Schizandrin prevents dexamethasone-induced cognitive deficits

To model glucocorticoid-induced cognitive impairment and evaluate the neuroprotection by schizandrin (Sch) against dexamethasone (Dex)-induced neurotoxicity in vivo and in vitro. Cerebral cortical cells from neonatal Sprague-Dawley rats (within 24 hours after birth) were cultured for 9 days, and then treated with Dex (10(-4), 10(-5), 10(-6) or 10(-7) mol/L) for 24 h or pretreated with 10(-4) mol/L Dex for 24 h followed by 10, 20, 40, or 80 mu mol/L Sch for 48 h. Cell viability was assessed using the MTT assay. Immunofluorescence and real-time PCR for MAP2 were performed to confirm the effects of Dex on neurite outgrowth. In vivo, kunming mice were randomly divided into six groups: control [(intragastric (i.g.) vehicle for 42 days]; Dex group I (5 mg/kg center dot d(-1) Dex i.g. treatment for 28 days followed by i.g. vehicle for 14 days); Dex group II (Dex i.g. for 42 days); Dex + Sch (Dex i.g. for 28 days followed by 5, 15, or 45 mg/kg center dot d(-1) Sch i.g. for 14 days). Learning and memory were assessed by Morris water maze test. Histological examination was used to assess pathology and apoptosis in neurons. Compared to the Dex groups, Sch increased cell viability in a dosedependent manner, improved performance in the Morris water maze and ameliorated the morphological changes. Sch has neuroprotective effects against insults induced by glucocorticoid.