Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2003) 5 P229

BES2003 Poster Presentations Steroids (39 abstracts)

Regulation of aldosterone synthase (CYP11B2) gene expression in the rat adrenal gland and central nervous system by sodium and angiotensin II

P Ye 1 , CJ Kenyon 2 , SM MacKenzie 1 , R Fraser 1 , JMC Connell 1 & E Davies 1

1MRC Blood Pressure Group, Division of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK; 2Molecular Endocrinology, University of Edinburgh, Molecular Medicine Centre, Edinburgh, UK.

Aldosterone synthase catalyses the synthesis of aldosterone in the adrenal cortex and is encoded by the CYP11B2 gene. Recent studies have shown that CYP11B2 is also expressed in the central nervous system (CNS) but little is known about its regulation. In this study, we have quantitated CYP11B2 expression in the CNS following dietary manipulation of sodium and infusion of angiotensin II.
In study 1, 3 groups of male WKY rats (n=6) were fed normal (0.3%), high (3%) or low (0.03%) sodium diets for 12 days. In study 2, 2 groups of animals (n=6) received vehicle or angiotensin II (200ng/kg/min) via an osmotic mini-pump for 7 days. RNA was isolated and CYP11B2 expression was measured using real-time quantitative RT-PCR(LightCycler).
Low sodium increased CYP11B2 expression in the adrenal gland from 1.6x105 plus/minus1.2x105 to 5.9x106 plus/minus 2.6x106copies/micrograms RNA (Mean plus/minus SEM, p<0.001), in the hippocampus from 7.0x102 plus/minus 1.3x102 to 6.0x103 plus/minus 2.9x102 copies/micrograms RNA (p=0.005) and in the cerebellum from 1.6x103 plus/minus 2.9x102 to 9.5x103 plus/minus 2.3x103copies/micrograms RNA (p<0.001). Low sodium had no significant effect on CYP11B2 gene expression in the brain stem or hypothalamus. High sodium decreased CYP11B2 expression in the adrenal gland to 4.0x104plus/minus 2.7x104 copies/micrograms RNA (p=0.02), but had no effect on CNS tissue. Plasma aldosterone levels were 308 plus/minus 52, 134 plus/minus 19 and 154 plus/minus 50 pM in the low, normal and high sodium groups respectively. Angiotensin II increased CYP11B2 expression in the adrenal gland from 2.7x106 plus/minus 8.7x105 to 1.7x107 plus/minus 6.5x106copies/micrograms RNA (p=0.03) but had no significant effect on CYP11B2 expression in the CNS. Plasma aldosterone increased from 414 plus/minus 50pM to 671 plus/minus 182pM.
The results suggest that CYP11B2 expression may be under the regulation of the renin angiotensin system in some, but not all, regions of the CNS.

Volume 5

22nd Joint Meeting of the British Endocrine Societies

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