Regulation of binding sites for atrial natriuretic factor (ANF) in rat brain

In two experiments, binding sites for atrial natriuretic factor (ANF) were studied in discrete areas of rat brain by quantitative autoradiography. In the first experiment, the maximum binding capacity of 125I-ANF was reduced significantly in the subfornical organ and choroid plexus of 4 and 14 week old spontaneously hypertensive (SHR) rats compared to aged-matched Wistar-Kyoto (WKY) normotensive controls. In contrast, the maximum binding capacity of 125I-ANF in the area postrema was similar for young and adult SHR and WKY rats. The second experiment involved a comparison of brain ANF binding sites in Long-Evans control rats and Brattleboro rats with inherited diabetes insipidus. The maximum binding capacity of 125I-ANF was significantly greater in the subfornical organ of Brattleboro rats compared to Long-Evans controls. However, no strain differences occurred for 125I-ANF binding in the choroid plexus or area postrema. These findings indicate that the number of ANF binding sites in discrete areas of rat brain may be influenced in a highly selective fashion by alterations in body fluid homeostasis (i.e., hypertension or diabetes insipidus). Changes in brain ANF binding sites within circumventricular areas may involve central as well as peripheral sources of ANF-related peptides.