The role of arachidonic acid cascade in the development of delayed neuronal death

用沙土鼠研究了花生四烯酸级联反应在沙土鼠前脑缺血后迟发性神经元死亡中的作用。首先，对缺血再灌流期合成的前列腺素(PG)F_2α和GT的免疫组织化学定位进行了研究。将含海马区的冰冻切片与兔抗前列腺素F_2α_(2α)_(Gt)血清孵育，用亲和素-生物素-过氧化物酶复合法进行染色。假手术对照组血管内皮细胞呈淡淡的抗PGF_2α_(gt；)血清染色。神经元和胶质细胞染色较少或未见染色。再灌流后，实验动物血管、神经元尤其是海马锥体神经元和神经胶质细胞中PGF_2α和GT_2呈明显阳性染色。接下来，我们研究了环氧合酶抑制剂吲哚美辛预防沙土鼠海马区缺血性迟发性神经元死亡的可能性。双侧颈总动脉结扎造成大鼠前脑缺血5min。动物于缺血前30min腹腔注射吲哚美辛(1、2、5、10 mg/kg)。缺血7d后灌流固定，计数CA1区神经元密度。各剂量的吲哚美辛均能显著阻止大鼠海马CA_1区迟发性神经元死亡。环氧合酶抑制剂而不是吲哚美辛和脂氧合酶抑制剂或延迟性神经元死亡也在相同的沙土鼠模型中被检测。吡罗昔康(10 mg/kg)和氟比洛芬(10 mg/kg)可明显减轻神经元死亡。然而，脂氧合酶抑制剂AA801和BW755C并不能改善迟发性神经元死亡。上述结果有力地表明环氧合酶产物可能参与了前脑缺血后迟发性神经元死亡的发生。

The role of arachdonic acid cascade in the develppent of delayed neuronal death following forebrain ischemia was investigated in the gerbils. First, immunohistochemical localization of prostaglandin(PG)F_<2alpha> synthesized during the recirculation phase following ischemia was studied. Frozen sebtions containing hippocampi were incubated with rabbit anti-PGF_<2alpha> serum and stained by the avidin-biotin-peroxidase complex method. In the control animals having sham operation, blood vessels were faintly stained with anti-PGF_<2alpha> serum. Less or no stain was found in neurons and glial cells. After recirculation, the experimental animals demonstrated marked positive staining for PGF_<2alpha> in blood vessels, neurons, especially hippocampal pyramidal neurons, and glial cells. Next, we examined the possibility that indomethain, a cyclooxygenase inhibiro, prevents ischemic delayed neuronal death in the gerbil hippocampus. Forebrain ischemia for 5 min was prduced by bilateral carotid occlusion. Animals received intraperitoneal injection of indomethacin(1, 2, 5 and 10mg/kg)30 min before ischemic insult. They were perfusion-fixed 7 days afere ischemic insult, and the neuronal density in the CA_1 sector was counted. Indomethacin at each dose significantly prevented delaye neuronal death in the hippocampal CA_1 sector. Effects of cyclooxygenase inhibior other than indomethacin and lipoxygenase inhibior delayed neuronal death were also examined in the same gerbil model. Piroxycam(10mg/kg)and Flurbiprofen(10mg/kg)ameliorated significantly delayed neuronal death. However, lipoxygenase inhibiotrs, AA801 and BW755C, did not ameliorated delayed neuronal death. Above results strongly suggest that cylooxygenase products may involved in the development of delayed neuronal death following forebrain ischemia in the ferels.