AJP - Regulatory, Integrative and Comparative Physiology, Vol 258, Issue 1 57-R63, Copyright © 1990 by American Physiological Society
Autoradiographic localization of atrial and brain natriuretic peptide receptors in rat brain
J. Brown and A. Czarnecki
Physiological Laboratory, Cambridge, United Kingdom.
Displacement of bound 125I-labeled atrial natriuretic peptide-(1-28) [alpha
125I-ANP-(1-28)] by alpha-ANP-(5-28) and porcine brain natriuretic peptide
(BNP) was used to map receptors common to these peptides in rat brain by in
vitro autoradiography. alpha-125I-ANP bound reversibly to subfornical
organ, area postrema, median preoptic, supraoptic and paraventricular
nuclei, and arachnoid mater. Binding at these sites was displaced similarly
by 1 microM unlabeled alpha-ANP, alpha-ANP-(5-28), and BNP. Binding
dissociation constants in the subfornical organ and arachnoid were 4.40 +/-
1.15 and 3.99 +/- 0.86 nM, respectively, for alpha-ANP, and 2.41 +/- 1.11
and 2.23 +/- 1.06 nM, respectively, for BNP. alpha-125I-ANP also bound to
choroid plexus. Here 1 microM unlabeled alpha-ANP displaced significantly
more radioligand than did 1 microM BNP, and the concentration displacing
50% of bound radioligand was 2.23 +/- 0.78 nM for alpha-ANP and 1.51 +/-
0.67 nM for BNP. alpha-ANP-(5-28) also displaced alpha 125I-ANP at all
sites with significantly greater affinity than did unlabeled alpha-ANP.
alpha-125I-ANP was not displaced by completely unrelated peptides.
Therefore, both atrial and brain natriuretic peptides may be high-affinity
ligands at common receptors in some cerebral localities.
