Distribution of Angiotensin Converting Enzyme in Sheep Hypothalamus and Medulla Oblongata Visualized by in Vitro Autoradiography

Abstract

In vitro autoradiographic mapping of angiotensin converting enzyme (ACE) in sheep brain using the specific ACE inhibitor, ¹²⁵I-351A, revealed very high densities of binding in large blood vessels and choroid plexus. In the forebrain, a very high density of labelling occurred in the organum vasculosum of the lamina terminalis and median eminence and a high density in the subfornical organ and moderate density in supraoptic, suprachiasmatic, arcuate and paraventricular nuclei. All fiber tracts were unlabelled. In the medulla oblongata, a very high density of binding was detected in the area postrema and a high density in the nucleus of the solitary tract and dorsal motor nucleus of the vagus; a moderate density was found in the substantia gelatinosa of the spinal tract and the inferior olivary nucleus.

Key Words:

• angiotensin converting enzyme
• brain
• sheep
• circumventricular organs
• autoradiography
• medulla oblongata
• hypothalamus
• renin
• angiotensin II
• kininase II
• blood pressure
• drinking
• vasopressin