tool. This is a report of the application of this method to four gross regions of mouse brain and three histologically defined layers of mouse cerebellum. Measurements were made both with normal mice and with mice depressed with phenobarbitone. To provide a background, experiments are also reported with whole brain from mice given different dosages of phenobarbitone. E X P E R I M E N T A LReagents. All enzymes were obtained from Boehringer and Sons through Calbiochem, Berkeley, Calif., except glycogen phosphorylase (Sigma Chemical Co., St. Louis) and ox heart lactate dehydrogenase (Worthington, Freehold, N.J.). The phosphorylase was used as purchased for glycogen determination but was recrystallized three of four times to free it of ATPase and Pi when used for measuring the latter. Glycogen was dialysed against 0.025 M-acetate buffer at pH 4.7 to free it of contaminating Pi.Preparation ofmaterial. Male white mice of a local strain weighing about 20 g were used. These were decapitated, and the heads frozen either immediately or after a measured time interval (20 or 30 sec). Rapid freezing was accomplished by violent agitation in Freon-12 that had been chilled to its freezing point (-150") with liquid N,. Subsequently the tissue was kept at -80" whenever possible until enzymes present had been removed or inactivated. For studies of whole brain, the frozen tissue was powdered and treated with HClO, in such a manner as to avoid thawing and consequent changes in substrate concentrations (LOWRY et al. , 1964). The entire brain rostra1 to the inferior colliculi was used in this case. For the gross regional studies, 5 mg samples were dissected at -15" from four areas of the frozen brain with great care