Abstract: ObjectiveTo investigate the effects of Chinese compound Sheng-wu Capsule on learning-memory ability and histology including the neurons, astrocytes and expression of nerve growth factor(NGF) and its receptor (TrkA) in hippocampus CA1 of aged rats. MethodsSheng-wu Capsule consists of 6 kinds of Chinese medicinal herbs such as polygonum multiflorum,ginseng, and Rhizoma Acori Tatarinowii.The water-soluble component of polygonum multiflorum,2,3,5,4'- tetrahydroxystibane-2-O-β-D-glucoside was the quality standard of Sheng-wu Capsule.Aged Wistar rats(22 months old) were orally administrated with Sheng-wu Capsule(1.8g/kg and 0.9g/kg) for 2 months. Positive control drug was Piracetam(0.56g/kg). The learning and memory ability was tested by passageway water maze; the number and morphology of neurons was detected by HE staining; the proliferation of astrocytes was detected by immuno-histochemistry for glial fibrillary acidic protein(GFAP); the expression of neurotrophic substance was detected by immuno-histochemistry for NGF and TrkA receptor by ABC method. Image analysis to determine average cell number, size(area) and staining density in hippocampal CA1 region was achieved by VISILOG 5.0 image pattern analyser.ResultsBoth NGF and TrkA-immunoreactive neurons in aged rats significantly decreased as well as cell number, size and staining density in CA1 region of hippocampus(P<0.01). Aged rats showed damage of neurons and increase of GFAP positive cells in the same area,model rats indicated learning-memory deficit too. In Sheng-wu Capsule administrated groups,the significant little decrease in cell number, size and staining density of NGF and TrkA-immunoreactive neurons in CA1 region of hippocampus was observed(P<0.01-0.05). The loss of Neurons and proliferation of astrocytes were inhibited and learning-memory ability was also improved in Sheng-wu groups.Conclusions Chinese compound Sheng-wu Capsule significantly promotes the expression of NGF and TrkA in aged rats and it relieves the damage of hippocampus.This may be the mechanism by which Sheng-wu Capsule improves the learning and memory ability. Enhancing endogenous neurotrophic substance plays an important role in the treatment of Alzheimer's disease.

Key words: Chinese herbs, learning-memory, aged, rats, hippocampus, nerve growth factor, TrkA receptor