Effect of Chinese compound 962 capsule on expression of nerve growth factor and Trk A receptor in hippocampus of aged rats

Objective In the pathology of Alzheimer's disease,age is the most important risk factor.For mimicking the pathological abnormality of the disease,we take the aged rats as the animal model of Alzheimer's disease.Our previous experiments demonstrated Chinese compound 962 capsule (composed of six kinds of Chinese herbs such as heshouwu and shichangpu) improved the learning and memory ability of aged rats significantly.In order to study the protective mechanism of this drug,we observed the expression of nerve growth factor (NGF) and its receptor (Trk A) in hippocampus of aged rats with or without 962 capsule administrated. Methods Aged Wistar rats(22 months old)were administrated with 962 capsule for 2 months (once a day) before testing the learning and memory ability.Positive control drug was Piracetam (0.56?g/kg),high dose of 962 capsule was 1.8?g/kg and low dose of this drug was 0.9?g/kg. After learning experiment the animals were killed for immunohistochemical analysis.Immunohistochemistry for the NGF and Trk A receptor were carried out in frozen slice (40?μm thick) of brain by ABC method according to a reported procedure.Image analysis to determine average cell number,size(area) and staining density in hippocampal CA1,CA2,CA3 and CA4 regions was achieved with VISILOG 5.0 image pattern analysor. Result ①Both NGF\|and TrkA\|immunoreactive neurons in aged rats significantly decreased in cell number,size and staining density in four regions of hippocampus.Decreasement in CA2 and CA3 region was most severe.among all four regions.②The significant increase in cell number,size and staining density of NGF\|and TrkA\|immunoreactive neurons in four regions of hippocampus was observed in 962 capsule administrated groups. Conclusion Decreased level of NGF and its receptor (Trk A) in hippocampus may account for the deficiency of learning and memory ability in aged rats.Chinese compound 962 Capsule administration significantly promotes the expression of NGF and Trk A in aged rats,and it may be the mechanism by which 962 Capsule improves the learning and memory ability.Enhancing endogenous neurotrophic substance plays an important role in the treatment of Alzheimer's disease.\;[