Neuroprotective effect of salvianolic acid B against cerebral ischemic injury in rats via the CD40/NF-κB pathway associated with suppression of platelets activation and neuroinflammation

Neuroinflammation plays a critical role in the pathogenesis of ischemia/reperfusion (I/R) injury. Activated platelets are increasingly regarded as initiators and/or amplifiers of inflammatory processes in cerebral I/R injury. Salvianolic acid B (SAB) is the most abundant bioactive compound of Salviae miltiorrhizae, a well-known Chinese herb used to promote blood circulation and eliminating blood stasis. S. miltiorrhizae has been used clinically in Asia for the treatment of ischemic cerebrovascular diseases. In the present study, a rat model of transient middle cerebral artery occlusion (tMCAO) was established to investigate the neuroprotective effects and mechanisms of SAB treatment against focal cerebral I/R insult. The results showed that SAB treatment (3 mg/kg, 6 mg/kg and 12 mg/kg, i.p.) dose-dependently decreased I/R-induced neurological deficits at 24, 48, and 72 h after reperfusion and decreased plasma-soluble P-selectin and soluble CD40 ligand as early as 6 h after onset of I/12 insult. At 24 h after reperfusion, SAB treatment significantly reduced neuronal and DNA damage in the hippocampal CA1 region and decreased neural cell loss in the ischemic core. The I/R-induced pro-inflammatory mediator mRNA and protein overexpression in the penumbra cortex, including ICAM-1, IL-1 beta, IL-6, IL-8, and MCP-1, were significantly inhibited by SAB in a dose-dependent manner. Further studies suggested SAB treatment attenuated CD40 expression and NF-kappa B activation, which involved NF-kappa B/p65 phosphorylation and h kappa B alpha phosphorylation and degradation. In conclusion, our findings indicated that the neuroprotective effects of SAB post cerebral I/R injury are associated with the inhibition of both platelets activation and production of pro-inflammatory mediators and the downregulation of the CD40/NF-kappa B pathway. (C) 2017 Elsevier B.V. All rights reserved.