To investigate whether the protective actions of ginsenoside Rb1 (Rb1) on astrocytes are mediated through the G_s-type G-protein-coupled receptor (GPCR-G_s).

Primary astrocyte cultures derived from neonatal mouse brain were used. Astrocyte injury was induced via oxygen-glucose deprivation/re-oxygenation (OGD/R). Cell morphology, viability, lactate dehydrogenase (LDH) leakage, apoptosis, glutamate uptake, and brain-derived neurotrophic factor (BDNF) secretion were assessed to gauge cell survival and functionality. Western blot was used to investigate the cyclic adenosine monophosphate (cAMP) and protein kinase B (Akt) signaling pathways. GPCR-G_s-specific inhibitors and molecular docking were used to identify target receptors.

Rb1 at concentrations ranging from 0.8 to 5 μM did not significantly affect the viability, glutamate uptake, or BDNF secretion in normal astrocytes. OGD/R reduced astrocyte viability, increasing their LDH leakage and apoptosis rate. It also decreased glutamate uptake and BDNF secretion by these cells. Rb1 had protective effects of astrocytes challenged by OGD/R, by improving viability, reducing apoptosis, and enhancing glutamate uptake and BDNF secretion. Additionally, Rb1 activated the cAMP and Akt pathways in these cells. When the GPCR-G_s inhibitor NF449 was introduced, the protective effects of Rb1 completely disappeared, and its activation of cAMP and Akt signaling pathways was significantly inhibited.

Rb1 protects against astrocytes from OGD/R-induced injury through GPCR-G_s mediation.

To evaluate whether ginsenoside Rb1 (Rb1) can attenuate lipopolysaccharide (LPS)-induced chronic neuroinflammation in mice and to explore its relationship with glial cell polarization.

Intraperitoneal injection with an escalating dose of LPS was used to establish a chronic neuroinflammation model in mice. Once LPS was initiated, 10 or 20 mg/kg Rb1, or sterile saline, was administered for 14 consecutive days. Open field test and beam walking test were used to monitor the changes in behavior. The concentration of cytokines in the serum and brain were used to monitor the systemic inflammation and neuroinflammation, respectively. Molecules specific to each glial cell phenotype were used to investigate glial cell polarization.

Mice in the LPS group had reduced spontaneous activities and impaired beam walking performance. Rb1 obviously eased LPS-induced behavior disturbances. Regarding the levels of serum cytokines, both tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were significantly increased, while interleukin-10 (IL-10) and transforming growth factor β (TGF-β) remarkably decreased after LPS treatment (all P < .001). Rb1 treatment significantly attenuated LPS-induced serum cytokine changes (all P < .05). The results of quantitative polymerase chain reaction and western blotting showed that the mRNA and protein expression levels of TNF-α and complement component 3 (C3) in the brain were significantly increased after LPS treatment (all P < .01). Rb1 treatment significantly inhibited LPS-induced inflammation in the brain (all P < .05). Glial cell polarization analysis showed that M1 and M2 microglia, and A1 astrocytes increased following LPS treatment, while A2 astrocytes decreased. Rb1 treatment reduced M1 and M2 microglia, and A1 astrocytes, and significantly increased A2 astrocytes.

Rb1 can attenuate chronic neuroinflammation induced by LPS in mice, which may be partially attributable to its fine tuning of microglia and astrocyte polarization. Rb1 has potential value for treating neurodegenerative diseases.