The present address of T.C. Tai is the Division of Medical Sciences, Northern Ontario School of Medicine, Laurentian University Campus, Sudbury, ON, Canada.
Stress-induced changes in epinephrine expression in the adrenal medulla in vivo
Article first published online: 20 FEB 2007
Journal of Neurochemistry
Volume 101, Issue 4, pages 1108–1118, May 2007
How to Cite
Tai, T. C., Claycomb, R., Siddall, B. J., Bell, R. A., Kvetnansky, R. and Wong, D. L. (2007), Stress-induced changes in epinephrine expression in the adrenal medulla in vivo. Journal of Neurochemistry, 101: 1108–1118. doi: 10.1111/j.1471-4159.2007.04484.x
- Issue published online: 20 FEB 2007
- Article first published online: 20 FEB 2007
- Received September 14, 2006; revised manuscript received November 2, 2006; accepted November 28, 2006.
- adrenergic function;
- gene transcription and post-transcriptional regulation;
- phenylethanolamine N-methyltransferase;
Immobilization (IMMO) stress was used to examine how stress alters the stress hormone epinephrine (EPI) in the adrenal medulla in vivo. In rats subjected to IMMO for 30 or 120 min, adrenal corticosterone increased to the same extent. In contrast, EPI changed very little, suggesting that EPI synthesis replenishes adrenal pools and sustains circulating levels for the heightened alertness and physiological responses of the ‘flight or fight’ response. In part, stress activates EPI via the phenylethanolamine N-methyltransferase (PNMT) gene as single or repeated IMMO elevated PNMT mRNA. The rise in PNMT mRNA was preceded by induction of the PNMT gene activator, Egr-1, with increases in Egr-1 mRNA, protein, and protein–DNA binding complex apparent. IMMO also evoked changes in Sp1 mRNA, protein, and Sp1–DNA complex formation, although for chronic IMMO changes were not entirely coincident. In contrast, glucocorticoid receptor and AP-2 mRNA, protein, and protein–DNA complex were unaltered. Finally, IMMO stress elevated PNMT protein. However, with seven daily IMMOs for 120 min and delayed killing, protein stimulation did not attain the highly elevated levels expected based on mRNA changes. The latter may perhaps suggest initiation of adrenergic desensitization to prolonged and repeated IMMO stress and/or dissociation of transcriptional and post-transcriptional regulatory mechanisms.