Acute treatment with fluvoxamine elevates rat brain serotonin synthesis in some terminal regions: an autoradiographic study.

A considerable body of evidence indicates the involvement of the neurotransmitter serotonin (5-HT) in the pathogenesis and treatment of depression. The acute effect of fluvoxamine, on 5-HT synthesis rates was investigated in rat brain regions, using α-(14)C-methyl-L-tryptophan as a tracer. Fluvoxamine (25 mg/kg) and saline (control) were injected intraperitoneally, one hour before the injection of the tracer (30 μCi). There was no significant effect of fluvoxamine on plasma free tryptophan. After Benjamini-Hochberg False Discovery Rate correction, a significant decrease in the 5-HT synthesis rate in the fluvoxamine treated rats, was found in the raphe magnus (-32%), but not in the median (-14%) and dorsal (-3%) raphe nuclei. In the regions with serotonergic axon terminals, significant increases in synthesis rates were observed in the dorsal (+41%) and ventral (+43%) hippocampus, visual (+38%), auditory (+65%) and parietal (+37%) cortex, and the substantia nigra pars compacta (+56%). There were no significant changes in the 5-HT synthesis rates in the median (+11%) and lateral (+24%) part of the caudate-putamen, nucleus accumbens (+5%), VTA (+16%) or frontal cortex (+ 6%). The data show that the acute administration of fluvoxamine affects 5-HT synthesis rates in a regionally specific pattern, with a general elevation of the synthesis in the terminal regions and a reduction in some cell body structures. The reasons for the regional specific effect of fluvoxamine on 5-HT synthesis are unclear, but may be mediated by the presynaptic serotonergic autoreceptors. Copyright © 2012 Elsevier Inc. All rights reserved.

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Dorotea Muck-Seler, Nela Pivac, Mirko Diksic. Acute treatment with fluvoxamine elevates rat brain serotonin synthesis in some terminal regions: an autoradiographic study. Nuclear medicine and biology. 2012 Oct;39(7):1053-7

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PMID: 22560971

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