Protective effect of iridoid glycosides of radix scrophulariae on endoplasmic reticulum stress induced by oxygen-glucose deprivation and reperfusion in vitro model

Abstract

To investigate the regulatory effect of iridoid glycoside of radix scrophulariae (IGRS) on endoplasmic reticulum stress induced by oxygen-glucose deprivation and reperfusion in vitro model. Rat pheochromocytoma PC12 cells were pretreated with IGRS (50, 100, 200 μg/mL) for 24h, and the in vitro model of oxygen-glucose deprivation/reoxygenation (OGD/R) was applied. The cell viability was determined by MTT and lactate dehydrogenase (LDH) assay. The apoptotic rate was detected by flow cytometry. The expression of B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), C/EBP homologous protein (CHOP), caspase-12 protein, and glucose-regulated protein-78(GRP78)were detected by Western blotting. The mRNA expression levels of sarco/endoplasmic reticulum Ca2+-ATPase2 (SERCA2), 1, 4, 5-triphosphate inositol receptor 1 (IP3R1), and ryanodine receptor 2 (RyR2)were detected by real-time RT-PCR. Free Ca2+ concentration [Ca2+]i was determined by using laser scanning confocal microscopy. The damage caused by OGD/R to PC12 cells was significantly reduced by IGRS, with significant effect on increasing survival rate and reducing LDH release (all P<0.01). The expression of GRP78, CHOP, Bax, and caspase-12 were down-regulated (all P<0.01), and the expression of Bcl-2 and Bcl-2/Bax ratio was up-regulated (all P<0.01); IGRS increased the expression of SERCA2 mRNA in PC12 cells after OGD/R injury (P<0.01), decreased [Ca2+]i and down-regulated the expression of RyR2 mRNA and IP3R1 mRNA. IGRS has neuroprotective effect, which may alleviate cerebral ischemia-reperfusion injury by regulating SERCA2, maintaining calcium balance, and inhibiting endoplasmic reticulum stress-mediated apoptosis.