Improving effects of DX-9386, a traditional Chinese medicinal prescription, on thymectomy-induced impairment of learning behaviors in mice.

The subject mice were thymectomized 4 weeks after birth. Ten months after the thymectomy, learning behaviors in passive and active avoidance performances and a spatial memory task, the contents of brain monoamines and brain choline acetyltransferase (ChAT) activity, as well as the immune response were evaluated. DX-9386, a traditional Chinese medicinal prescription consisting of ginseng, polygala, acorus and hoelen, was prepared in CE-2 mouse food (1%, w/w) and given to the thymectomized mice after the operation until all the experiments were finished. DX-9386 treatment significantly ameliorated the learning and memory ability impaired by thymectomy in passive avoidance performances and in a spatial memory task, and the mice tended to improve in the active avoidance performance of a lever press test. However, DX-9386 treatment did not improve the thymectomy-reduced immune response. The contents of hypothalamic norepinephrine, 3,4-dihydroxyphenylacetic acid and homovanillic acid, and hypothalamic ChAT activity were significantly increased in thymectomized mice, and DX-9386 restored them to the control levels. These results suggested that DX-9386 mainly affected the cognitive process of the central nervous system to ameliorate the learning and memory deficit induced by thymectomy.