背景:红景天苷是红景天中主要的生物活性和药理活性物质。据报道,红景天苷对脑缺血/再灌注(I/R)具有神经保护作用。然而,红景天苷是否能促进脑I/R后神经再生尚不清楚。本研究探讨红景天苷对脑I/R后内源性神经再生的影响及相关机制。
方法:通过短暂的大脑中动脉阻塞/再灌注(MCAO/R)在大鼠中诱导局灶性脑I/R。将大鼠腹膜内处理红景天苷,每天一次,连续7天。在损伤后3天和7天进行神经行为评估。进行TTC染色以评估脑梗死体积。为了评估神经元的存活,对缺血半球的神经元核(NeuN)进行免疫组织化学染色。此外,对缺血半球脑室下区(SVZ)和纹状体的增殖神经祖细胞的生物标志物进行免疫荧光双重或三重染色,以研究神经发生。此外,采用逆转录-聚合酶链反应(RT-PCR)和酶联免疫吸附试验(ELISA)检测神经营养因子(NTFs)脑源性神经营养因子(BDNF)和神经生长因子(NGF)的表达。还通过蛋白质印迹和RT-PCR分析了Notch1及其靶分子Hes1的表达。
结果:红景天苷治疗可改善I/R诱导的神经行为障碍,减少梗死体积。红景天苷还恢复了I/R损伤后的NeuN阳性细胞损失。脑I/R损伤显著增加5-溴-2'-脱氧尿苷(BrdU)和dublecotin(DCX)的表达,提高了SVZ中BrdU/Nestin/DCX三重标记细胞的数量,和纹状体中BrdU/Nestin/神经胶质原纤维酸性蛋白(GFAP)三重标记的细胞。红景天苷处理进一步促进BrdU/DCX标记的成神经细胞和BrdU/Nestin/GFAP标记的反应性星形胶质细胞的增殖。此外,红景天苷升高缺血周边区BDNF和NGF的mRNA表达和蛋白浓度,也是。机械上,红景天苷升高SVZ中Notch1/Hes1mRNA的表达。红景天苷给药后,它们的蛋白质水平也增加。
结论:红景天苷增强脑I/R后内源性神经再生其作用机制可能涉及BDNF/NGF和Notch信号通路的调控。
BACKGROUND: Salidroside is the major bioactive and pharmacological active substance in Rhodiola rosea L. It has been reported to have neuroprotective effects on cerebral ischemia/reperfusion (I/R). However, whether salidroside can enhance neural regeneration after cerebral I/R is still unknown. This study investigated the effects of salidroside on the endogenous neural regeneration after cerebral I/R and the related mechanism.
METHODS: Focal cerebral I/R was induced in rats by transient middle cerebral artery occlusion/reperfusion (MCAO/R). The rats were intraperitoneally treated salidroside once daily for 7 consecutive days. Neurobehavioral assessments were performed at 3 days and 7 days after the injury. TTC staining was performed to assess cerebral infarct volume. To evaluate the survival of neurons, immunohistochemical staining of Neuronal Nuclei (NeuN) in the ischemic hemisphere were conducted. Also, immunofluorescence double or triple staining of the biomarkers of proliferating neural progenitor cells in Subventricular Zone (SVZ) and striatum of the ischemia hemisphere were performed to investigate the neurogenesis. Furthermore, reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect the expression of neurotrophic factors (NTFs) brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). Expression of Notch1 and its target molecular Hes1 were also analyzed by western-blotting and RT-PCR.
RESULTS: Salidroside treatment ameliorated I/R induced neurobehavioral impairment, and reduced infarct volume. Salidroside also restored NeuN positive cells loss after I/R injury. Cerebral I/R injury significantly increased the expression of 5-Bromo-2\'-Deoxyuridine (BrdU) and doublecotin (DCX), elevated the number of BrdU/Nestin/DCX triple-labeled cells in SVZ, and BrdU/Nestin/glial fibrillary acidic protein (GFAP) triple-labeled cells in striatum. Salidroside treatment further promoted the proliferation of BrdU/DCX labeled neuroblasts and BrdU/Nestin/GFAP labeled reactive astrocytes. Furthermore, salidroside elevated the mRNA expression and protein concentration of BDNF and NGF in ischemia periphery area, as well. Mechanistically, salidroside elevated Notch1/Hes1 mRNA expression in SVZ. The protein levels of them were also increased after salidroside administration.
CONCLUSIONS: Salidroside enhances the endogenous neural regeneration after cerebral I/R. The mechanism of the effect may involve the regulation of BDNF/NGF and Notch signaling pathway.