Objective: To study the effect of Buyin Yizhi decoction on learning and memory disorder induced by scopolamine

and investigate its possible mechanism through neurotransmitter and synaptic plasticity related proteins. Method: The learning and memory disorder models were established by intraperitoneal injection of scopolamine (3.0 mg·kg-1) in 50 male Kunming mice. Then these mice were randomly divided into normal blank group

model group and Buyin Yizhi decoction high dose group (18 g·kg-1)

middle dose group (6 g·kg-1)

and low dose group (2 g·kg-1). The treatment lasted for 2 weeks after modeling. Step-down test

Morris water maze test and novel object test were used to explore the the ability of learning and memory in mice. Meanwhile

the amino acid neurotransmitter levels in prefrontal cortex and hippocampus of the mice were determined by high performance liquid chromatography (HPLC). The expression levels of Synembry(Syn)

PSD-95 and brain derived neurotrophic factor(BDNF) in hippocampus were determined by Western blot. Result: As compared with the normal blank group

the latency in step-down test and Morris water maze test was shortened significantly in model group (P<0.01); the electric shocks number was increased (P<0.01); and the exploration time of new object was shortened (P<0.01); at the same time

the contents of gamma-aminobutyric acid (GABA) was increased while the contents of glutamic acid (Glu) were reduced (P<0.01) in hippocampus and prefrontal cortex; and the expression levels of Syn

PSD-95 and BDNF protein were reduced in hippocampus. As compared to the model group

the latency was significantly prolonged in middle and high dose groups (P<0.05

P<0.01); the number of electric shocks in the high dose group was decreased significantly (P<0.05)

and the exploration time of new objects was significantly prolonged (P<0.05); GABA content was significantly reduced (P<0.05

P<0.01)

while Glu content and the expression levels of Syn

PSD-95 and BDNF protein were significantly increased (P<0.05

P<0.01). Conclusion: These findings suggest that Buyin Yizhi decoction could improve the learning and memory disorder induced by scopolamine and the underlying mechanism may be associated with the increased Glu/GABA ratio in hippocampus and prefrontal cortex and the higher expression levels of Syn and PSD-95 in hippocampus.