有機水銀中毒ラット脳の血液脳関門—Gd-DTPA enhanced magnetic resonance imagingによる検討

THE OBSERVATION OF BLOOD-BRAIN BARRIER OF ORGANIC MERCURY POISONED RAT: A GD-DTPA ENHANCED MAGNETIC RESONANCE STUDY

　抄録　Magnetic resonance imaging （MRI）を用いて有機水銀中毒ラット脳での血液脳関門（blood-brainbarrier, BBB）の破綻の有無をin vivoで検討した。塩化メチル水銀（MMC）中毒ラットは体重100gの雄性Wistar ratにMMC 10mg／kgを7日間連日皮下投与することで作成した。Gd-DTPAを静脈内に投与し前後でT₁，　T₂値の変化を検討した。Gd-DTPA投与前では対照群に比べMMC中毒群の大脳白質におけるT₁ならびに小脳皮質におけるT₂の延長が認められた。Gd-DTPA投与によりMMC群の大脳ならびに小脳の白質のT₁は短縮した。しかしながらT₂はGd-DTPA投与により変化しなかった。Gd-DTPA投与によるT₁の短縮は，実験的脳虚血に比べて軽度であったがMMC中毒ラット脳におけるBBBの透過性亢進を示すものと考えられた。

Permeability of the blood-brain barrier (BBB) of methymercury chrolide (MMC) intoxicated rat brain was studied in vivo by gadrinium diethyl-enetriamine pentaacetic acid (Gd-DTPA) enhanced magnetic resonance imging (MRI), measuring the longitudinal relaxation time (T₁) and the transverserelaxation time (T₂).

MMC intoxicated rat brain showed the prolong-ed T₁ in the cerebral white matter and prolonged T₂ in the cerebellar cortex.

After Gd-DTPA administration, T₁ of cerebral and cerebellar white matter shortened from 1. 647 to 1.344 sec., and 1.290 to 1. 223 sec. respectively. On the contrary, T₂ showed no change after Gd-DTPA injection.

It was concluded that, although the shortening of T₁ after Gd-DTPA enhancement was rather little when compaired with experimental brain ischemia, the shortening of the relaxation time of the MMC intoxicated rat brain was caused by the increased permeability of BBB.