Investigation of Senile dementia of Alzheimer type(SDAT) in brain transplantation of rats.

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Destruction and/or loss of cholinergic neurons in the nucleus basalis of Meynert are involved in Senile dementia of Alzheimer type(SDAT). The aim of the present study was to investigate the morphological and histochemical changes in cholinergic neurons and their circuitry in the aged rats and fetal brain tissues transplanted into the adult rats. In the first year, (1)in the immunohisto-chemical study of choline acetyltransferase(ChAT) using a monoclonal antibody, the ChAT-positive neurons in the ventral pallidum(VP) grafts showed morphological features identical to those in the host VP. (2)Electron microscopic observation revealed that neural circuits were well developed and formed synaptic contacts in the grafts. (3)Blood capillaries were developed in the junctional area between grafts and host tissue.In the second year, the morphology of ChAT-positive neurons of VP in aged rats(25 month-old) was compared to those in young adult rats(2 month-old). The size, the number of dendrites, the dendritic intersection and the length of dendrites of ChAT-positive neurons were significantly reduced in the aged group. These findings suggested that the rat VP cholinergic neurons were also affected by aging.In the final year, we modified acetylcholinesterase(AChE) histo chemical procedure to observe neuronal cell bodies and fibers in the transplants. Moreover, VP tissues transplanted in the lateral ventricle for one year will be compared to the transplants processed a short term.