Adrenal Regulation of Regional Brain Angiotensinogen Content*

Abstract

The present study was designed to determine the effects of bilateral adrenalectomy and subsequent treatment with corticosterone on regional brain and plasma levels of angiotensinogen in the male Sprague-Dawley rat. Simultaneous measurements of [3H]deoxyglucose accumulation in brain regions provided an indicator of regional neural activity and, indirectly, of blood flow. Adrenalectomy reduced angiotensinogen content significantly in the preoptic area, anterior hypothalamus, periaqueductal grey, area postrema, and plasma. Replacement therapy with corticosterone (1 mg/day for 4 days, sc) reversed the effect of adrenalectomy in all regions listed above and increased angiotensinogen content in the septum and mediobasal hypothalamus. There was no correlation between deoxyglucose accumulation and angiotensinogen content of brain regions in either sham-operated or adrenalectomized animals. Lastly, an attempt was made to determine the effect of adrenalectomy on endogenous brain angiotensin I and II. Endogenous angiotensin I and II were not detectable in brain tissue after acid extraction and chromatography on Dowex 50W×2. There was no apparent relationship between angiotensinogen content of individual brain regions and the regional blood flow, the presence of the blood-brain barrier in the region, or its proximity to the cerebral ventricles. The regions most affected by adrenalectomy were those known to respond to exogenously applied angiotensin II with increased drinking behavior, vasopressin release, or cardiovascular changes. (Endocrinology106: 337, 1980)