The Effect of Acori Graminei Rhizoma and Extract Fractions on Spatial Memory and Hippocampal Neurogenesis in Amyloid Beta 1-42 Injected Mice

Acori graminei Rhizoma (AGR), the dry rhizoma of Acorus gramineus Soland (Araceae), has been used as an Asian traditional herbal medicine against senile dementia, stroke, and cardiovascular disease. Previous studies have revealed neuroprotective effects of AGR on neuronal damage and learning impairment, while mostly focused on the effect of volatile oil fraction of AGR. This study aimed to investigate the neuroprotective effects of different extract fractions from AGR against Alzheimer disease-like symptoms induced by Amyloid Beta (Aß) 1-42 intra-hippocampal injection. On day 7 after intra-hippocampal injection of saline or Aβ1-42, spatial memory was assessed by the first Morris water maze, followed by 3-week intra-gastric administration of saline or water extract, volatile oil fraction, or defatted decoction fraction of AGR respectively. Mice were subsequently subjected to the second Morris water maze task. Levels of Aβ1-42 and expressions of doublecortin and nestin in the hippocampus were examined using immunohistochemistry. Our results suggested that treatment with these different extract fractions from AGR could ameliorate cognitive impairment and down-regulate expressions of doublecortin and nestin in the hippocampus of Aβ1-42 injected mice, in which water extract and volatile oil fractions were more effective in spatial memory than defatted decoction fraction. Keywords: Acori graminei rhizoma, extract fraction, amyloid beta, doublecortin, nestin, Alzheimer disease.