脳のシスタチオニン 第Ⅰ編 L-シスタチオニンの脳内侵入

1)マウスに50mg/kg体重のL-シスタチオニンを皮下注射し,その組織内分布をしらべたが,大部分は肝で分解を受け,少なくとも生理的条件では脳以外のシスタチオニンが血液脳関門を通つて脳に侵入し得る可能性はない.2)脳切片を用いてL-シスタチオニンのactive transportをしらべたが,これが脳に積極的に取り入れられ蓄積される可能性はない.3)脳に入つたL-シスタチオニンはin vivo, In vitro共に殆んど分解されない.

The distribution of cystathionine in blood, liver and brain was examined paperchromatographically at various intervals up to 6 hours after administration of L-cystathionine to mice. When L-cystathionine was administered subcutaneously (500 mg/kg) to adult male mice, cystathionine disappeared rappidly from the blood, while large amount of it were taken up by the liver. But in the brain tissue, scarcly significant amount or this amino acid was found even after administration of it. On the other hond, when albino rats brain cortex slices were incubated in a medium containing L-cystathionine, cystathionine was not actively accumulated into the brain slices during the periods of more than 1 hour. Results of these experiments suggest that cystathionine can not enter into the brain tissues of any kinds of mammalian animals under physiological conditions, and it is reasonable to assume, therefore, that the cystathionine detected in the human brain has been not absorbed from any other organs but originated in the brain itself.