AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 1 168-R173, Copyright © 1989 by American Physiological Society
Lack of vasopressin increases hypothalamic atrial natriuretic peptide binding sites
E. Castren and J. M. Saavedra
Unit of Preclinical Neuropharmacology, National Institute of Mental Health, Bethesda, Maryland 20892.
Atrial natriuretic peptide (ANP) binding sites were measured by
quantitative autoradiography in the supraoptic and paraventricular nuclei
and in the subfornical organ of hypophysectomized, adrenalectomized, and
genetically vasopressin-deficient (Brattleboro) rats. Hypophysectomized and
Brattleboro rats had significantly higher numbers of ANP binding sites in
the supraoptic nucleus and in the magnocellular subdivision of the
paraventricular nucleus than their respective controls. ANP binding density
was also increased in the parvocellular subdivision of the paraventricular
nucleus in hypophysectomized rats and in the subfornical organ of
homozygous Brattleboro rats. When homozygous Brattleboro rats were treated
with vasopressin, the density of ANP binding sites was restored to control
level in the subfornical organ but not in the supraoptic or paraventricular
nuclei. Adrenalectomy did not influence ANP binding in the brain areas
studied. Increased ANP binding density in Brattleboro rats and after
hypophysectomy in the nuclei in which vasopressin neurons are located
suggest that ANP binding sites may represent physiologically active
receptors and may mediate the inhibitory action of ANP on vasopressin
secretion.
