The effect of porcine brain natriuretic peptide (pBNP) on cyclic guanosine monophosphate (cGMP) production was investigated in localized rat brain areas by radioimmunoassay procedure. Porcine BNP activated particulate guanylate cyclase in the median eminence, subfornical organ, choroid plexus, olfactory bulb, paraventricular nucleus and pineal gland in a concentration-dependent fashion and its action was comparable to that of rat atrial natriuretic peptide (alpha-ANP), with ED50 values ranging from 5 to 7 x 10(-7) M for both peptides. Our results suggest that the activation of a specific receptor coupled to the guanylate cyclase system and the subsequent elevation of cGMP levels constitutes the common mechanism of the central action of BNP and ANP.