GABA and serotonin (5-HT) pattern in the supraependymal fibers of the rat epithalamus: combined radioautographic and immunocytochemical studies. Effect of 5-HT content on [3H]GABA accumulation.
Numerous studies have suggested the serotoninergic nature of the supraependymal plexuses; moreover, several supraependymal fibers are also able to take up [3H]GABA and could be GABA-containing fibers. In this approach, by combined immunocytochemistry and radioautography, we analyzed and compared the distribution of endogenous and exogenous GABA and 5-HT in the supraependymal layer, after inhibition of their respective catabolisms. The majority of the supraependymal fibers are reactive to GABA and 5-HT antisera which indicates that they could contain both GABA and 5-HT. Furthermore it is possible to show that endogenous 5-HT containing fibers are able to accumulate [3H]GABA and conversely. These data point to a functional role for both neurotransmitters in these nerve elements. On the other hand, GABA and 5-HT contents may be connected since p-chlorophenylalanine treatment which inhibits 5-HT synthesis increased [3H]GABA labelling of these plexuses. Finally, several supraependymal fibers are also able to take up [3H]glutamate (but not [3H]glutamine); this compound might be accumulated as GABA precursor and/or as neurotransmitter.
D000818:Animals; D001345:Autoradiography; D004027:Diencephalon / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D010134:Fenclonine / Q000494:pharmacology; D005971:Glutamates / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D006651:Histocytochemistry; D008854:Microscopy, Electron; D010293:Pargyline / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D014316:Tritium; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D005971:Glutamates; D005973:Glutamine; D014316:Tritium; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D010293:Pargyline; D010134:Fenclonine