Beneficial effects of DX-9386, a traditional Chinese prescription, on memory disorder produced by lesioning the amygdala in mice.

The amygdala is one of the key areas of the brain involved in learning and memory. Bilateral lesions of the amygdala in 9-week-old mice induced impairment of memory acquisition and retention. DX-9386, a traditional Chinese medicinal prescription consisting of ginseng, polygala, acorus and hoelen, was orally administered to the lesioned mice after the operation until all the experiments were completed. From 15d after surgery, learning behavior in the step-down test was observed daily for 10 d. DX-9386 treatment ameliorated the memory acquisition deficit. The number of step-down events in the first testing trial was significantly decreased by administration of 250 mg/kg of the prescription to the lesioned group of mice. Choline acetyltransferase activity in the cerebral cortex of the lesioned mice was significantly decreased, while repeated administration of the prescription did not affect this biochemical parameter. These results indicate that the memory acquisition enhancing effect of DX-9386 may not be achieved by direct activation of cholinergic transmission in the brain but by some other mechanism(s).