Ginsenoside Rb1 Maintains Tunneling Nanotubes between Astrocytes and Neurons To Protect Mice from Cerebral ischemia/reperfusion Injury

Ginsenoside Rb1 (GRb1), the major bioactive component of ginseng, exhibits multiple therapeutic effects. However, its neuroprotective role in cerebral ischemia/reperfusion (I/R) injury remains unclear. The neuroprotective effects of GRb1 were investigated using a mouse middle cerebral artery occlusion (MCAO) model and in vitro oxygen-glucose deprivation/reoxygenation (OGD/R) models. GRb1 was administered intraperitoneally to MCAO mice, and the effects on neurological function, brain edema, blood-brain barrier (BBB) integrity, and extracellular matrix (ECM) remodeling were evaluated. In the OGD/R model, tunneling nanotubes (TnTs) formation, oxidative stress, and mitochondrial integrity were evaluated in a co-culture of astrocytes and neurons. GRb1 markedly enhanced neurological function, alleviated brain edema, and maintained BBB integrity in MCAO mice. It also inhibited the expression of matrix metalloproteinases and Granzyme B while increasing Serpina3n, indicating protection of ECM integrity. In OGD/R-treated neurons, GRb1 reduced oxidative stress, restored superoxide dismutase activity, and preserved ATP and mitochondrial DNA. Importantly, GRb1 significantly enhanced TnTs formation, and inhibition of TnTs with cytochalasin B markedly reversed these protective effects, supporting a TnT-dependent mechanism. GRb1 effectively protected against I/R-induced neuronal injury through TnTs-dependent mechanisms, modulating oxidative stress, ECM remodeling, and mitochondrial integrity.