Cellular and Molecular Neurobiology

, Volume 26, Issue 4–6, pp 843–854

Stress Triggered Changes in Gene Expression in Adrenal Medulla: Transcriptional Responses to Acute and Chronic Stress

  • Esther L. Sabban
  • Xiaoping Liu
  • Lidia Serova
  • Volodia Gueorguiev
  • Richard Kvetnansky
Article

1. Stress elicits activation of several transcription factors involved in the regulation of catecholamine biosynthetic enzyme gene expression depending on its duration or repetition. However, the dynamic of the conversion of transient transcriptional activation with acute stress to sustained changes in transcription in response to repeated exposure to stress in adrenomedullary catecholaminergic systems is not clear.

2. Here, we analyzed changes in levels of phospho-CREB (P-CREB), phospho-ERK1/2 (P-ERK1/2) and Fra-2 by Western Blot analysis in adrenal medulla of Sprague Dawley male rats exposed to single or repeated immobilization stress (IMO). For single stress, rats were immobilized for 5 min, 30 min, or 2 h and sacrificed immediately afterwards. In the repeated stress conditions, animals were immobilized for 2 h daily on each consecutive day prior to the final day (day 2 for 2× IMO, day 6 for 6× IMO) in which the rats were immobilized for a session lasting 5 min, 30 min or 2 h. There were two control groups, an absolute control (AC) not exposed to stress, and a handled control (HC) gently handled daily for 6 days.

3. Phosphorylation of CREB was rapid and elevated at the earliest time examined, even with single stress. However, with a second daily episode of stress the increase in P-CREB was observed for at least the entire duration of the stress. In contrast, phosphorylation of ERK1/2 was only significant after brief exposure to a single IMO. The elevation of Fra-2 protein level was slower, but was significant after 2 h of a single IMO. With repeated IMO, there were marked elevations of Fra-2 throughout the 2 h IMO, which were especially pronounced at the end of the immobilization.

4. The transient nature of the phosphorylation of CREB may be responsible for the short-lived induction of transcription of catecholamine biosynthetic enzymes after brief exposure to a single immobilization stress. The sustained phosphorylation of CREB throughout the repeated stress coupled with induction of Fra-2 may mediate the longer lasting responses to repeated stress.

KEY WORDS:

stress transcription factors adrenal medulla CREB MAP kinase Fra-2 

Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  • Esther L. Sabban
    • 1
    • 3
  • Xiaoping Liu
    • 1
  • Lidia Serova
    • 1
  • Volodia Gueorguiev
    • 1
  • Richard Kvetnansky
    • 2
  1. 1.Department of Biochemistry and Molecular BiologyNew York Medical CollegeValhallaUSA
  2. 2.Institute of Experimental Endocrinology, Slovak Academy of SciencesBratislavaSlovak Republic
  3. 3.Department of Biochemistry and Molecular BiologyNew York Medical CollegeValhallaUSA

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