Increased specific binding of angiotensin II in the organum vasculosum of the laminae terminalis area of the spontaneously hypertensive rat brain.

Three localized sites, the organum vasculosum, lamina terminalis (OVLT) subfornical organ (SFO) and cortex in the brains of spontaneously hypertensive (SH) rats and normotensive Wistar-Kyoto (WKY) rats were micro-dissected out. The membranes were assayed for 125I-labelled angiotensin II specific binding. The only significant difference was a 129% greater specific binding in the OVLT in SH compared to WKY rats. Specific binding of 125I-labelled angiotensin II in the SFO and the cerebral cortex was not significantly different between the two strains. SH rats are known to have a greater sensitivity to centrally administered angiotensin II, which may contribute to the hypertension. This data suggests that a difference in central angiotensin II receptors is at least partially responsible for the increased sensitivity.