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Effects of dietary sucrose on hippocampal serotonin release: a microdialysis study in the freely-moving rat

Published online by Cambridge University Press:  09 March 2007

Ilse Smolders
Affiliation:
Department of Pharmaceutical Chemistry and Drug Analysis, Phamaceutical Institue, virije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
jan Van Loo
Affiliation:
ORAFTI, Aandroenstraat 1, 3300 Tienen, Belgium
Sophie Sarre
Affiliation:
Department of Pharmaceutical Chemistry and Drug Analysis, Phamaceutical Institue, virije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
Guy Ebinger
Affiliation:
Department of Neurology, University Hospital, Laarbeeklaan 101, 1090 Brussels, Belgium
Y vette Michotte*
Affiliation:
Department of Pharmaceutical Chemistry and Drug Analysis, Phamaceutical Institue, virije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
*
*Corresponding author: Professor Yvette Michotte, fax +32 2 477 41 13, email ymichot@minf.vub.ac.be
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Abstract

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The effects of dietary supplementation with either sucrose or starch (50 g/kg regular food for 2 weeks) on central 5-hydroxytryptamine (5HT; serotonin) release were investigated in freely-moving rats. It has been suggested that the amount of transmitter that serotoninergic neurons release might be altered by food intake. We monitored the effects of sucrose and starch on concentrations of extracellular 5HT, its metabolite 5-hydroxyindoleacetic acid (5HIAA), γ-aminobutyric acid (GABA) and dopamine in the hippocampus, using in vivo microdialysis. The major finding was that baseline levels of extracellular hippocampal 5HT in rats with ad libitum access to food supplemented with sucrose were significantly higher compared with the starch control group. We then verified that sucrose supplementation affected the potency of S(+)fenfluramine to increase hippocampal 5HT levels. In both groups of rats, acute intraperitoneal injection (1 mg/kg) of this anorectic drug induced a response curve of the extracellular hippocampal 5HT levels, with a shape that corresponded with earlier data for different brain areas often using up to 10-fold higher doses of S(+)fenfluramine. Nevertheless, we showed that throughout the experiment the absolute values of the sucrose response curve remained higher than in the starch group. On the other hand, S(+)fenfluramine exerted longer lasting effects in the starch group, as compared with the sucrose group. Significant decreases in levels of extracellular hippocampal 5HIAA levels following S(+)fenfluramine administration were simultaneously observed. A practical implication of the present findings is that dietary sucrose may bias the results of studies investigating brain serotoninergic mechanisms and the effects of (anorectic) drugs interacting with 5HT systems in the hippocampus.

Type
Short communication
Copyright
Copyright © The Nutrition Society 2001

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