High-affinity binding of [3H]paroxetine to caudate nucleus and microvessels from porcine brain.
Serotonin (5-HT) is an important signal molecule not only for neurones but also for a variety of other cell types. Targeting the brain endothelium, the constitutive element of the blood-brain barrier (BBB), it elicits permeability changes. Using the selective 5-HT uptake inhibitor [3H]paroxetine we demonstrated the presence of a 5-HT transporter-like protein at the BBB. The binding capacities (Bmax) at the BBB (382 fmol mg-1) and on caudate nucleus membranes (392 fmol mg-1) were similar. However, the binding affinities differed by a factor of 5 (membranes: Kd = 0.10 nM, BBB: 0.47 nM). The affinities of various specific uptake inhibitors were also 2- to 13-fold lower in the microvessel preparation. It is suggested that the 5-HT transporter(s) in the brain and microvessels are different or differently regulated proteins.
Brust
P
P
Research Center Rossendorf, Institute of Bioinorganic and Radiopharmaceutical Chemistry, Dresden, Germany.
Bergmann
R
R
Johannsen
B
B
D000818:Animals; D001667:Binding, Competitive; D002421:Caudate Nucleus / Q000098:blood supply / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism*; D008833:Microcirculation / Q000378:metabolism; D017374:Paroxetine / Q000378:metabolism*; D011869:Radioligand Assay; D013552:Swine; D014316:Tritium
D014316:Tritium; D017374:Paroxetine