目的 探讨不同褪黑素治疗方案对缺氧缺血性脑损伤（HIBD）新生大鼠远期行为学及脑白质损伤的影响，以寻求较优的褪黑素治疗方案。方法 健康7日龄Sprague-Dawley大鼠随机分为假手术组、HIBD组、单次即刻注射褪黑素治疗（SDIT）组及7日连续注射褪黑素治疗（7DCT）组（n=8）。采用经典Rice法建立新生大鼠HIBD模型。HIBD后21 d，采用Morris水迷宫法检测各组大鼠的空间学习记忆能力；HIBD后70 d，采用免疫荧光法检测各组新生大鼠大脑皮质和海马CA1区神经元核抗原（NeuN）表达情况，采用免疫荧光双标法检测各组新生大鼠脑组织纹状体区和胼胝体区髓鞘碱性蛋白（MBP）、神经丝蛋白重链（NF200）表达情况。结果 Morris水迷宫测试结果显示，SDIT和7DCT组大鼠平均逃避潜伏期均显著短于HIBD组，且7DCT组平均逃避潜伏期显著短于SDIT组（P < 0.05）。NeuN免疫荧光结果显示，SDIT与7DCT组大鼠大脑皮质和海马CA1区NeuN⁺细胞数均显著多于HIBD组，且7DCT组显著多于SDIT组（P < 0.05）。MBP/NF200免疫荧光双重染色结果显示，SDIT组和7DCT组大鼠大脑纹状体区荧光强度（FI）_MBP、FI_NF200均显著高于HIBD组，且7DCT组显著高于SDIT组（P < 0.05）；7DCT组大鼠大脑胼胝体区FI_MBP与FI_NF200显著高于SDIT及HIBD组（P < 0.05）。结论 SDIT和7DCT均可改善HIBD大鼠远期行为学，减轻HIBD新生大鼠脑白质损伤，且7DCT疗效优于SDIT。

Objective To study the effect of different melatonin treatment regimens on long-term behavior and white matter damage in neonatal rats with hypoxic-ischemic brain damage (HIBD), and to seek an optimal melatonin treatment regimen. Methods Healthy Sprague-Dawley rats, aged 7 days, were randomly divided into four groups: sham-operation, HIBD, single-dose immediate treatment (SDIT), and 7-day continuous treatment (7DCT), with 8 rats in each group. A neonatal rat model of HIBD was prepared according to the classical Rice-Vannucci method. On day 21 after HIBD, the Morris water maze test was used to evaluate spatial learning and memory abilities. On day 70 after HIBD, immunofluorescence assay was used to measure the expression of neuronal nuclear antigen (NeuN) in the cerebral cortex and the hippocampal CA1 region of neonatal rats, and double-label immunofluorescence was used to measure the expression of myelin basic protein (MBP) and neurofilament 200 (NF200) in the corpus striatum and the corpus callosum. Results The results of the Morris water maze test showed that the SDIT and 7DCT groups had a significantly shorter mean escape latency than the HIBD group, and the 7DCT group had a significantly shorter mean escape latency than the SDIT group (P < 0.05). The results of immunofluorescence assay for NeuN showed that the SDIT and 7DCT groups had a significantly higher number of NeuN⁺ cells in the cerebral cortex and the hippocampal CA1 region than the HIBD group, and the 7DCT group had a significantly higher number than the SDIT group (P < 0.05). MBP/NF200 double-label immunofluorescence showed that compared with the HIBD group, the SDIT group and the 7DCT group had significantly higher fluorescence intensities of MBP and NF200 in the corpus striatum, and the 7DCT group had significantly higher fluorescence intensities than the SDIT group (P < 0.05); the 7DCT group had significantly higher fluorescence intensities of MBP and NF200 in the corpus callosum than the SDIT and HIBD groups (P < 0.05). Conclusions Both SDIT and 7DCT can improve long-term behavior and reduce white matter damage in neonatal rats with HIBD, and 7DCT is more effective than SDIT.