Reduction of Ischemic Brain Edema by Combined use of Paeoniflorin and Astragaloside IV via Down-Regulating Connexin 43
Paeoniflorin (PF) and astragaloside IV (AS-IV) have protective effects on cerebral ischemia. We aimed to test the effects of combined use of PF and AS-IV on ischemic brain edema and investigate whether the effects were dependent on connexin43 (Cx43). We detected the expression of Cx43 induced by PF and AS-IV after cerebral ischemia. We also examined the effects of combined use of PF and AS-IV on ischemic edema and further investigated the related pathways. We demonstrated PF and AS-IV decreased Cx43 and aquaporin4 (AQP4) associating with reduction of brain edema by dry-wet weight and brain-specific gravity methods after cerebral ischemia. Administration of PF and AS-IV displayed a further attenuation of brain edema with lower Cx43 levels. Meanwhile, Cx43 blockade inhibited AQP4 down-regulation by the two drugs. Moreover, phosphorylation of C-Jun amino-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) were increased by PF and AS-IV, respectively. The effects of PF and AS-IV to down-regulate Cx43 were suppressed by JNK and ERK inhibitors, respectively. Our data indicate that PF and AS-IV alleviate ischemic brain edema, which has close relation to Cx43 down-regulation causing decrease of AQP4 via JNK and ERK pathways activation, respectively. Combined administration elicits synergistic effects on brain edema reduction.