Changes of hippocampal synaptophysin and choline acetyltransferase in age-increasing rats

Objective To investigate the changes of hippocampal synaptophysin (SYP) and choline acetyltransferase (ChAT) in age-increasing rats (1,3,6,12,18 and 24 months),and evaluate the correlation with learning-memory abilities.Methods The expression of SYP in whole hippocampus and ChAT in CA1 area was measured by immunohistochemistry.Results Under the light microscope,SYP immunoreaction products located in all regions of hippocampus,mainly in the form of particles and dot sands.The expression of SYP was low at the age of 1 month,increased gradually,reached the peak in 6-month-old,then decreased gradually.But from 3 to 18-month-old,there were not significant difference among different groups.The expression of SYP decreased markedly at 24 months of age,and had significant difference compared with other groups (P0.01).ChAT immunoreaction neurons in CA1 area were few at the age of 1 month,most and staining darkly in 3 and 6-month-old,then decreased markedly.There were rare ChAT immunoreaction neurons at the age of 24 months.Conclusions The expression of hippocampal SYP and ChAT shows changes with aging,decreases in aged rats especially,which may be one of the mechanisms involved in learning-memory deficit.