ホルマリンおよび凍結保存による脳脂質脂酸構成の変化について

THE EFFECT OF FREEZING AND FORMALIN PRESERVATION ON LIPID, FATTY ACID COMPOSITION AND GANGLIOSIDE PATTERN IN RAT BRAINS

はじめに

　各種クロマトグラフィーの開発により，脳の脂質脂酸構成の分析が可能になり，脳脂質代謝に関する研究も著しく発展してきた。臨床分野においても，各種の脂質代謝異常疾患がみいだされ，その原因も解明されてきている。ところで，各種疾患脳は現在でも全脳をホルマリンで固定し保存する傾向か強く，ホルマリン固定脳を用いて脂質分析した報告も少なくない。脳脂質へおよぼすホルマリンの影響については，かなり報告がなされている。しかし，各脂質の脂酸構成におよぼす影響について検討した報告はみあたらない。さらに，最近は，脳の一部を凍結保存する傾向があるが，凍結保存によつて脳脂質脂酸構成に変化がないかどうか充分検討した報告もみあたらない。故に，各種疾患脳を分析する際，その基礎資料として必要なホルマリンおよび凍結保存による脳脂質脂酸構成の変化について検討を加えたのでここに報告する。

Lipid, fatty acid composition and ganglioside pat-tern in adult rat brains were investigated afterpreservation in following conditions : 1) kept atroom temperature (26℃) for 24 hr., 2) Stored in10% formalin solution for 3, 6 and 12 months, 3)frozen at-20℃ for 3, 6 and 12 months. Thinlayer chromatography and gas-liquid chromato-graphy were used for analysis.

The results were compared with those of freshadult rat brains as follows :

1) Post mordem changes :

Slight increase of cholesterol, and decrease ofsulfatide and phosphatidyl serine were observed.However, cerebroside sphingomyelin, phosphatidylethanolamine and phosphatidyl choline and gan-glioside pattern remained unchanged.

Regarding fatty acid composition of each lipid,decrease of long chain fatty acids in cerebrosideand slight changes of fatty acid composition insulfatide and phosphatidyl serine were found.

2) Effect of formalin preservation :

In the formalin preserved brain for 3 months,phosphatidyl ethanolamine disappeared and sulfatideslightly decreased. Moreover, in the preservedbrain for one year, phosphatidyl serine and phos-phatidyl choline slightly decreased. While choles-terol, cerebroside and sphingomyelin remained un-changed.

Moreover, changes of fatty acid composition inall lipids except phosphatidyl choline were observed.Particulary, long chain fatty acids in cerebrosidemarkedly decreased.

On the other hand, marked changes of ganglio-side pattern were found. G 1, a trisialoganglioside,disappeared in the formalin preserved brain for 3months, and G 1, G 2 and G 3 disappeared and onlyG 4, a monosialoganglioside, was found in the pre-served brain for one year.

3) Effect of freezing :

Lipid, fatty acid composition and gangliosidepattern in frozen brain for one year remained un-changed. However, decrease of long chain fattyacids in cerebroside and changes of fatty acidcomposition in sulfatide were observed.

From these results, it can be concluded as fol-lows : Formalin preserved brain is not suitable forchemical analysis of lipid, fatty acid compositionand ganglioside pattern. On the other hand, frozenbrain can be available enough even if after frozenfor one year.