Our overall aim is to gain insights into mechanisms of human autonomic disorders and to develop therapeutic strategies for them by studying autonomic neuropathology in selected animal and in vitro systems. Project emphasizes the unique, pre-ganglionic immunosympathectomy induced in rats by antibodies to acetylcholinesterase (AChE).
The specific aims are to answer three questions: 1) Why do ACHE antibodies cause nerve terminal lesions in pre-ganglionic sympathetic neurons but not motor or parasympathetic neurons? 2) Does the loss of nerve terminals cause actual depth of pre-ganglionic neurons in the spinal cord? 3) Do the reactive changes in the cord reflect deprivation of trophic factors, excitotoxic stimulation, or another mechanism? We want to investigate the factors that make some ACHE-bearing targets vulnerable to immunolesion, because the answer may help us understand a wider range of autoimmune disorders in the nervous system. Our working hypothesis is that, in addition to antibody access, a key determinant of the outcome is the availability of protein regulatory proteins that limit complement-mediated cell damage. We will examine and manipulate two such proteins, rat CD59 and Crry/P65, using a novel in vitro model, which reproduces the main features of immunolesion by AChE antibodies in live rats. The results should add greatly to our picture of the initial events that trigger the acute and massive sympathetic dysfunction caused by AChE antibodies in live rats. The results should add greatly to our picture of the initial events that trigger the acute and massive sympathetic dysfunction caused by AChE antibodies in vivo. The remainder of the project will deal with long term consequences of AChE- immunolesion, which has been shown to cause two thirds of the identifiable central autonomic neurons in intermedioateral spinal cord to disappear over a period of months. Central autonomic neurons will be pre-labeled with a long-lifetime fluorescent dye, fast blue, so that we can know whether the neuronal disappearance truly represents cell death. If cell death occurs, we will have validated an animal model of autonomic neurodegeneration. Further studies will use intraspinal delivery of neurotrophic factors to attempt rescuing immunolesion neurons. The results may not only provide clues to the molecular triggers for neural loss but may also suggest potential therapies, with long-term implications for treatment of human autonomic nerve disease.
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