The adverse effects of prenatal alcohol exposure on CNS function have been well documented and may be permanent in nature, resulting in limited mental capabilities and abnormal behavior. The substrates for these abnormalities are unknown, although subtle alterations in brain structure and dendritic morphology have been observed in animal models. Few correlative physiological studies have appeared and the crucial question of how morphological alterations translate into CNS dysfunction remains to be answered. In the present proposal, several important questions relating to the neurotoxic effects of alcohol on the neuronal differentiation will be addressed. The overall goal is to identify alterations in neuronal structure or function that may be the basis for neurotoxic effects of alcohol on CNS function when chronic exposure occurs during the developmental period. An identified CNS neuronal type, the Purkinje neuron (PN) of the cerebellum, will be used. The PN is a sensitive and favorable subject for alcohol-related studies in adult animals. The PN offers several advantages for developmental studies: it is relatively immature at birth, develops rapidly during the postnatal period, displays predictable morphological stages during development and receives afferent input from morphologically and chemically defined sources. A tissue culture preparation of cerebellar neurons that offers considerable technical and anatomical advantage will be used for the proposed studies. Alcohol will be added to the culture media by a method that provides known and stable alcohol levels during the treatment period. Several alcohol concentrations and treatment schedules will be tested. The use of a culture system will minimize interpretative problems commonly associated with in vivo studies, resulting from questions of alcohol distribution, actions of metabolic products, nutritional deficits and indirect effects via other sensitive brain regions. Several different experimental techniques will be used to assess and characterize neurotoxicity including morphological, immunohistochemical and three types of electrophysiological recording techniques (extracellular, intracellular, single channel). Electrophysiological recordings will be performed in both the somatic and dendritic regions. Cellular physiology, membrane excitability and transmitter regulated ion channel function will be studied in detail. These studies will provide comprehensive, in-depth information on the toxic effects of alcohol on neuronal development and function.
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