Angiotensin and the Lamina Terminalis: Illustrations of a Complex Unity

Abstract

The subfornical organ, the median preoptic nucleus, and the OVLT are arranged in a dorsal to ventral column to form the lamina terminalis (“end wall”) of the third cerebral ventricle. In the decade of the 1970s, several labs showed that angiotensin II produces many of its effects in the brain by interacting with the structures of the lamina terminalis. This review concentrates on drinking behavior and on two structures: The subfornical organ as an important sensor of blood-borne angiotensin, and the median preoptic nucleus as a sensitive zone for central angiotensin. In the 1980s, histochemistry and tract-tracing have begun to clarify the structural framework for a complex of interactions. All three structures of the lamina terminalis are filled with angiotensin immunoreactive neural processes and angiotensin binding sites. The evidence suggests that angiotensinergic axons have intrinsic and extrinsic origins. Neurosecretion of angiotensin is apparent in some inbred strains of rats. It is concluded that the lamina terminalis is best considered a single functional entity tuned to the detection of fluid imbalance as signaled by angiotensin.

Key Words:

• Angiotensin
• AV3V
• Median preoptic nucleus
• OVLT
• Subfornical organ