Cerebral edema is characterized by fluid accumulation, and the glymphatic system (GS) plays a pivotal role in regulating fluid transport. Using the Tenecteplase system, magnesium salt of salvianolic acid B/ginsenoside Rg1 (SalB/Rg1) was injected intravenously into mice 4.5 h after middle cerebral artery occlusion and once every 24 h for the following 72 h. GS function was assessed by Evans blue imaging, near-infrared fluorescence region II (NIR-II) imaging, and magnetic resonance imaging (MRI). SalB/Rg1 had significant effects on reducing the infarct volume and hemorrhagic transformation score, improving neurobehavioral function, and protecting tissue structure, especially inhibiting cerebral edema. Meanwhile, the influx/efflux drainage of GS was enhanced by SalB/Rg1 according to NIR-II imaging and MRI. SalB/Rg1 inhibited matrix metalloproteinase-9 (MMP-9) activity, reduced cleaved β-dystroglycan (β-DG), and stabilized aquaporin-4 (AQP4) polarity, which was verified by colocalization with CD31. Our findings indicated that SalB/Rg1 treatment enhances GS function and attenuates cerebral edema, accompanying the regulation of the MMP9/β-DG/AQP4 pathway.
Animals ; Ginsenosides/administration & dosage* ; Brain Edema/etiology* ; Male ; Benzofurans/administration & dosage* ; Glymphatic System/diagnostic imaging* ; Mice ; Infarction, Middle Cerebral Artery/drug therapy* ; Aquaporin 4/metabolism* ; Disease Models, Animal ; Mice, Inbred C57BL ; Matrix Metalloproteinase 9/metabolism* ; Neuroprotective Agents/pharmacology* ; Depsides

The glymphatic system can remove metabolic wastes from the brain, which plays a significant role in maintaining the homeostasis of the central nervous system. It is an important basis for advanced cognitive functions such as learning and memory. Studies have analyzed the function of glymphatic system by diffusion tensor imaging analysis along the perivascular space (DTI-ALPS) recently. Compared with other invasive examinations that require fluorescent tracer technique or the injection of contrast agents, DTI-ALPS can evaluate the hydromechanics of the glymphatic system via quantifying the diffusion rate of water molecules in different directions, which turns out to be a non-invasive in vivo neuroimaging method. The ALPS-index calculated by the DTI-ALPS method is significantly correlated with the cognitive function in diseases of central nervous system and other system and can reflect the dynamic changes of diseases. In general, ALPS-index is expected to become a novel neuroimaging biomarker for predicting prognosis and clinical effects.
Glymphatic System/diagnostic imaging* ; Diffusion Tensor Imaging ; Brain/diagnostic imaging* ; Central Nervous System ; Cognition