Journal of Neuroscience, Vol 6, 2004-2011, Copyright © 1986 by Society for Neuroscience
Autoradiographic localization and characterization of atrial natriuretic peptide binding sites in the rat central nervous system and adrenal gland
TR Gibson, GM Wildey, S Manaker and CC Glembotski
Atrial natriuretic peptides (ANP) have recently been identified in both
heart and CNS. These peptides possess potent natriuretic, diuretic, and
vasorelaxant activities, and are all apparently derived from a single
prohormone. Specific ANP binding sites have been characterized in the
adrenal zona glomerulosa and kidney cortex, and one study reported ANP
binding sites in the CNS. However, a detailed examination of the
localization of ANP binding sites throughout the brain has not been
reported. In this study, quantitative autoradiography was employed to
examine the distribution of ANP receptors in the rat CNS. The binding of
(3-125I-iodotyrosyl28) rat ANP-28 to binding sites in the rat CNS was
saturable, specific for ANP-related peptides, and displayed high affinity
(Kd = 600 pM). When the relative concentrations of ANP binding sites were
determined throughout the rat brain, the highest levels of ANP binding were
localized to the circumventricular organs, including the area postrema and
subfornical organ, and the olfactory apparatus. Moderate levels of ANP
binding sites were present throughout the midbrain and brain stem, while
low levels were found in the forebrain, diencephalon, basal ganglia,
cortex, and cerebellum. The presence of ANP binding sites in the
subfornical organ and the area postrema, regions considered to be outside
the blood-brain barrier, suggests that peripheral ANP levels may regulate
some aspects of CNS control of salt and water balance. The possible
functions of ANP binding sites in other regions of the rat brain are not
known, but, like many other peptides, ANP may act as a neurotransmitter or
neuromodulator at these loci.