Abstract
Central dopaminergic neurons have been suggested to be involved in the pathophysiology of several psychiatric disorders, including depression, and appear to be modulated by noradrenergic activity both at the nerve terminal level and at the somatodendritic level. In recent years reboxetine, a selective noradrenaline reuptake inhibitor that differs from tricyclic antidepressants by its low affinity for muscarinic, cholinergic and α1-adrenergic receptors, has been introduced clinically. In the present study the effect of reboxetine on the function of the mesolimbocortical dopamine system was investigated by means of single cell recording and microdialysis in rats following administration of reboxetine in doses that appear to yield clinically relevant plasma concentrations. Reboxetine (0.625–20 mg/kg intravenously) induced an increase in burst firing, but not in average firing frequency of dopamine (DA) cells in the ventral tegmental area (VTA). Moreover, reboxetine (0.15–13.5 mg/kg intraperitoneally) caused a significantly enhanced DA output in the medial prefrontal cortex, whereas no effect was observed in the nucleus accumbens. Local administration of reboxetine (333 μM, 60 min), by means of reversed microdialysis into these brain regions, caused a significant increase in DA output in both brain regions. However, local administration of reboxetine into the VTA (333 μM, 60 min) did not affect DA availability in these terminal areas. Our results imply that clinical treatment with reboxetine may result in facilitation of both prefrontal DA output and the excitability of VTA DA neurons, effects that may contribute to its antidepressant action, especially on drive and motivation.
Footnotes
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Send reprint requests to: Prof. Torgny H. Svensson, Section of Neuropsychopharmacology, Department of Physiology and Pharmacology, Nanna Svartz väg 2, Karolinska Institutet, S-171 77, Stockholm, Sweden. E-mail:torgny.svensson{at}fyfa.ki.se
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This work was supported by the Swedish Medical Research Council (Grant 4747), and the Karolinska Institutet, Stockholm, Sweden, and a grant from the Pharmacia Corporation.
- Abbreviations:
- DA
- dopamine
- NA
- noradrenaline
- VTA
- ventral tegmental area
- NAC
- nucleus accumbens
- REB
- reboxetine
- NRI
- noradrenaline reuptake inhibitor
- mPFC
- medial prefrontal cortex
- SSRI
- selective serotonin reuptake inhibitor
- Received October 26, 2000.
- Accepted January 18, 2001.
- The American Society for Pharmacology and Experimental Therapeutics
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