脳代謝の部位別変化について

Studies on metabolism of the various parts of guinea pig brain

I．緒言

　従来，脳代謝に関する研究は，主として全脳あるいは大脳皮質について行われており，部位別に比較検討された業績は少く，1931年，Gavrilescu ＆ Peters^1）の鳩の脳についての成績以来散見されるにとどまる。しかし，脳の各部位は解剖学的に差異があり，また機能的にも種々異る如く，生化学的反応にも部位別差があることは容易に想像される。われわれはこれまで各種条件下における脳各部位の代謝動態を追求し，いずれの条件下においても脳代謝は全脳一様に反応することなく，部位により異つた態度を示すことを明かにしてきた。Himwichら^2）は，脳各部位の代謝序列はその系統発生的序列と関係があるとし，Verjbinskaya^3）は全脳についてではあるが，エネルギー代謝につき比較生化学的に検討して，系統発生的序列における剛係を呈示しているので，この点に関して検討すべく，正常状態，インスリン昏睡およびカリウム効果について追求し，その成績をまとめたのでここに報告する。

　Studies were made on the energetic metabolism. of the various parts of guinea pig brain whichcontained cerebral cortex, cerebellar cortex, diencephalon, corpora quadrigemina and the basis ofthe fourth ventricle. Oxygen uptake, lactic acidformation and glucose consumption were examinedrespectively by Warburg's manometrics, Barker-Summerson's method and Somagyis method. Theresults were as follows:

　1. Little difference of oxygen uptake amongthe various parts of the brain was observed. Thehigher lactic acid formation was observed in thebasis of the fourth ventricle and cerebellar cortex, while in cerebral cortex and diencephalon it waslow.

　2. "Potassium-effect" which had been reportedonly in the cerebral cortex slice was also observedin the different parts of the brain. Potassium-effect in the basis of the fourth ventricle was lowerthan that in cortex.

　The metabolism of the slice, which was isolatedfrom the cerebral cortex of the animal inducedto insulin coma, was remarkably decreased, whilethe slice of the basis of the fourth ventricle showedlittle decrease of metabolism in this condition. The number of neuronal and glial cells in thevarious parts of the brain was examined and littlerelation was found between the number of cellsand those reactivity, which was the degree of Potassium-effect or metabolic change in insulin. coma.

　3. a) The grade of oxygen uptake of thevarious parts of the brain in Krebs-Ringer phosphate with various substrates such as glucose,lactate, pyruvate and TCA intermediates showeddifferent results.

　b) The inhibitory action of malonate on Potassium effect was observed in not only cerebralcortex but also the other parts of the brain.

　The relation between energetic metabolism especially the reactivity as described above in the. various parts of the brain and the order of phylogenetical development was considered to beclose, and in every parts of the brain the energeticmetabolism were considered to be carried Out by-way of glycolysis and TCA cycle.

　The differences of metabolic level or reactivity. in the various parts of the brain were consideredto be depend upon the quantitative differencesof the enzyme activity.