実験的水頭症ラットにおける〔14C〕デオキシグルコース法を用いた局所脳グルコース代謝に関する研究

LOCAL CEREBRAL GLUCOSE UTILIZATION ON KAOLIN INDUCED HYDROCEPHALUS OF RATS BY 〔14C〕DEOXYGLUCOSE METHOD

　抄録　水頭症の異常な脳室拡大は，頭蓋内環境を大きく変化させ，種々の神経症候を呈するに至ると信じられている。水頭症の病態を理解する上で，中枢神経機能に直結する局所脳グルコース代謝率の測定（1978年Sokoloff）が重要であると考え実験的水頭症を作成し，局所脳代謝の測定を行った。実験的水頭症はHock座wald，山木らの方法に準じ，カオリン溶液をS-D系雄ラットの大槽内に注入して作成し，4週間待機した後，局所脳グルコース代謝率を測定した。カオリン注入後behavioralには全く正常であった軽度水頭症群（4匹）と，著しい神経脱落症状を呈した高度水頭症群（6匹）とに大別され，無処置のラット5匹を対照群として各群における局所代謝率の変化を測定し，比較検討した。軽度水頭症群における代謝率の変化では，すべての部位で一様な低値を示したにもかかわらず，高度水頭症群では，大脳辺縁系，視床下部，脳幹部における特殊神経核では対照群と比較して同じに保たれるか，あるいは高値を示しており，著しく不均一な代謝パターンを示した。従って水頭症に特有な神経症状の発現には，脳血流・脳代謝の全体的な低下に基づくというよりは，局所脳代謝のheterogeneity （不均一性）が関与しているものと考えられる。

Hydrocephalus is known to produce progressive mental deterioration and other peculior neurolo-gical symptoms and signs, such as gait disturbance, pyramidal and extrapyramidal signs and urinary incontinence. Alteration of energy metabolism in various cerebral regions in association with hydrocephalus, however, has not been fully understood.

The quantitative carbon 14 deoxyglucose auto-radiographic method was employed in kaolin induced hydrocephalus of rats. The hydrocephalic rats developed marked emaciation with normal physiological parameters. They showed reduced motor activity and muscle tone and sluggish reflexes. The animals remained conscious and displayed no seizure activity. The rates of local cerebral glucose utilization in the cortical areas and the thalamus were significantly lower than those of the control animals. In the limbic system, the hypothalamus, and basal ganglia, the values showed considerable variation, however, the degrees of reduction were relatively mild. The values in the brain stem were either lower or higher than those of the control animals. The lower values were seen in the sensory system and higher values in the nucleus raphe and locus ceruleus. Decrease of the glucose utilization rate in the cerebellum was moderate and uniform in all the cerebellar structures. Reductions of the metabolic rates in the white matter structures were relatively uniform throughout the brain.

This study not only demonstrated marked heterogeneous impairment of cerebral metabolism in the hydrocephalus but also suggested the important rule of the metabolic or functional decortication in the hydrocephalus which may help to understand peculior behavioral and neuro-logical changes in the hydrocephalus.