Neuroprotective efficacy and therapeutic window of Forsythoside B: In a rat model of cerebral ischemia and reperfusion injury

The present study was to investigate the neuroprotective efficacy and mechanism of Forsythoside B. Male Sprague–Dawley rats were subjected to middle cerebral artery occlusion for 1 h followed by reperfusion for 23 h. Rats received an intravenous bolus injection of Forsythoside B at 15 min after reperfusion. The results showed that Forsythoside B at doses higher than 8 mg/kg produced a significant neuroprotective potential in cerebral ischemia and reperfusion rats. Forsythoside B (20 mg/kg) demonstrated significant neuroprotective activity even after delayed administration at 1 h, 3 h and 5 h after cerebral ischemia and reperfusion. Forsythoside B 20 mg/kg attenuated histopathological damage as demonstrated by smaller brain infarct size and brain edema, decreased cerebral Evans blue extravasation and myeloperoxidase (MPO) activity, inhibited cerebral phosphor-IκB-α and nuclear transcription factors kappaB (NF-κB) expression. Meanwhile, NF-κB expression with immunohistochemical staining was reduced, while circulating polymorphonuclear leukocytes was increased. All of these findings suggested that Forsythoside B exerted potent neuroprotective effects with a favorable therapeutic time-window, reduce of cerebral ischemia and reperfusion injury degree, attenuating blood-brain barrier (BBB) breakdown, and its protective effects may be due to inhibition of inflammatory response.