FRAGMENTATION OF CALCITONIN GENE-RELATED PEPTIDE AND SUBSTANCE-P IN THE RAT CENTRAL-NERVOUS-SYSTEM

Calcitonin gene-related peptide (CGRP) and its carboxy-terminal fragments, substance P (SP) and the SP (1-7) fragment have been measured in the rat central nervous system (CNS). The peptides were separated by ion-exchange chromatography and determined by radioimmunoassay. Two major carboxy-terminal fragments of CGRP occurred in high concentrations which approached those of the parent peptide in the medulla and the dorsal spinal cord. In most areas of the CNS the concentrations of SP (1-7) were about 10% those of SP, except in the dorsal spinal cord where the levels were about 20% those of the parent peptide. In hypothalamus, medulla and dorsal spinal cord the levels of each of the two fragments of CGRP correlated to a high degree with those of the SP (1-7) fragment. The results suggest a common route of fragmentation for SP and CGRP in the areas of the CNS where these peptides are known to co-exist.