Distribution of C-type natriuretic peptide and its messenger RNA in rat central nervous system and peripheral tissue

In rat, the highest concentration of immunoreactive (ir-) C-type natriuretic peptide (CNP) was found in the central nervous system, as is the case in pig and human. Although its concentration in peripheral tissue was much lower than that in brain, CNP was present mainly as CNP-53 in ileum-jejunum, colon-cecum, stomach, kidney, lung, testis and submaxillary gland, but not in heart. By Northern blot analysis, CNP mRNA was detected in ileum-jejunum, testis, thymus, adrenal gland and submaxillary gland as well as in brain and spinal cord. CNP mRNA was further verified by reverse transcription-polymerase chain reaction to be present in most peripheral tissue, including aorta and bone marrow. These results indicate that CNP is synthesized in peripheral tissue and possibly functions as a local regulator in addition to acting as a neuropeptide in the central nervous system.