Increased atrial natriuretic peptide binding sites in the rat subfornical organ after water deprivation.

Binding sites for rat atrial natriuretic peptide (99-126) were localized and quantified in the subfornical organ and choroid plexus of control and water-deprived rats. Brain sections were analyzed after incubation with 125I-rat atrial natriuretic peptide (99-126), autoradiography, computerized microdensitometry and comparison to 125I-standards. Higher numbers of atrial natriuretic peptide binding sites were present in both the subfornical organ and the choroid plexus after 4 days of water deprivation. Our results indicate a central role for atrial natriuretic peptide in the regulation of water balance.