The central theme of the program is to evaluate the hypothesis that gonadal proteins of the inhibin/activin family and neuroendocrine peptides especially GNRH, oxytocin and CRF and play important roles in the regulation of reproduction. 'These substances gain access to or are localized within the pituitary, gonads, placenta and brain where they act in an endocrine, paracrine or autocrine manner to control the differentiation, growth and functions of those tissues. In general we have three goals: (1) To characterize biologically important peptides/proteins, their precursors and their genes on the chemical and molecular level; (2) to explore their physiologic and pathophysiologic significance at the molecular, cellular and system levels-understanding both the control of peptide expression as well as their mode of action; (3) to develop a I pharmacology of the peptides that will provide tools for the investigation of their structures and functions. This multidisciplinary program brings together specialists in system physiology, reproduction biology, pharmacology, cell biology, receptor biology, molecular biology. peptide and protein isolation, analytical biochemistry, mass spectrometry and synthetic chemistry. The program comprises five Projects and five Cores which provide administrative, immunoassay, peptide analysis., purification, and molecular biology services. The five projects explore the distribution, chemical nature, regulation of gene expression and physiological roles of inhibin/activin subunits and other peptides in the gonads, pituitary, placenta and brain. Concepts and tools developed by this program will continue to contribute to our understanding of the reproductive, endocrine and central nervous systems in normal and diseased circumstances and may lead to improved methods for fertility regulation.