ABSTRACT
Notoginseng leaf triterpenes (PNGL), derived from the dried stems and leaves of P. notoginseng, is a phytoestrogen that exerts many neuroprotective effects in vivo and in vitro of ischemic stroke. However, its impact on neurological restoration specifically in relation to angiogenesis following ischemic stroke remains unexplored. The aim of this study was to assess the effects of PNGL on angiogenesis subsequent to ischemic stroke. Male Sprague-Dawley rats were utilized in this study and were subjected to middle cerebral artery occlusion/reperfusion (MCAO/R). Post-ischemia, PNGL were administered through intraperitoneal (i.p.) injection. The high-performance liquid chromatography (HPLC) fingerprinting, triphenyltetrazolium chloride (TTC) staining, immunofluorescent staining, network pharmacology and western blot analyses were assessed to determine the therapeutical effect and molecular mechanisms of PNGL on cerebral ischemia/reperfusion injury. Our findings demonstrate that PNGL effectively reduced infarct volume, enhanced cerebral blood flow, and induced angiogenesis in rats subjected to MCAO/R. Notably, PNGL also facilitated neuronal proliferation and migration in HUMECs in vitro. The proangiogenic effects of PNGL were found to be linked to the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway and the AMPK/SIRT1-mediated PGC-1/ERα axis, as well as the activation of neurological function. Our study provides evidence that PNGL hold promise as an active ingredient of inducing proangiogenic effects, potentially through the activation of the Nrf2 pathway and the AMPK/SIRT1-mediated PGC-1/ERα axis. These findings contribute to the understanding of novel mechanisms involved in the restoration of neurological function following PNGL treatment for ischemic stroke.
ABSTRACT
BACKGROUND: Ischemic stroke is a leading cause of death and long-term disability worldwide. Studies have suggested that cerebral ischemia induces massive mitochondrial damage. Valerianic acid A (VaA) is the main active ingredient of valerianic acid with neuroprotective activity. PURPOSE: This study aimed to investigate the neuroprotective effects of VaA with ischemic stroke and explore the underlying mechanisms. METHOD: In this study, we established the oxygen-glucose deprivation and reperfusion (OGD/R) cell model and the middle cerebral artery occlusion and reperfusion (MCAO/R) animal model in vitro and in vivo. Neurological behavior score, 2, 3, 5-triphenyl tetrazolium chloride (TTC) staining and Hematoxylin and Eosin (HE) Staining were used to detect the neuroprotection of VaA in MCAO/R rats. Also, the levels of ROS, mitochondrial membrane potential (MMP), and activities of NAD+ were detected to reflect mitochondrial function. Mechanistically, gene knockout experiments, transfection experiments, immunofluorescence, DARTS, and molecular dynamics simulation experiments showed that VaA bound to IDO1 regulated the kynurenine pathway of tryptophan metabolism and prevented Stat3 dephosphorylation, promoting Stat3 activation and subsequent transcription of the mitochondrial fusion-related gene Opa1. RESULTS: We showed that VaA decreased the infarct volume in a dose-dependent manner and exerted neuroprotective effects against reperfusion injury. Furthermore, VaA promoted Opa1-related mitochondrial fusion and reversed neuronal mitochondrial damage and loss after reperfusion injury. In SH-SY5Y cells, VaA (5, 10, 20 µM) exerted similar protective effects against OGD/R-induced injury. We then examined the expression of significant enzymes regulating the kynurenine (Kyn) pathway of the ipsilateral brain tissue of the ischemic stroke rat model, and these enzymes may play essential roles in ischemic stroke. Furthermore, we found that VaA can bind to the initial rate-limiting enzyme IDO1 in the Kyn pathway and prevent Stat3 phosphorylation, promoting Stat3 activation and subsequent transcription of the mitochondrial fusion-related gene Opa1. Using in vivo IDO1 knockdown and in vitro IDO1 overexpressing models, we demonstrated that the promoted mitochondrial fusion and neuroprotective effects of VaA were IDO1-dependent. CONCLUSION: VaA administration improved neurological function by promoting mitochondrial fusion through the IDO1-mediated Stat3-Opa1 pathway, indicating its potential as a therapeutic drug for ischemic stroke.
