Objective: To study the effects of different melatonin treatment regimens on the proliferation of neural stem cells (NSCs) and long-term histopathology in neonatal rats with hypoxic-ischemic brain damage (HIBD), and to identify better melatonin treatment regimens.
Methods: A total of 96 Sprague-Dawley rats aged 7 days were randomly divided into normal control, HIBD, single-dose immediate melatonin treatment (SDIT), and 7-day continuous melatonin treatment (7DCT) groups, with 24 rats in each group. The rat model of HIBD was prepared by isolation and electrocoagulation of the right common carotid artery as well as hypoxic treatment in a hypoxic chamber (oxygen concentration 8.00% ± 0.01%) for 2 hours. On day 7 after modeling, proliferating cell nuclear antigen/Nestin double-labeling immunofluorescence was used to measure the proliferation of endogenous NSCs in the subventricular zone (SVZ) and the hippocampal dentate gyrus (DG) region in 8 rats in each group, and Western blot was used to measure the protein expression of Nestin in brain. On day 28 after modeling, hematoxylin-eosin (HE) staining and Nissl staining were used to observe the changes in the histopathology and the number of pyramidal cells in the hippocampal CA1 region in 8 rats in each group.
Results: Immunofluorescent staining showed that compared with the HIBD group, the SDIT and 7DCT groups had a significant increase in the number of PCNA+Nestin+DAPI+ cells, and the 7DCT group had a significantly higher number than the SDIT group (P<0.01). Western blot showed that the SDIT and 7DCT groups had significantly higher protein expression of Nestin than the HIBD group, and the 7DCT group had significantly higher expression than the SDIT group (P<0.05). HE staining showed that the SDIT and 7DCT groups had alleviated cell injury, and Nissl staining showed that compared with the HIBD group, the SDIT and 7DCT groups had a significant increase in the number of pyramidal cells, and the 7DCT group had a significantly higher number than the SDIT group (P<0.01).
Conclusions: Both single-dose immediate melatonin treatment and 7-day continuous melatonin treatment can promote the proliferation of endogenous NSCs and alleviate long-term histological injury in the brain of neonatal rats with HIBD. A 7-day continuous melatonin treatment has a better effect than single-dose immediate melatonin treatment.
目的: 探讨不同褪黑素治疗方案对缺氧缺血性脑损伤（HIBD）新生大鼠脑内源性神经干细胞（NSCs）增殖及远期组织学的影响，以寻求褪黑素治疗的较优方案。
方法: 将96只7日龄Sprague-Dawley大鼠随机分为正常对照组、缺氧缺血性脑损伤（HIBD）组、单剂量即刻褪黑素治疗（SDIT）组及7日连续褪黑素治疗（7DCT）组（n=24）。HIBD大鼠模型采用分离并电凝大鼠右侧颈总动脉，低氧舱（氧气浓度为8%±0.01%）内缺氧2 h的方法建立。造模后7 d，采用增殖细胞核抗原（PCNA）/巢蛋白（Nestin）免疫荧光双标法检测各组大鼠侧脑室室管膜下区（SVZ）及海马齿状回（DG）区内源性NSCs的增殖情况（n=8）；采用Western blot法检测各组大鼠脑Nestin蛋白的表达水平（n=8）。造模后28 d，采用苏木精-伊红染色（HE）和尼氏染色法观察海马CA1区的组织病理学及锥体细胞数的变化（n=8）。
结果: 免疫荧光染色结果显示：SDIT组和7DCT组PCNA+Nestin+DAPI+细胞数均较HIBD组增加，且7DCT组显著多于SDIT组（P < 0.01）；Western blot结果显示：SDIT组与7DCT组Nestin蛋白的表达水平均显著高于HIBD组，且7DCT组显著高于SDIT组（P < 0.05）；HE染色结果显示：SDIT组及7DCT组细胞损伤减轻；尼氏染色结果显示：SDIT组和7DCT组锥体细胞数均较HIBD组增加，且7DCT组显著高于SDIT组（P < 0.01）。
结论: SDIT和7DCT均可促进HIBD新生大鼠脑内源性NSCs的增殖，减轻远期组织学损伤，且7DCT疗效优于SDIT。