This is a request for a Research Scientist Development Award Level II. Neuropeptides are recognized as integral components of information transfer in the central nervous system (CNS). They are widely, but discretely, distributed and subserve a number of physiological and electrophysiological functions. Recent progress in molecular biology has allowed the cloning and sequencing of the cDNAs and genes encoding the precursor proteins for a variety of neuropeptides. These studies have provided information on neuropeptide gene expression, precursor protein structure, and apparent abnormalities in neuropeptide expression in several CNS disorders. One recently identiifged peptide, neuropeptide Y (NPY), is the most abundant peptide yet found in the CNS and subserves such physiological functions as regulation of the cardiovascular system, feeding behavior and cortical function. Despite the identification of the cDNA and gene for NPY, little is known regarding the regulation of NPY biosynthesis and gene expression in the CNS. The proposed research will address the regulation of NPY synthesis by both "extra-synaptic" and "Transsynaptic" mechanisms. The "extra- synaptic" modulation of hypothalamic NPY synthesis will be investigated in model systems designed to investigate the molecular mechanisms regulating feeding behavior. The proposed studies will determine in vivo and in vitro how glucose and insulin modulate hypothalamic NPY neurons in normal animals and in a model of genetic obesity (the Zucker fatty rat). To investigate "trans-synaptic" regulation of NPY synthesis, in vitro hippocampal and hypothalamic slices will be prepared and the effects of various pharmacological agents, known to either directly modulate NPY expression or to modulate hippocampal neuronal activity, will be determined. Modulation of NPY expression and synthesis will be monitored by nuclear run-on assay, nuclease protection analysis of preproNPY mRNA content, biosynthetic labeling and purification of NPY and radioimmunoassay. The proposed studies will combine well-defined model systems with a variety of molecular biological techniques to uniquely address several aspects of the regulation of the expression and synthesis of NPY. Moreover, the proposed studies will provide insights into the interactions between the periphery and CNS to modulate neuropeptide expression and, thus, are of fundamental importance to understanding the diversity of mechanisms regulating behavior and CNS function.