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Type: Journal article
Title: Gluococorticoids decrease phenylethanolamine N - methyltransferase mRNA expression in the immature foetal sheep adrenal
Author: Adams, Michael Brenton
Ross, Jacob T.
Butler, Timothy G.
McMillen, Isabella Caroline
Citation: Journal of Neuroendocrinology, 1999; 11(7):569-575
Issue Date: 1999
ISSN: 0953-8194
Abstract: This study examined the impact of a chronic physiological elevation of plasma cortisol levels on adrenal catecholamine synthetic enzyme and proenkephalin A mRNA expression in foetal sheep. Cortisol (2.5–3.0 mg.5 ml−1.24 h−1, n=9) or saline (0.9% saline, n=6) was infused into foetal sheep for 7 days between 109 days and 116 days gestation. Foetal plasma cortisol concentrations were higher (P<0.0005) in the cortisol infused foetuses when compared with the saline infused group (43.07±4.13 nmol.l−1 vs 1.67±0.10 nmol.l−1). There were no differences, however, in the plasma ACTH levels between the two groups. Using Northern blot analysis, adrenal phenylethanolamine N-methyltransferase (PNMT) mRNA expression was found to be reduced (P<0.005) fivefold in the cortisol infused foetuses when compared with the controls, as was the relative area of the adrenal medulla which stained positively with anti-PNMT (28.1±2.5%vs 44.8±4.8%, P<0.007). No effect of cortisol infusion was observed on adrenal tyrosine hydroxylase mRNA and protein expression or proenkephalin A mRNA expression. We conclude that before birth, adrenaline synthesis may be suppressed by a novel direct, or indirect, inhibitory effect of glucocorticoids on PNMT mRNA expression.
Keywords: tyrosine hydroxylase; catecholamines; proenkephalin A; adrenal medulla; cortisol
DOI: 10.1046/j.1365-2826.1999.00359.x
Appears in Collections:Physiology publications

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