The objective of this project is to exploit the rapid changes in levels of ornithine decarboxylase (ODC) in tissues that respond to damage by regenerative or adaptive changes. Chlordecone administration to rats, at levels causing tremor (40 mg/kg body weight) causes a 21-24-fold increase in levels of adrenal ODC. This is a rapidly occurring, reversible event of much greater magnitude than any other biochemical response to chlordecone hitherto reported. Other neurotoxic agents, such as triethyl lead chloride also cause a several-fold elevation in the adrenal level of this enzyme. These data will be expanded so that the precise region of this effect will be determined together with a definition of those neuronal or endocrine inputs which are needed to allow this increase. A time course study allows the detection of those cerebral or peripheral areas which initially respond to the presence of various neurotoxicants. The significance of this project is that sites of reaction to extremely low levels of toxicants may be detected by this means.