Pharmacopsychiatry 2004; 37: 113-119
DOI: 10.1055/s-2004-832664
General Concepts
© Georg Thieme Verlag KG Stuttgart · New York

Effect of Chronic Antidepressant Treatment on β-Receptor Coupled Signal Transduction Cascade. Which Effect Matters Most?

G. Holoubek1 , M. Nöldner2 , K. Treiber1 , W. E. Müller1
  • 1Department of Pharmacology, Biocenter, University of Frankfurt
  • 2Department of Pharmacology, Dr. W. Schwabe Arzneimittel, Karlsruhe
Further Information

Publication History

Publication Date:
16 November 2004 (online)

Preview

Background: ß-Receptor down-regulation has been described as a common biochemical effect of chronic treatment with many but not all antidepressant drugs. ß-Receptor activation leads to elevated intracellular levels of cAMP followed by the activation of several protein kinases which in turn activate various transcription factors. One of those, CREP has received increasing interest as an relevant component within the antidepressant drug modulated signal cascade as it represents a down-stream signal not only of the ß-receptor but also of serotonin receptor activation. Chronic treatment with many antidpressant drugs has been shown to alter CREP levels in several brain regions. While ß-receptor down-regulation by chronic antidepressant treatment has been a consistent finding, alterations of CREP levels have been observed in both direction. Similary divergent findings have been reported for BDNF a major gene targeted of CREB, where most but not all findings suggest up-regulation at least at the message level following chronic antidepressant treatment. Methods: Because of these rather divergent data, we investigated the possible effects of chronic treatment (9 or 19 days) with three different antidepressant drugs (reboxetine, citalopram, imipramine) on the individual parameters of the ß-receptor coupled signal transduction cascade. All animals were also tested for possible antidepressant effects using the forced swimming test. Results: While ß-receptor density was down-regulated by reboxetine and imipramine but not citalopram, CREB protein was only mildly elevated after 9 days, and not changed or slightly reduced after 19 days. BDNF protein levels were not or only slightly enhanced, but only for the 9 days treatment. Citalopram was most active. Under the conditions chosen, all three drugs were active in the forced swimming test. Conclusion: Taken together, the findings reported make it difficult to identify one single component of the ß-receptor coupled signal transduction cascade as common final target of chronic antidepressant treatment.

Abbreviations

CERB:cAMP response element binding protein

ECT:electronconvulsive therapy

BDNF:brain derived neurotrophic factor

FST:Forced swimming test

References

Prof. Dr. Walter E. Müller

Department of Pharmacology Biocenter

University of Frankfurt

60439 Frankfurt

Germany

Email: pharmacolNat@em.uni-frankfurt.de