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Location, development, control, and function of extraadrenal phenylethanolamine N-methyltransferase
Michael G Ziegler1, Xuping Bao, Brian P Kennedy
1University of California San Diego Medical Center, San Diego, California 92103, USA. mziegler@UCSD.edu
Annals of the New York Academy of Sciences
|November 20, 2002
Summary
Phenylethanolamine N-methyltransferase (PNMT) is crucial for epinephrine synthesis in the adrenal medulla and heart. Its development and regulation differ between fetal and adult stages, and it impacts blood pressure and glucose levels.
Area of Science:
- Biochemistry
- Cardiovascular Physiology
- Endocrinology
Background:
- Phenylethanolamine N-methyltransferase (PNMT) catalyzes the conversion of norepinephrine to epinephrine.
- PNMT is highly expressed in the adrenal medulla but also found in the brain, retina, and heart.
- Cardiac PNMT is present early in fetal development and in adult cardiac tissues.
Purpose of the Study:
- To investigate the developmental regulation and tissue-specific expression of PNMT.
- To explore the role of glucocorticoids in PNMT gene expression.
- To understand the physiological functions of extra-adrenal PNMT.
Main Methods:
- Analysis of PNMT expression in fetal and adult rat tissues.
- Investigation of PNMT gene promoter activity and glucocorticoid responsiveness.
- Examination of PNMT mRNA splice variants in cardiac tissue.
- Studies in adrenalectomized animals to assess extra-adrenal PNMT function.
Main Results:
- Fetal cardiac PNMT development is initially glucocorticoid-independent, becoming sensitive later.
- Adult cardiac PNMT is inducible by glucocorticoids and exhibits distinct mRNA splicing.
- Extra-adrenal PNMT influences blood pressure, blood glucose, and cytokine production.
- PNMT may regulate fetal heart rate before adrenal medulla development.
Conclusions:
- PNMT plays a significant role in both adrenal and extra-adrenal physiology.
- Glucocorticoids differentially regulate PNMT expression and mRNA splicing in the heart.
- PNMT is a key enzyme in epinephrine synthesis with diverse physiological functions.