RESUMEN
Schisandrin A and B (Sch A and B) are the main effective components extracted from the oriental medicine Schisandra chinensis which is traditionally used to enhance mental and intellectual function. Although their neuroprotective effects have been demonstrated, their influences on neurogenesis are still unknown. In the brain, new neural cells born in the subventricular zone (SVZ) next to the lateral ventricles migrate along the rostral migratory stream (RMS) to the olfactory bulb (OB). To investigate the effects of Sch A and B on neurogenesis in the SVZ-RMS-OB system, Sch A and B were intragastrically administrated at dosages of 1, 10 and 20 mg/kg d respectively. The dose of 10 mg/kg d was selected for further analysis based on the preliminary analysis. In the SVZ, significant increases of phosphohistone H3 positive proliferating cells and the intensity of glial fibrillary acidic protein (GFAP+) cells were noticed in Sch B group. In the RMS, Sch A treatment augmented the intensity of doublecortin positive neuroblasts. In the OB, Sch A decreased tyrosine hydroxylase cells and Calbindin (CalB+) cells, while Sch B increased CalB+ cells and Calretinin (CalR+) cells. These results suggest that Sch B stimulates SVZ proliferation by enhancing GFAP+ cells and improves the survival of OB interneurons, while Sch A promotes neuroblast formation in the RMS but impairs the survival of OB interneurons. The present study provides the first evidence that Sch B exerts neuroprotective functions by enhancing neurogenesis, but Sch A mainly negatively regulates neurogenesis, in the adult SVZ-RMS-OB system.