The Central Neurotransmitter ACh And NE And The Cognitive Function Of Alzheimer's Disease

Purpose: To study the change of cognitive function by mensurating amplitude and latency of one of the major component in ERP-P300 when the ACh or NE neurotransmitter in hippocampus was derogated. So analysis the important function of this two type (ACh and NE) neurotransmitters on learning and memory, and the complex correlation Besides, this study also observed the synaptic plasticity in CA3 neurons of hippocampus, so combine conformation with function. We wish this experiment can offer theoretical warranty for study on AD. Methods: 1. ACh system lesion model was made by severing fimbrial-fornix(FF) transaction, NE system impairment model by injection of 6-hydroxysopamine into the bilateral dorsal noradrenergic bundle in DG. 2. Then Y-type maze test and elicitation of P3-like latency and amplitude were carried out separately before and after the all models were built. 3. The electron micro graphs of Gray I type synapses in the hippocampus of rats were quantitatively analyzed by means of an TIGER cell image processing system. Measured parameters included the thickness of postsynaptic density, the width of synaptic cleft, the curvature of synaptic interface, and the length of active zone. Results: In either two experiment group,the breakdown of NE or Ach neuron system in hippocampus can lead to: 1. The ability of memory retention was decreased significantly. 2. P3-like latency were prolonged statistically as compared with the controls and had positive correlation with indices of Y-maze test (EN, TRT),but have no signally difference between the two experiment group. 3. The thickness of postsynaptic density (PSD) and the curvature of synaptic interface was reduced; while the width of synaptic cleft were remarkably increased. In the meantime, the occurrence of perforated synapses were also changed in the hippocampus CA3 areas. Conclusion: I. It is necessary for maintain of memory retention that normal Ach and NE level in hippocainpus, they condition each other , maintain in balance of physiological level. 2. ACh and NE are important mechanisms in produce and conformity of P3-like potential. 3. The functional state of the hippocampal neurons and the nomal connection of synapses played an importuned role in cognition and memory. 4. As the similar change occur in the breaking of Ach or NE in hippocampus, we suggest that the Ach and NE in hippocampus have a involved synergetic relationship,the disfunction of this two chemical system may be an important factor in production of AD.This study offer theoretical warranty for prevention and cure of clinical of AD.