This project was discontinued after the beginning of FY-88. Two articles were published on this topic: J. Neurosci. Meth. 23:161- 172 (1988) and Ann. N.Y. Acad. Sci., in press (1988). Other manuscripts are being prepared by collaborators in Sweden and Italy dealing with the immunohistochemical distribution of neuromedin B in selected regions of mammalian and urodele brains using antisera to neuromedin B supplied by this Group. Using this technique, we were unable to find an extensive neuromedin B-specific network of nerve fibers or cell bodies in rat brain. These data contrast to the broad distribution of bombesin-containing nerve fiber network: bombesin and neuromedin B belong to the same peptide family and contain 70% sequence similarity, but are derived from separate genes. This lack of immunohistochemical evidence may be related to the specificity of the antisera or the relatively low concentration of neuromedin B in the tissue slices, or both. Further studies on its localization in the pituitary continues at the University of North Carolina.