生理学报Acta Physiologica Sinica, April
研究论文
一氧化氮合酶抑制剂L-NAME对大鼠脑缺血耐受诱导的影响
刘惠卿, 李文斌*, 冯荣芳, 李清君, 陈晓玲, 周爱民, 赵红岗, 艾洁
河北医科大学基础医学研究所病理生理学研究室, 石家庄 050017
摘要: 采用大鼠四血管闭塞全脑缺血耐受模型和脑组织切片形态学方法, 观察应用一氧化氮合酶(NOS)抑制剂L-NAME对大鼠海马CA1区脑缺血耐受(BIT)诱导的影响, 在整体水平探讨一氧化氮(NO)在BIT诱导中的作用。54只Wistar大鼠凝闭双侧椎动脉后分为6组:(1)假手术组(n=6): 分离双侧颈总动脉, 但不阻断脑血流; (2)损伤性缺血组(n=6): 全脑缺血10 min; (3)预缺血+损伤性缺血组(n=6): 脑缺血预处理(CIP)3 min, 再灌注72 h后行全脑缺血10 min; (4)L-NAME组: 分别于CIP前1 h和后1、 12及36 h腹腔注射L-NAME (5 mg/kg),每个时间点6只动物, 其余步骤同预缺血+损伤性缺血组; (5)L-NAME+L-精氨酸组(n=6): 于CIP前1 h腹腔注射L-NAME (5 mg/kg)和L-精氨酸(300 mg/kg), 其它步骤同L-NAME组; (6)L-NAME+损伤性缺血组(n=6): 于腹腔注射L-NAME (5 mg/kg) 72 h后行全脑缺血10 min。实验结果表明, (1)单纯10 min全脑缺血可使海马CA1区组织学分级增加(表明损伤加重), 神经元密度降低(P<0.01); (2)预缺血+损伤性缺血组的海马CA1区组织学分级、 神经元密度与假手术组相比, 无显著性差别(P>0.05); (3) L-NAME组中, 应用L-NAME后海马CA1区组织学分级增加, 神经元密度降低, 与预缺血+损伤性缺血组相比有显著性差异(P<0.05), 表明L-NAME可阻断CIP对神经元的保护作用; (4) L-NAME+L-精氨酸组与L-NAME组相比, 海马CA1区组织损伤明显减轻(P<0.05), 但与预缺血+损伤性缺血组相比仍有显著性差别(P<0.05), 提示L-精氨酸可部分逆转L-NAME的作用; (5) L-NAME+损伤性缺血组的组织学表现与损伤性缺血组相同(P>0.05)。这些结果表明， 在整体情况下NO参与BIT的诱导。与CIP前1 h及后1、 12 h给予L-NAME组相比, CIP后36 h给予L-NAME对CIP保护作用的阻断效应明显减弱, 提示NO在CIP后较早阶段即开始参与BIT的诱导。
关键词: 神经生物学; 脑缺血预处理; 一氧化氮; L-硝基-精氨酸甲酯; 海马; 大鼠
中图分类号: Q426; R338
Effect of NOS
inhibitor L-NAME on the induction of brain ischemic tolerance in rats
LIU Hui-Qing, LI Wen-Bin*, FENG Rong-Fang, LI Qing-Jun, CHEN Xiao-Ling, ZHOU Ai-Min,ZHAO Hong-Gang, AI Jie
Department of Pathophysiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017
Abstract: To explore the role of NO in the induction of brain ischemic tolerance (BIT) in vivo, the effect of NOS inhibitor L-NAME on the induction of BIT induced by cerebral ischemic preconditioning (CIP) was investigated in the hippocampal CA1 subfield in CIP and ischemic insult models established by rat four-vessel occlusion using brain tissue section and thionine staining methods. Fifty-four male Wistar rats were divided into 6 groups: (1) sham-operated group (n=6): bilateral common arteries were separated without occluding the cerebral blood flow; (2) ischemia group (n=6): an ischemic insult for 10 min was given; (3) CIP+ischemia group (n=6): 3-min CIP was preformed 72 h prior to 10-min ischemic insult; (4) L-NAME group (total n=24, n=6 for each subgroup): L-NAME (5 mg/kg, i.p.) was administered 1 h prior to CIP and 1, 12 and 36 h after CIP, respectively. Other procedures were the same as those for the CIP+ischemia group; (5) L-NAME+L-Arg group (n=6): L-NAME (5 mg/kg, i.p.) and L-Arg (300 mg/kg, i.p.) were administered 1 h prior to CIP, other procedures were the same as those for the L-NAME group; (6) L-NAME+ischemia group (n=6): L-NAME (5 mg/kg, i.p.) was administered 72 h before the 10-min ischemic insult. The results showed that (1)10-min ischemic insult resulted in an increase in the histological grade (indicating a more serious tissue injury) and a decrease in pyramidal neuronal density (P<0.01); (2) the histological grade and neuronal density in hippocampal CA1 in the CIP+ischemia group were similar to those in the sham-operated group (P>0.05); (3) in the L-NAME group, administration of L-NAME brought about an increase in the histological grade and a decrease in neuronal density (P<0.01), suggesting that L-NAME blocked the protection of CIP; (4) the neuronal damage in L-NAME+L-Arg group was slighter than that in the L-NAME group, but still more serious than that in the CIP+ischemia group, suggesting that L-Arg partly reversed the blocking effect of L-NAME; (5) the morphological representations in L-NAME+ischemia group were basically similar to those in the ischemia group. The results mentioned above indicate that NO is involved in the induction of BIT in vivo. The blocking effect of L-NAME administered at 36 h after CIP was obviously weaker than the effects of L-NAME administered 1 h prior to CIP, and 1 or 12 h after CIP. It is suggested that NO is involved in the induction of BIT at an early stage and that the involvement might take place via activating cascades of the events.
Key words: neurobiology; ischemic preconditioning; nitric oxide; L-NAME; hippocampus; rats