新・旧・古皮質系の電気的活動におよぼす低級脂酸の影響

EFFECTS OF SHORT CHAIN FATTY ACID ANIONS ON THE ELECTRICAL ACTIVITY OF NEO-, PALEO-, AND ARCHICORTICAL SYSTEMS

　Flaxédil処置，人工呼吸下のネコ35匹に，低級脂酸（n-butyric acid, i—，　n-valeric acid, n-caproic acid）　Na塩（pH 7.4），2〜4mM／kgを静注し，新・旧・古皮質系の電気的活動におよぼす影響を観察した。

　1）　低級脂酸投与によつて，著明な脳波水準の低下作用がみられ，とくに新皮質は注入40秒後より，高振幅徐波と紡錘群発の出現を伴う深睡眠パタンを示し，約40〜60分後可逆的に覚醒する。ところが，海馬や扁桃核などの旧・古皮質系では，新皮質の深睡眠パタンに比して，活動水準の低下は，一般に軽度であり，いつたん睡眠パタンまで低下しても，約5〜10分後から，覚醒パタンに移行して，新皮質と旧・古皮質の脳波水準に著明な分離を容易に生ずるのが特徴である。

　2）　海馬や扁桃核が，覚醒パタンに移行する時期に一致して，新皮質に限局して，棘波や4〜5c／sの二重棘波，時として三相性の波が，観察できる。

　3）　末梢からの求心性インプルスの影響を，ほとんど除外したmidpontine pretrigeminal transectionネコにおいても，低級脂酸投与により，新皮質は，著明な脳波水準の低下を示すが，旧・古皮質では，水準の低下が軽度であり，分離の傾向を示す。

The effects of short chain fatty acid anions (SCFA), including n-butyric, n-, i-valeric and n-caproic acid, upon the electrical activities of the neo-, paleoa, and archicortical systems were observed in 35 unanesthe-tized amd Flaxédil immobilized cats under artifieial respiration, and the following results were obtained;

1) The deep sleep patterns of the high amplitude slow waves with spindle bursts on the neocortex were induced immediately after the intravenous in-jection of 2~4mM/kg of SCFA and persisted from 40 seconds to about 60 minutes, while the electrical activities of the limbic systems (the amygdala and hippocampus) were decreased to a lesser extent than that of the neocortex and then the manifest dissocia-tion of the electrical activities between the neocortex and limbic cortices was observed; that is characteris-tic of the EEG changes by the administration of SCFA.

2) The bilaterally synchronous spiky waves or triphasic waves (4~5 c/s) were observed solely on the neocortex.

3) In the midpontine pretrigeminal transected preparations, cutted-off the most of the peripheral impulses, were also decreased the electrical activities of the neocortex and then the same dissociation of the EEG changes between the neocortex and limbic cortices was also observed by the injection of SCFA.

4) The evoked potentials of the midbrain reticular formation by the contralateral sciatic nerve stimula-tion were strongly suppressed in amplitude without any remarkable changes of the neocortical potentials.

Taking these results into consideration, it may be conclude that SCFA mainly suppress the midbrain-neocortical reticular activating systems.