亚低温持续不同时间对缺血脑组织中氨基酸和单胺类递质含量的影响

Duration of Mild Brain Hypothermia on the Changes of Amino Acid and Monoamine Neurotransmitter in Brain Regions after Cerebral Ischemia/Reperfusion in Rats

目的 观察脑缺血后即时亚低温并维持不同时间对脑缺血损伤的影响 ,探讨亚低温脑保护作用的生物学机制。方法 脑缺血动物模型采用改良的 Pulsinelli四动脉阻断法。采用氨基酸分析仪测定脑组织中谷氨酸( Glu)、天门冬氨酸 ( Asp)、甘氨酸 ( Gly)和 γ-氨基丁酸 ( GABA)含量 ;采用荧光分光光度法测定多巴胺 ( DA)、去甲肾上腺素 ( NE)、5 -羟色胺 ( 5 -HT)及其代谢产物 5 -羟吲哚乙酸 ( 5 -HIAA)。结果 常温脑缺血组织中 Glu、Asp、Gly和 GABA的含量明显低于假手术组 ( P<0 .0 1 ) ,亚低温持续 3 0～ 2 40 min脑组织中 Glu、Asp、Gly和GABA含量明显高于常温脑缺血组 ( P<0 .0 5或 P<0 .0 1 )。常温脑缺血后组织中 DA、NE和 5 -HT的含量明显低于假手术组 ( P <0 .0 1 ) ,5 -HIAA含量高于假手术组 ( P <0 .0 1 ) ;亚低温持续 3 0 min脑组织中 5 -HT含量明显高于常温脑缺血组 ( P <0 .0 1 ) ,5 -HIAA的含量低于常温脑缺血组 ( P <0 .0 5 ) ;亚低温持续 60～ 2 40 min脑组织中 DA、NE和 5 -HT含量明显高于常温脑缺血组 ( P <0 .0 5或 P <0 .0 1 ) ,5 -HIAA含量低于常温脑缺血组 ( P <0 .0 1 )。结论 脑缺血后即时亚低温明显减轻常温脑缺血时组织中氨基酸和单胺类神经递质的代谢紊乱 ,提示亚低温减轻脑缺血?

Objective To study the effect of mild hyothermiaduringdifferenttimeintervalsoncerebral ischemia/reperfusion injury. Methods Global cerebral ischemia was established by modified Pulsinelli 4-vessel occlusion model. Brain tissue were used to measure the levels of glutamate(Glu),aspartate(Asp),glycine(Gly),gamma- aminobutyric acid(GABA),dopamine(DA),norepinephrine(NE),serotonin(5-HT) and its products hydroxyindoleacetic acid(5-HIAA). Results In normothermic ischemic group the levels of Glu,Asp,Gly and GABA weresignificantlylowerthanthoseinsham-operatedgroup(P<0.01).Post- ischemia hypothermia lasting 30 min to 240 min delayed the decrease of those amino acids compared with normothermia group(P<0.05 or P<0.01). The levels of DA,NE,5-HT decreased and 5-HIAA elevated significantly in normothermic ischemic groups as compared with sham-operated group (P<0.05). Postischemia hypothermialasting for 30min delayed the decreased of 5-HT and increased of 5-HIAA as compared with normothermia group (P<0.05). Postischemia hypothermia lasting 60 min to 240 min were able to postponed the decreased of DA,NE,5-HT and increase of 5-HIAA as compared with normothermia group (P<0.05 or P<0.01). Concultions Postischemia mild brain hypothermia start immediately may significantly suppress the excessive releases of amino acid and monoamine neurotransmitters,which is associated with the mechanism of cerebral protection by mild hypothermia. These results suggest that the neuroprotection of mild hypothermia should be carried out immediately and lasting not less than 60 min.