Quantitative autoradiography of 5-HT1D and 5-HT1E binding sites labelled by [3H]5-HT, in frontal cortex and the hippocampal region of the human brain.
In human cortex and hippocampus area, [3H]5-HT (5 nM) labels 5-HT1A, 5-HT1D and 5-HT1E sites. After masking 5-HT1A receptors by 0.1 microM 8-OH-DPAT, the binding displaced by 0.1 microM 5-CT presumably represented 5-HT1D sites and the remaining binding 5-HT1E sites. In frontal cortex, 5-HT1A receptors represented the main binding in layers II and VI and a lower fraction in other layers. 5-HT1D and 5-HT1E sites, were more homogeneously distributed in layers II to VI (21-34% of specific [3H]5-HT binding). 5-HT1E sites were of similar affinities (KD close to 6-8 nM) in the cortical layers II to VI. In CA1 field of hippocampus, (pyramidal layer, stratum radiatum, molecular layer), CA2 and dentate gyrus, 5-HT1A receptors represented the major fraction, 5-HT1D sites a significant fraction and 5-HT1E a minor fraction of the specific [3H]5-HT binding. In CA3-CA4 fields, 5-HT1A receptors were less densely present, 5-HT1D sites were predominant and 5-HT1E sites represented a significant fraction (27%). The highest densities of 5-HT1E sites have been measured in subiculum, where 5-HT1A, 5-HT1D and 5-HT1E binding sites were equally represented and in entorhinal cortex where 5-HT1E sites represented the major binding in layer III. They were also present in layers II and IV (29 and 24%) and, to a lesser extent, in layers V and VI. 5-HT1A sites were predominant in layer VI, II and V and were less abundant in other layers. 5-HT1D were homogeneously present in layers II, III, IV and were present in low amounts in other layers. No 5-HT1E were detected in choroid plexus, where [3H]5-HT was dramatically reduced by mesulergine (5-HT2C receptors). No significant displacement of [3H]5-HT by mesulergine was measured in other structures.
Barone
P
P
Laboratoire de Pharmacologie NIE, Institut Pasteur, Paris, France.
Jordan
D
D
Atger
F
F
Kopp
N
N
Fillion
G
G
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000378:metabolism; D001345:Autoradiography / Q000379:methods; D001667:Binding, Competitive; D002831:Choroid Plexus / Q000378:metabolism; D005625:Frontal Lobe / Q000378:metabolism*; D006624:Hippocampus / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D009474:Neurons / Q000378:metabolism*; D009928:Organ Specificity; D017966:Pyramidal Cells / Q000378:metabolism; D011985:Receptors, Serotonin / Q000032:analysis / Q000378:metabolism*; D012701:Serotonin / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D014316:Tritium
D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D014316:Tritium; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C047087:5-carboxamidotryptamine