Effects of Nelumbo nucifera rhizome extract on cell proliferation and neuroblast differentiation in the hippocampal dentate gyrus in a scopolamine-induced amnesia animal model.

A large aquatic herb, Nelumbo nucifera Gaertn, has psychopharmacological effects similar to minor tranquillizers and antistress agents. This study examined the effects of Nelumbo nucifera rhizome extracts (NRE) on cell proliferation and neuroblast differentiation in the hippocampal dentate gyrus (DG) of a rat model of scopolamine-induced amnesia. Immunohistochemical markers included Ki67, an endogenous marker for active cell cycle, and doublecortin (DCX), a marker for immature neurons and migratory neuroblasts. Scopolamine was administered for 28 days via an ALzet minipump (44 mg/mL delivered at 2.5 µL/h). NRE was administered by gavage, 1 g/kg per day for 28 days. The administration of scopolamine significantly reduced the number of Ki67- and DCX-immunoreactive cells in the DG, whereas scopolamine did not induce any significant changes in mature neurons in the DG. The administration of NRE significantly ameliorated the scopolamine-induced reduction of Ki67- and DCX-immunoreactive cells in the DG. In addition, the administration of NRE significantly restored the scopolamine-induced reduction of brain-derived neurotrophic factor in DG homogenates. These results suggest that NRE can ameliorate the scopolamine-induced reductions of cell proliferation, neuroblast differentiation and BDNF levels.