OBJECTIVETo observe the effects of schizandrins on the learning and memory disorder in mice, and explore its mechanism.

METHODThe memory impairment model was established by using the pentobarbital sodium (20 mg x kg(-1)) intraperitoneally injected in mice. Schizandrins (0.5, 1.0, 2.0 g x kg(-1)) were administered through intragavage for consecutive 14 days. Morris Water Maze test was used to evaluate the impairment of learning and memory. The energy of superoxide dismutase (SOD), nitric oxide (NO) and catalase (CAT) of brain tissue were measured. And the positive expression of nuclear transcription factor-kappaB p65 (NF-kappaB p65), caspase-3 in the hippocampus CA1 region were determined by immunohistochemical analysis. At the cellular level, 24 h after schizandrins (0.062 5, 0.125, 0.25 g x L(-1)) were pre-administered, the apoptosis model of PC12 cell was induced by H2O2, and activity of PC12 cell was detected by MTT colorimetric assay, the energy of NO in cell serum were measured. The expression of Bcl-2 was determined by the combination of immunocytochemical staining and image analysis software.

RESULTMorris Water Maze test showed that the model group mice took shorter searching time and distance on the previous flat area than those in the control group (P < 0.05), which could be prolonged after schizandrins treatment (P < 0.05, P < 0.01). Compared with the control group, the level of NO increased while the activity of SOD, CAT decreased in the model group (both P < 0.01). After treated with schizandrins, the level of NO significantly decreased (P < 0.01), while the activity of SOD increased (P < 0.01). Immunohistochemistry analysis showed that the protein expression of NF-kappaB p65, Caspase-3 in the hippocampal CA1 region significantly increased after modeling, while schizandrins (1.0 g x kg(-1)) can significantly inhibit the protein expression of NF-kappaB p65, Caspase-3 (P < 0.05, P < 0.01). Compared with the H2O2, model group, schizandrins (0.125, 0.25 g x L(-1)) can significantly increased PC12 cell activity and decreased the NO level (P < 0.05, P < 0.01), the expression of Bcl-2 in the schizandrins group (0.125, 0.25 g x L(-1)) was up-regulated.

CONCLUSIONSchizandrins could improve the learning-memory dysfunction induced by the sodium pentobarbital in mice, and its protective mechanism is related to the lowering oxidative damage and inhibiting the cell apoptosis through up-regulating the expression of Bcl-2.