Stress Triggered Changes in Gene Expression in Adrenal Medulla: Transcriptional Responses to Acute and Chronic Stress
- Esther L. SabbanAffiliated withDepartment of Biochemistry and Molecular Biology, New York Medical CollegeDepartment of Biochemistry and Molecular Biology, New York Medical College Email author
- , Xiaoping LiuAffiliated withDepartment of Biochemistry and Molecular Biology, New York Medical College
- , Lidia SerovaAffiliated withDepartment of Biochemistry and Molecular Biology, New York Medical College
- , Volodia GueorguievAffiliated withDepartment of Biochemistry and Molecular Biology, New York Medical College
- , Richard KvetnanskyAffiliated withInstitute of Experimental Endocrinology, Slovak Academy of Sciences
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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
- Stress Triggered Changes in Gene Expression in Adrenal Medulla: Transcriptional Responses to Acute and Chronic Stress
Cellular and Molecular Neurobiology
Volume 26, Issue 4-6 , pp 843-854
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- Kluwer Academic Publishers-Plenum Publishers
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- transcription factors
- adrenal medulla
- MAP kinase
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- Author Affiliations
- 1. Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, 10595, USA
- 3. Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA, 10595
- 2. Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic