Neuromedin B is a major bombesin-like peptide in rat brain: regional distribution of neuromedin B and neuromedin C in rat brain, pituitary and spinal cord.

Neuromedin B and neuromedin C are the novel mammalian bombesin-like peptides isolated from porcine spinal cord. We have developed highly specific and sensitive radioimmunoassays for neuromedin B and neuromedin C, and determined their regional distribution in rat central nervous system. Prior to measurements of the tissue contents, immunoreactive neuromedin B and C were characterized by gel-filtration and high performance liquid chromatography. Neuromedin B and C immunoreactivities have similar regional distribution in rat brain, but the content of immunoreactive neuromedin B is 2-6 times higher than that of immunoreactive neuromedin C in every region. These results indicate that neuromedin B is a major endogenous bombesin-like peptide in rat brain and has specific functions of physiological importance.