Department of Neurosurgery, The third XiangYa Hospital, Central South University, Changsha 410013, China.
Department of Physiology and Pharmacology, Loma Linda University, CA 92354, USA.
Exp Neurol. 2019 Jan;311:274-284. doi: 10.1016/j.expneurol.2018.10.011. Epub 2018 Oct 23.
Subarachnoid hemorrhage (SAH) is a devastating cerebrovascular disease that leads to poor outcomes. Neurogenesis, an essential recovery mechanism after brain injury, has not been fully elucidated after SAH.
A total of 122 SD rats were used in this study. For experiment one, the rats were randomly divided into six groups: sham and SAH with different time points (1,3,5,7,14 days) (n = 12/group). An endovascular perforation method was conducted for SAH model. Rats were injected with 5-Bromo-2'-deoxyuridine (BrdU, 50 mg/kg) 24 h before euthanasia at different time points after SAH. The BrdU labeled cells were detected by immunohistochemistry; Doublecortin (DCX) and glial fibrillary acidic protein (GFAP) were measured by western blot and immunohistochemistry. For experiment two, rats were randomly divided into five groups: sham and SAH with different time points (1, 2, 4, 8 weeks) (n = 6/group). Rats received BrdU (50 mg/kg) once daily for 7 days after the induction of SAH. Double immunofluorescence staining was used to verify proliferation, differentiation and migration of progenitor cells. Rotarod test and water maze used to test the neurobehavioral recovery.
Our results showed that BrdU positive cells in hippocampus changed overtime after SAH. BrdU positive cells decreased as early as 1 day reaching lowest levels at 3 days after SAH, after which it gradually recovered. Similar change patterns were observed with DCX, which was reversed with GFAP. In addition, BrdU did not co-localize with cleaved caspase-3. The BrdU positive cells mainly differentiated into immature neurons for short-term fate, whereas they differentiated into mature neurons for long-term fate but not astrocytes, which facilitated neurobehavioral recovery after SAH.
Neurogenesis in the hippocampus changes overtime after SAH. The neuronal progenitor cells may play an essential role in the neurobehavioral recovery after brain injury induced by SAH, since short-term progenitors helped with the recovery of immature neurons in the hippocampus, whereas long-term progenitors differentiated into mature neurons.
蛛网膜下腔出血（SAH）是一种破坏性的脑血管疾病，导致预后不良。神经发生是脑损伤后的一种重要恢复机制，但在 SAH 后尚未得到充分阐明。
本研究共使用了 122 只 SD 大鼠。实验一，将大鼠随机分为六组：假手术组和不同时间点（1、3、5、7、14 天）的 SAH 组（每组 n=12）。采用血管内穿破法制作 SAH 模型。SAH 后不同时间点，大鼠在安乐死前 24 小时注射 5-溴-2'-脱氧尿苷（BrdU，50mg/kg）。免疫组织化学法检测 BrdU 标记细胞；Western blot 和免疫组织化学法检测双皮质素（DCX）和胶质纤维酸性蛋白（GFAP）。实验二，将大鼠随机分为五组：假手术组和不同时间点（1、2、4、8 周）的 SAH 组（每组 n=6）。SAH 后，大鼠接受 BrdU（50mg/kg）每日一次，连续 7 天。双免疫荧光染色验证祖细胞的增殖、分化和迁移。转棒试验和水迷宫用于测试神经行为恢复。
我们的结果表明，SAH 后海马区 BrdU 阳性细胞随时间发生变化。SAH 后 1 天 BrdU 阳性细胞最早减少，3 天达到最低水平，之后逐渐恢复。DCX 也呈现类似的变化模式，与 GFAP 相反。此外，BrdU 与 cleaved caspase-3 不共定位。BrdU 阳性细胞主要分化为短期命运的不成熟神经元，而长期命运则分化为成熟神经元，而不是星形胶质细胞，这有助于 SAH 后神经行为的恢复。
SAH 后海马区的神经发生随时间发生变化。神经元祖细胞在 SAH 引起的脑损伤后的神经行为恢复中可能发挥重要作用，因为短期祖细胞有助于海马区不成熟神经元的恢复，而长期祖细胞则分化为成熟神经元。
