Neuroprotective effects of Alpinia katsumadai against neuronal damage in the gerbil hippocampus induced by transient cerebral ischemia.

Alpinia katsumadai, one of the family Zingiberaceae, contains chalcone, flavonoids, diarylheptanoids, monoterpenes, sesquiterpenoids, stilbenes, and labdanes. It has been reported that the extract of Alpinia katsumadai seed (EAKS) has antiinflammatory effects, and enhances antioxidant activities. We observed the neuroprotective effects of EAKS against ischemic damage in gerbils received oral administrations of EAKS (50 mg/kg) once a day for 7 days before transient cerebral ischemia. In the EAKS-treated ischemia group, neuronal nuclei (NeuN, a marker for neurons)-immunoreactive pyramidal neurons were abundant (68.3% of the sham group) in the hippocampal CA1 region (CA1) 4 days after ischemia/reperfusion (I/R) compared to those in the vehicle-treated ischemia group (13.18%). We also observed that EAKS treatment significantly decreased the activation of astrocytes and microglia in the CA1 compared with the vehicle-treated ischemia group 4 days postischemia. In addition, protein levels of GFAP and Iba-1 in the EAKS-treated ischemia group were much lower than those in the vehicle-treated ischemia group 4 days after I/P. Our findings indicate that the repeated supplements of EAKS could protect neurons from an ischemic damage, showing that glial activation is markedly decreased in the ischemic area.