As evidence exists that C-type natriuretic peptide (CNP) exerts effects opposing those of atrial natriuretic peptide (ANP), we studied the behavioural properties of CNP after central infusion in rats by their performance in the elevated plus maze. Doses of 0.5 microg and 5 microg i.c.v. had distinct anxiogenic properties. Our data suggest opposing effects of CNP and ANP on anxiety-related behaviour in rats, which appear to be mediated via different receptor occupation and brain regions by a corticotropin-releasing hormone (CRH)-dependent mechanism.
