[The effect of vitamin A on leukotriene production in the ischemic rat brain]

Human plasma leukotriene C4 (LTC4) levels of cerebral infarcted patients showed a significant increase and plasma vitamin A (VA) levels showed a significant decrease compared to the normal plasma obtained from age-matched control. Therefore, the effect of VA on leukotriene (LT) levels and the progress of cerebral edema were investigated in VA deficient Wistar rat brains. Incomplete global cerebral ischemia was induced by occluding the bilateral common carotid arteries (BLCO) with clips. Wistar rats were made VA deficient by feeding them a vitamin A deficient diet for 5 weeks on a specific pathogen free status. After 3 hours of BLCO the blood was reperfused by removing the clips. After each period of reperfusion, the rat brain was fixed by freezing in situ and used for assaying leukotrienes, vitamin A, and water content. Slow reacting substance of anaphylaxis (LTC4 + LTD4 + LTE4) levels showed an increase at the end of BLCO in the VA deficient group and the high levels persisted for 30 min and then decreased to the control level. Brain water contents were elevated significantly at the 30 min phase of reperfusion. With VA administration, the water contents tended to be lower than in the VA deficient group at any phase. Histologically, after ischemia and reperfusion, evans blue extravasation and marked spongioid formations around small vessels were observed in the VA deficient rats only. These facts indicate that VA functions to stabilize cell membranes and suppress ischemic cerebral damage.