Maslinic acid promotes synaptogenesis and axon growth via Akt/GSK-3β activation in cerebral ischemia model

Abstract

Maslinic acid, a natural pentacyclic triterpene from Olea europaea plants, possesses neuroprotective effects both in vivo and in vitro. However, the mechanism of its action is not well understood. In this study, we investigated the potential effects of maslinic acid on synaptogenesis and axonal regeneration, as well as the possible signal pathway involved in a cerebral ischemia mouse model. Adult male C57BL/6J mice were subjected to 1h of cerebral ischemia by middle cerebral artery occlusion (MCAO). Maslinic acid (0.1, 1 and 10mg/kg) was administered intragastrically 24h after MCAO once daily for 7 consecutive days. Axonal loss and synaptophysin expression in the ischemic boundary area was evaluated by histological assay. The Akt/GSK-3β signal pathway was determined by western blot analysis. Two Akt inhibitors, LY294002 and MK2206, were used to verify the involvement of Akt/GSK-3β pathway in maslinic acid-mediated neuroprotection. Maslinic acid significantly prevented axonal damage, promoted axonal regeneration and increased synaptophysin expression 7 days after ischemia. In addition, maslinic acid treatment was shown to enhance Akt activity and promote GSK-3β phorsphorylation in stoke mice. The increased neurite outgrowth and synaptophysin expression by maslinic acid treatment was blocked by the Akt inhibitors both in vivo and in vitro.. These findings suggested that maslinic acid promotes synaptogenesis and axonal regeneration by regulating Akt/GSK-3β signaling pathway, which may, in turn, provide neuroprotection.