Displacement of the PET ligand 18F-MPPF by the electrically evoked serotonin release in the rat hippocampus.
The effects of the electrically evoked serotonin release were evaluated on the binding of (18)F-MPPF in the hippocampus of anesthetized rats. The specific binding of (18)F-MPPF was measured by an implanted beta-microprobe and the serotonin (5-HT) extracellular concentration was measured by microdialysis under the same conditions. Our results showed that the 10-, 20-, or 30-min electrical stimulation of the raphe nucleus elicited a significant increase in extracellular 5-HT, only detectable in the presence of a 5-HT reuptake inhibitor in the perfusate (5 microM clomipramine). Interestingly, the raphe stimulations were associated with a 27-76% reversible decrease of the (18)F-MPPF specific binding in the hippocampus, but an unchanged extracellular (18)F-MPPF collected in dialysates. Considered together, these observations suggest that (18)F-MPPF binding is sensitive to 5-HT released at a neuronal level. This compartment, explored by the beta-microprobe, is probably distinct from the extracellular compartment, explored by microdialysis.
Rbah
Latifa
L
CERMEP Biomedical Cyclotron, 59 boulevard Pinel, F-69003 Lyon, France.
Leviel
Vincent
V
Zimmer
Luc
L
D000631:Aminopyridines / Q000378:metabolism*; D000818:Animals; D002531:Cerebellum / Q000378:metabolism; D002997:Clomipramine / Q000494:pharmacology; D004558:Electric Stimulation; D005110:Extracellular Space / Q000378:metabolism; D005462:Fluorine Radioisotopes / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism*; D008024:Ligands; D008297:Male; D017551:Microdialysis; D010879:Piperazines / Q000378:metabolism*; D011903:Raphe Nuclei; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000378:metabolism*; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D014055:Tomography, Emission-Computed
D000631:Aminopyridines; D002997:Clomipramine; D005462:Fluorine Radioisotopes; D008024:Ligands; D010879:Piperazines; D012701:Serotonin; D012702:Serotonin Antagonists; D017367:Selective Serotonin Reuptake Inhibitors; C099463:4-(2' methoxyphenyl)-1-(2'-(N-(2''-pyridinyl)-4-fluorobenzamido)ethyl)piperazine