DEVELOPMENT OF NEUROPROTECTIVE STRATEGY BY THE COMBINATION THERAPY OF IMMUNOSUPPRESANT AND NEURONAL NITRIC OXIDE INHIBITOR ADMINISTRATION AGAINST NEONATAL BRAIN DAMAGE.

本研究旨在探讨免疫抑制剂FK506与神经元型一氧化氮抑制剂7-硝基吲唑联合治疗新生大鼠缺氧缺血性脑损伤的临床神经保护策略。我们还研究了FK506对新生儿缺氧缺血脑损伤的剂量依赖性和治疗时间窗。大鼠采用左颈动脉短暂闭塞和8%氧（HI）暴露90min的方法。然后在HI后24小时对大脑进行组织学检查。HI损伤引起以下神经元损伤的混合；海马、额叶和颞叶皮质和/或基底神经节巨噬细胞的Piknosis、嗜酸性改变、核裂、神经元丧失、caspase 3阳性细胞、海海绵变性和/或囊性改变。脑损伤的严重程度是通过大脑中受损神经元的程度来估计的，使用的是脑损伤评分。在HI损伤后立即给予2mg /kg FK506（高剂量），而不是1mg /kg（低剂量），与载体注射（剂量依赖性）相比，损伤后24小时神经元损伤的严重程度和caspase-3的激活显著降低。与车辆注射（治疗时间窗）相比，立即和HI损伤后30分钟（而不是60分钟）给予2mg /kg FK506治疗显示出显著的神经保护作用。1 mg/kg（低剂量）FK506与7-硝基吲唑联合治疗的神经保护作用明显优于单用FK506或7NI。

The goal of this study was to investigate the clinical neuroprotective strategy by means of the combination therapy of immunosuppressant, FK506, and the neuronal nitric oxide inhibitor, 7-nitroindazole, administration against hypoxic-ischemic (HI) brain damage in neonatal rats. We also investigated the dose dependency and therapeutic time window of FK506 against neonatal brain damage due to hypoxia-ischemia. The rats were performed by the transient occlusion of left carotid artery and the exposure to 8 % oxygen (HI) for 90 min. Then the brains were histologically examined 24 hrs after the HI. The HI insult induced the admixtures of the following neuronal damages; piknosis, eosinophilic change, karyorrhexis, loss of neurons, caspase 3-positive cells, spongy degeneration, and/or cystic change with macrophages in the hippocampus, frontal and temporal cortices, and/or basal ganglia. The severity of the brain damage was estimated by the extent of the damaged neurons in the brain, using the brain damage scores. The treatment of 2 mg/kg FK506 (high dose), but not 1 mg/kg (low dose), immediately after HI insult demonstrated significant decreases in the severity of the neuronal damage and caspase-3 activation 24 h after the insult, compared with vehicle injection (dose dependency). The treatment of 2 mg/kg FK506 immediately and 30 min after HI insult, but not 60 min after, demonstrated significant neuroprotective effect, compared with vehicle injection (therapeutic time window). The combination therapy of 1 mg/kg (low dose) FK506 and 7-nitroindazole demonstrated significantly more neuroprotetive effect than the single usage of either FK506 or 7NI.