Regional distribution of extracellular 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in the brain of freely moving rats.
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, striatum, 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.
Department of Neurochemistry, C.S.I.C., Barcelona, Spain.
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Adell
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Carceller
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Artigas
D000818:Animals; D001923:Brain Chemistry; D003342:Corpus Striatum / Q000737:chemistry; D005110:Extracellular Space / Q000737:chemistry*; D005625:Frontal Lobe / Q000737:chemistry; D006624:Hippocampus / Q000737:chemistry; D006897:Hydroxyindoleacetic Acid / Q000032:analysis*; D007031:Hypothalamus / Q000737:chemistry; D007245:Inferior Colliculi / Q000737:chemistry; D008297:Male; D011903:Raphe Nuclei / Q000737:chemistry; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000032:analysis*; D014018:Tissue Distribution
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid