Calycosin-7-O-β-D-glucoside regulates nitric oxide /caveolin-1/matrix metalloproteinases pathway and protects blood-brain barrier integrity in experimental cerebral ischemia-reperfusion injury

Ethnopharmacology relevance: Astragali Radix (AR) has been used for thousands years to treat ischemic stroke. Calycosin and its glycoside form calycosin-7-O-β-D-glucoside (CG) are two representative Isoflavones in Astragali Radix. However, its neurological effects and related molecular mechanisms are largely unknown. The present study aims to evaluate the neuroprotective effects of CG on blood-brain barrier (BBB) integrity of ischemic brain tissue and explore the relevant signaling mechanisms.

Material and method: Male adult Sprague-Daweley rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) plus 24 h or 14 days of reperfusion. CG (26.8 mg/kg) was intraperitoneally administered into the rats at 15 min before onset of ischemia. The neuroprotective effects of CG were evaluated by measuring infarct volume, histological damage and BBB permeability. Furthermore, the effects of CG on scavenging nitric oxide (NO), and modulating Matrix Metalloproteinases (MMPs) and caveolin-1 (cav-1) were investigated with in vitro cultured brain microvascular endothelial cells treated with NO donor or oxygen-glucose deprivation (OGD) and/or in vivo rat model of MCAO cerebral ischemia-reperfusion injury.

Results: CG treatment significantly reduced infarct volume, histological damage and BBB permeability in the in vivo MCAO ischemia-reperfusion rat model. CG treatment remarkably inhibited the expression and activities of MMPs, and secured the expression of cav-1 and tight junction proteins in the microvessels isolated from ischemic rat cortex. Furthermore, CG was revealed to scavenge NO, inhibit the activities of MMP-2 and MMP-9, and attenuate cell death in the in vitro cultured brain microvascular endothelial cells under OGD condition.

Conclusion: CG could protect BBB integrity in experimental cerebral ischemia-reperfusion injury via regulating NO/cav-1/MMPs pathway.