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Author Notes:

Department of Psychiatry, Emory University School of Medicine, Emory Briarcliff Campus, Building A, Room 504-N, 1256 Briarcliff Road, NE, Atlanta, GA 30306, USA. Tel: +404 712 9770, Fax: +404 712 9755, E-mail: cwest@emory.edu

We thank Dr Michael Owens of Emory University for his help in preparing the paroxetine used in this study.

The authors declare no conflict of interest.


Research Funding:

This research was supported by the Public Health Services Grant MH079794.


  • selective serotonin reuptake inhibitor
  • suicidality
  • adolescent
  • AD
  • LC
  • PAR
  • Depression
  • Unipolar / Bipolar
  • Catecholamines
  • Drug Discovery / Development
  • Biological Psychiatry
  • selective serotonin reuptake inhibitor
  • suicidality
  • adolescent
  • antidepressant
  • locus coeruleus
  • paroxetine

Paroxetine-Induced Increase in Activity of Locus Coeruleus Neurons in Adolescent Rats: Implication of a Countertherapeutic Effect of an Antidepressant


Journal Title:



Volume 35, Number 8


, Pages 1653-1663

Type of Work:

Article | Post-print: After Peer Review


The concern that antidepressant (AD) drugs, especially selective serotonin reuptake inhibitors and paroxetine (PAR) in particular, can increase suicidality during the early treatment of juvenile patients (children and adolescents) has created a dilemma for clinicians treating depressives. Although preclinical research cannot resolve controversy in this area, our present findings may provide insight into how AD drugs might, under certain conditions, exacerbate rather than ameliorate the depressive state. Both clinical and preclinical evidences indicate that the principal noradrenergic cell group in the brain, the locus coeruleus (LC), is overactive in depressives and that, conversely, effective AD treatments decrease the activity of LC neurons. We report here that short-term (2 and 4 days) administration of PAR produces an increase in the activity of LC neurons (spontaneous firing rate and sensory-evoked responses) in young rats, contrary to the ‘therapeutic' decrease in activity typically observed in adult rats. Blood levels of PAR were lower in young rats than in adult rats, although similar low blood levels produced by a lower dose of PAR in adult rats failed to produce an increase in LC activity. In addition, activity of young rats in the swim test was determined to assess depressive-like responses. The same dose/durations of PAR, which produced the largest increases in LC activity in young rats, produced decreases in swim-test activity, indicating that brief administration of PAR in young rats can promote, rather than reduce, the depressive state. These results offer a model that may help screen potential adjunctive treatments to avoid early adverse effects of ADs.

Copyright information:

© 2010 American College of Neuropsychopharmacology

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