Quantitative Autoradiography Reveals Different Angiotensin II Receptor Subtypes in Selected Rat Brain Nuclei

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Abstract
Heterogeneity of rat brain angiotensin II receptors was revealed by quantitative autoradiography after incubation with 125I-Sar1-angiotensin II and displacement with the angiotensin II antagonists CGP 42112 A and DuP-753 and by receptor sensitivity to dithiothreitol. Receptors in areas involved in cardiovascular and fluid control—the subfornical organ, nucleus of the solitary tract, paraventricular nucleus, and area postrema—are displaced by DuP-753 with an IC50 of 1 × 10−7M, are sensitive to 5 mM dithiothreitol, and thus are angiotensin II type-1. Receptors in the inferior olive are displaced by CGP 42112 A (IC50, 1 × 10−9M) but not by DuP-753 in concentrations up to 10−4M, are insensitive to 5 mM dithiothreitol, and thus are angiotensin II type-2.