Regional Distribution of Extracellular 5‐Hydroxytryptamine and 5‐Hydroxyindoleacetic Acid in the Brain of Freely Moving Rats
- 1 February 1991
- journal article
- Published by Wiley in Journal of Neurochemistry
- Vol. 56 (2), 709-712
- https://doi.org/10.1111/j.1471-4159.1991.tb08208.x
Abstract
The extracellular concentrations of 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) have been determined in six brain areas of awake rats (frontal cortex, striaturn, hypothalamus, hippocampus, inferior colliculus, and raphe nuclei) using intracerebral microdialysis. The extracellular levels of 5-HT showed no significant differences among the brain regions studied. The tissue levels of 5-HT and 5-HIAA as well as the extracellular concentration of 5-HIAA were significantly higher in raphe nuclei. The regional distribution of tissue and extracellular 5-HIAA were very similar, suggesting that extracellular 5-HIAA depends mainly on the output from the intracellular compartment. On the other hand, extracellular 5-HT and tissue 5-HT showed a different distribution pattern. The tissue/extracellular ratio for 5-HT ranged from 739 in frontal cortex to 2,882 in raphe, whereas it only amounted to 1.8–3.6 for 5-HIAA. The relationship between the present results and the density of 5-HT uptake sites in these areas is discussed.Keywords
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