脳血管障害の恢復に関与する脳内代謝に関する実験的研究

A STUDY ON CEREBRAL METABOLISM PARTICIPATED IN RECOVERY OF EXPERIMENTAL CEREBROVASCULAR ACCIDENT IN RATS

I．はじめに

　脳血管障害時，脳酸素消費最は低下し，脳血流は減少すると共に，脳浮腫の発展による頭蓋内圧亢進が脳の神経機能不全を助長する^11,13）。この状態の患者では，脳脊髄液の酸塩基平衝の異常^19）やアミノ酸含量に変化をきたす^18）ことが知られている。

　実験的脳虚血時，脳浮腫が観察され，脳組織のenergyレベルが速やかに低下する一方，嫌気的解糖にようlactate：pyruvate （LIP）比の増加が重認められる^4,8）。また脳虚血状態では，脳の代謝および神経機能の維持に重要な役割りを果す脳内遊離アミノ酸が変化することも報告されている^3,14）。しかしこれらの多くは，脳の血流遮断および再開^6,27），頭蓋内圧迫^9）など一過性条件下の実験である。

This study was designed to examine the changes of water contents, electrolytes balance, energy metabolism and free amino acids, in connection with the change of EEG, of hematomal (H) and non-hematomal (N-H) hemisphere in the process of absorption of cerebral hematoma in rats.

Experimental unilateral intracerebral hematoma was prepared by the injection of O.25 ml of auto-logous blood into the region around capsula interna, putamen and caudate nucleus of right cerebral hemisphere of the rats and the investigation about metabolic parameters of the brain was made until 14th day after the preparation of hematoma.

The increase in water and sodium contents attained maximum on the 1st day in H hemisphere and the 3rd day in N-H hemisphere. ATP level showed the lowest level on the 3rd day in both H and N-H hemisphere. The change with laps of day of potassium contents in H and N-H hemi-sphere showed reciprocally inverse correlation with that of sodium contents in each hemisphere. These changes mentioned above recovered to normal level by the 7th day. Pyruvate and lactate contents increased for prolonged days from the 1st day and the same pattern with less demonstrative increase was also observed in N-H hemisphere. Slow wave of EEG pattern was recorded in parallel with de-crease of ATP and with brain edema from the 1st to 4th day. The recovery process of EEG pattern correlated with lactate: pyruvate ratio (L/P ratio) and abnormal EEG pattern remained even on the 14th day in H hemisphere. All of these changes of the parameters were less dominant but signifi-cant in N-H hemisphere. Free amino acids contents began to increase in the same degree in H and N-H hemisphere in accordance with recovery of energy level and brain edema. Glutamate content increased on the 3rd and 4th day. Glutamine content markedly increased on the 4th day and maintained high level on the 14th day. Contents of aspartate, GABA, alanine, glycine and taurine increased on the 4th or 5th day.

These findings indicate that the decrease of energy production leads to accumulation of intracellular sodium and release of potassium through cell membrane and aggravates brain edema, and lowers electrical activity of brain cells. A cerebral meta-bolism was activated after the prolonged days. It is regarded that the increase in free amino acids in H and N-H hemisphere might be an early metabolic response in the whole brain which precedeto morphological repairing mechanism of brain tissue.